[Concept] [PATCH 01/17] ext4l: bring in extents.c

16 Dec 2025

From: Simon Glass <simon.glass@canonical.com>

Copy extents.c and ext4_extents.h from Linux v6.18 fs/ext4 directory.
These files implement the extent-based block mapping used by ext4.

Co-developed-by: Claude Opus 4.5 <noreply@anthropic.com>
---

 fs/ext4l/ext4_extents.h |  268 ++
 fs/ext4l/extents.c      | 6189 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 6457 insertions(+)
 create mode 100644 fs/ext4l/ext4_extents.h
 create mode 100644 fs/ext4l/extents.c

diff --git a/fs/ext4l/ext4_extents.h b/fs/ext4l/ext4_extents.h
new file mode 100644
index 00000000000..c484125d963
--- /dev/null
+++ b/fs/ext4l/ext4_extents.h
@@ -0,0 +1,268 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com
+ * Written by Alex Tomas <alex@clusterfs.com>
+ */
+
+#ifndef _EXT4_EXTENTS
+#define _EXT4_EXTENTS
+
+#include "ext4.h"
+
+/*
+ * With AGGRESSIVE_TEST defined, the capacity of index/leaf blocks
+ * becomes very small, so index split, in-depth growing and
+ * other hard changes happen much more often.
+ * This is for debug purposes only.
+ */
+#define AGGRESSIVE_TEST_
+
+/*
+ * With EXTENTS_STATS defined, the number of blocks and extents
+ * are collected in the truncate path. They'll be shown at
+ * umount time.
+ */
+#define EXTENTS_STATS__
+
+/*
+ * If CHECK_BINSEARCH is defined, then the results of the binary search
+ * will also be checked by linear search.
+ */
+#define CHECK_BINSEARCH__
+
+/*
+ * ext4_inode has i_block array (60 bytes total).
+ * The first 12 bytes store ext4_extent_header;
+ * the remainder stores an array of ext4_extent.
+ * For non-inode extent blocks, ext4_extent_tail
+ * follows the array.
+ */
+
+/*
+ * This is the extent tail on-disk structure.
+ * All other extent structures are 12 bytes long.  It turns out that
+ * block_size % 12 >= 4 for at least all powers of 2 greater than 512, which
+ * covers all valid ext4 block sizes.  Therefore, this tail structure can be
+ * crammed into the end of the block without having to rebalance the tree.
+ */
+struct ext4_extent_tail {
+	__le32	et_checksum;	/* crc32c(uuid+inum+extent_block) */
+};
+
+/*
+ * This is the extent on-disk structure.
+ * It's used at the bottom of the tree.
+ */
+struct ext4_extent {
+	__le32	ee_block;	/* first logical block extent covers */
+	__le16	ee_len;		/* number of blocks covered by extent */
+	__le16	ee_start_hi;	/* high 16 bits of physical block */
+	__le32	ee_start_lo;	/* low 32 bits of physical block */
+};
+
+/*
+ * This is index on-disk structure.
+ * It's used at all the levels except the bottom.
+ */
+struct ext4_extent_idx {
+	__le32	ei_block;	/* index covers logical blocks from 'block' */
+	__le32	ei_leaf_lo;	/* pointer to the physical block of the next *
+				 * level. leaf or next index could be there */
+	__le16	ei_leaf_hi;	/* high 16 bits of physical block */
+	__u16	ei_unused;
+};
+
+/*
+ * Each block (leaves and indexes), even inode-stored has header.
+ */
+struct ext4_extent_header {
+	__le16	eh_magic;	/* probably will support different formats */
+	__le16	eh_entries;	/* number of valid entries */
+	__le16	eh_max;		/* capacity of store in entries */
+	__le16	eh_depth;	/* has tree real underlying blocks? */
+	__le32	eh_generation;	/* generation of the tree */
+};
+
+#define EXT4_EXT_MAGIC		cpu_to_le16(0xf30a)
+#define EXT4_MAX_EXTENT_DEPTH 5
+
+#define EXT4_EXTENT_TAIL_OFFSET(hdr) \
+	(sizeof(struct ext4_extent_header) + \
+	 (sizeof(struct ext4_extent) * le16_to_cpu((hdr)->eh_max)))
+
+static inline struct ext4_extent_tail *
+find_ext4_extent_tail(struct ext4_extent_header *eh)
+{
+	return (struct ext4_extent_tail *)(((void *)eh) +
+					   EXT4_EXTENT_TAIL_OFFSET(eh));
+}
+
+/*
+ * Array of ext4_ext_path contains path to some extent.
+ * Creation/lookup routines use it for traversal/splitting/etc.
+ * Truncate uses it to simulate recursive walking.
+ */
+struct ext4_ext_path {
+	ext4_fsblk_t			p_block;
+	__u16				p_depth;
+	__u16				p_maxdepth;
+	struct ext4_extent		*p_ext;
+	struct ext4_extent_idx		*p_idx;
+	struct ext4_extent_header	*p_hdr;
+	struct buffer_head		*p_bh;
+};
+
+/*
+ * Used to record a portion of a cluster found at the beginning or end
+ * of an extent while traversing the extent tree during space removal.
+ * A partial cluster may be removed if it does not contain blocks shared
+ * with extents that aren't being deleted (tofree state).  Otherwise,
+ * it cannot be removed (nofree state).
+ */
+struct partial_cluster {
+	ext4_fsblk_t pclu;  /* physical cluster number */
+	ext4_lblk_t lblk;   /* logical block number within logical cluster */
+	enum {initial, tofree, nofree} state;
+};
+
+/*
+ * structure for external API
+ */
+
+/*
+ * EXT_INIT_MAX_LEN is the maximum number of blocks we can have in an
+ * initialized extent. This is 2^15 and not (2^16 - 1), since we use the
+ * MSB of ee_len field in the extent datastructure to signify if this
+ * particular extent is an initialized extent or an unwritten (i.e.
+ * preallocated).
+ * EXT_UNWRITTEN_MAX_LEN is the maximum number of blocks we can have in an
+ * unwritten extent.
+ * If ee_len is <= 0x8000, it is an initialized extent. Otherwise, it is an
+ * unwritten one. In other words, if MSB of ee_len is set, it is an
+ * unwritten extent with only one special scenario when ee_len = 0x8000.
+ * In this case we can not have an unwritten extent of zero length and
+ * thus we make it as a special case of initialized extent with 0x8000 length.
+ * This way we get better extent-to-group alignment for initialized extents.
+ * Hence, the maximum number of blocks we can have in an *initialized*
+ * extent is 2^15 (32768) and in an *unwritten* extent is 2^15-1 (32767).
+ */
+#define EXT_INIT_MAX_LEN	(1UL << 15)
+#define EXT_UNWRITTEN_MAX_LEN	(EXT_INIT_MAX_LEN - 1)
+
+
+#define EXT_FIRST_EXTENT(__hdr__) \
+	((struct ext4_extent *) (((char *) (__hdr__)) +		\
+				 sizeof(struct ext4_extent_header)))
+#define EXT_FIRST_INDEX(__hdr__) \
+	((struct ext4_extent_idx *) (((char *) (__hdr__)) +	\
+				     sizeof(struct ext4_extent_header)))
+#define EXT_HAS_FREE_INDEX(__path__) \
+	(le16_to_cpu((__path__)->p_hdr->eh_entries) \
+				     < le16_to_cpu((__path__)->p_hdr->eh_max))
+#define EXT_LAST_EXTENT(__hdr__) \
+	(EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
+#define EXT_LAST_INDEX(__hdr__) \
+	(EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_entries) - 1)
+#define EXT_MAX_EXTENT(__hdr__)	\
+	((le16_to_cpu((__hdr__)->eh_max)) ? \
+	((EXT_FIRST_EXTENT((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)) \
+					: NULL)
+#define EXT_MAX_INDEX(__hdr__) \
+	((le16_to_cpu((__hdr__)->eh_max)) ? \
+	((EXT_FIRST_INDEX((__hdr__)) + le16_to_cpu((__hdr__)->eh_max) - 1)) \
+					: NULL)
+
+static inline struct ext4_extent_header *ext_inode_hdr(struct inode *inode)
+{
+	return (struct ext4_extent_header *) EXT4_I(inode)->i_data;
+}
+
+static inline struct ext4_extent_header *ext_block_hdr(struct buffer_head *bh)
+{
+	return (struct ext4_extent_header *) bh->b_data;
+}
+
+static inline unsigned short ext_depth(struct inode *inode)
+{
+	return le16_to_cpu(ext_inode_hdr(inode)->eh_depth);
+}
+
+static inline void ext4_ext_mark_unwritten(struct ext4_extent *ext)
+{
+	/* We can not have an unwritten extent of zero length! */
+	BUG_ON((le16_to_cpu(ext->ee_len) & ~EXT_INIT_MAX_LEN) == 0);
+	ext->ee_len |= cpu_to_le16(EXT_INIT_MAX_LEN);
+}
+
+static inline int ext4_ext_is_unwritten(struct ext4_extent *ext)
+{
+	/* Extent with ee_len of 0x8000 is treated as an initialized extent */
+	return (le16_to_cpu(ext->ee_len) > EXT_INIT_MAX_LEN);
+}
+
+static inline int ext4_ext_get_actual_len(struct ext4_extent *ext)
+{
+	return (le16_to_cpu(ext->ee_len) <= EXT_INIT_MAX_LEN ?
+		le16_to_cpu(ext->ee_len) :
+		(le16_to_cpu(ext->ee_len) - EXT_INIT_MAX_LEN));
+}
+
+static inline void ext4_ext_mark_initialized(struct ext4_extent *ext)
+{
+	ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext));
+}
+
+/*
+ * ext4_ext_pblock:
+ * combine low and high parts of physical block number into ext4_fsblk_t
+ */
+static inline ext4_fsblk_t ext4_ext_pblock(struct ext4_extent *ex)
+{
+	ext4_fsblk_t block;
+
+	block = le32_to_cpu(ex->ee_start_lo);
+	block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1;
+	return block;
+}
+
+/*
+ * ext4_idx_pblock:
+ * combine low and high parts of a leaf physical block number into ext4_fsblk_t
+ */
+static inline ext4_fsblk_t ext4_idx_pblock(struct ext4_extent_idx *ix)
+{
+	ext4_fsblk_t block;
+
+	block = le32_to_cpu(ix->ei_leaf_lo);
+	block |= ((ext4_fsblk_t) le16_to_cpu(ix->ei_leaf_hi) << 31) << 1;
+	return block;
+}
+
+/*
+ * ext4_ext_store_pblock:
+ * stores a large physical block number into an extent struct,
+ * breaking it into parts
+ */
+static inline void ext4_ext_store_pblock(struct ext4_extent *ex,
+					 ext4_fsblk_t pb)
+{
+	ex->ee_start_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
+	ex->ee_start_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
+				      0xffff);
+}
+
+/*
+ * ext4_idx_store_pblock:
+ * stores a large physical block number into an index struct,
+ * breaking it into parts
+ */
+static inline void ext4_idx_store_pblock(struct ext4_extent_idx *ix,
+					 ext4_fsblk_t pb)
+{
+	ix->ei_leaf_lo = cpu_to_le32((unsigned long) (pb & 0xffffffff));
+	ix->ei_leaf_hi = cpu_to_le16((unsigned long) ((pb >> 31) >> 1) &
+				     0xffff);
+}
+
+#endif /* _EXT4_EXTENTS */
+
diff --git a/fs/ext4l/extents.c b/fs/ext4l/extents.c
new file mode 100644
index 00000000000..ca5499e9412
--- /dev/null
+++ b/fs/ext4l/extents.c
@@ -0,0 +1,6189 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com
+ * Written by Alex Tomas <alex@clusterfs.com>
+ *
+ * Architecture independence:
+ *   Copyright (c) 2005, Bull S.A.
+ *   Written by Pierre Peiffer <pierre.peiffer@bull.net>
+ */
+
+/*
+ * Extents support for EXT4
+ *
+ * TODO:
+ *   - ext4*_error() should be used in some situations
+ *   - analyze all BUG()/BUG_ON(), use -EIO where appropriate
+ *   - smart tree reduction
+ */
+
+#include <linux/fs.h>
+#include <linux/time.h>
+#include <linux/jbd2.h>
+#include <linux/highuid.h>
+#include <linux/pagemap.h>
+#include <linux/quotaops.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/fiemap.h>
+#include <linux/iomap.h>
+#include <linux/sched/mm.h>
+#include "ext4_jbd2.h"
+#include "ext4_extents.h"
+#include "xattr.h"
+
+#include <trace/events/ext4.h>
+
+/*
+ * used by extent splitting.
+ */
+#define EXT4_EXT_MAY_ZEROOUT	0x1  /* safe to zeroout if split fails \
+					due to ENOSPC */
+#define EXT4_EXT_MARK_UNWRIT1	0x2  /* mark first half unwritten */
+#define EXT4_EXT_MARK_UNWRIT2	0x4  /* mark second half unwritten */
+
+#define EXT4_EXT_DATA_VALID1	0x8  /* first half contains valid data */
+#define EXT4_EXT_DATA_VALID2	0x10 /* second half contains valid data */
+
+static __le32 ext4_extent_block_csum(struct inode *inode,
+				     struct ext4_extent_header *eh)
+{
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	__u32 csum;
+
+	csum = ext4_chksum(ei->i_csum_seed, (__u8 *)eh,
+			   EXT4_EXTENT_TAIL_OFFSET(eh));
+	return cpu_to_le32(csum);
+}
+
+static int ext4_extent_block_csum_verify(struct inode *inode,
+					 struct ext4_extent_header *eh)
+{
+	struct ext4_extent_tail *et;
+
+	if (!ext4_has_feature_metadata_csum(inode->i_sb))
+		return 1;
+
+	et = find_ext4_extent_tail(eh);
+	if (et->et_checksum != ext4_extent_block_csum(inode, eh))
+		return 0;
+	return 1;
+}
+
+static void ext4_extent_block_csum_set(struct inode *inode,
+				       struct ext4_extent_header *eh)
+{
+	struct ext4_extent_tail *et;
+
+	if (!ext4_has_feature_metadata_csum(inode->i_sb))
+		return;
+
+	et = find_ext4_extent_tail(eh);
+	et->et_checksum = ext4_extent_block_csum(inode, eh);
+}
+
+static struct ext4_ext_path *ext4_split_extent_at(handle_t *handle,
+						  struct inode *inode,
+						  struct ext4_ext_path *path,
+						  ext4_lblk_t split,
+						  int split_flag, int flags);
+
+static int ext4_ext_trunc_restart_fn(struct inode *inode, int *dropped)
+{
+	/*
+	 * Drop i_data_sem to avoid deadlock with ext4_map_blocks.  At this
+	 * moment, get_block can be called only for blocks inside i_size since
+	 * page cache has been already dropped and writes are blocked by
+	 * i_rwsem. So we can safely drop the i_data_sem here.
+	 */
+	BUG_ON(EXT4_JOURNAL(inode) == NULL);
+	ext4_discard_preallocations(inode);
+	up_write(&EXT4_I(inode)->i_data_sem);
+	*dropped = 1;
+	return 0;
+}
+
+static inline void ext4_ext_path_brelse(struct ext4_ext_path *path)
+{
+	brelse(path->p_bh);
+	path->p_bh = NULL;
+}
+
+static void ext4_ext_drop_refs(struct ext4_ext_path *path)
+{
+	int depth, i;
+
+	if (IS_ERR_OR_NULL(path))
+		return;
+	depth = path->p_depth;
+	for (i = 0; i <= depth; i++, path++)
+		ext4_ext_path_brelse(path);
+}
+
+void ext4_free_ext_path(struct ext4_ext_path *path)
+{
+	if (IS_ERR_OR_NULL(path))
+		return;
+	ext4_ext_drop_refs(path);
+	kfree(path);
+}
+
+/*
+ * Make sure 'handle' has at least 'check_cred' credits. If not, restart
+ * transaction with 'restart_cred' credits. The function drops i_data_sem
+ * when restarting transaction and gets it after transaction is restarted.
+ *
+ * The function returns 0 on success, 1 if transaction had to be restarted,
+ * and < 0 in case of fatal error.
+ */
+int ext4_datasem_ensure_credits(handle_t *handle, struct inode *inode,
+				int check_cred, int restart_cred,
+				int revoke_cred)
+{
+	int ret;
+	int dropped = 0;
+
+	ret = ext4_journal_ensure_credits_fn(handle, check_cred, restart_cred,
+		revoke_cred, ext4_ext_trunc_restart_fn(inode, &dropped));
+	if (dropped)
+		down_write(&EXT4_I(inode)->i_data_sem);
+	return ret;
+}
+
+/*
+ * could return:
+ *  - EROFS
+ *  - ENOMEM
+ */
+static int ext4_ext_get_access(handle_t *handle, struct inode *inode,
+				struct ext4_ext_path *path)
+{
+	int err = 0;
+
+	if (path->p_bh) {
+		/* path points to block */
+		BUFFER_TRACE(path->p_bh, "get_write_access");
+		err = ext4_journal_get_write_access(handle, inode->i_sb,
+						    path->p_bh, EXT4_JTR_NONE);
+		/*
+		 * The extent buffer's verified bit will be set again in
+		 * __ext4_ext_dirty(). We could leave an inconsistent
+		 * buffer if the extents updating procudure break off du
+		 * to some error happens, force to check it again.
+		 */
+		if (!err)
+			clear_buffer_verified(path->p_bh);
+	}
+	/* path points to leaf/index in inode body */
+	/* we use in-core data, no need to protect them */
+	return err;
+}
+
+/*
+ * could return:
+ *  - EROFS
+ *  - ENOMEM
+ *  - EIO
+ */
+static int __ext4_ext_dirty(const char *where, unsigned int line,
+			    handle_t *handle, struct inode *inode,
+			    struct ext4_ext_path *path)
+{
+	int err;
+
+	WARN_ON(!rwsem_is_locked(&EXT4_I(inode)->i_data_sem));
+	if (path->p_bh) {
+		ext4_extent_block_csum_set(inode, ext_block_hdr(path->p_bh));
+		/* path points to block */
+		err = __ext4_handle_dirty_metadata(where, line, handle,
+						   inode, path->p_bh);
+		/* Extents updating done, re-set verified flag */
+		if (!err)
+			set_buffer_verified(path->p_bh);
+	} else {
+		/* path points to leaf/index in inode body */
+		err = ext4_mark_inode_dirty(handle, inode);
+	}
+	return err;
+}
+
+#define ext4_ext_dirty(handle, inode, path) \
+		__ext4_ext_dirty(__func__, __LINE__, (handle), (inode), (path))
+
+static ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
+			      struct ext4_ext_path *path,
+			      ext4_lblk_t block)
+{
+	if (path) {
+		int depth = path->p_depth;
+		struct ext4_extent *ex;
+
+		/*
+		 * Try to predict block placement assuming that we are
+		 * filling in a file which will eventually be
+		 * non-sparse --- i.e., in the case of libbfd writing
+		 * an ELF object sections out-of-order but in a way
+		 * the eventually results in a contiguous object or
+		 * executable file, or some database extending a table
+		 * space file.  However, this is actually somewhat
+		 * non-ideal if we are writing a sparse file such as
+		 * qemu or KVM writing a raw image file that is going
+		 * to stay fairly sparse, since it will end up
+		 * fragmenting the file system's free space.  Maybe we
+		 * should have some hueristics or some way to allow
+		 * userspace to pass a hint to file system,
+		 * especially if the latter case turns out to be
+		 * common.
+		 */
+		ex = path[depth].p_ext;
+		if (ex) {
+			ext4_fsblk_t ext_pblk = ext4_ext_pblock(ex);
+			ext4_lblk_t ext_block = le32_to_cpu(ex->ee_block);
+
+			if (block > ext_block)
+				return ext_pblk + (block - ext_block);
+			else
+				return ext_pblk - (ext_block - block);
+		}
+
+		/* it looks like index is empty;
+		 * try to find starting block from index itself */
+		if (path[depth].p_bh)
+			return path[depth].p_bh->b_blocknr;
+	}
+
+	/* OK. use inode's group */
+	return ext4_inode_to_goal_block(inode);
+}
+
+/*
+ * Allocation for a meta data block
+ */
+static ext4_fsblk_t
+ext4_ext_new_meta_block(handle_t *handle, struct inode *inode,
+			struct ext4_ext_path *path,
+			struct ext4_extent *ex, int *err, unsigned int flags)
+{
+	ext4_fsblk_t goal, newblock;
+
+	goal = ext4_ext_find_goal(inode, path, le32_to_cpu(ex->ee_block));
+	newblock = ext4_new_meta_blocks(handle, inode, goal, flags,
+					NULL, err);
+	return newblock;
+}
+
+static inline int ext4_ext_space_block(struct inode *inode, int check)
+{
+	int size;
+
+	size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
+			/ sizeof(struct ext4_extent);
+#ifdef AGGRESSIVE_TEST
+	if (!check && size > 6)
+		size = 6;
+#endif
+	return size;
+}
+
+static inline int ext4_ext_space_block_idx(struct inode *inode, int check)
+{
+	int size;
+
+	size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
+			/ sizeof(struct ext4_extent_idx);
+#ifdef AGGRESSIVE_TEST
+	if (!check && size > 5)
+		size = 5;
+#endif
+	return size;
+}
+
+static inline int ext4_ext_space_root(struct inode *inode, int check)
+{
+	int size;
+
+	size = sizeof(EXT4_I(inode)->i_data);
+	size -= sizeof(struct ext4_extent_header);
+	size /= sizeof(struct ext4_extent);
+#ifdef AGGRESSIVE_TEST
+	if (!check && size > 3)
+		size = 3;
+#endif
+	return size;
+}
+
+static inline int ext4_ext_space_root_idx(struct inode *inode, int check)
+{
+	int size;
+
+	size = sizeof(EXT4_I(inode)->i_data);
+	size -= sizeof(struct ext4_extent_header);
+	size /= sizeof(struct ext4_extent_idx);
+#ifdef AGGRESSIVE_TEST
+	if (!check && size > 4)
+		size = 4;
+#endif
+	return size;
+}
+
+static inline struct ext4_ext_path *
+ext4_force_split_extent_at(handle_t *handle, struct inode *inode,
+			   struct ext4_ext_path *path, ext4_lblk_t lblk,
+			   int nofail)
+{
+	int unwritten = ext4_ext_is_unwritten(path[path->p_depth].p_ext);
+	int flags = EXT4_EX_NOCACHE | EXT4_GET_BLOCKS_PRE_IO;
+
+	if (nofail)
+		flags |= EXT4_GET_BLOCKS_METADATA_NOFAIL | EXT4_EX_NOFAIL;
+
+	return ext4_split_extent_at(handle, inode, path, lblk, unwritten ?
+			EXT4_EXT_MARK_UNWRIT1|EXT4_EXT_MARK_UNWRIT2 : 0,
+			flags);
+}
+
+static int
+ext4_ext_max_entries(struct inode *inode, int depth)
+{
+	int max;
+
+	if (depth == ext_depth(inode)) {
+		if (depth == 0)
+			max = ext4_ext_space_root(inode, 1);
+		else
+			max = ext4_ext_space_root_idx(inode, 1);
+	} else {
+		if (depth == 0)
+			max = ext4_ext_space_block(inode, 1);
+		else
+			max = ext4_ext_space_block_idx(inode, 1);
+	}
+
+	return max;
+}
+
+static int ext4_valid_extent(struct inode *inode, struct ext4_extent *ext)
+{
+	ext4_fsblk_t block = ext4_ext_pblock(ext);
+	int len = ext4_ext_get_actual_len(ext);
+	ext4_lblk_t lblock = le32_to_cpu(ext->ee_block);
+
+	/*
+	 * We allow neither:
+	 *  - zero length
+	 *  - overflow/wrap-around
+	 */
+	if (lblock + len <= lblock)
+		return 0;
+	return ext4_inode_block_valid(inode, block, len);
+}
+
+static int ext4_valid_extent_idx(struct inode *inode,
+				struct ext4_extent_idx *ext_idx)
+{
+	ext4_fsblk_t block = ext4_idx_pblock(ext_idx);
+
+	return ext4_inode_block_valid(inode, block, 1);
+}
+
+static int ext4_valid_extent_entries(struct inode *inode,
+				     struct ext4_extent_header *eh,
+				     ext4_lblk_t lblk, ext4_fsblk_t *pblk,
+				     int depth)
+{
+	unsigned short entries;
+	ext4_lblk_t lblock = 0;
+	ext4_lblk_t cur = 0;
+
+	if (eh->eh_entries == 0)
+		return 1;
+
+	entries = le16_to_cpu(eh->eh_entries);
+
+	if (depth == 0) {
+		/* leaf entries */
+		struct ext4_extent *ext = EXT_FIRST_EXTENT(eh);
+
+		/*
+		 * The logical block in the first entry should equal to
+		 * the number in the index block.
+		 */
+		if (depth != ext_depth(inode) &&
+		    lblk != le32_to_cpu(ext->ee_block))
+			return 0;
+		while (entries) {
+			if (!ext4_valid_extent(inode, ext))
+				return 0;
+
+			/* Check for overlapping extents */
+			lblock = le32_to_cpu(ext->ee_block);
+			if (lblock < cur) {
+				*pblk = ext4_ext_pblock(ext);
+				return 0;
+			}
+			cur = lblock + ext4_ext_get_actual_len(ext);
+			ext++;
+			entries--;
+		}
+	} else {
+		struct ext4_extent_idx *ext_idx = EXT_FIRST_INDEX(eh);
+
+		/*
+		 * The logical block in the first entry should equal to
+		 * the number in the parent index block.
+		 */
+		if (depth != ext_depth(inode) &&
+		    lblk != le32_to_cpu(ext_idx->ei_block))
+			return 0;
+		while (entries) {
+			if (!ext4_valid_extent_idx(inode, ext_idx))
+				return 0;
+
+			/* Check for overlapping index extents */
+			lblock = le32_to_cpu(ext_idx->ei_block);
+			if (lblock < cur) {
+				*pblk = ext4_idx_pblock(ext_idx);
+				return 0;
+			}
+			ext_idx++;
+			entries--;
+			cur = lblock + 1;
+		}
+	}
+	return 1;
+}
+
+static int __ext4_ext_check(const char *function, unsigned int line,
+			    struct inode *inode, struct ext4_extent_header *eh,
+			    int depth, ext4_fsblk_t pblk, ext4_lblk_t lblk)
+{
+	const char *error_msg;
+	int max = 0, err = -EFSCORRUPTED;
+
+	if (unlikely(eh->eh_magic != EXT4_EXT_MAGIC)) {
+		error_msg = "invalid magic";
+		goto corrupted;
+	}
+	if (unlikely(le16_to_cpu(eh->eh_depth) != depth)) {
+		error_msg = "unexpected eh_depth";
+		goto corrupted;
+	}
+	if (unlikely(eh->eh_max == 0)) {
+		error_msg = "invalid eh_max";
+		goto corrupted;
+	}
+	max = ext4_ext_max_entries(inode, depth);
+	if (unlikely(le16_to_cpu(eh->eh_max) > max)) {
+		error_msg = "too large eh_max";
+		goto corrupted;
+	}
+	if (unlikely(le16_to_cpu(eh->eh_entries) > le16_to_cpu(eh->eh_max))) {
+		error_msg = "invalid eh_entries";
+		goto corrupted;
+	}
+	if (unlikely((eh->eh_entries == 0) && (depth > 0))) {
+		error_msg = "eh_entries is 0 but eh_depth is > 0";
+		goto corrupted;
+	}
+	if (!ext4_valid_extent_entries(inode, eh, lblk, &pblk, depth)) {
+		error_msg = "invalid extent entries";
+		goto corrupted;
+	}
+	if (unlikely(depth > 32)) {
+		error_msg = "too large eh_depth";
+		goto corrupted;
+	}
+	/* Verify checksum on non-root extent tree nodes */
+	if (ext_depth(inode) != depth &&
+	    !ext4_extent_block_csum_verify(inode, eh)) {
+		error_msg = "extent tree corrupted";
+		err = -EFSBADCRC;
+		goto corrupted;
+	}
+	return 0;
+
+corrupted:
+	ext4_error_inode_err(inode, function, line, 0, -err,
+			     "pblk %llu bad header/extent: %s - magic %x, "
+			     "entries %u, max %u(%u), depth %u(%u)",
+			     (unsigned long long) pblk, error_msg,
+			     le16_to_cpu(eh->eh_magic),
+			     le16_to_cpu(eh->eh_entries),
+			     le16_to_cpu(eh->eh_max),
+			     max, le16_to_cpu(eh->eh_depth), depth);
+	return err;
+}
+
+#define ext4_ext_check(inode, eh, depth, pblk)			\
+	__ext4_ext_check(__func__, __LINE__, (inode), (eh), (depth), (pblk), 0)
+
+int ext4_ext_check_inode(struct inode *inode)
+{
+	return ext4_ext_check(inode, ext_inode_hdr(inode), ext_depth(inode), 0);
+}
+
+static void ext4_cache_extents(struct inode *inode,
+			       struct ext4_extent_header *eh)
+{
+	struct ext4_extent *ex = EXT_FIRST_EXTENT(eh);
+	ext4_lblk_t prev = 0;
+	int i;
+
+	for (i = le16_to_cpu(eh->eh_entries); i > 0; i--, ex++) {
+		unsigned int status = EXTENT_STATUS_WRITTEN;
+		ext4_lblk_t lblk = le32_to_cpu(ex->ee_block);
+		int len = ext4_ext_get_actual_len(ex);
+
+		if (prev && (prev != lblk))
+			ext4_es_cache_extent(inode, prev, lblk - prev, ~0,
+					     EXTENT_STATUS_HOLE);
+
+		if (ext4_ext_is_unwritten(ex))
+			status = EXTENT_STATUS_UNWRITTEN;
+		ext4_es_cache_extent(inode, lblk, len,
+				     ext4_ext_pblock(ex), status);
+		prev = lblk + len;
+	}
+}
+
+static struct buffer_head *
+__read_extent_tree_block(const char *function, unsigned int line,
+			 struct inode *inode, struct ext4_extent_idx *idx,
+			 int depth, int flags)
+{
+	struct buffer_head		*bh;
+	int				err;
+	gfp_t				gfp_flags = __GFP_MOVABLE | GFP_NOFS;
+	ext4_fsblk_t			pblk;
+
+	if (flags & EXT4_EX_NOFAIL)
+		gfp_flags |= __GFP_NOFAIL;
+
+	pblk = ext4_idx_pblock(idx);
+	bh = sb_getblk_gfp(inode->i_sb, pblk, gfp_flags);
+	if (unlikely(!bh))
+		return ERR_PTR(-ENOMEM);
+
+	if (!bh_uptodate_or_lock(bh)) {
+		trace_ext4_ext_load_extent(inode, pblk, _RET_IP_);
+		err = ext4_read_bh(bh, 0, NULL, false);
+		if (err < 0)
+			goto errout;
+	}
+	if (buffer_verified(bh) && !(flags & EXT4_EX_FORCE_CACHE))
+		return bh;
+	err = __ext4_ext_check(function, line, inode, ext_block_hdr(bh),
+			       depth, pblk, le32_to_cpu(idx->ei_block));
+	if (err)
+		goto errout;
+	set_buffer_verified(bh);
+	/*
+	 * If this is a leaf block, cache all of its entries
+	 */
+	if (!(flags & EXT4_EX_NOCACHE) && depth == 0) {
+		struct ext4_extent_header *eh = ext_block_hdr(bh);
+		ext4_cache_extents(inode, eh);
+	}
+	return bh;
+errout:
+	put_bh(bh);
+	return ERR_PTR(err);
+
+}
+
+#define read_extent_tree_block(inode, idx, depth, flags)		\
+	__read_extent_tree_block(__func__, __LINE__, (inode), (idx),	\
+				 (depth), (flags))
+
+/*
+ * This function is called to cache a file's extent information in the
+ * extent status tree
+ */
+int ext4_ext_precache(struct inode *inode)
+{
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	struct ext4_ext_path *path = NULL;
+	struct buffer_head *bh;
+	int i = 0, depth, ret = 0;
+
+	if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+		return 0;	/* not an extent-mapped inode */
+
+	ext4_check_map_extents_env(inode);
+
+	down_read(&ei->i_data_sem);
+	depth = ext_depth(inode);
+
+	/* Don't cache anything if there are no external extent blocks */
+	if (!depth) {
+		up_read(&ei->i_data_sem);
+		return ret;
+	}
+
+	path = kcalloc(depth + 1, sizeof(struct ext4_ext_path),
+		       GFP_NOFS);
+	if (path == NULL) {
+		up_read(&ei->i_data_sem);
+		return -ENOMEM;
+	}
+
+	path[0].p_hdr = ext_inode_hdr(inode);
+	ret = ext4_ext_check(inode, path[0].p_hdr, depth, 0);
+	if (ret)
+		goto out;
+	path[0].p_idx = EXT_FIRST_INDEX(path[0].p_hdr);
+	while (i >= 0) {
+		/*
+		 * If this is a leaf block or we've reached the end of
+		 * the index block, go up
+		 */
+		if ((i == depth) ||
+		    path[i].p_idx > EXT_LAST_INDEX(path[i].p_hdr)) {
+			ext4_ext_path_brelse(path + i);
+			i--;
+			continue;
+		}
+		bh = read_extent_tree_block(inode, path[i].p_idx++,
+					    depth - i - 1,
+					    EXT4_EX_FORCE_CACHE);
+		if (IS_ERR(bh)) {
+			ret = PTR_ERR(bh);
+			break;
+		}
+		i++;
+		path[i].p_bh = bh;
+		path[i].p_hdr = ext_block_hdr(bh);
+		path[i].p_idx = EXT_FIRST_INDEX(path[i].p_hdr);
+	}
+	ext4_set_inode_state(inode, EXT4_STATE_EXT_PRECACHED);
+out:
+	up_read(&ei->i_data_sem);
+	ext4_free_ext_path(path);
+	return ret;
+}
+
+#ifdef EXT_DEBUG
+static void ext4_ext_show_path(struct inode *inode, struct ext4_ext_path *path)
+{
+	int k, l = path->p_depth;
+
+	ext_debug(inode, "path:");
+	for (k = 0; k <= l; k++, path++) {
+		if (path->p_idx) {
+			ext_debug(inode, "  %d->%llu",
+				  le32_to_cpu(path->p_idx->ei_block),
+				  ext4_idx_pblock(path->p_idx));
+		} else if (path->p_ext) {
+			ext_debug(inode, "  %d:[%d]%d:%llu ",
+				  le32_to_cpu(path->p_ext->ee_block),
+				  ext4_ext_is_unwritten(path->p_ext),
+				  ext4_ext_get_actual_len(path->p_ext),
+				  ext4_ext_pblock(path->p_ext));
+		} else
+			ext_debug(inode, "  []");
+	}
+	ext_debug(inode, "\n");
+}
+
+static void ext4_ext_show_leaf(struct inode *inode, struct ext4_ext_path *path)
+{
+	int depth = ext_depth(inode);
+	struct ext4_extent_header *eh;
+	struct ext4_extent *ex;
+	int i;
+
+	if (IS_ERR_OR_NULL(path))
+		return;
+
+	eh = path[depth].p_hdr;
+	ex = EXT_FIRST_EXTENT(eh);
+
+	ext_debug(inode, "Displaying leaf extents\n");
+
+	for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ex++) {
+		ext_debug(inode, "%d:[%d]%d:%llu ", le32_to_cpu(ex->ee_block),
+			  ext4_ext_is_unwritten(ex),
+			  ext4_ext_get_actual_len(ex), ext4_ext_pblock(ex));
+	}
+	ext_debug(inode, "\n");
+}
+
+static void ext4_ext_show_move(struct inode *inode, struct ext4_ext_path *path,
+			ext4_fsblk_t newblock, int level)
+{
+	int depth = ext_depth(inode);
+	struct ext4_extent *ex;
+
+	if (depth != level) {
+		struct ext4_extent_idx *idx;
+		idx = path[level].p_idx;
+		while (idx <= EXT_MAX_INDEX(path[level].p_hdr)) {
+			ext_debug(inode, "%d: move %d:%llu in new index %llu\n",
+				  level, le32_to_cpu(idx->ei_block),
+				  ext4_idx_pblock(idx), newblock);
+			idx++;
+		}
+
+		return;
+	}
+
+	ex = path[depth].p_ext;
+	while (ex <= EXT_MAX_EXTENT(path[depth].p_hdr)) {
+		ext_debug(inode, "move %d:%llu:[%d]%d in new leaf %llu\n",
+				le32_to_cpu(ex->ee_block),
+				ext4_ext_pblock(ex),
+				ext4_ext_is_unwritten(ex),
+				ext4_ext_get_actual_len(ex),
+				newblock);
+		ex++;
+	}
+}
+
+#else
+#define ext4_ext_show_path(inode, path)
+#define ext4_ext_show_leaf(inode, path)
+#define ext4_ext_show_move(inode, path, newblock, level)
+#endif
+
+/*
+ * ext4_ext_binsearch_idx:
+ * binary search for the closest index of the given block
+ * the header must be checked before calling this
+ */
+static void
+ext4_ext_binsearch_idx(struct inode *inode,
+			struct ext4_ext_path *path, ext4_lblk_t block)
+{
+	struct ext4_extent_header *eh = path->p_hdr;
+	struct ext4_extent_idx *r, *l, *m;
+
+
+	ext_debug(inode, "binsearch for %u(idx):  ", block);
+
+	l = EXT_FIRST_INDEX(eh) + 1;
+	r = EXT_LAST_INDEX(eh);
+	while (l <= r) {
+		m = l + (r - l) / 2;
+		ext_debug(inode, "%p(%u):%p(%u):%p(%u) ", l,
+			  le32_to_cpu(l->ei_block), m, le32_to_cpu(m->ei_block),
+			  r, le32_to_cpu(r->ei_block));
+
+		if (block < le32_to_cpu(m->ei_block))
+			r = m - 1;
+		else
+			l = m + 1;
+	}
+
+	path->p_idx = l - 1;
+	ext_debug(inode, "  -> %u->%lld ", le32_to_cpu(path->p_idx->ei_block),
+		  ext4_idx_pblock(path->p_idx));
+
+#ifdef CHECK_BINSEARCH
+	{
+		struct ext4_extent_idx *chix, *ix;
+		int k;
+
+		chix = ix = EXT_FIRST_INDEX(eh);
+		for (k = 0; k < le16_to_cpu(eh->eh_entries); k++, ix++) {
+			if (k != 0 && le32_to_cpu(ix->ei_block) <=
+			    le32_to_cpu(ix[-1].ei_block)) {
+				printk(KERN_DEBUG "k=%d, ix=0x%p, "
+				       "first=0x%p\n", k,
+				       ix, EXT_FIRST_INDEX(eh));
+				printk(KERN_DEBUG "%u <= %u\n",
+				       le32_to_cpu(ix->ei_block),
+				       le32_to_cpu(ix[-1].ei_block));
+			}
+			BUG_ON(k && le32_to_cpu(ix->ei_block)
+					   <= le32_to_cpu(ix[-1].ei_block));
+			if (block < le32_to_cpu(ix->ei_block))
+				break;
+			chix = ix;
+		}
+		BUG_ON(chix != path->p_idx);
+	}
+#endif
+
+}
+
+/*
+ * ext4_ext_binsearch:
+ * binary search for closest extent of the given block
+ * the header must be checked before calling this
+ */
+static void
+ext4_ext_binsearch(struct inode *inode,
+		struct ext4_ext_path *path, ext4_lblk_t block)
+{
+	struct ext4_extent_header *eh = path->p_hdr;
+	struct ext4_extent *r, *l, *m;
+
+	if (eh->eh_entries == 0) {
+		/*
+		 * this leaf is empty:
+		 * we get such a leaf in split/add case
+		 */
+		return;
+	}
+
+	ext_debug(inode, "binsearch for %u:  ", block);
+
+	l = EXT_FIRST_EXTENT(eh) + 1;
+	r = EXT_LAST_EXTENT(eh);
+
+	while (l <= r) {
+		m = l + (r - l) / 2;
+		ext_debug(inode, "%p(%u):%p(%u):%p(%u) ", l,
+			  le32_to_cpu(l->ee_block), m, le32_to_cpu(m->ee_block),
+			  r, le32_to_cpu(r->ee_block));
+
+		if (block < le32_to_cpu(m->ee_block))
+			r = m - 1;
+		else
+			l = m + 1;
+	}
+
+	path->p_ext = l - 1;
+	ext_debug(inode, "  -> %d:%llu:[%d]%d ",
+			le32_to_cpu(path->p_ext->ee_block),
+			ext4_ext_pblock(path->p_ext),
+			ext4_ext_is_unwritten(path->p_ext),
+			ext4_ext_get_actual_len(path->p_ext));
+
+#ifdef CHECK_BINSEARCH
+	{
+		struct ext4_extent *chex, *ex;
+		int k;
+
+		chex = ex = EXT_FIRST_EXTENT(eh);
+		for (k = 0; k < le16_to_cpu(eh->eh_entries); k++, ex++) {
+			BUG_ON(k && le32_to_cpu(ex->ee_block)
+					  <= le32_to_cpu(ex[-1].ee_block));
+			if (block < le32_to_cpu(ex->ee_block))
+				break;
+			chex = ex;
+		}
+		BUG_ON(chex != path->p_ext);
+	}
+#endif
+
+}
+
+void ext4_ext_tree_init(handle_t *handle, struct inode *inode)
+{
+	struct ext4_extent_header *eh;
+
+	eh = ext_inode_hdr(inode);
+	eh->eh_depth = 0;
+	eh->eh_entries = 0;
+	eh->eh_magic = EXT4_EXT_MAGIC;
+	eh->eh_max = cpu_to_le16(ext4_ext_space_root(inode, 0));
+	eh->eh_generation = 0;
+	ext4_mark_inode_dirty(handle, inode);
+}
+
+struct ext4_ext_path *
+ext4_find_extent(struct inode *inode, ext4_lblk_t block,
+		 struct ext4_ext_path *path, int flags)
+{
+	struct ext4_extent_header *eh;
+	struct buffer_head *bh;
+	short int depth, i, ppos = 0;
+	int ret;
+	gfp_t gfp_flags = GFP_NOFS;
+
+	if (flags & EXT4_EX_NOFAIL)
+		gfp_flags |= __GFP_NOFAIL;
+
+	eh = ext_inode_hdr(inode);
+	depth = ext_depth(inode);
+	if (depth < 0 || depth > EXT4_MAX_EXTENT_DEPTH) {
+		EXT4_ERROR_INODE(inode, "inode has invalid extent depth: %d",
+				 depth);
+		ret = -EFSCORRUPTED;
+		goto err;
+	}
+
+	if (path) {
+		ext4_ext_drop_refs(path);
+		if (depth > path[0].p_maxdepth) {
+			kfree(path);
+			path = NULL;
+		}
+	}
+	if (!path) {
+		/* account possible depth increase */
+		path = kcalloc(depth + 2, sizeof(struct ext4_ext_path),
+				gfp_flags);
+		if (unlikely(!path))
+			return ERR_PTR(-ENOMEM);
+		path[0].p_maxdepth = depth + 1;
+	}
+	path[0].p_hdr = eh;
+	path[0].p_bh = NULL;
+
+	i = depth;
+	if (!(flags & EXT4_EX_NOCACHE) && depth == 0)
+		ext4_cache_extents(inode, eh);
+	/* walk through the tree */
+	while (i) {
+		ext_debug(inode, "depth %d: num %d, max %d\n",
+			  ppos, le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
+
+		ext4_ext_binsearch_idx(inode, path + ppos, block);
+		path[ppos].p_block = ext4_idx_pblock(path[ppos].p_idx);
+		path[ppos].p_depth = i;
+		path[ppos].p_ext = NULL;
+
+		bh = read_extent_tree_block(inode, path[ppos].p_idx, --i, flags);
+		if (IS_ERR(bh)) {
+			ret = PTR_ERR(bh);
+			goto err;
+		}
+
+		eh = ext_block_hdr(bh);
+		ppos++;
+		path[ppos].p_bh = bh;
+		path[ppos].p_hdr = eh;
+	}
+
+	path[ppos].p_depth = i;
+	path[ppos].p_ext = NULL;
+	path[ppos].p_idx = NULL;
+
+	/* find extent */
+	ext4_ext_binsearch(inode, path + ppos, block);
+	/* if not an empty leaf */
+	if (path[ppos].p_ext)
+		path[ppos].p_block = ext4_ext_pblock(path[ppos].p_ext);
+
+	ext4_ext_show_path(inode, path);
+
+	return path;
+
+err:
+	ext4_free_ext_path(path);
+	return ERR_PTR(ret);
+}
+
+/*
+ * ext4_ext_insert_index:
+ * insert new index [@logical;@ptr] into the block at @curp;
+ * check where to insert: before @curp or after @curp
+ */
+static int ext4_ext_insert_index(handle_t *handle, struct inode *inode,
+				 struct ext4_ext_path *curp,
+				 int logical, ext4_fsblk_t ptr)
+{
+	struct ext4_extent_idx *ix;
+	int len, err;
+
+	err = ext4_ext_get_access(handle, inode, curp);
+	if (err)
+		return err;
+
+	if (unlikely(logical == le32_to_cpu(curp->p_idx->ei_block))) {
+		EXT4_ERROR_INODE(inode,
+				 "logical %d == ei_block %d!",
+				 logical, le32_to_cpu(curp->p_idx->ei_block));
+		return -EFSCORRUPTED;
+	}
+
+	if (unlikely(le16_to_cpu(curp->p_hdr->eh_entries)
+			     >= le16_to_cpu(curp->p_hdr->eh_max))) {
+		EXT4_ERROR_INODE(inode,
+				 "eh_entries %d >= eh_max %d!",
+				 le16_to_cpu(curp->p_hdr->eh_entries),
+				 le16_to_cpu(curp->p_hdr->eh_max));
+		return -EFSCORRUPTED;
+	}
+
+	if (logical > le32_to_cpu(curp->p_idx->ei_block)) {
+		/* insert after */
+		ext_debug(inode, "insert new index %d after: %llu\n",
+			  logical, ptr);
+		ix = curp->p_idx + 1;
+	} else {
+		/* insert before */
+		ext_debug(inode, "insert new index %d before: %llu\n",
+			  logical, ptr);
+		ix = curp->p_idx;
+	}
+
+	if (unlikely(ix > EXT_MAX_INDEX(curp->p_hdr))) {
+		EXT4_ERROR_INODE(inode, "ix > EXT_MAX_INDEX!");
+		return -EFSCORRUPTED;
+	}
+
+	len = EXT_LAST_INDEX(curp->p_hdr) - ix + 1;
+	BUG_ON(len < 0);
+	if (len > 0) {
+		ext_debug(inode, "insert new index %d: "
+				"move %d indices from 0x%p to 0x%p\n",
+				logical, len, ix, ix + 1);
+		memmove(ix + 1, ix, len * sizeof(struct ext4_extent_idx));
+	}
+
+	ix->ei_block = cpu_to_le32(logical);
+	ext4_idx_store_pblock(ix, ptr);
+	le16_add_cpu(&curp->p_hdr->eh_entries, 1);
+
+	if (unlikely(ix > EXT_LAST_INDEX(curp->p_hdr))) {
+		EXT4_ERROR_INODE(inode, "ix > EXT_LAST_INDEX!");
+		return -EFSCORRUPTED;
+	}
+
+	err = ext4_ext_dirty(handle, inode, curp);
+	ext4_std_error(inode->i_sb, err);
+
+	return err;
+}
+
+/*
+ * ext4_ext_split:
+ * inserts new subtree into the path, using free index entry
+ * at depth @at:
+ * - allocates all needed blocks (new leaf and all intermediate index blocks)
+ * - makes decision where to split
+ * - moves remaining extents and index entries (right to the split point)
+ *   into the newly allocated blocks
+ * - initializes subtree
+ */
+static int ext4_ext_split(handle_t *handle, struct inode *inode,
+			  unsigned int flags,
+			  struct ext4_ext_path *path,
+			  struct ext4_extent *newext, int at)
+{
+	struct buffer_head *bh = NULL;
+	int depth = ext_depth(inode);
+	struct ext4_extent_header *neh;
+	struct ext4_extent_idx *fidx;
+	int i = at, k, m, a;
+	ext4_fsblk_t newblock, oldblock;
+	__le32 border;
+	ext4_fsblk_t *ablocks = NULL; /* array of allocated blocks */
+	gfp_t gfp_flags = GFP_NOFS;
+	int err = 0;
+	size_t ext_size = 0;
+
+	if (flags & EXT4_EX_NOFAIL)
+		gfp_flags |= __GFP_NOFAIL;
+
+	/* make decision: where to split? */
+	/* FIXME: now decision is simplest: at current extent */
+
+	/* if current leaf will be split, then we should use
+	 * border from split point */
+	if (unlikely(path[depth].p_ext > EXT_MAX_EXTENT(path[depth].p_hdr))) {
+		EXT4_ERROR_INODE(inode, "p_ext > EXT_MAX_EXTENT!");
+		return -EFSCORRUPTED;
+	}
+	if (path[depth].p_ext != EXT_MAX_EXTENT(path[depth].p_hdr)) {
+		border = path[depth].p_ext[1].ee_block;
+		ext_debug(inode, "leaf will be split."
+				" next leaf starts at %d\n",
+				  le32_to_cpu(border));
+	} else {
+		border = newext->ee_block;
+		ext_debug(inode, "leaf will be added."
+				" next leaf starts at %d\n",
+				le32_to_cpu(border));
+	}
+
+	/*
+	 * If error occurs, then we break processing
+	 * and mark filesystem read-only. index won't
+	 * be inserted and tree will be in consistent
+	 * state. Next mount will repair buffers too.
+	 */
+
+	/*
+	 * Get array to track all allocated blocks.
+	 * We need this to handle errors and free blocks
+	 * upon them.
+	 */
+	ablocks = kcalloc(depth, sizeof(ext4_fsblk_t), gfp_flags);
+	if (!ablocks)
+		return -ENOMEM;
+
+	/* allocate all needed blocks */
+	ext_debug(inode, "allocate %d blocks for indexes/leaf\n", depth - at);
+	for (a = 0; a < depth - at; a++) {
+		newblock = ext4_ext_new_meta_block(handle, inode, path,
+						   newext, &err, flags);
+		if (newblock == 0)
+			goto cleanup;
+		ablocks[a] = newblock;
+	}
+
+	/* initialize new leaf */
+	newblock = ablocks[--a];
+	if (unlikely(newblock == 0)) {
+		EXT4_ERROR_INODE(inode, "newblock == 0!");
+		err = -EFSCORRUPTED;
+		goto cleanup;
+	}
+	bh = sb_getblk_gfp(inode->i_sb, newblock, __GFP_MOVABLE | GFP_NOFS);
+	if (unlikely(!bh)) {
+		err = -ENOMEM;
+		goto cleanup;
+	}
+	lock_buffer(bh);
+
+	err = ext4_journal_get_create_access(handle, inode->i_sb, bh,
+					     EXT4_JTR_NONE);
+	if (err)
+		goto cleanup;
+
+	neh = ext_block_hdr(bh);
+	neh->eh_entries = 0;
+	neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0));
+	neh->eh_magic = EXT4_EXT_MAGIC;
+	neh->eh_depth = 0;
+	neh->eh_generation = 0;
+
+	/* move remainder of path[depth] to the new leaf */
+	if (unlikely(path[depth].p_hdr->eh_entries !=
+		     path[depth].p_hdr->eh_max)) {
+		EXT4_ERROR_INODE(inode, "eh_entries %d != eh_max %d!",
+				 path[depth].p_hdr->eh_entries,
+				 path[depth].p_hdr->eh_max);
+		err = -EFSCORRUPTED;
+		goto cleanup;
+	}
+	/* start copy from next extent */
+	m = EXT_MAX_EXTENT(path[depth].p_hdr) - path[depth].p_ext++;
+	ext4_ext_show_move(inode, path, newblock, depth);
+	if (m) {
+		struct ext4_extent *ex;
+		ex = EXT_FIRST_EXTENT(neh);
+		memmove(ex, path[depth].p_ext, sizeof(struct ext4_extent) * m);
+		le16_add_cpu(&neh->eh_entries, m);
+	}
+
+	/* zero out unused area in the extent block */
+	ext_size = sizeof(struct ext4_extent_header) +
+		sizeof(struct ext4_extent) * le16_to_cpu(neh->eh_entries);
+	memset(bh->b_data + ext_size, 0, inode->i_sb->s_blocksize - ext_size);
+	ext4_extent_block_csum_set(inode, neh);
+	set_buffer_uptodate(bh);
+	unlock_buffer(bh);
+
+	err = ext4_handle_dirty_metadata(handle, inode, bh);
+	if (err)
+		goto cleanup;
+	brelse(bh);
+	bh = NULL;
+
+	/* correct old leaf */
+	if (m) {
+		err = ext4_ext_get_access(handle, inode, path + depth);
+		if (err)
+			goto cleanup;
+		le16_add_cpu(&path[depth].p_hdr->eh_entries, -m);
+		err = ext4_ext_dirty(handle, inode, path + depth);
+		if (err)
+			goto cleanup;
+
+	}
+
+	/* create intermediate indexes */
+	k = depth - at - 1;
+	if (unlikely(k < 0)) {
+		EXT4_ERROR_INODE(inode, "k %d < 0!", k);
+		err = -EFSCORRUPTED;
+		goto cleanup;
+	}
+	if (k)
+		ext_debug(inode, "create %d intermediate indices\n", k);
+	/* insert new index into current index block */
+	/* current depth stored in i var */
+	i = depth - 1;
+	while (k--) {
+		oldblock = newblock;
+		newblock = ablocks[--a];
+		bh = sb_getblk(inode->i_sb, newblock);
+		if (unlikely(!bh)) {
+			err = -ENOMEM;
+			goto cleanup;
+		}
+		lock_buffer(bh);
+
+		err = ext4_journal_get_create_access(handle, inode->i_sb, bh,
+						     EXT4_JTR_NONE);
+		if (err)
+			goto cleanup;
+
+		neh = ext_block_hdr(bh);
+		neh->eh_entries = cpu_to_le16(1);
+		neh->eh_magic = EXT4_EXT_MAGIC;
+		neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode, 0));
+		neh->eh_depth = cpu_to_le16(depth - i);
+		neh->eh_generation = 0;
+		fidx = EXT_FIRST_INDEX(neh);
+		fidx->ei_block = border;
+		ext4_idx_store_pblock(fidx, oldblock);
+
+		ext_debug(inode, "int.index at %d (block %llu): %u -> %llu\n",
+				i, newblock, le32_to_cpu(border), oldblock);
+
+		/* move remainder of path[i] to the new index block */
+		if (unlikely(EXT_MAX_INDEX(path[i].p_hdr) !=
+					EXT_LAST_INDEX(path[i].p_hdr))) {
+			EXT4_ERROR_INODE(inode,
+					 "EXT_MAX_INDEX != EXT_LAST_INDEX ee_block %d!",
+					 le32_to_cpu(path[i].p_ext->ee_block));
+			err = -EFSCORRUPTED;
+			goto cleanup;
+		}
+		/* start copy indexes */
+		m = EXT_MAX_INDEX(path[i].p_hdr) - path[i].p_idx++;
+		ext_debug(inode, "cur 0x%p, last 0x%p\n", path[i].p_idx,
+				EXT_MAX_INDEX(path[i].p_hdr));
+		ext4_ext_show_move(inode, path, newblock, i);
+		if (m) {
+			memmove(++fidx, path[i].p_idx,
+				sizeof(struct ext4_extent_idx) * m);
+			le16_add_cpu(&neh->eh_entries, m);
+		}
+		/* zero out unused area in the extent block */
+		ext_size = sizeof(struct ext4_extent_header) +
+		   (sizeof(struct ext4_extent) * le16_to_cpu(neh->eh_entries));
+		memset(bh->b_data + ext_size, 0,
+			inode->i_sb->s_blocksize - ext_size);
+		ext4_extent_block_csum_set(inode, neh);
+		set_buffer_uptodate(bh);
+		unlock_buffer(bh);
+
+		err = ext4_handle_dirty_metadata(handle, inode, bh);
+		if (err)
+			goto cleanup;
+		brelse(bh);
+		bh = NULL;
+
+		/* correct old index */
+		if (m) {
+			err = ext4_ext_get_access(handle, inode, path + i);
+			if (err)
+				goto cleanup;
+			le16_add_cpu(&path[i].p_hdr->eh_entries, -m);
+			err = ext4_ext_dirty(handle, inode, path + i);
+			if (err)
+				goto cleanup;
+		}
+
+		i--;
+	}
+
+	/* insert new index */
+	err = ext4_ext_insert_index(handle, inode, path + at,
+				    le32_to_cpu(border), newblock);
+
+cleanup:
+	if (bh) {
+		if (buffer_locked(bh))
+			unlock_buffer(bh);
+		brelse(bh);
+	}
+
+	if (err) {
+		/* free all allocated blocks in error case */
+		for (i = 0; i < depth; i++) {
+			if (!ablocks[i])
+				continue;
+			ext4_free_blocks(handle, inode, NULL, ablocks[i], 1,
+					 EXT4_FREE_BLOCKS_METADATA);
+		}
+	}
+	kfree(ablocks);
+
+	return err;
+}
+
+/*
+ * ext4_ext_grow_indepth:
+ * implements tree growing procedure:
+ * - allocates new block
+ * - moves top-level data (index block or leaf) into the new block
+ * - initializes new top-level, creating index that points to the
+ *   just created block
+ */
+static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
+				 unsigned int flags)
+{
+	struct ext4_extent_header *neh;
+	struct buffer_head *bh;
+	ext4_fsblk_t newblock, goal = 0;
+	struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es;
+	int err = 0;
+	size_t ext_size = 0;
+
+	/* Try to prepend new index to old one */
+	if (ext_depth(inode))
+		goal = ext4_idx_pblock(EXT_FIRST_INDEX(ext_inode_hdr(inode)));
+	if (goal > le32_to_cpu(es->s_first_data_block)) {
+		flags |= EXT4_MB_HINT_TRY_GOAL;
+		goal--;
+	} else
+		goal = ext4_inode_to_goal_block(inode);
+	newblock = ext4_new_meta_blocks(handle, inode, goal, flags,
+					NULL, &err);
+	if (newblock == 0)
+		return err;
+
+	bh = sb_getblk_gfp(inode->i_sb, newblock, __GFP_MOVABLE | GFP_NOFS);
+	if (unlikely(!bh))
+		return -ENOMEM;
+	lock_buffer(bh);
+
+	err = ext4_journal_get_create_access(handle, inode->i_sb, bh,
+					     EXT4_JTR_NONE);
+	if (err) {
+		unlock_buffer(bh);
+		goto out;
+	}
+
+	ext_size = sizeof(EXT4_I(inode)->i_data);
+	/* move top-level index/leaf into new block */
+	memmove(bh->b_data, EXT4_I(inode)->i_data, ext_size);
+	/* zero out unused area in the extent block */
+	memset(bh->b_data + ext_size, 0, inode->i_sb->s_blocksize - ext_size);
+
+	/* set size of new block */
+	neh = ext_block_hdr(bh);
+	/* old root could have indexes or leaves
+	 * so calculate e_max right way */
+	if (ext_depth(inode))
+		neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode, 0));
+	else
+		neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0));
+	neh->eh_magic = EXT4_EXT_MAGIC;
+	ext4_extent_block_csum_set(inode, neh);
+	set_buffer_uptodate(bh);
+	set_buffer_verified(bh);
+	unlock_buffer(bh);
+
+	err = ext4_handle_dirty_metadata(handle, inode, bh);
+	if (err)
+		goto out;
+
+	/* Update top-level index: num,max,pointer */
+	neh = ext_inode_hdr(inode);
+	neh->eh_entries = cpu_to_le16(1);
+	ext4_idx_store_pblock(EXT_FIRST_INDEX(neh), newblock);
+	if (neh->eh_depth == 0) {
+		/* Root extent block becomes index block */
+		neh->eh_max = cpu_to_le16(ext4_ext_space_root_idx(inode, 0));
+		EXT_FIRST_INDEX(neh)->ei_block =
+			EXT_FIRST_EXTENT(neh)->ee_block;
+	}
+	ext_debug(inode, "new root: num %d(%d), lblock %d, ptr %llu\n",
+		  le16_to_cpu(neh->eh_entries), le16_to_cpu(neh->eh_max),
+		  le32_to_cpu(EXT_FIRST_INDEX(neh)->ei_block),
+		  ext4_idx_pblock(EXT_FIRST_INDEX(neh)));
+
+	le16_add_cpu(&neh->eh_depth, 1);
+	err = ext4_mark_inode_dirty(handle, inode);
+out:
+	brelse(bh);
+
+	return err;
+}
+
+/*
+ * ext4_ext_create_new_leaf:
+ * finds empty index and adds new leaf.
+ * if no free index is found, then it requests in-depth growing.
+ */
+static struct ext4_ext_path *
+ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode,
+			 unsigned int mb_flags, unsigned int gb_flags,
+			 struct ext4_ext_path *path,
+			 struct ext4_extent *newext)
+{
+	struct ext4_ext_path *curp;
+	int depth, i, err = 0;
+	ext4_lblk_t ee_block = le32_to_cpu(newext->ee_block);
+
+repeat:
+	i = depth = ext_depth(inode);
+
+	/* walk up to the tree and look for free index entry */
+	curp = path + depth;
+	while (i > 0 && !EXT_HAS_FREE_INDEX(curp)) {
+		i--;
+		curp--;
+	}
+
+	/* we use already allocated block for index block,
+	 * so subsequent data blocks should be contiguous */
+	if (EXT_HAS_FREE_INDEX(curp)) {
+		/* if we found index with free entry, then use that
+		 * entry: create all needed subtree and add new leaf */
+		err = ext4_ext_split(handle, inode, mb_flags, path, newext, i);
+		if (err)
+			goto errout;
+
+		/* refill path */
+		path = ext4_find_extent(inode, ee_block, path, gb_flags);
+		return path;
+	}
+
+	/* tree is full, time to grow in depth */
+	err = ext4_ext_grow_indepth(handle, inode, mb_flags);
+	if (err)
+		goto errout;
+
+	/* refill path */
+	path = ext4_find_extent(inode, ee_block, path, gb_flags);
+	if (IS_ERR(path))
+		return path;
+
+	/*
+	 * only first (depth 0 -> 1) produces free space;
+	 * in all other cases we have to split the grown tree
+	 */
+	depth = ext_depth(inode);
+	if (path[depth].p_hdr->eh_entries == path[depth].p_hdr->eh_max) {
+		/* now we need to split */
+		goto repeat;
+	}
+
+	return path;
+
+errout:
+	ext4_free_ext_path(path);
+	return ERR_PTR(err);
+}
+
+/*
+ * search the closest allocated block to the left for *logical
+ * and returns it at @logical + it's physical address at @phys
+ * if *logical is the smallest allocated block, the function
+ * returns 0 at @phys
+ * return value contains 0 (success) or error code
+ */
+static int ext4_ext_search_left(struct inode *inode,
+				struct ext4_ext_path *path,
+				ext4_lblk_t *logical, ext4_fsblk_t *phys)
+{
+	struct ext4_extent_idx *ix;
+	struct ext4_extent *ex;
+	int depth, ee_len;
+
+	if (unlikely(path == NULL)) {
+		EXT4_ERROR_INODE(inode, "path == NULL *logical %d!", *logical);
+		return -EFSCORRUPTED;
+	}
+	depth = path->p_depth;
+	*phys = 0;
+
+	if (depth == 0 && path->p_ext == NULL)
+		return 0;
+
+	/* usually extent in the path covers blocks smaller
+	 * then *logical, but it can be that extent is the
+	 * first one in the file */
+
+	ex = path[depth].p_ext;
+	ee_len = ext4_ext_get_actual_len(ex);
+	if (*logical < le32_to_cpu(ex->ee_block)) {
+		if (unlikely(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex)) {
+			EXT4_ERROR_INODE(inode,
+					 "EXT_FIRST_EXTENT != ex *logical %d ee_block %d!",
+					 *logical, le32_to_cpu(ex->ee_block));
+			return -EFSCORRUPTED;
+		}
+		while (--depth >= 0) {
+			ix = path[depth].p_idx;
+			if (unlikely(ix != EXT_FIRST_INDEX(path[depth].p_hdr))) {
+				EXT4_ERROR_INODE(inode,
+				  "ix (%d) != EXT_FIRST_INDEX (%d) (depth %d)!",
+				  ix != NULL ? le32_to_cpu(ix->ei_block) : 0,
+				  le32_to_cpu(EXT_FIRST_INDEX(path[depth].p_hdr)->ei_block),
+				  depth);
+				return -EFSCORRUPTED;
+			}
+		}
+		return 0;
+	}
+
+	if (unlikely(*logical < (le32_to_cpu(ex->ee_block) + ee_len))) {
+		EXT4_ERROR_INODE(inode,
+				 "logical %d < ee_block %d + ee_len %d!",
+				 *logical, le32_to_cpu(ex->ee_block), ee_len);
+		return -EFSCORRUPTED;
+	}
+
+	*logical = le32_to_cpu(ex->ee_block) + ee_len - 1;
+	*phys = ext4_ext_pblock(ex) + ee_len - 1;
+	return 0;
+}
+
+/*
+ * Search the closest allocated block to the right for *logical
+ * and returns it at @logical + it's physical address at @phys.
+ * If not exists, return 0 and @phys is set to 0. We will return
+ * 1 which means we found an allocated block and ret_ex is valid.
+ * Or return a (< 0) error code.
+ */
+static int ext4_ext_search_right(struct inode *inode,
+				 struct ext4_ext_path *path,
+				 ext4_lblk_t *logical, ext4_fsblk_t *phys,
+				 struct ext4_extent *ret_ex, int flags)
+{
+	struct buffer_head *bh = NULL;
+	struct ext4_extent_header *eh;
+	struct ext4_extent_idx *ix;
+	struct ext4_extent *ex;
+	int depth;	/* Note, NOT eh_depth; depth from top of tree */
+	int ee_len;
+
+	if (unlikely(path == NULL)) {
+		EXT4_ERROR_INODE(inode, "path == NULL *logical %d!", *logical);
+		return -EFSCORRUPTED;
+	}
+	depth = path->p_depth;
+	*phys = 0;
+
+	if (depth == 0 && path->p_ext == NULL)
+		return 0;
+
+	/* usually extent in the path covers blocks smaller
+	 * then *logical, but it can be that extent is the
+	 * first one in the file */
+
+	ex = path[depth].p_ext;
+	ee_len = ext4_ext_get_actual_len(ex);
+	if (*logical < le32_to_cpu(ex->ee_block)) {
+		if (unlikely(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex)) {
+			EXT4_ERROR_INODE(inode,
+					 "first_extent(path[%d].p_hdr) != ex",
+					 depth);
+			return -EFSCORRUPTED;
+		}
+		while (--depth >= 0) {
+			ix = path[depth].p_idx;
+			if (unlikely(ix != EXT_FIRST_INDEX(path[depth].p_hdr))) {
+				EXT4_ERROR_INODE(inode,
+						 "ix != EXT_FIRST_INDEX *logical %d!",
+						 *logical);
+				return -EFSCORRUPTED;
+			}
+		}
+		goto found_extent;
+	}
+
+	if (unlikely(*logical < (le32_to_cpu(ex->ee_block) + ee_len))) {
+		EXT4_ERROR_INODE(inode,
+				 "logical %d < ee_block %d + ee_len %d!",
+				 *logical, le32_to_cpu(ex->ee_block), ee_len);
+		return -EFSCORRUPTED;
+	}
+
+	if (ex != EXT_LAST_EXTENT(path[depth].p_hdr)) {
+		/* next allocated block in this leaf */
+		ex++;
+		goto found_extent;
+	}
+
+	/* go up and search for index to the right */
+	while (--depth >= 0) {
+		ix = path[depth].p_idx;
+		if (ix != EXT_LAST_INDEX(path[depth].p_hdr))
+			goto got_index;
+	}
+
+	/* we've gone up to the root and found no index to the right */
+	return 0;
+
+got_index:
+	/* we've found index to the right, let's
+	 * follow it and find the closest allocated
+	 * block to the right */
+	ix++;
+	while (++depth < path->p_depth) {
+		/* subtract from p_depth to get proper eh_depth */
+		bh = read_extent_tree_block(inode, ix, path->p_depth - depth,
+					    flags);
+		if (IS_ERR(bh))
+			return PTR_ERR(bh);
+		eh = ext_block_hdr(bh);
+		ix = EXT_FIRST_INDEX(eh);
+		put_bh(bh);
+	}
+
+	bh = read_extent_tree_block(inode, ix, path->p_depth - depth, flags);
+	if (IS_ERR(bh))
+		return PTR_ERR(bh);
+	eh = ext_block_hdr(bh);
+	ex = EXT_FIRST_EXTENT(eh);
+found_extent:
+	*logical = le32_to_cpu(ex->ee_block);
+	*phys = ext4_ext_pblock(ex);
+	if (ret_ex)
+		*ret_ex = *ex;
+	if (bh)
+		put_bh(bh);
+	return 1;
+}
+
+/*
+ * ext4_ext_next_allocated_block:
+ * returns allocated block in subsequent extent or EXT_MAX_BLOCKS.
+ * NOTE: it considers block number from index entry as
+ * allocated block. Thus, index entries have to be consistent
+ * with leaves.
+ */
+ext4_lblk_t
+ext4_ext_next_allocated_block(struct ext4_ext_path *path)
+{
+	int depth;
+
+	BUG_ON(path == NULL);
+	depth = path->p_depth;
+
+	if (depth == 0 && path->p_ext == NULL)
+		return EXT_MAX_BLOCKS;
+
+	while (depth >= 0) {
+		struct ext4_ext_path *p = &path[depth];
+
+		if (depth == path->p_depth) {
+			/* leaf */
+			if (p->p_ext && p->p_ext != EXT_LAST_EXTENT(p->p_hdr))
+				return le32_to_cpu(p->p_ext[1].ee_block);
+		} else {
+			/* index */
+			if (p->p_idx != EXT_LAST_INDEX(p->p_hdr))
+				return le32_to_cpu(p->p_idx[1].ei_block);
+		}
+		depth--;
+	}
+
+	return EXT_MAX_BLOCKS;
+}
+
+/*
+ * ext4_ext_next_leaf_block:
+ * returns first allocated block from next leaf or EXT_MAX_BLOCKS
+ */
+static ext4_lblk_t ext4_ext_next_leaf_block(struct ext4_ext_path *path)
+{
+	int depth;
+
+	BUG_ON(path == NULL);
+	depth = path->p_depth;
+
+	/* zero-tree has no leaf blocks at all */
+	if (depth == 0)
+		return EXT_MAX_BLOCKS;
+
+	/* go to index block */
+	depth--;
+
+	while (depth >= 0) {
+		if (path[depth].p_idx !=
+				EXT_LAST_INDEX(path[depth].p_hdr))
+			return (ext4_lblk_t)
+				le32_to_cpu(path[depth].p_idx[1].ei_block);
+		depth--;
+	}
+
+	return EXT_MAX_BLOCKS;
+}
+
+/*
+ * ext4_ext_correct_indexes:
+ * if leaf gets modified and modified extent is first in the leaf,
+ * then we have to correct all indexes above.
+ * TODO: do we need to correct tree in all cases?
+ */
+static int ext4_ext_correct_indexes(handle_t *handle, struct inode *inode,
+				struct ext4_ext_path *path)
+{
+	struct ext4_extent_header *eh;
+	int depth = ext_depth(inode);
+	struct ext4_extent *ex;
+	__le32 border;
+	int k, err = 0;
+
+	eh = path[depth].p_hdr;
+	ex = path[depth].p_ext;
+
+	if (unlikely(ex == NULL || eh == NULL)) {
+		EXT4_ERROR_INODE(inode,
+				 "ex %p == NULL or eh %p == NULL", ex, eh);
+		return -EFSCORRUPTED;
+	}
+
+	if (depth == 0) {
+		/* there is no tree at all */
+		return 0;
+	}
+
+	if (ex != EXT_FIRST_EXTENT(eh)) {
+		/* we correct tree if first leaf got modified only */
+		return 0;
+	}
+
+	/*
+	 * TODO: we need correction if border is smaller than current one
+	 */
+	k = depth - 1;
+	border = path[depth].p_ext->ee_block;
+	err = ext4_ext_get_access(handle, inode, path + k);
+	if (err)
+		return err;
+	path[k].p_idx->ei_block = border;
+	err = ext4_ext_dirty(handle, inode, path + k);
+	if (err)
+		return err;
+
+	while (k--) {
+		/* change all left-side indexes */
+		if (path[k+1].p_idx != EXT_FIRST_INDEX(path[k+1].p_hdr))
+			break;
+		err = ext4_ext_get_access(handle, inode, path + k);
+		if (err)
+			goto clean;
+		path[k].p_idx->ei_block = border;
+		err = ext4_ext_dirty(handle, inode, path + k);
+		if (err)
+			goto clean;
+	}
+	return 0;
+
+clean:
+	/*
+	 * The path[k].p_bh is either unmodified or with no verified bit
+	 * set (see ext4_ext_get_access()). So just clear the verified bit
+	 * of the successfully modified extents buffers, which will force
+	 * these extents to be checked to avoid using inconsistent data.
+	 */
+	while (++k < depth)
+		clear_buffer_verified(path[k].p_bh);
+
+	return err;
+}
+
+static int ext4_can_extents_be_merged(struct inode *inode,
+				      struct ext4_extent *ex1,
+				      struct ext4_extent *ex2)
+{
+	unsigned short ext1_ee_len, ext2_ee_len;
+
+	if (ext4_ext_is_unwritten(ex1) != ext4_ext_is_unwritten(ex2))
+		return 0;
+
+	ext1_ee_len = ext4_ext_get_actual_len(ex1);
+	ext2_ee_len = ext4_ext_get_actual_len(ex2);
+
+	if (le32_to_cpu(ex1->ee_block) + ext1_ee_len !=
+			le32_to_cpu(ex2->ee_block))
+		return 0;
+
+	if (ext1_ee_len + ext2_ee_len > EXT_INIT_MAX_LEN)
+		return 0;
+
+	if (ext4_ext_is_unwritten(ex1) &&
+	    ext1_ee_len + ext2_ee_len > EXT_UNWRITTEN_MAX_LEN)
+		return 0;
+#ifdef AGGRESSIVE_TEST
+	if (ext1_ee_len >= 4)
+		return 0;
+#endif
+
+	if (ext4_ext_pblock(ex1) + ext1_ee_len == ext4_ext_pblock(ex2))
+		return 1;
+	return 0;
+}
+
+/*
+ * This function tries to merge the "ex" extent to the next extent in the tree.
+ * It always tries to merge towards right. If you want to merge towards
+ * left, pass "ex - 1" as argument instead of "ex".
+ * Returns 0 if the extents (ex and ex+1) were _not_ merged and returns
+ * 1 if they got merged.
+ */
+static int ext4_ext_try_to_merge_right(struct inode *inode,
+				 struct ext4_ext_path *path,
+				 struct ext4_extent *ex)
+{
+	struct ext4_extent_header *eh;
+	unsigned int depth, len;
+	int merge_done = 0, unwritten;
+
+	depth = ext_depth(inode);
+	BUG_ON(path[depth].p_hdr == NULL);
+	eh = path[depth].p_hdr;
+
+	while (ex < EXT_LAST_EXTENT(eh)) {
+		if (!ext4_can_extents_be_merged(inode, ex, ex + 1))
+			break;
+		/* merge with next extent! */
+		unwritten = ext4_ext_is_unwritten(ex);
+		ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
+				+ ext4_ext_get_actual_len(ex + 1));
+		if (unwritten)
+			ext4_ext_mark_unwritten(ex);
+
+		if (ex + 1 < EXT_LAST_EXTENT(eh)) {
+			len = (EXT_LAST_EXTENT(eh) - ex - 1)
+				* sizeof(struct ext4_extent);
+			memmove(ex + 1, ex + 2, len);
+		}
+		le16_add_cpu(&eh->eh_entries, -1);
+		merge_done = 1;
+		WARN_ON(eh->eh_entries == 0);
+		if (!eh->eh_entries)
+			EXT4_ERROR_INODE(inode, "eh->eh_entries = 0!");
+	}
+
+	return merge_done;
+}
+
+/*
+ * This function does a very simple check to see if we can collapse
+ * an extent tree with a single extent tree leaf block into the inode.
+ */
+static void ext4_ext_try_to_merge_up(handle_t *handle,
+				     struct inode *inode,
+				     struct ext4_ext_path *path)
+{
+	size_t s;
+	unsigned max_root = ext4_ext_space_root(inode, 0);
+	ext4_fsblk_t blk;
+
+	if ((path[0].p_depth != 1) ||
+	    (le16_to_cpu(path[0].p_hdr->eh_entries) != 1) ||
+	    (le16_to_cpu(path[1].p_hdr->eh_entries) > max_root))
+		return;
+
+	/*
+	 * We need to modify the block allocation bitmap and the block
+	 * group descriptor to release the extent tree block.  If we
+	 * can't get the journal credits, give up.
+	 */
+	if (ext4_journal_extend(handle, 2,
+			ext4_free_metadata_revoke_credits(inode->i_sb, 1)))
+		return;
+
+	/*
+	 * Copy the extent data up to the inode
+	 */
+	blk = ext4_idx_pblock(path[0].p_idx);
+	s = le16_to_cpu(path[1].p_hdr->eh_entries) *
+		sizeof(struct ext4_extent_idx);
+	s += sizeof(struct ext4_extent_header);
+
+	path[1].p_maxdepth = path[0].p_maxdepth;
+	memcpy(path[0].p_hdr, path[1].p_hdr, s);
+	path[0].p_depth = 0;
+	path[0].p_ext = EXT_FIRST_EXTENT(path[0].p_hdr) +
+		(path[1].p_ext - EXT_FIRST_EXTENT(path[1].p_hdr));
+	path[0].p_hdr->eh_max = cpu_to_le16(max_root);
+
+	ext4_ext_path_brelse(path + 1);
+	ext4_free_blocks(handle, inode, NULL, blk, 1,
+			 EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
+}
+
+/*
+ * This function tries to merge the @ex extent to neighbours in the tree, then
+ * tries to collapse the extent tree into the inode.
+ */
+static void ext4_ext_try_to_merge(handle_t *handle,
+				  struct inode *inode,
+				  struct ext4_ext_path *path,
+				  struct ext4_extent *ex)
+{
+	struct ext4_extent_header *eh;
+	unsigned int depth;
+	int merge_done = 0;
+
+	depth = ext_depth(inode);
+	BUG_ON(path[depth].p_hdr == NULL);
+	eh = path[depth].p_hdr;
+
+	if (ex > EXT_FIRST_EXTENT(eh))
+		merge_done = ext4_ext_try_to_merge_right(inode, path, ex - 1);
+
+	if (!merge_done)
+		(void) ext4_ext_try_to_merge_right(inode, path, ex);
+
+	ext4_ext_try_to_merge_up(handle, inode, path);
+}
+
+/*
+ * check if a portion of the "newext" extent overlaps with an
+ * existing extent.
+ *
+ * If there is an overlap discovered, it updates the length of the newext
+ * such that there will be no overlap, and then returns 1.
+ * If there is no overlap found, it returns 0.
+ */
+static unsigned int ext4_ext_check_overlap(struct ext4_sb_info *sbi,
+					   struct inode *inode,
+					   struct ext4_extent *newext,
+					   struct ext4_ext_path *path)
+{
+	ext4_lblk_t b1, b2;
+	unsigned int depth, len1;
+	unsigned int ret = 0;
+
+	b1 = le32_to_cpu(newext->ee_block);
+	len1 = ext4_ext_get_actual_len(newext);
+	depth = ext_depth(inode);
+	if (!path[depth].p_ext)
+		goto out;
+	b2 = EXT4_LBLK_CMASK(sbi, le32_to_cpu(path[depth].p_ext->ee_block));
+
+	/*
+	 * get the next allocated block if the extent in the path
+	 * is before the requested block(s)
+	 */
+	if (b2 < b1) {
+		b2 = ext4_ext_next_allocated_block(path);
+		if (b2 == EXT_MAX_BLOCKS)
+			goto out;
+		b2 = EXT4_LBLK_CMASK(sbi, b2);
+	}
+
+	/* check for wrap through zero on extent logical start block*/
+	if (b1 + len1 < b1) {
+		len1 = EXT_MAX_BLOCKS - b1;
+		newext->ee_len = cpu_to_le16(len1);
+		ret = 1;
+	}
+
+	/* check for overlap */
+	if (b1 + len1 > b2) {
+		newext->ee_len = cpu_to_le16(b2 - b1);
+		ret = 1;
+	}
+out:
+	return ret;
+}
+
+/*
+ * ext4_ext_insert_extent:
+ * tries to merge requested extent into the existing extent or
+ * inserts requested extent as new one into the tree,
+ * creating new leaf in the no-space case.
+ */
+struct ext4_ext_path *
+ext4_ext_insert_extent(handle_t *handle, struct inode *inode,
+		       struct ext4_ext_path *path,
+		       struct ext4_extent *newext, int gb_flags)
+{
+	struct ext4_extent_header *eh;
+	struct ext4_extent *ex, *fex;
+	struct ext4_extent *nearex; /* nearest extent */
+	int depth, len, err = 0;
+	ext4_lblk_t next;
+	int mb_flags = 0, unwritten;
+
+	if (gb_flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
+		mb_flags |= EXT4_MB_DELALLOC_RESERVED;
+	if (unlikely(ext4_ext_get_actual_len(newext) == 0)) {
+		EXT4_ERROR_INODE(inode, "ext4_ext_get_actual_len(newext) == 0");
+		err = -EFSCORRUPTED;
+		goto errout;
+	}
+	depth = ext_depth(inode);
+	ex = path[depth].p_ext;
+	eh = path[depth].p_hdr;
+	if (unlikely(path[depth].p_hdr == NULL)) {
+		EXT4_ERROR_INODE(inode, "path[%d].p_hdr == NULL", depth);
+		err = -EFSCORRUPTED;
+		goto errout;
+	}
+
+	/* try to insert block into found extent and return */
+	if (ex && !(gb_flags & EXT4_GET_BLOCKS_PRE_IO)) {
+
+		/*
+		 * Try to see whether we should rather test the extent on
+		 * right from ex, or from the left of ex. This is because
+		 * ext4_find_extent() can return either extent on the
+		 * left, or on the right from the searched position. This
+		 * will make merging more effective.
+		 */
+		if (ex < EXT_LAST_EXTENT(eh) &&
+		    (le32_to_cpu(ex->ee_block) +
+		    ext4_ext_get_actual_len(ex) <
+		    le32_to_cpu(newext->ee_block))) {
+			ex += 1;
+			goto prepend;
+		} else if ((ex > EXT_FIRST_EXTENT(eh)) &&
+			   (le32_to_cpu(newext->ee_block) +
+			   ext4_ext_get_actual_len(newext) <
+			   le32_to_cpu(ex->ee_block)))
+			ex -= 1;
+
+		/* Try to append newex to the ex */
+		if (ext4_can_extents_be_merged(inode, ex, newext)) {
+			ext_debug(inode, "append [%d]%d block to %u:[%d]%d"
+				  "(from %llu)\n",
+				  ext4_ext_is_unwritten(newext),
+				  ext4_ext_get_actual_len(newext),
+				  le32_to_cpu(ex->ee_block),
+				  ext4_ext_is_unwritten(ex),
+				  ext4_ext_get_actual_len(ex),
+				  ext4_ext_pblock(ex));
+			err = ext4_ext_get_access(handle, inode,
+						  path + depth);
+			if (err)
+				goto errout;
+			unwritten = ext4_ext_is_unwritten(ex);
+			ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
+					+ ext4_ext_get_actual_len(newext));
+			if (unwritten)
+				ext4_ext_mark_unwritten(ex);
+			nearex = ex;
+			goto merge;
+		}
+
+prepend:
+		/* Try to prepend newex to the ex */
+		if (ext4_can_extents_be_merged(inode, newext, ex)) {
+			ext_debug(inode, "prepend %u[%d]%d block to %u:[%d]%d"
+				  "(from %llu)\n",
+				  le32_to_cpu(newext->ee_block),
+				  ext4_ext_is_unwritten(newext),
+				  ext4_ext_get_actual_len(newext),
+				  le32_to_cpu(ex->ee_block),
+				  ext4_ext_is_unwritten(ex),
+				  ext4_ext_get_actual_len(ex),
+				  ext4_ext_pblock(ex));
+			err = ext4_ext_get_access(handle, inode,
+						  path + depth);
+			if (err)
+				goto errout;
+
+			unwritten = ext4_ext_is_unwritten(ex);
+			ex->ee_block = newext->ee_block;
+			ext4_ext_store_pblock(ex, ext4_ext_pblock(newext));
+			ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
+					+ ext4_ext_get_actual_len(newext));
+			if (unwritten)
+				ext4_ext_mark_unwritten(ex);
+			nearex = ex;
+			goto merge;
+		}
+	}
+
+	depth = ext_depth(inode);
+	eh = path[depth].p_hdr;
+	if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max))
+		goto has_space;
+
+	/* probably next leaf has space for us? */
+	fex = EXT_LAST_EXTENT(eh);
+	next = EXT_MAX_BLOCKS;
+	if (le32_to_cpu(newext->ee_block) > le32_to_cpu(fex->ee_block))
+		next = ext4_ext_next_leaf_block(path);
+	if (next != EXT_MAX_BLOCKS) {
+		struct ext4_ext_path *npath;
+
+		ext_debug(inode, "next leaf block - %u\n", next);
+		npath = ext4_find_extent(inode, next, NULL, gb_flags);
+		if (IS_ERR(npath)) {
+			err = PTR_ERR(npath);
+			goto errout;
+		}
+		BUG_ON(npath->p_depth != path->p_depth);
+		eh = npath[depth].p_hdr;
+		if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max)) {
+			ext_debug(inode, "next leaf isn't full(%d)\n",
+				  le16_to_cpu(eh->eh_entries));
+			ext4_free_ext_path(path);
+			path = npath;
+			goto has_space;
+		}
+		ext_debug(inode, "next leaf has no free space(%d,%d)\n",
+			  le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
+		ext4_free_ext_path(npath);
+	}
+
+	/*
+	 * There is no free space in the found leaf.
+	 * We're gonna add a new leaf in the tree.
+	 */
+	if (gb_flags & EXT4_GET_BLOCKS_METADATA_NOFAIL)
+		mb_flags |= EXT4_MB_USE_RESERVED;
+	path = ext4_ext_create_new_leaf(handle, inode, mb_flags, gb_flags,
+					path, newext);
+	if (IS_ERR(path))
+		return path;
+	depth = ext_depth(inode);
+	eh = path[depth].p_hdr;
+
+has_space:
+	nearex = path[depth].p_ext;
+
+	err = ext4_ext_get_access(handle, inode, path + depth);
+	if (err)
+		goto errout;
+
+	if (!nearex) {
+		/* there is no extent in this leaf, create first one */
+		ext_debug(inode, "first extent in the leaf: %u:%llu:[%d]%d\n",
+				le32_to_cpu(newext->ee_block),
+				ext4_ext_pblock(newext),
+				ext4_ext_is_unwritten(newext),
+				ext4_ext_get_actual_len(newext));
+		nearex = EXT_FIRST_EXTENT(eh);
+	} else {
+		if (le32_to_cpu(newext->ee_block)
+			   > le32_to_cpu(nearex->ee_block)) {
+			/* Insert after */
+			ext_debug(inode, "insert %u:%llu:[%d]%d before: "
+					"nearest %p\n",
+					le32_to_cpu(newext->ee_block),
+					ext4_ext_pblock(newext),
+					ext4_ext_is_unwritten(newext),
+					ext4_ext_get_actual_len(newext),
+					nearex);
+			nearex++;
+		} else {
+			/* Insert before */
+			BUG_ON(newext->ee_block == nearex->ee_block);
+			ext_debug(inode, "insert %u:%llu:[%d]%d after: "
+					"nearest %p\n",
+					le32_to_cpu(newext->ee_block),
+					ext4_ext_pblock(newext),
+					ext4_ext_is_unwritten(newext),
+					ext4_ext_get_actual_len(newext),
+					nearex);
+		}
+		len = EXT_LAST_EXTENT(eh) - nearex + 1;
+		if (len > 0) {
+			ext_debug(inode, "insert %u:%llu:[%d]%d: "
+					"move %d extents from 0x%p to 0x%p\n",
+					le32_to_cpu(newext->ee_block),
+					ext4_ext_pblock(newext),
+					ext4_ext_is_unwritten(newext),
+					ext4_ext_get_actual_len(newext),
+					len, nearex, nearex + 1);
+			memmove(nearex + 1, nearex,
+				len * sizeof(struct ext4_extent));
+		}
+	}
+
+	le16_add_cpu(&eh->eh_entries, 1);
+	path[depth].p_ext = nearex;
+	nearex->ee_block = newext->ee_block;
+	ext4_ext_store_pblock(nearex, ext4_ext_pblock(newext));
+	nearex->ee_len = newext->ee_len;
+
+merge:
+	/* try to merge extents */
+	if (!(gb_flags & EXT4_GET_BLOCKS_PRE_IO))
+		ext4_ext_try_to_merge(handle, inode, path, nearex);
+
+	/* time to correct all indexes above */
+	err = ext4_ext_correct_indexes(handle, inode, path);
+	if (err)
+		goto errout;
+
+	err = ext4_ext_dirty(handle, inode, path + path->p_depth);
+	if (err)
+		goto errout;
+
+	return path;
+
+errout:
+	ext4_free_ext_path(path);
+	return ERR_PTR(err);
+}
+
+static int ext4_fill_es_cache_info(struct inode *inode,
+				   ext4_lblk_t block, ext4_lblk_t num,
+				   struct fiemap_extent_info *fieinfo)
+{
+	ext4_lblk_t next, end = block + num - 1;
+	struct extent_status es;
+	unsigned char blksize_bits = inode->i_sb->s_blocksize_bits;
+	unsigned int flags;
+	int err;
+
+	while (block <= end) {
+		next = 0;
+		flags = 0;
+		if (!ext4_es_lookup_extent(inode, block, &next, &es))
+			break;
+		if (ext4_es_is_unwritten(&es))
+			flags |= FIEMAP_EXTENT_UNWRITTEN;
+		if (ext4_es_is_delayed(&es))
+			flags |= (FIEMAP_EXTENT_DELALLOC |
+				  FIEMAP_EXTENT_UNKNOWN);
+		if (ext4_es_is_hole(&es))
+			flags |= EXT4_FIEMAP_EXTENT_HOLE;
+		if (next == 0)
+			flags |= FIEMAP_EXTENT_LAST;
+		if (flags & (FIEMAP_EXTENT_DELALLOC|
+			     EXT4_FIEMAP_EXTENT_HOLE))
+			es.es_pblk = 0;
+		else
+			es.es_pblk = ext4_es_pblock(&es);
+		err = fiemap_fill_next_extent(fieinfo,
+				(__u64)es.es_lblk << blksize_bits,
+				(__u64)es.es_pblk << blksize_bits,
+				(__u64)es.es_len << blksize_bits,
+				flags);
+		if (next == 0)
+			break;
+		block = next;
+		if (err < 0)
+			return err;
+		if (err == 1)
+			return 0;
+	}
+	return 0;
+}
+
+
+/*
+ * ext4_ext_find_hole - find hole around given block according to the given path
+ * @inode:	inode we lookup in
+ * @path:	path in extent tree to @lblk
+ * @lblk:	pointer to logical block around which we want to determine hole
+ *
+ * Determine hole length (and start if easily possible) around given logical
+ * block. We don't try too hard to find the beginning of the hole but @path
+ * actually points to extent before @lblk, we provide it.
+ *
+ * The function returns the length of a hole starting at @lblk. We update @lblk
+ * to the beginning of the hole if we managed to find it.
+ */
+static ext4_lblk_t ext4_ext_find_hole(struct inode *inode,
+				      struct ext4_ext_path *path,
+				      ext4_lblk_t *lblk)
+{
+	int depth = ext_depth(inode);
+	struct ext4_extent *ex;
+	ext4_lblk_t len;
+
+	ex = path[depth].p_ext;
+	if (ex == NULL) {
+		/* there is no extent yet, so gap is [0;-] */
+		*lblk = 0;
+		len = EXT_MAX_BLOCKS;
+	} else if (*lblk < le32_to_cpu(ex->ee_block)) {
+		len = le32_to_cpu(ex->ee_block) - *lblk;
+	} else if (*lblk >= le32_to_cpu(ex->ee_block)
+			+ ext4_ext_get_actual_len(ex)) {
+		ext4_lblk_t next;
+
+		*lblk = le32_to_cpu(ex->ee_block) + ext4_ext_get_actual_len(ex);
+		next = ext4_ext_next_allocated_block(path);
+		BUG_ON(next == *lblk);
+		len = next - *lblk;
+	} else {
+		BUG();
+	}
+	return len;
+}
+
+/*
+ * ext4_ext_rm_idx:
+ * removes index from the index block.
+ */
+static int ext4_ext_rm_idx(handle_t *handle, struct inode *inode,
+			struct ext4_ext_path *path, int depth)
+{
+	int err;
+	ext4_fsblk_t leaf;
+	int k = depth - 1;
+
+	/* free index block */
+	leaf = ext4_idx_pblock(path[k].p_idx);
+	if (unlikely(path[k].p_hdr->eh_entries == 0)) {
+		EXT4_ERROR_INODE(inode, "path[%d].p_hdr->eh_entries == 0", k);
+		return -EFSCORRUPTED;
+	}
+	err = ext4_ext_get_access(handle, inode, path + k);
+	if (err)
+		return err;
+
+	if (path[k].p_idx != EXT_LAST_INDEX(path[k].p_hdr)) {
+		int len = EXT_LAST_INDEX(path[k].p_hdr) - path[k].p_idx;
+		len *= sizeof(struct ext4_extent_idx);
+		memmove(path[k].p_idx, path[k].p_idx + 1, len);
+	}
+
+	le16_add_cpu(&path[k].p_hdr->eh_entries, -1);
+	err = ext4_ext_dirty(handle, inode, path + k);
+	if (err)
+		return err;
+	ext_debug(inode, "index is empty, remove it, free block %llu\n", leaf);
+	trace_ext4_ext_rm_idx(inode, leaf);
+
+	ext4_free_blocks(handle, inode, NULL, leaf, 1,
+			 EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
+
+	while (--k >= 0) {
+		if (path[k + 1].p_idx != EXT_FIRST_INDEX(path[k + 1].p_hdr))
+			break;
+		err = ext4_ext_get_access(handle, inode, path + k);
+		if (err)
+			goto clean;
+		path[k].p_idx->ei_block = path[k + 1].p_idx->ei_block;
+		err = ext4_ext_dirty(handle, inode, path + k);
+		if (err)
+			goto clean;
+	}
+	return 0;
+
+clean:
+	/*
+	 * The path[k].p_bh is either unmodified or with no verified bit
+	 * set (see ext4_ext_get_access()). So just clear the verified bit
+	 * of the successfully modified extents buffers, which will force
+	 * these extents to be checked to avoid using inconsistent data.
+	 */
+	while (++k < depth)
+		clear_buffer_verified(path[k].p_bh);
+
+	return err;
+}
+
+/*
+ * ext4_ext_calc_credits_for_single_extent:
+ * This routine returns max. credits that needed to insert an extent
+ * to the extent tree.
+ * When pass the actual path, the caller should calculate credits
+ * under i_data_sem.
+ */
+int ext4_ext_calc_credits_for_single_extent(struct inode *inode, int nrblocks,
+						struct ext4_ext_path *path)
+{
+	if (path) {
+		int depth = ext_depth(inode);
+		int ret = 0;
+
+		/* probably there is space in leaf? */
+		if (le16_to_cpu(path[depth].p_hdr->eh_entries)
+				< le16_to_cpu(path[depth].p_hdr->eh_max)) {
+
+			/*
+			 *  There are some space in the leaf tree, no
+			 *  need to account for leaf block credit
+			 *
+			 *  bitmaps and block group descriptor blocks
+			 *  and other metadata blocks still need to be
+			 *  accounted.
+			 */
+			/* 1 bitmap, 1 block group descriptor */
+			ret = 2 + EXT4_META_TRANS_BLOCKS(inode->i_sb);
+			return ret;
+		}
+	}
+
+	return ext4_chunk_trans_blocks(inode, nrblocks);
+}
+
+/*
+ * How many index/leaf blocks need to change/allocate to add @extents extents?
+ *
+ * If we add a single extent, then in the worse case, each tree level
+ * index/leaf need to be changed in case of the tree split.
+ *
+ * If more extents are inserted, they could cause the whole tree split more
+ * than once, but this is really rare.
+ */
+int ext4_ext_index_trans_blocks(struct inode *inode, int extents)
+{
+	int index;
+
+	/* If we are converting the inline data, only one is needed here. */
+	if (ext4_has_inline_data(inode))
+		return 1;
+
+	/*
+	 * Extent tree can change between the time we estimate credits and
+	 * the time we actually modify the tree. Assume the worst case.
+	 */
+	if (extents <= 1)
+		index = (EXT4_MAX_EXTENT_DEPTH * 2) + extents;
+	else
+		index = (EXT4_MAX_EXTENT_DEPTH * 3) +
+			DIV_ROUND_UP(extents, ext4_ext_space_block(inode, 0));
+
+	return index;
+}
+
+static inline int get_default_free_blocks_flags(struct inode *inode)
+{
+	if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode) ||
+	    ext4_test_inode_flag(inode, EXT4_INODE_EA_INODE))
+		return EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET;
+	else if (ext4_should_journal_data(inode))
+		return EXT4_FREE_BLOCKS_FORGET;
+	return 0;
+}
+
+/*
+ * ext4_rereserve_cluster - increment the reserved cluster count when
+ *                          freeing a cluster with a pending reservation
+ *
+ * @inode - file containing the cluster
+ * @lblk - logical block in cluster to be reserved
+ *
+ * Increments the reserved cluster count and adjusts quota in a bigalloc
+ * file system when freeing a partial cluster containing at least one
+ * delayed and unwritten block.  A partial cluster meeting that
+ * requirement will have a pending reservation.  If so, the
+ * RERESERVE_CLUSTER flag is used when calling ext4_free_blocks() to
+ * defer reserved and allocated space accounting to a subsequent call
+ * to this function.
+ */
+static void ext4_rereserve_cluster(struct inode *inode, ext4_lblk_t lblk)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	struct ext4_inode_info *ei = EXT4_I(inode);
+
+	dquot_reclaim_block(inode, EXT4_C2B(sbi, 1));
+
+	spin_lock(&ei->i_block_reservation_lock);
+	ei->i_reserved_data_blocks++;
+	percpu_counter_add(&sbi->s_dirtyclusters_counter, 1);
+	spin_unlock(&ei->i_block_reservation_lock);
+
+	percpu_counter_add(&sbi->s_freeclusters_counter, 1);
+	ext4_remove_pending(inode, lblk);
+}
+
+static int ext4_remove_blocks(handle_t *handle, struct inode *inode,
+			      struct ext4_extent *ex,
+			      struct partial_cluster *partial,
+			      ext4_lblk_t from, ext4_lblk_t to)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	unsigned short ee_len = ext4_ext_get_actual_len(ex);
+	ext4_fsblk_t last_pblk, pblk;
+	ext4_lblk_t num;
+	int flags;
+
+	/* only extent tail removal is allowed */
+	if (from < le32_to_cpu(ex->ee_block) ||
+	    to != le32_to_cpu(ex->ee_block) + ee_len - 1) {
+		ext4_error(sbi->s_sb,
+			   "strange request: removal(2) %u-%u from %u:%u",
+			   from, to, le32_to_cpu(ex->ee_block), ee_len);
+		return 0;
+	}
+
+#ifdef EXTENTS_STATS
+	spin_lock(&sbi->s_ext_stats_lock);
+	sbi->s_ext_blocks += ee_len;
+	sbi->s_ext_extents++;
+	if (ee_len < sbi->s_ext_min)
+		sbi->s_ext_min = ee_len;
+	if (ee_len > sbi->s_ext_max)
+		sbi->s_ext_max = ee_len;
+	if (ext_depth(inode) > sbi->s_depth_max)
+		sbi->s_depth_max = ext_depth(inode);
+	spin_unlock(&sbi->s_ext_stats_lock);
+#endif
+
+	trace_ext4_remove_blocks(inode, ex, from, to, partial);
+
+	/*
+	 * if we have a partial cluster, and it's different from the
+	 * cluster of the last block in the extent, we free it
+	 */
+	last_pblk = ext4_ext_pblock(ex) + ee_len - 1;
+
+	if (partial->state != initial &&
+	    partial->pclu != EXT4_B2C(sbi, last_pblk)) {
+		if (partial->state == tofree) {
+			flags = get_default_free_blocks_flags(inode);
+			if (ext4_is_pending(inode, partial->lblk))
+				flags |= EXT4_FREE_BLOCKS_RERESERVE_CLUSTER;
+			ext4_free_blocks(handle, inode, NULL,
+					 EXT4_C2B(sbi, partial->pclu),
+					 sbi->s_cluster_ratio, flags);
+			if (flags & EXT4_FREE_BLOCKS_RERESERVE_CLUSTER)
+				ext4_rereserve_cluster(inode, partial->lblk);
+		}
+		partial->state = initial;
+	}
+
+	num = le32_to_cpu(ex->ee_block) + ee_len - from;
+	pblk = ext4_ext_pblock(ex) + ee_len - num;
+
+	/*
+	 * We free the partial cluster at the end of the extent (if any),
+	 * unless the cluster is used by another extent (partial_cluster
+	 * state is nofree).  If a partial cluster exists here, it must be
+	 * shared with the last block in the extent.
+	 */
+	flags = get_default_free_blocks_flags(inode);
+
+	/* partial, left end cluster aligned, right end unaligned */
+	if ((EXT4_LBLK_COFF(sbi, to) != sbi->s_cluster_ratio - 1) &&
+	    (EXT4_LBLK_CMASK(sbi, to) >= from) &&
+	    (partial->state != nofree)) {
+		if (ext4_is_pending(inode, to))
+			flags |= EXT4_FREE_BLOCKS_RERESERVE_CLUSTER;
+		ext4_free_blocks(handle, inode, NULL,
+				 EXT4_PBLK_CMASK(sbi, last_pblk),
+				 sbi->s_cluster_ratio, flags);
+		if (flags & EXT4_FREE_BLOCKS_RERESERVE_CLUSTER)
+			ext4_rereserve_cluster(inode, to);
+		partial->state = initial;
+		flags = get_default_free_blocks_flags(inode);
+	}
+
+	flags |= EXT4_FREE_BLOCKS_NOFREE_LAST_CLUSTER;
+
+	/*
+	 * For bigalloc file systems, we never free a partial cluster
+	 * at the beginning of the extent.  Instead, we check to see if we
+	 * need to free it on a subsequent call to ext4_remove_blocks,
+	 * or at the end of ext4_ext_rm_leaf or ext4_ext_remove_space.
+	 */
+	flags |= EXT4_FREE_BLOCKS_NOFREE_FIRST_CLUSTER;
+	ext4_free_blocks(handle, inode, NULL, pblk, num, flags);
+
+	/* reset the partial cluster if we've freed past it */
+	if (partial->state != initial && partial->pclu != EXT4_B2C(sbi, pblk))
+		partial->state = initial;
+
+	/*
+	 * If we've freed the entire extent but the beginning is not left
+	 * cluster aligned and is not marked as ineligible for freeing we
+	 * record the partial cluster at the beginning of the extent.  It
+	 * wasn't freed by the preceding ext4_free_blocks() call, and we
+	 * need to look farther to the left to determine if it's to be freed
+	 * (not shared with another extent). Else, reset the partial
+	 * cluster - we're either  done freeing or the beginning of the
+	 * extent is left cluster aligned.
+	 */
+	if (EXT4_LBLK_COFF(sbi, from) && num == ee_len) {
+		if (partial->state == initial) {
+			partial->pclu = EXT4_B2C(sbi, pblk);
+			partial->lblk = from;
+			partial->state = tofree;
+		}
+	} else {
+		partial->state = initial;
+	}
+
+	return 0;
+}
+
+/*
+ * ext4_ext_rm_leaf() Removes the extents associated with the
+ * blocks appearing between "start" and "end".  Both "start"
+ * and "end" must appear in the same extent or EIO is returned.
+ *
+ * @handle: The journal handle
+ * @inode:  The files inode
+ * @path:   The path to the leaf
+ * @partial_cluster: The cluster which we'll have to free if all extents
+ *                   has been released from it.  However, if this value is
+ *                   negative, it's a cluster just to the right of the
+ *                   punched region and it must not be freed.
+ * @start:  The first block to remove
+ * @end:   The last block to remove
+ */
+static int
+ext4_ext_rm_leaf(handle_t *handle, struct inode *inode,
+		 struct ext4_ext_path *path,
+		 struct partial_cluster *partial,
+		 ext4_lblk_t start, ext4_lblk_t end)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	int err = 0, correct_index = 0;
+	int depth = ext_depth(inode), credits, revoke_credits;
+	struct ext4_extent_header *eh;
+	ext4_lblk_t a, b;
+	unsigned num;
+	ext4_lblk_t ex_ee_block;
+	unsigned short ex_ee_len;
+	unsigned unwritten = 0;
+	struct ext4_extent *ex;
+	ext4_fsblk_t pblk;
+
+	/* the header must be checked already in ext4_ext_remove_space() */
+	ext_debug(inode, "truncate since %u in leaf to %u\n", start, end);
+	if (!path[depth].p_hdr)
+		path[depth].p_hdr = ext_block_hdr(path[depth].p_bh);
+	eh = path[depth].p_hdr;
+	if (unlikely(path[depth].p_hdr == NULL)) {
+		EXT4_ERROR_INODE(inode, "path[%d].p_hdr == NULL", depth);
+		return -EFSCORRUPTED;
+	}
+	/* find where to start removing */
+	ex = path[depth].p_ext;
+	if (!ex)
+		ex = EXT_LAST_EXTENT(eh);
+
+	ex_ee_block = le32_to_cpu(ex->ee_block);
+	ex_ee_len = ext4_ext_get_actual_len(ex);
+
+	trace_ext4_ext_rm_leaf(inode, start, ex, partial);
+
+	while (ex >= EXT_FIRST_EXTENT(eh) &&
+			ex_ee_block + ex_ee_len > start) {
+
+		if (ext4_ext_is_unwritten(ex))
+			unwritten = 1;
+		else
+			unwritten = 0;
+
+		ext_debug(inode, "remove ext %u:[%d]%d\n", ex_ee_block,
+			  unwritten, ex_ee_len);
+		path[depth].p_ext = ex;
+
+		a = max(ex_ee_block, start);
+		b = min(ex_ee_block + ex_ee_len - 1, end);
+
+		ext_debug(inode, "  border %u:%u\n", a, b);
+
+		/* If this extent is beyond the end of the hole, skip it */
+		if (end < ex_ee_block) {
+			/*
+			 * We're going to skip this extent and move to another,
+			 * so note that its first cluster is in use to avoid
+			 * freeing it when removing blocks.  Eventually, the
+			 * right edge of the truncated/punched region will
+			 * be just to the left.
+			 */
+			if (sbi->s_cluster_ratio > 1) {
+				pblk = ext4_ext_pblock(ex);
+				partial->pclu = EXT4_B2C(sbi, pblk);
+				partial->state = nofree;
+			}
+			ex--;
+			ex_ee_block = le32_to_cpu(ex->ee_block);
+			ex_ee_len = ext4_ext_get_actual_len(ex);
+			continue;
+		} else if (b != ex_ee_block + ex_ee_len - 1) {
+			EXT4_ERROR_INODE(inode,
+					 "can not handle truncate %u:%u "
+					 "on extent %u:%u",
+					 start, end, ex_ee_block,
+					 ex_ee_block + ex_ee_len - 1);
+			err = -EFSCORRUPTED;
+			goto out;
+		} else if (a != ex_ee_block) {
+			/* remove tail of the extent */
+			num = a - ex_ee_block;
+		} else {
+			/* remove whole extent: excellent! */
+			num = 0;
+		}
+		/*
+		 * 3 for leaf, sb, and inode plus 2 (bmap and group
+		 * descriptor) for each block group; assume two block
+		 * groups plus ex_ee_len/blocks_per_block_group for
+		 * the worst case
+		 */
+		credits = 7 + 2*(ex_ee_len/EXT4_BLOCKS_PER_GROUP(inode->i_sb));
+		if (ex == EXT_FIRST_EXTENT(eh)) {
+			correct_index = 1;
+			credits += (ext_depth(inode)) + 1;
+		}
+		credits += EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb);
+		/*
+		 * We may end up freeing some index blocks and data from the
+		 * punched range. Note that partial clusters are accounted for
+		 * by ext4_free_data_revoke_credits().
+		 */
+		revoke_credits =
+			ext4_free_metadata_revoke_credits(inode->i_sb,
+							  ext_depth(inode)) +
+			ext4_free_data_revoke_credits(inode, b - a + 1);
+
+		err = ext4_datasem_ensure_credits(handle, inode, credits,
+						  credits, revoke_credits);
+		if (err) {
+			if (err > 0)
+				err = -EAGAIN;
+			goto out;
+		}
+
+		err = ext4_ext_get_access(handle, inode, path + depth);
+		if (err)
+			goto out;
+
+		err = ext4_remove_blocks(handle, inode, ex, partial, a, b);
+		if (err)
+			goto out;
+
+		if (num == 0)
+			/* this extent is removed; mark slot entirely unused */
+			ext4_ext_store_pblock(ex, 0);
+
+		ex->ee_len = cpu_to_le16(num);
+		/*
+		 * Do not mark unwritten if all the blocks in the
+		 * extent have been removed.
+		 */
+		if (unwritten && num)
+			ext4_ext_mark_unwritten(ex);
+		/*
+		 * If the extent was completely released,
+		 * we need to remove it from the leaf
+		 */
+		if (num == 0) {
+			if (end != EXT_MAX_BLOCKS - 1) {
+				/*
+				 * For hole punching, we need to scoot all the
+				 * extents up when an extent is removed so that
+				 * we dont have blank extents in the middle
+				 */
+				memmove(ex, ex+1, (EXT_LAST_EXTENT(eh) - ex) *
+					sizeof(struct ext4_extent));
+
+				/* Now get rid of the one at the end */
+				memset(EXT_LAST_EXTENT(eh), 0,
+					sizeof(struct ext4_extent));
+			}
+			le16_add_cpu(&eh->eh_entries, -1);
+		}
+
+		err = ext4_ext_dirty(handle, inode, path + depth);
+		if (err)
+			goto out;
+
+		ext_debug(inode, "new extent: %u:%u:%llu\n", ex_ee_block, num,
+				ext4_ext_pblock(ex));
+		ex--;
+		ex_ee_block = le32_to_cpu(ex->ee_block);
+		ex_ee_len = ext4_ext_get_actual_len(ex);
+	}
+
+	if (correct_index && eh->eh_entries)
+		err = ext4_ext_correct_indexes(handle, inode, path);
+
+	/*
+	 * If there's a partial cluster and at least one extent remains in
+	 * the leaf, free the partial cluster if it isn't shared with the
+	 * current extent.  If it is shared with the current extent
+	 * we reset the partial cluster because we've reached the start of the
+	 * truncated/punched region and we're done removing blocks.
+	 */
+	if (partial->state == tofree && ex >= EXT_FIRST_EXTENT(eh)) {
+		pblk = ext4_ext_pblock(ex) + ex_ee_len - 1;
+		if (partial->pclu != EXT4_B2C(sbi, pblk)) {
+			int flags = get_default_free_blocks_flags(inode);
+
+			if (ext4_is_pending(inode, partial->lblk))
+				flags |= EXT4_FREE_BLOCKS_RERESERVE_CLUSTER;
+			ext4_free_blocks(handle, inode, NULL,
+					 EXT4_C2B(sbi, partial->pclu),
+					 sbi->s_cluster_ratio, flags);
+			if (flags & EXT4_FREE_BLOCKS_RERESERVE_CLUSTER)
+				ext4_rereserve_cluster(inode, partial->lblk);
+		}
+		partial->state = initial;
+	}
+
+	/* if this leaf is free, then we should
+	 * remove it from index block above */
+	if (err == 0 && eh->eh_entries == 0 && path[depth].p_bh != NULL)
+		err = ext4_ext_rm_idx(handle, inode, path, depth);
+
+out:
+	return err;
+}
+
+/*
+ * ext4_ext_more_to_rm:
+ * returns 1 if current index has to be freed (even partial)
+ */
+static int
+ext4_ext_more_to_rm(struct ext4_ext_path *path)
+{
+	BUG_ON(path->p_idx == NULL);
+
+	if (path->p_idx < EXT_FIRST_INDEX(path->p_hdr))
+		return 0;
+
+	/*
+	 * if truncate on deeper level happened, it wasn't partial,
+	 * so we have to consider current index for truncation
+	 */
+	if (le16_to_cpu(path->p_hdr->eh_entries) == path->p_block)
+		return 0;
+	return 1;
+}
+
+int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start,
+			  ext4_lblk_t end)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	int depth = ext_depth(inode);
+	struct ext4_ext_path *path = NULL;
+	struct partial_cluster partial;
+	handle_t *handle;
+	int i = 0, err = 0;
+	int flags = EXT4_EX_NOCACHE | EXT4_EX_NOFAIL;
+
+	partial.pclu = 0;
+	partial.lblk = 0;
+	partial.state = initial;
+
+	ext_debug(inode, "truncate since %u to %u\n", start, end);
+
+	/* probably first extent we're gonna free will be last in block */
+	handle = ext4_journal_start_with_revoke(inode, EXT4_HT_TRUNCATE,
+			depth + 1,
+			ext4_free_metadata_revoke_credits(inode->i_sb, depth));
+	if (IS_ERR(handle))
+		return PTR_ERR(handle);
+
+again:
+	trace_ext4_ext_remove_space(inode, start, end, depth);
+
+	/*
+	 * Check if we are removing extents inside the extent tree. If that
+	 * is the case, we are going to punch a hole inside the extent tree
+	 * so we have to check whether we need to split the extent covering
+	 * the last block to remove so we can easily remove the part of it
+	 * in ext4_ext_rm_leaf().
+	 */
+	if (end < EXT_MAX_BLOCKS - 1) {
+		struct ext4_extent *ex;
+		ext4_lblk_t ee_block, ex_end, lblk;
+		ext4_fsblk_t pblk;
+
+		/* find extent for or closest extent to this block */
+		path = ext4_find_extent(inode, end, NULL, flags);
+		if (IS_ERR(path)) {
+			ext4_journal_stop(handle);
+			return PTR_ERR(path);
+		}
+		depth = ext_depth(inode);
+		/* Leaf not may not exist only if inode has no blocks at all */
+		ex = path[depth].p_ext;
+		if (!ex) {
+			if (depth) {
+				EXT4_ERROR_INODE(inode,
+						 "path[%d].p_hdr == NULL",
+						 depth);
+				err = -EFSCORRUPTED;
+			}
+			goto out;
+		}
+
+		ee_block = le32_to_cpu(ex->ee_block);
+		ex_end = ee_block + ext4_ext_get_actual_len(ex) - 1;
+
+		/*
+		 * See if the last block is inside the extent, if so split
+		 * the extent at 'end' block so we can easily remove the
+		 * tail of the first part of the split extent in
+		 * ext4_ext_rm_leaf().
+		 */
+		if (end >= ee_block && end < ex_end) {
+
+			/*
+			 * If we're going to split the extent, note that
+			 * the cluster containing the block after 'end' is
+			 * in use to avoid freeing it when removing blocks.
+			 */
+			if (sbi->s_cluster_ratio > 1) {
+				pblk = ext4_ext_pblock(ex) + end - ee_block + 1;
+				partial.pclu = EXT4_B2C(sbi, pblk);
+				partial.state = nofree;
+			}
+
+			/*
+			 * Split the extent in two so that 'end' is the last
+			 * block in the first new extent. Also we should not
+			 * fail removing space due to ENOSPC so try to use
+			 * reserved block if that happens.
+			 */
+			path = ext4_force_split_extent_at(handle, inode, path,
+							  end + 1, 1);
+			if (IS_ERR(path)) {
+				err = PTR_ERR(path);
+				goto out;
+			}
+		} else if (sbi->s_cluster_ratio > 1 && end >= ex_end &&
+			   partial.state == initial) {
+			/*
+			 * If we're punching, there's an extent to the right.
+			 * If the partial cluster hasn't been set, set it to
+			 * that extent's first cluster and its state to nofree
+			 * so it won't be freed should it contain blocks to be
+			 * removed. If it's already set (tofree/nofree), we're
+			 * retrying and keep the original partial cluster info
+			 * so a cluster marked tofree as a result of earlier
+			 * extent removal is not lost.
+			 */
+			lblk = ex_end + 1;
+			err = ext4_ext_search_right(inode, path, &lblk, &pblk,
+						    NULL, flags);
+			if (err < 0)
+				goto out;
+			if (pblk) {
+				partial.pclu = EXT4_B2C(sbi, pblk);
+				partial.state = nofree;
+			}
+		}
+	}
+	/*
+	 * We start scanning from right side, freeing all the blocks
+	 * after i_size and walking into the tree depth-wise.
+	 */
+	depth = ext_depth(inode);
+	if (path) {
+		int k = i = depth;
+		while (--k > 0)
+			path[k].p_block =
+				le16_to_cpu(path[k].p_hdr->eh_entries)+1;
+	} else {
+		path = kcalloc(depth + 1, sizeof(struct ext4_ext_path),
+			       GFP_NOFS | __GFP_NOFAIL);
+		if (path == NULL) {
+			ext4_journal_stop(handle);
+			return -ENOMEM;
+		}
+		path[0].p_maxdepth = path[0].p_depth = depth;
+		path[0].p_hdr = ext_inode_hdr(inode);
+		i = 0;
+
+		if (ext4_ext_check(inode, path[0].p_hdr, depth, 0)) {
+			err = -EFSCORRUPTED;
+			goto out;
+		}
+	}
+	err = 0;
+
+	while (i >= 0 && err == 0) {
+		if (i == depth) {
+			/* this is leaf block */
+			err = ext4_ext_rm_leaf(handle, inode, path,
+					       &partial, start, end);
+			/* root level has p_bh == NULL, brelse() eats this */
+			ext4_ext_path_brelse(path + i);
+			i--;
+			continue;
+		}
+
+		/* this is index block */
+		if (!path[i].p_hdr) {
+			ext_debug(inode, "initialize header\n");
+			path[i].p_hdr = ext_block_hdr(path[i].p_bh);
+		}
+
+		if (!path[i].p_idx) {
+			/* this level hasn't been touched yet */
+			path[i].p_idx = EXT_LAST_INDEX(path[i].p_hdr);
+			path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries)+1;
+			ext_debug(inode, "init index ptr: hdr 0x%p, num %d\n",
+				  path[i].p_hdr,
+				  le16_to_cpu(path[i].p_hdr->eh_entries));
+		} else {
+			/* we were already here, see at next index */
+			path[i].p_idx--;
+		}
+
+		ext_debug(inode, "level %d - index, first 0x%p, cur 0x%p\n",
+				i, EXT_FIRST_INDEX(path[i].p_hdr),
+				path[i].p_idx);
+		if (ext4_ext_more_to_rm(path + i)) {
+			struct buffer_head *bh;
+			/* go to the next level */
+			ext_debug(inode, "move to level %d (block %llu)\n",
+				  i + 1, ext4_idx_pblock(path[i].p_idx));
+			memset(path + i + 1, 0, sizeof(*path));
+			bh = read_extent_tree_block(inode, path[i].p_idx,
+						    depth - i - 1, flags);
+			if (IS_ERR(bh)) {
+				/* should we reset i_size? */
+				err = PTR_ERR(bh);
+				break;
+			}
+			/* Yield here to deal with large extent trees.
+			 * Should be a no-op if we did IO above. */
+			cond_resched();
+			if (WARN_ON(i + 1 > depth)) {
+				err = -EFSCORRUPTED;
+				break;
+			}
+			path[i + 1].p_bh = bh;
+
+			/* save actual number of indexes since this
+			 * number is changed at the next iteration */
+			path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries);
+			i++;
+		} else {
+			/* we finished processing this index, go up */
+			if (path[i].p_hdr->eh_entries == 0 && i > 0) {
+				/* index is empty, remove it;
+				 * handle must be already prepared by the
+				 * truncatei_leaf() */
+				err = ext4_ext_rm_idx(handle, inode, path, i);
+			}
+			/* root level has p_bh == NULL, brelse() eats this */
+			ext4_ext_path_brelse(path + i);
+			i--;
+			ext_debug(inode, "return to level %d\n", i);
+		}
+	}
+
+	trace_ext4_ext_remove_space_done(inode, start, end, depth, &partial,
+					 path->p_hdr->eh_entries);
+
+	/*
+	 * if there's a partial cluster and we have removed the first extent
+	 * in the file, then we also free the partial cluster, if any
+	 */
+	if (partial.state == tofree && err == 0) {
+		int flags = get_default_free_blocks_flags(inode);
+
+		if (ext4_is_pending(inode, partial.lblk))
+			flags |= EXT4_FREE_BLOCKS_RERESERVE_CLUSTER;
+		ext4_free_blocks(handle, inode, NULL,
+				 EXT4_C2B(sbi, partial.pclu),
+				 sbi->s_cluster_ratio, flags);
+		if (flags & EXT4_FREE_BLOCKS_RERESERVE_CLUSTER)
+			ext4_rereserve_cluster(inode, partial.lblk);
+		partial.state = initial;
+	}
+
+	/* TODO: flexible tree reduction should be here */
+	if (path->p_hdr->eh_entries == 0) {
+		/*
+		 * truncate to zero freed all the tree,
+		 * so we need to correct eh_depth
+		 */
+		err = ext4_ext_get_access(handle, inode, path);
+		if (err == 0) {
+			ext_inode_hdr(inode)->eh_depth = 0;
+			ext_inode_hdr(inode)->eh_max =
+				cpu_to_le16(ext4_ext_space_root(inode, 0));
+			err = ext4_ext_dirty(handle, inode, path);
+		}
+	}
+out:
+	ext4_free_ext_path(path);
+	path = NULL;
+	if (err == -EAGAIN)
+		goto again;
+	ext4_journal_stop(handle);
+
+	return err;
+}
+
+/*
+ * called at mount time
+ */
+void ext4_ext_init(struct super_block *sb)
+{
+	/*
+	 * possible initialization would be here
+	 */
+
+	if (ext4_has_feature_extents(sb)) {
+#if defined(AGGRESSIVE_TEST) || defined(CHECK_BINSEARCH) || defined(EXTENTS_STATS)
+		printk(KERN_INFO "EXT4-fs: file extents enabled"
+#ifdef AGGRESSIVE_TEST
+		       ", aggressive tests"
+#endif
+#ifdef CHECK_BINSEARCH
+		       ", check binsearch"
+#endif
+#ifdef EXTENTS_STATS
+		       ", stats"
+#endif
+		       "\n");
+#endif
+#ifdef EXTENTS_STATS
+		spin_lock_init(&EXT4_SB(sb)->s_ext_stats_lock);
+		EXT4_SB(sb)->s_ext_min = 1 << 30;
+		EXT4_SB(sb)->s_ext_max = 0;
+#endif
+	}
+}
+
+/*
+ * called at umount time
+ */
+void ext4_ext_release(struct super_block *sb)
+{
+	if (!ext4_has_feature_extents(sb))
+		return;
+
+#ifdef EXTENTS_STATS
+	if (EXT4_SB(sb)->s_ext_blocks && EXT4_SB(sb)->s_ext_extents) {
+		struct ext4_sb_info *sbi = EXT4_SB(sb);
+		printk(KERN_ERR "EXT4-fs: %lu blocks in %lu extents (%lu ave)\n",
+			sbi->s_ext_blocks, sbi->s_ext_extents,
+			sbi->s_ext_blocks / sbi->s_ext_extents);
+		printk(KERN_ERR "EXT4-fs: extents: %lu min, %lu max, max depth %lu\n",
+			sbi->s_ext_min, sbi->s_ext_max, sbi->s_depth_max);
+	}
+#endif
+}
+
+static void ext4_zeroout_es(struct inode *inode, struct ext4_extent *ex)
+{
+	ext4_lblk_t  ee_block;
+	ext4_fsblk_t ee_pblock;
+	unsigned int ee_len;
+
+	ee_block  = le32_to_cpu(ex->ee_block);
+	ee_len    = ext4_ext_get_actual_len(ex);
+	ee_pblock = ext4_ext_pblock(ex);
+
+	if (ee_len == 0)
+		return;
+
+	ext4_es_insert_extent(inode, ee_block, ee_len, ee_pblock,
+			      EXTENT_STATUS_WRITTEN, false);
+}
+
+/* FIXME!! we need to try to merge to left or right after zero-out  */
+static int ext4_ext_zeroout(struct inode *inode, struct ext4_extent *ex)
+{
+	ext4_fsblk_t ee_pblock;
+	unsigned int ee_len;
+
+	ee_len    = ext4_ext_get_actual_len(ex);
+	ee_pblock = ext4_ext_pblock(ex);
+	return ext4_issue_zeroout(inode, le32_to_cpu(ex->ee_block), ee_pblock,
+				  ee_len);
+}
+
+/*
+ * ext4_split_extent_at() splits an extent at given block.
+ *
+ * @handle: the journal handle
+ * @inode: the file inode
+ * @path: the path to the extent
+ * @split: the logical block where the extent is splitted.
+ * @split_flags: indicates if the extent could be zeroout if split fails, and
+ *		 the states(init or unwritten) of new extents.
+ * @flags: flags used to insert new extent to extent tree.
+ *
+ *
+ * Splits extent [a, b] into two extents [a, @split) and [@split, b], states
+ * of which are determined by split_flag.
+ *
+ * There are two cases:
+ *  a> the extent are splitted into two extent.
+ *  b> split is not needed, and just mark the extent.
+ *
+ * Return an extent path pointer on success, or an error pointer on failure.
+ */
+static struct ext4_ext_path *ext4_split_extent_at(handle_t *handle,
+						  struct inode *inode,
+						  struct ext4_ext_path *path,
+						  ext4_lblk_t split,
+						  int split_flag, int flags)
+{
+	ext4_fsblk_t newblock;
+	ext4_lblk_t ee_block;
+	struct ext4_extent *ex, newex, orig_ex, zero_ex;
+	struct ext4_extent *ex2 = NULL;
+	unsigned int ee_len, depth;
+	int err = 0;
+
+	BUG_ON((split_flag & (EXT4_EXT_DATA_VALID1 | EXT4_EXT_DATA_VALID2)) ==
+	       (EXT4_EXT_DATA_VALID1 | EXT4_EXT_DATA_VALID2));
+
+	ext_debug(inode, "logical block %llu\n", (unsigned long long)split);
+
+	ext4_ext_show_leaf(inode, path);
+
+	depth = ext_depth(inode);
+	ex = path[depth].p_ext;
+	ee_block = le32_to_cpu(ex->ee_block);
+	ee_len = ext4_ext_get_actual_len(ex);
+	newblock = split - ee_block + ext4_ext_pblock(ex);
+
+	BUG_ON(split < ee_block || split >= (ee_block + ee_len));
+	BUG_ON(!ext4_ext_is_unwritten(ex) &&
+	       split_flag & (EXT4_EXT_MAY_ZEROOUT |
+			     EXT4_EXT_MARK_UNWRIT1 |
+			     EXT4_EXT_MARK_UNWRIT2));
+
+	err = ext4_ext_get_access(handle, inode, path + depth);
+	if (err)
+		goto out;
+
+	if (split == ee_block) {
+		/*
+		 * case b: block @split is the block that the extent begins with
+		 * then we just change the state of the extent, and splitting
+		 * is not needed.
+		 */
+		if (split_flag & EXT4_EXT_MARK_UNWRIT2)
+			ext4_ext_mark_unwritten(ex);
+		else
+			ext4_ext_mark_initialized(ex);
+
+		if (!(flags & EXT4_GET_BLOCKS_PRE_IO))
+			ext4_ext_try_to_merge(handle, inode, path, ex);
+
+		err = ext4_ext_dirty(handle, inode, path + path->p_depth);
+		goto out;
+	}
+
+	/* case a */
+	memcpy(&orig_ex, ex, sizeof(orig_ex));
+	ex->ee_len = cpu_to_le16(split - ee_block);
+	if (split_flag & EXT4_EXT_MARK_UNWRIT1)
+		ext4_ext_mark_unwritten(ex);
+
+	/*
+	 * path may lead to new leaf, not to original leaf any more
+	 * after ext4_ext_insert_extent() returns,
+	 */
+	err = ext4_ext_dirty(handle, inode, path + depth);
+	if (err)
+		goto fix_extent_len;
+
+	ex2 = &newex;
+	ex2->ee_block = cpu_to_le32(split);
+	ex2->ee_len   = cpu_to_le16(ee_len - (split - ee_block));
+	ext4_ext_store_pblock(ex2, newblock);
+	if (split_flag & EXT4_EXT_MARK_UNWRIT2)
+		ext4_ext_mark_unwritten(ex2);
+
+	path = ext4_ext_insert_extent(handle, inode, path, &newex, flags);
+	if (!IS_ERR(path))
+		goto out;
+
+	err = PTR_ERR(path);
+	if (err != -ENOSPC && err != -EDQUOT && err != -ENOMEM)
+		return path;
+
+	/*
+	 * Get a new path to try to zeroout or fix the extent length.
+	 * Using EXT4_EX_NOFAIL guarantees that ext4_find_extent()
+	 * will not return -ENOMEM, otherwise -ENOMEM will cause a
+	 * retry in do_writepages(), and a WARN_ON may be triggered
+	 * in ext4_da_update_reserve_space() due to an incorrect
+	 * ee_len causing the i_reserved_data_blocks exception.
+	 */
+	path = ext4_find_extent(inode, ee_block, NULL, flags | EXT4_EX_NOFAIL);
+	if (IS_ERR(path)) {
+		EXT4_ERROR_INODE(inode, "Failed split extent on %u, err %ld",
+				 split, PTR_ERR(path));
+		return path;
+	}
+	depth = ext_depth(inode);
+	ex = path[depth].p_ext;
+
+	if (EXT4_EXT_MAY_ZEROOUT & split_flag) {
+		if (split_flag & (EXT4_EXT_DATA_VALID1|EXT4_EXT_DATA_VALID2)) {
+			if (split_flag & EXT4_EXT_DATA_VALID1) {
+				err = ext4_ext_zeroout(inode, ex2);
+				zero_ex.ee_block = ex2->ee_block;
+				zero_ex.ee_len = cpu_to_le16(
+						ext4_ext_get_actual_len(ex2));
+				ext4_ext_store_pblock(&zero_ex,
+						      ext4_ext_pblock(ex2));
+			} else {
+				err = ext4_ext_zeroout(inode, ex);
+				zero_ex.ee_block = ex->ee_block;
+				zero_ex.ee_len = cpu_to_le16(
+						ext4_ext_get_actual_len(ex));
+				ext4_ext_store_pblock(&zero_ex,
+						      ext4_ext_pblock(ex));
+			}
+		} else {
+			err = ext4_ext_zeroout(inode, &orig_ex);
+			zero_ex.ee_block = orig_ex.ee_block;
+			zero_ex.ee_len = cpu_to_le16(
+						ext4_ext_get_actual_len(&orig_ex));
+			ext4_ext_store_pblock(&zero_ex,
+					      ext4_ext_pblock(&orig_ex));
+		}
+
+		if (!err) {
+			/* update the extent length and mark as initialized */
+			ex->ee_len = cpu_to_le16(ee_len);
+			ext4_ext_try_to_merge(handle, inode, path, ex);
+			err = ext4_ext_dirty(handle, inode, path + path->p_depth);
+			if (!err)
+				/* update extent status tree */
+				ext4_zeroout_es(inode, &zero_ex);
+			/* If we failed at this point, we don't know in which
+			 * state the extent tree exactly is so don't try to fix
+			 * length of the original extent as it may do even more
+			 * damage.
+			 */
+			goto out;
+		}
+	}
+
+fix_extent_len:
+	ex->ee_len = orig_ex.ee_len;
+	/*
+	 * Ignore ext4_ext_dirty return value since we are already in error path
+	 * and err is a non-zero error code.
+	 */
+	ext4_ext_dirty(handle, inode, path + path->p_depth);
+out:
+	if (err) {
+		ext4_free_ext_path(path);
+		path = ERR_PTR(err);
+	}
+	ext4_ext_show_leaf(inode, path);
+	return path;
+}
+
+/*
+ * ext4_split_extent() splits an extent and mark extent which is covered
+ * by @map as split_flags indicates
+ *
+ * It may result in splitting the extent into multiple extents (up to three)
+ * There are three possibilities:
+ *   a> There is no split required
+ *   b> Splits in two extents: Split is happening at either end of the extent
+ *   c> Splits in three extents: Somone is splitting in middle of the extent
+ *
+ */
+static struct ext4_ext_path *ext4_split_extent(handle_t *handle,
+					       struct inode *inode,
+					       struct ext4_ext_path *path,
+					       struct ext4_map_blocks *map,
+					       int split_flag, int flags,
+					       unsigned int *allocated)
+{
+	ext4_lblk_t ee_block;
+	struct ext4_extent *ex;
+	unsigned int ee_len, depth;
+	int unwritten;
+	int split_flag1, flags1;
+
+	depth = ext_depth(inode);
+	ex = path[depth].p_ext;
+	ee_block = le32_to_cpu(ex->ee_block);
+	ee_len = ext4_ext_get_actual_len(ex);
+	unwritten = ext4_ext_is_unwritten(ex);
+
+	if (map->m_lblk + map->m_len < ee_block + ee_len) {
+		split_flag1 = split_flag & EXT4_EXT_MAY_ZEROOUT;
+		flags1 = flags | EXT4_GET_BLOCKS_PRE_IO;
+		if (unwritten)
+			split_flag1 |= EXT4_EXT_MARK_UNWRIT1 |
+				       EXT4_EXT_MARK_UNWRIT2;
+		if (split_flag & EXT4_EXT_DATA_VALID2)
+			split_flag1 |= EXT4_EXT_DATA_VALID1;
+		path = ext4_split_extent_at(handle, inode, path,
+				map->m_lblk + map->m_len, split_flag1, flags1);
+		if (IS_ERR(path))
+			return path;
+		/*
+		 * Update path is required because previous ext4_split_extent_at
+		 * may result in split of original leaf or extent zeroout.
+		 */
+		path = ext4_find_extent(inode, map->m_lblk, path, flags);
+		if (IS_ERR(path))
+			return path;
+		depth = ext_depth(inode);
+		ex = path[depth].p_ext;
+		if (!ex) {
+			EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
+					(unsigned long) map->m_lblk);
+			ext4_free_ext_path(path);
+			return ERR_PTR(-EFSCORRUPTED);
+		}
+		unwritten = ext4_ext_is_unwritten(ex);
+	}
+
+	if (map->m_lblk >= ee_block) {
+		split_flag1 = split_flag & EXT4_EXT_DATA_VALID2;
+		if (unwritten) {
+			split_flag1 |= EXT4_EXT_MARK_UNWRIT1;
+			split_flag1 |= split_flag & (EXT4_EXT_MAY_ZEROOUT |
+						     EXT4_EXT_MARK_UNWRIT2);
+		}
+		path = ext4_split_extent_at(handle, inode, path,
+				map->m_lblk, split_flag1, flags);
+		if (IS_ERR(path))
+			return path;
+	}
+
+	if (allocated) {
+		if (map->m_lblk + map->m_len > ee_block + ee_len)
+			*allocated = ee_len - (map->m_lblk - ee_block);
+		else
+			*allocated = map->m_len;
+	}
+	ext4_ext_show_leaf(inode, path);
+	return path;
+}
+
+/*
+ * This function is called by ext4_ext_map_blocks() if someone tries to write
+ * to an unwritten extent. It may result in splitting the unwritten
+ * extent into multiple extents (up to three - one initialized and two
+ * unwritten).
+ * There are three possibilities:
+ *   a> There is no split required: Entire extent should be initialized
+ *   b> Splits in two extents: Write is happening at either end of the extent
+ *   c> Splits in three extents: Somone is writing in middle of the extent
+ *
+ * Pre-conditions:
+ *  - The extent pointed to by 'path' is unwritten.
+ *  - The extent pointed to by 'path' contains a superset
+ *    of the logical span [map->m_lblk, map->m_lblk + map->m_len).
+ *
+ * Post-conditions on success:
+ *  - the returned value is the number of blocks beyond map->l_lblk
+ *    that are allocated and initialized.
+ *    It is guaranteed to be >= map->m_len.
+ */
+static struct ext4_ext_path *
+ext4_ext_convert_to_initialized(handle_t *handle, struct inode *inode,
+			struct ext4_map_blocks *map, struct ext4_ext_path *path,
+			int flags, unsigned int *allocated)
+{
+	struct ext4_sb_info *sbi;
+	struct ext4_extent_header *eh;
+	struct ext4_map_blocks split_map;
+	struct ext4_extent zero_ex1, zero_ex2;
+	struct ext4_extent *ex, *abut_ex;
+	ext4_lblk_t ee_block, eof_block;
+	unsigned int ee_len, depth, map_len = map->m_len;
+	int err = 0;
+	int split_flag = EXT4_EXT_DATA_VALID2;
+	unsigned int max_zeroout = 0;
+
+	ext_debug(inode, "logical block %llu, max_blocks %u\n",
+		  (unsigned long long)map->m_lblk, map_len);
+
+	sbi = EXT4_SB(inode->i_sb);
+	eof_block = (EXT4_I(inode)->i_disksize + inode->i_sb->s_blocksize - 1)
+			>> inode->i_sb->s_blocksize_bits;
+	if (eof_block < map->m_lblk + map_len)
+		eof_block = map->m_lblk + map_len;
+
+	depth = ext_depth(inode);
+	eh = path[depth].p_hdr;
+	ex = path[depth].p_ext;
+	ee_block = le32_to_cpu(ex->ee_block);
+	ee_len = ext4_ext_get_actual_len(ex);
+	zero_ex1.ee_len = 0;
+	zero_ex2.ee_len = 0;
+
+	trace_ext4_ext_convert_to_initialized_enter(inode, map, ex);
+
+	/* Pre-conditions */
+	BUG_ON(!ext4_ext_is_unwritten(ex));
+	BUG_ON(!in_range(map->m_lblk, ee_block, ee_len));
+
+	/*
+	 * Attempt to transfer newly initialized blocks from the currently
+	 * unwritten extent to its neighbor. This is much cheaper
+	 * than an insertion followed by a merge as those involve costly
+	 * memmove() calls. Transferring to the left is the common case in
+	 * steady state for workloads doing fallocate(FALLOC_FL_KEEP_SIZE)
+	 * followed by append writes.
+	 *
+	 * Limitations of the current logic:
+	 *  - L1: we do not deal with writes covering the whole extent.
+	 *    This would require removing the extent if the transfer
+	 *    is possible.
+	 *  - L2: we only attempt to merge with an extent stored in the
+	 *    same extent tree node.
+	 */
+	*allocated = 0;
+	if ((map->m_lblk == ee_block) &&
+		/* See if we can merge left */
+		(map_len < ee_len) &&		/*L1*/
+		(ex > EXT_FIRST_EXTENT(eh))) {	/*L2*/
+		ext4_lblk_t prev_lblk;
+		ext4_fsblk_t prev_pblk, ee_pblk;
+		unsigned int prev_len;
+
+		abut_ex = ex - 1;
+		prev_lblk = le32_to_cpu(abut_ex->ee_block);
+		prev_len = ext4_ext_get_actual_len(abut_ex);
+		prev_pblk = ext4_ext_pblock(abut_ex);
+		ee_pblk = ext4_ext_pblock(ex);
+
+		/*
+		 * A transfer of blocks from 'ex' to 'abut_ex' is allowed
+		 * upon those conditions:
+		 * - C1: abut_ex is initialized,
+		 * - C2: abut_ex is logically abutting ex,
+		 * - C3: abut_ex is physically abutting ex,
+		 * - C4: abut_ex can receive the additional blocks without
+		 *   overflowing the (initialized) length limit.
+		 */
+		if ((!ext4_ext_is_unwritten(abut_ex)) &&		/*C1*/
+			((prev_lblk + prev_len) == ee_block) &&		/*C2*/
+			((prev_pblk + prev_len) == ee_pblk) &&		/*C3*/
+			(prev_len < (EXT_INIT_MAX_LEN - map_len))) {	/*C4*/
+			err = ext4_ext_get_access(handle, inode, path + depth);
+			if (err)
+				goto errout;
+
+			trace_ext4_ext_convert_to_initialized_fastpath(inode,
+				map, ex, abut_ex);
+
+			/* Shift the start of ex by 'map_len' blocks */
+			ex->ee_block = cpu_to_le32(ee_block + map_len);
+			ext4_ext_store_pblock(ex, ee_pblk + map_len);
+			ex->ee_len = cpu_to_le16(ee_len - map_len);
+			ext4_ext_mark_unwritten(ex); /* Restore the flag */
+
+			/* Extend abut_ex by 'map_len' blocks */
+			abut_ex->ee_len = cpu_to_le16(prev_len + map_len);
+
+			/* Result: number of initialized blocks past m_lblk */
+			*allocated = map_len;
+		}
+	} else if (((map->m_lblk + map_len) == (ee_block + ee_len)) &&
+		   (map_len < ee_len) &&	/*L1*/
+		   ex < EXT_LAST_EXTENT(eh)) {	/*L2*/
+		/* See if we can merge right */
+		ext4_lblk_t next_lblk;
+		ext4_fsblk_t next_pblk, ee_pblk;
+		unsigned int next_len;
+
+		abut_ex = ex + 1;
+		next_lblk = le32_to_cpu(abut_ex->ee_block);
+		next_len = ext4_ext_get_actual_len(abut_ex);
+		next_pblk = ext4_ext_pblock(abut_ex);
+		ee_pblk = ext4_ext_pblock(ex);
+
+		/*
+		 * A transfer of blocks from 'ex' to 'abut_ex' is allowed
+		 * upon those conditions:
+		 * - C1: abut_ex is initialized,
+		 * - C2: abut_ex is logically abutting ex,
+		 * - C3: abut_ex is physically abutting ex,
+		 * - C4: abut_ex can receive the additional blocks without
+		 *   overflowing the (initialized) length limit.
+		 */
+		if ((!ext4_ext_is_unwritten(abut_ex)) &&		/*C1*/
+		    ((map->m_lblk + map_len) == next_lblk) &&		/*C2*/
+		    ((ee_pblk + ee_len) == next_pblk) &&		/*C3*/
+		    (next_len < (EXT_INIT_MAX_LEN - map_len))) {	/*C4*/
+			err = ext4_ext_get_access(handle, inode, path + depth);
+			if (err)
+				goto errout;
+
+			trace_ext4_ext_convert_to_initialized_fastpath(inode,
+				map, ex, abut_ex);
+
+			/* Shift the start of abut_ex by 'map_len' blocks */
+			abut_ex->ee_block = cpu_to_le32(next_lblk - map_len);
+			ext4_ext_store_pblock(abut_ex, next_pblk - map_len);
+			ex->ee_len = cpu_to_le16(ee_len - map_len);
+			ext4_ext_mark_unwritten(ex); /* Restore the flag */
+
+			/* Extend abut_ex by 'map_len' blocks */
+			abut_ex->ee_len = cpu_to_le16(next_len + map_len);
+
+			/* Result: number of initialized blocks past m_lblk */
+			*allocated = map_len;
+		}
+	}
+	if (*allocated) {
+		/* Mark the block containing both extents as dirty */
+		err = ext4_ext_dirty(handle, inode, path + depth);
+
+		/* Update path to point to the right extent */
+		path[depth].p_ext = abut_ex;
+		if (err)
+			goto errout;
+		goto out;
+	} else
+		*allocated = ee_len - (map->m_lblk - ee_block);
+
+	WARN_ON(map->m_lblk < ee_block);
+	/*
+	 * It is safe to convert extent to initialized via explicit
+	 * zeroout only if extent is fully inside i_size or new_size.
+	 */
+	split_flag |= ee_block + ee_len <= eof_block ? EXT4_EXT_MAY_ZEROOUT : 0;
+
+	if (EXT4_EXT_MAY_ZEROOUT & split_flag)
+		max_zeroout = sbi->s_extent_max_zeroout_kb >>
+			(inode->i_sb->s_blocksize_bits - 10);
+
+	/*
+	 * five cases:
+	 * 1. split the extent into three extents.
+	 * 2. split the extent into two extents, zeroout the head of the first
+	 *    extent.
+	 * 3. split the extent into two extents, zeroout the tail of the second
+	 *    extent.
+	 * 4. split the extent into two extents with out zeroout.
+	 * 5. no splitting needed, just possibly zeroout the head and / or the
+	 *    tail of the extent.
+	 */
+	split_map.m_lblk = map->m_lblk;
+	split_map.m_len = map->m_len;
+
+	if (max_zeroout && (*allocated > split_map.m_len)) {
+		if (*allocated <= max_zeroout) {
+			/* case 3 or 5 */
+			zero_ex1.ee_block =
+				 cpu_to_le32(split_map.m_lblk +
+					     split_map.m_len);
+			zero_ex1.ee_len =
+				cpu_to_le16(*allocated - split_map.m_len);
+			ext4_ext_store_pblock(&zero_ex1,
+				ext4_ext_pblock(ex) + split_map.m_lblk +
+				split_map.m_len - ee_block);
+			err = ext4_ext_zeroout(inode, &zero_ex1);
+			if (err)
+				goto fallback;
+			split_map.m_len = *allocated;
+		}
+		if (split_map.m_lblk - ee_block + split_map.m_len <
+								max_zeroout) {
+			/* case 2 or 5 */
+			if (split_map.m_lblk != ee_block) {
+				zero_ex2.ee_block = ex->ee_block;
+				zero_ex2.ee_len = cpu_to_le16(split_map.m_lblk -
+							ee_block);
+				ext4_ext_store_pblock(&zero_ex2,
+						      ext4_ext_pblock(ex));
+				err = ext4_ext_zeroout(inode, &zero_ex2);
+				if (err)
+					goto fallback;
+			}
+
+			split_map.m_len += split_map.m_lblk - ee_block;
+			split_map.m_lblk = ee_block;
+			*allocated = map->m_len;
+		}
+	}
+
+fallback:
+	path = ext4_split_extent(handle, inode, path, &split_map, split_flag,
+				 flags, NULL);
+	if (IS_ERR(path))
+		return path;
+out:
+	/* If we have gotten a failure, don't zero out status tree */
+	ext4_zeroout_es(inode, &zero_ex1);
+	ext4_zeroout_es(inode, &zero_ex2);
+	return path;
+
+errout:
+	ext4_free_ext_path(path);
+	return ERR_PTR(err);
+}
+
+/*
+ * This function is called by ext4_ext_map_blocks() from
+ * ext4_get_blocks_dio_write() when DIO to write
+ * to an unwritten extent.
+ *
+ * Writing to an unwritten extent may result in splitting the unwritten
+ * extent into multiple initialized/unwritten extents (up to three)
+ * There are three possibilities:
+ *   a> There is no split required: Entire extent should be unwritten
+ *   b> Splits in two extents: Write is happening at either end of the extent
+ *   c> Splits in three extents: Somone is writing in middle of the extent
+ *
+ * This works the same way in the case of initialized -> unwritten conversion.
+ *
+ * One of more index blocks maybe needed if the extent tree grow after
+ * the unwritten extent split. To prevent ENOSPC occur at the IO
+ * complete, we need to split the unwritten extent before DIO submit
+ * the IO. The unwritten extent called at this time will be split
+ * into three unwritten extent(at most). After IO complete, the part
+ * being filled will be convert to initialized by the end_io callback function
+ * via ext4_convert_unwritten_extents().
+ *
+ * The size of unwritten extent to be written is passed to the caller via the
+ * allocated pointer. Return an extent path pointer on success, or an error
+ * pointer on failure.
+ */
+static struct ext4_ext_path *ext4_split_convert_extents(handle_t *handle,
+					struct inode *inode,
+					struct ext4_map_blocks *map,
+					struct ext4_ext_path *path,
+					int flags, unsigned int *allocated)
+{
+	ext4_lblk_t eof_block;
+	ext4_lblk_t ee_block;
+	struct ext4_extent *ex;
+	unsigned int ee_len;
+	int split_flag = 0, depth;
+
+	ext_debug(inode, "logical block %llu, max_blocks %u\n",
+		  (unsigned long long)map->m_lblk, map->m_len);
+
+	eof_block = (EXT4_I(inode)->i_disksize + inode->i_sb->s_blocksize - 1)
+			>> inode->i_sb->s_blocksize_bits;
+	if (eof_block < map->m_lblk + map->m_len)
+		eof_block = map->m_lblk + map->m_len;
+	/*
+	 * It is safe to convert extent to initialized via explicit
+	 * zeroout only if extent is fully inside i_size or new_size.
+	 */
+	depth = ext_depth(inode);
+	ex = path[depth].p_ext;
+	ee_block = le32_to_cpu(ex->ee_block);
+	ee_len = ext4_ext_get_actual_len(ex);
+
+	/* Convert to unwritten */
+	if (flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN) {
+		split_flag |= EXT4_EXT_DATA_VALID1;
+	/* Convert to initialized */
+	} else if (flags & EXT4_GET_BLOCKS_CONVERT) {
+		split_flag |= ee_block + ee_len <= eof_block ?
+			      EXT4_EXT_MAY_ZEROOUT : 0;
+		split_flag |= (EXT4_EXT_MARK_UNWRIT2 | EXT4_EXT_DATA_VALID2);
+	}
+	flags |= EXT4_GET_BLOCKS_PRE_IO;
+	return ext4_split_extent(handle, inode, path, map, split_flag, flags,
+				 allocated);
+}
+
+static struct ext4_ext_path *
+ext4_convert_unwritten_extents_endio(handle_t *handle, struct inode *inode,
+				     struct ext4_map_blocks *map,
+				     struct ext4_ext_path *path)
+{
+	struct ext4_extent *ex;
+	ext4_lblk_t ee_block;
+	unsigned int ee_len;
+	int depth;
+	int err = 0;
+
+	depth = ext_depth(inode);
+	ex = path[depth].p_ext;
+	ee_block = le32_to_cpu(ex->ee_block);
+	ee_len = ext4_ext_get_actual_len(ex);
+
+	ext_debug(inode, "logical block %llu, max_blocks %u\n",
+		  (unsigned long long)ee_block, ee_len);
+
+	/* If extent is larger than requested it is a clear sign that we still
+	 * have some extent state machine issues left. So extent_split is still
+	 * required.
+	 * TODO: Once all related issues will be fixed this situation should be
+	 * illegal.
+	 */
+	if (ee_block != map->m_lblk || ee_len > map->m_len) {
+#ifdef CONFIG_EXT4_DEBUG
+		ext4_warning(inode->i_sb, "Inode (%ld) finished: extent logical block %llu,"
+			     " len %u; IO logical block %llu, len %u",
+			     inode->i_ino, (unsigned long long)ee_block, ee_len,
+			     (unsigned long long)map->m_lblk, map->m_len);
+#endif
+		path = ext4_split_convert_extents(handle, inode, map, path,
+						EXT4_GET_BLOCKS_CONVERT, NULL);
+		if (IS_ERR(path))
+			return path;
+
+		path = ext4_find_extent(inode, map->m_lblk, path, 0);
+		if (IS_ERR(path))
+			return path;
+		depth = ext_depth(inode);
+		ex = path[depth].p_ext;
+	}
+
+	err = ext4_ext_get_access(handle, inode, path + depth);
+	if (err)
+		goto errout;
+	/* first mark the extent as initialized */
+	ext4_ext_mark_initialized(ex);
+
+	/* note: ext4_ext_correct_indexes() isn't needed here because
+	 * borders are not changed
+	 */
+	ext4_ext_try_to_merge(handle, inode, path, ex);
+
+	/* Mark modified extent as dirty */
+	err = ext4_ext_dirty(handle, inode, path + path->p_depth);
+	if (err)
+		goto errout;
+
+	ext4_ext_show_leaf(inode, path);
+	return path;
+
+errout:
+	ext4_free_ext_path(path);
+	return ERR_PTR(err);
+}
+
+static struct ext4_ext_path *
+convert_initialized_extent(handle_t *handle, struct inode *inode,
+			   struct ext4_map_blocks *map,
+			   struct ext4_ext_path *path,
+			   unsigned int *allocated)
+{
+	struct ext4_extent *ex;
+	ext4_lblk_t ee_block;
+	unsigned int ee_len;
+	int depth;
+	int err = 0;
+
+	/*
+	 * Make sure that the extent is no bigger than we support with
+	 * unwritten extent
+	 */
+	if (map->m_len > EXT_UNWRITTEN_MAX_LEN)
+		map->m_len = EXT_UNWRITTEN_MAX_LEN / 2;
+
+	depth = ext_depth(inode);
+	ex = path[depth].p_ext;
+	ee_block = le32_to_cpu(ex->ee_block);
+	ee_len = ext4_ext_get_actual_len(ex);
+
+	ext_debug(inode, "logical block %llu, max_blocks %u\n",
+		  (unsigned long long)ee_block, ee_len);
+
+	if (ee_block != map->m_lblk || ee_len > map->m_len) {
+		path = ext4_split_convert_extents(handle, inode, map, path,
+				EXT4_GET_BLOCKS_CONVERT_UNWRITTEN, NULL);
+		if (IS_ERR(path))
+			return path;
+
+		path = ext4_find_extent(inode, map->m_lblk, path, 0);
+		if (IS_ERR(path))
+			return path;
+		depth = ext_depth(inode);
+		ex = path[depth].p_ext;
+		if (!ex) {
+			EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
+					 (unsigned long) map->m_lblk);
+			err = -EFSCORRUPTED;
+			goto errout;
+		}
+	}
+
+	err = ext4_ext_get_access(handle, inode, path + depth);
+	if (err)
+		goto errout;
+	/* first mark the extent as unwritten */
+	ext4_ext_mark_unwritten(ex);
+
+	/* note: ext4_ext_correct_indexes() isn't needed here because
+	 * borders are not changed
+	 */
+	ext4_ext_try_to_merge(handle, inode, path, ex);
+
+	/* Mark modified extent as dirty */
+	err = ext4_ext_dirty(handle, inode, path + path->p_depth);
+	if (err)
+		goto errout;
+	ext4_ext_show_leaf(inode, path);
+
+	ext4_update_inode_fsync_trans(handle, inode, 1);
+
+	map->m_flags |= EXT4_MAP_UNWRITTEN;
+	if (*allocated > map->m_len)
+		*allocated = map->m_len;
+	map->m_len = *allocated;
+	return path;
+
+errout:
+	ext4_free_ext_path(path);
+	return ERR_PTR(err);
+}
+
+static struct ext4_ext_path *
+ext4_ext_handle_unwritten_extents(handle_t *handle, struct inode *inode,
+			struct ext4_map_blocks *map,
+			struct ext4_ext_path *path, int flags,
+			unsigned int *allocated, ext4_fsblk_t newblock)
+{
+	int err = 0;
+
+	ext_debug(inode, "logical block %llu, max_blocks %u, flags 0x%x, allocated %u\n",
+		  (unsigned long long)map->m_lblk, map->m_len, flags,
+		  *allocated);
+	ext4_ext_show_leaf(inode, path);
+
+	/*
+	 * When writing into unwritten space, we should not fail to
+	 * allocate metadata blocks for the new extent block if needed.
+	 */
+	flags |= EXT4_GET_BLOCKS_METADATA_NOFAIL;
+
+	trace_ext4_ext_handle_unwritten_extents(inode, map, flags,
+						*allocated, newblock);
+
+	/* get_block() before submitting IO, split the extent */
+	if (flags & EXT4_GET_BLOCKS_PRE_IO) {
+		path = ext4_split_convert_extents(handle, inode, map, path,
+				flags | EXT4_GET_BLOCKS_CONVERT, allocated);
+		if (IS_ERR(path))
+			return path;
+		/*
+		 * shouldn't get a 0 allocated when splitting an extent unless
+		 * m_len is 0 (bug) or extent has been corrupted
+		 */
+		if (unlikely(*allocated == 0)) {
+			EXT4_ERROR_INODE(inode,
+					 "unexpected allocated == 0, m_len = %u",
+					 map->m_len);
+			err = -EFSCORRUPTED;
+			goto errout;
+		}
+		map->m_flags |= EXT4_MAP_UNWRITTEN;
+		goto out;
+	}
+	/* IO end_io complete, convert the filled extent to written */
+	if (flags & EXT4_GET_BLOCKS_CONVERT) {
+		path = ext4_convert_unwritten_extents_endio(handle, inode,
+							    map, path);
+		if (IS_ERR(path))
+			return path;
+		ext4_update_inode_fsync_trans(handle, inode, 1);
+		goto map_out;
+	}
+	/* buffered IO cases */
+	/*
+	 * repeat fallocate creation request
+	 * we already have an unwritten extent
+	 */
+	if (flags & EXT4_GET_BLOCKS_UNWRIT_EXT) {
+		map->m_flags |= EXT4_MAP_UNWRITTEN;
+		goto map_out;
+	}
+
+	/* buffered READ or buffered write_begin() lookup */
+	if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
+		/*
+		 * We have blocks reserved already.  We
+		 * return allocated blocks so that delalloc
+		 * won't do block reservation for us.  But
+		 * the buffer head will be unmapped so that
+		 * a read from the block returns 0s.
+		 */
+		map->m_flags |= EXT4_MAP_UNWRITTEN;
+		goto out1;
+	}
+
+	/*
+	 * Default case when (flags & EXT4_GET_BLOCKS_CREATE) == 1.
+	 * For buffered writes, at writepage time, etc.  Convert a
+	 * discovered unwritten extent to written.
+	 */
+	path = ext4_ext_convert_to_initialized(handle, inode, map, path,
+					       flags, allocated);
+	if (IS_ERR(path))
+		return path;
+	ext4_update_inode_fsync_trans(handle, inode, 1);
+	/*
+	 * shouldn't get a 0 allocated when converting an unwritten extent
+	 * unless m_len is 0 (bug) or extent has been corrupted
+	 */
+	if (unlikely(*allocated == 0)) {
+		EXT4_ERROR_INODE(inode, "unexpected allocated == 0, m_len = %u",
+				 map->m_len);
+		err = -EFSCORRUPTED;
+		goto errout;
+	}
+
+out:
+	map->m_flags |= EXT4_MAP_NEW;
+map_out:
+	map->m_flags |= EXT4_MAP_MAPPED;
+out1:
+	map->m_pblk = newblock;
+	if (*allocated > map->m_len)
+		*allocated = map->m_len;
+	map->m_len = *allocated;
+	ext4_ext_show_leaf(inode, path);
+	return path;
+
+errout:
+	ext4_free_ext_path(path);
+	return ERR_PTR(err);
+}
+
+/*
+ * get_implied_cluster_alloc - check to see if the requested
+ * allocation (in the map structure) overlaps with a cluster already
+ * allocated in an extent.
+ *	@sb	The filesystem superblock structure
+ *	@map	The requested lblk->pblk mapping
+ *	@ex	The extent structure which might contain an implied
+ *			cluster allocation
+ *
+ * This function is called by ext4_ext_map_blocks() after we failed to
+ * find blocks that were already in the inode's extent tree.  Hence,
+ * we know that the beginning of the requested region cannot overlap
+ * the extent from the inode's extent tree.  There are three cases we
+ * want to catch.  The first is this case:
+ *
+ *		 |--- cluster # N--|
+ *    |--- extent ---|	|---- requested region ---|
+ *			|==========|
+ *
+ * The second case that we need to test for is this one:
+ *
+ *   |--------- cluster # N ----------------|
+ *	   |--- requested region --|   |------- extent ----|
+ *	   |=======================|
+ *
+ * The third case is when the requested region lies between two extents
+ * within the same cluster:
+ *          |------------- cluster # N-------------|
+ * |----- ex -----|                  |---- ex_right ----|
+ *                  |------ requested region ------|
+ *                  |================|
+ *
+ * In each of the above cases, we need to set the map->m_pblk and
+ * map->m_len so it corresponds to the return the extent labelled as
+ * "|====|" from cluster #N, since it is already in use for data in
+ * cluster EXT4_B2C(sbi, map->m_lblk).	We will then return 1 to
+ * signal to ext4_ext_map_blocks() that map->m_pblk should be treated
+ * as a new "allocated" block region.  Otherwise, we will return 0 and
+ * ext4_ext_map_blocks() will then allocate one or more new clusters
+ * by calling ext4_mb_new_blocks().
+ */
+static int get_implied_cluster_alloc(struct super_block *sb,
+				     struct ext4_map_blocks *map,
+				     struct ext4_extent *ex,
+				     struct ext4_ext_path *path)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(sb);
+	ext4_lblk_t c_offset = EXT4_LBLK_COFF(sbi, map->m_lblk);
+	ext4_lblk_t ex_cluster_start, ex_cluster_end;
+	ext4_lblk_t rr_cluster_start;
+	ext4_lblk_t ee_block = le32_to_cpu(ex->ee_block);
+	ext4_fsblk_t ee_start = ext4_ext_pblock(ex);
+	unsigned short ee_len = ext4_ext_get_actual_len(ex);
+
+	/* The extent passed in that we are trying to match */
+	ex_cluster_start = EXT4_B2C(sbi, ee_block);
+	ex_cluster_end = EXT4_B2C(sbi, ee_block + ee_len - 1);
+
+	/* The requested region passed into ext4_map_blocks() */
+	rr_cluster_start = EXT4_B2C(sbi, map->m_lblk);
+
+	if ((rr_cluster_start == ex_cluster_end) ||
+	    (rr_cluster_start == ex_cluster_start)) {
+		if (rr_cluster_start == ex_cluster_end)
+			ee_start += ee_len - 1;
+		map->m_pblk = EXT4_PBLK_CMASK(sbi, ee_start) + c_offset;
+		map->m_len = min(map->m_len,
+				 (unsigned) sbi->s_cluster_ratio - c_offset);
+		/*
+		 * Check for and handle this case:
+		 *
+		 *   |--------- cluster # N-------------|
+		 *		       |------- extent ----|
+		 *	   |--- requested region ---|
+		 *	   |===========|
+		 */
+
+		if (map->m_lblk < ee_block)
+			map->m_len = min(map->m_len, ee_block - map->m_lblk);
+
+		/*
+		 * Check for the case where there is already another allocated
+		 * block to the right of 'ex' but before the end of the cluster.
+		 *
+		 *          |------------- cluster # N-------------|
+		 * |----- ex -----|                  |---- ex_right ----|
+		 *                  |------ requested region ------|
+		 *                  |================|
+		 */
+		if (map->m_lblk > ee_block) {
+			ext4_lblk_t next = ext4_ext_next_allocated_block(path);
+			map->m_len = min(map->m_len, next - map->m_lblk);
+		}
+
+		trace_ext4_get_implied_cluster_alloc_exit(sb, map, 1);
+		return 1;
+	}
+
+	trace_ext4_get_implied_cluster_alloc_exit(sb, map, 0);
+	return 0;
+}
+
+/*
+ * Determine hole length around the given logical block, first try to
+ * locate and expand the hole from the given @path, and then adjust it
+ * if it's partially or completely converted to delayed extents, insert
+ * it into the extent cache tree if it's indeed a hole, finally return
+ * the length of the determined extent.
+ */
+static ext4_lblk_t ext4_ext_determine_insert_hole(struct inode *inode,
+						  struct ext4_ext_path *path,
+						  ext4_lblk_t lblk)
+{
+	ext4_lblk_t hole_start, len;
+	struct extent_status es;
+
+	hole_start = lblk;
+	len = ext4_ext_find_hole(inode, path, &hole_start);
+again:
+	ext4_es_find_extent_range(inode, &ext4_es_is_delayed, hole_start,
+				  hole_start + len - 1, &es);
+	if (!es.es_len)
+		goto insert_hole;
+
+	/*
+	 * There's a delalloc extent in the hole, handle it if the delalloc
+	 * extent is in front of, behind and straddle the queried range.
+	 */
+	if (lblk >= es.es_lblk + es.es_len) {
+		/*
+		 * The delalloc extent is in front of the queried range,
+		 * find again from the queried start block.
+		 */
+		len -= lblk - hole_start;
+		hole_start = lblk;
+		goto again;
+	} else if (in_range(lblk, es.es_lblk, es.es_len)) {
+		/*
+		 * The delalloc extent containing lblk, it must have been
+		 * added after ext4_map_blocks() checked the extent status
+		 * tree so we are not holding i_rwsem and delalloc info is
+		 * only stabilized by i_data_sem we are going to release
+		 * soon. Don't modify the extent status tree and report
+		 * extent as a hole, just adjust the length to the delalloc
+		 * extent's after lblk.
+		 */
+		len = es.es_lblk + es.es_len - lblk;
+		return len;
+	} else {
+		/*
+		 * The delalloc extent is partially or completely behind
+		 * the queried range, update hole length until the
+		 * beginning of the delalloc extent.
+		 */
+		len = min(es.es_lblk - hole_start, len);
+	}
+
+insert_hole:
+	/* Put just found gap into cache to speed up subsequent requests */
+	ext_debug(inode, " -> %u:%u\n", hole_start, len);
+	ext4_es_insert_extent(inode, hole_start, len, ~0,
+			      EXTENT_STATUS_HOLE, false);
+
+	/* Update hole_len to reflect hole size after lblk */
+	if (hole_start != lblk)
+		len -= lblk - hole_start;
+
+	return len;
+}
+
+/*
+ * Block allocation/map/preallocation routine for extents based files
+ *
+ *
+ * Need to be called with
+ * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system block
+ * (ie, flags is zero). Otherwise down_write(&EXT4_I(inode)->i_data_sem)
+ *
+ * return > 0, number of blocks already mapped/allocated
+ *          if flags doesn't contain EXT4_GET_BLOCKS_CREATE and these are pre-allocated blocks
+ *          	buffer head is unmapped
+ *          otherwise blocks are mapped
+ *
+ * return = 0, if plain look up failed (blocks have not been allocated)
+ *          buffer head is unmapped
+ *
+ * return < 0, error case.
+ */
+int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
+			struct ext4_map_blocks *map, int flags)
+{
+	struct ext4_ext_path *path = NULL;
+	struct ext4_extent newex, *ex, ex2;
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	ext4_fsblk_t newblock = 0, pblk;
+	int err = 0, depth;
+	unsigned int allocated = 0, offset = 0;
+	unsigned int allocated_clusters = 0;
+	struct ext4_allocation_request ar;
+	ext4_lblk_t cluster_offset;
+
+	ext_debug(inode, "blocks %u/%u requested\n", map->m_lblk, map->m_len);
+	trace_ext4_ext_map_blocks_enter(inode, map->m_lblk, map->m_len, flags);
+
+	/* find extent for this block */
+	path = ext4_find_extent(inode, map->m_lblk, NULL, flags);
+	if (IS_ERR(path)) {
+		err = PTR_ERR(path);
+		goto out;
+	}
+
+	depth = ext_depth(inode);
+
+	/*
+	 * consistent leaf must not be empty;
+	 * this situation is possible, though, _during_ tree modification;
+	 * this is why assert can't be put in ext4_find_extent()
+	 */
+	if (unlikely(path[depth].p_ext == NULL && depth != 0)) {
+		EXT4_ERROR_INODE(inode, "bad extent address "
+				 "lblock: %lu, depth: %d pblock %lld",
+				 (unsigned long) map->m_lblk, depth,
+				 path[depth].p_block);
+		err = -EFSCORRUPTED;
+		goto out;
+	}
+
+	ex = path[depth].p_ext;
+	if (ex) {
+		ext4_lblk_t ee_block = le32_to_cpu(ex->ee_block);
+		ext4_fsblk_t ee_start = ext4_ext_pblock(ex);
+		unsigned short ee_len;
+
+
+		/*
+		 * unwritten extents are treated as holes, except that
+		 * we split out initialized portions during a write.
+		 */
+		ee_len = ext4_ext_get_actual_len(ex);
+
+		trace_ext4_ext_show_extent(inode, ee_block, ee_start, ee_len);
+
+		/* if found extent covers block, simply return it */
+		if (in_range(map->m_lblk, ee_block, ee_len)) {
+			newblock = map->m_lblk - ee_block + ee_start;
+			/* number of remaining blocks in the extent */
+			allocated = ee_len - (map->m_lblk - ee_block);
+			ext_debug(inode, "%u fit into %u:%d -> %llu\n",
+				  map->m_lblk, ee_block, ee_len, newblock);
+
+			/*
+			 * If the extent is initialized check whether the
+			 * caller wants to convert it to unwritten.
+			 */
+			if ((!ext4_ext_is_unwritten(ex)) &&
+			    (flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN)) {
+				path = convert_initialized_extent(handle,
+					inode, map, path, &allocated);
+				if (IS_ERR(path))
+					err = PTR_ERR(path);
+				goto out;
+			} else if (!ext4_ext_is_unwritten(ex)) {
+				map->m_flags |= EXT4_MAP_MAPPED;
+				map->m_pblk = newblock;
+				if (allocated > map->m_len)
+					allocated = map->m_len;
+				map->m_len = allocated;
+				ext4_ext_show_leaf(inode, path);
+				goto out;
+			}
+
+			path = ext4_ext_handle_unwritten_extents(
+				handle, inode, map, path, flags,
+				&allocated, newblock);
+			if (IS_ERR(path))
+				err = PTR_ERR(path);
+			goto out;
+		}
+	}
+
+	/*
+	 * requested block isn't allocated yet;
+	 * we couldn't try to create block if flags doesn't contain EXT4_GET_BLOCKS_CREATE
+	 */
+	if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) {
+		ext4_lblk_t len;
+
+		len = ext4_ext_determine_insert_hole(inode, path, map->m_lblk);
+
+		map->m_pblk = 0;
+		map->m_len = min_t(unsigned int, map->m_len, len);
+		goto out;
+	}
+
+	/*
+	 * Okay, we need to do block allocation.
+	 */
+	newex.ee_block = cpu_to_le32(map->m_lblk);
+	cluster_offset = EXT4_LBLK_COFF(sbi, map->m_lblk);
+
+	/*
+	 * If we are doing bigalloc, check to see if the extent returned
+	 * by ext4_find_extent() implies a cluster we can use.
+	 */
+	if (cluster_offset && ex &&
+	    get_implied_cluster_alloc(inode->i_sb, map, ex, path)) {
+		ar.len = allocated = map->m_len;
+		newblock = map->m_pblk;
+		goto got_allocated_blocks;
+	}
+
+	/* find neighbour allocated blocks */
+	ar.lleft = map->m_lblk;
+	err = ext4_ext_search_left(inode, path, &ar.lleft, &ar.pleft);
+	if (err)
+		goto out;
+	ar.lright = map->m_lblk;
+	err = ext4_ext_search_right(inode, path, &ar.lright, &ar.pright,
+				    &ex2, flags);
+	if (err < 0)
+		goto out;
+
+	/* Check if the extent after searching to the right implies a
+	 * cluster we can use. */
+	if ((sbi->s_cluster_ratio > 1) && err &&
+	    get_implied_cluster_alloc(inode->i_sb, map, &ex2, path)) {
+		ar.len = allocated = map->m_len;
+		newblock = map->m_pblk;
+		err = 0;
+		goto got_allocated_blocks;
+	}
+
+	/*
+	 * See if request is beyond maximum number of blocks we can have in
+	 * a single extent. For an initialized extent this limit is
+	 * EXT_INIT_MAX_LEN and for an unwritten extent this limit is
+	 * EXT_UNWRITTEN_MAX_LEN.
+	 */
+	if (map->m_len > EXT_INIT_MAX_LEN &&
+	    !(flags & EXT4_GET_BLOCKS_UNWRIT_EXT))
+		map->m_len = EXT_INIT_MAX_LEN;
+	else if (map->m_len > EXT_UNWRITTEN_MAX_LEN &&
+		 (flags & EXT4_GET_BLOCKS_UNWRIT_EXT))
+		map->m_len = EXT_UNWRITTEN_MAX_LEN;
+
+	/* Check if we can really insert (m_lblk)::(m_lblk + m_len) extent */
+	newex.ee_len = cpu_to_le16(map->m_len);
+	err = ext4_ext_check_overlap(sbi, inode, &newex, path);
+	if (err)
+		allocated = ext4_ext_get_actual_len(&newex);
+	else
+		allocated = map->m_len;
+
+	/* allocate new block */
+	ar.inode = inode;
+	ar.goal = ext4_ext_find_goal(inode, path, map->m_lblk);
+	ar.logical = map->m_lblk;
+	/*
+	 * We calculate the offset from the beginning of the cluster
+	 * for the logical block number, since when we allocate a
+	 * physical cluster, the physical block should start at the
+	 * same offset from the beginning of the cluster.  This is
+	 * needed so that future calls to get_implied_cluster_alloc()
+	 * work correctly.
+	 */
+	offset = EXT4_LBLK_COFF(sbi, map->m_lblk);
+	ar.len = EXT4_NUM_B2C(sbi, offset+allocated);
+	ar.goal -= offset;
+	ar.logical -= offset;
+	if (S_ISREG(inode->i_mode))
+		ar.flags = EXT4_MB_HINT_DATA;
+	else
+		/* disable in-core preallocation for non-regular files */
+		ar.flags = 0;
+	if (flags & EXT4_GET_BLOCKS_NO_NORMALIZE)
+		ar.flags |= EXT4_MB_HINT_NOPREALLOC;
+	if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
+		ar.flags |= EXT4_MB_DELALLOC_RESERVED;
+	if (flags & EXT4_GET_BLOCKS_METADATA_NOFAIL)
+		ar.flags |= EXT4_MB_USE_RESERVED;
+	newblock = ext4_mb_new_blocks(handle, &ar, &err);
+	if (!newblock)
+		goto out;
+	allocated_clusters = ar.len;
+	ar.len = EXT4_C2B(sbi, ar.len) - offset;
+	ext_debug(inode, "allocate new block: goal %llu, found %llu/%u, requested %u\n",
+		  ar.goal, newblock, ar.len, allocated);
+	if (ar.len > allocated)
+		ar.len = allocated;
+
+got_allocated_blocks:
+	/* try to insert new extent into found leaf and return */
+	pblk = newblock + offset;
+	ext4_ext_store_pblock(&newex, pblk);
+	newex.ee_len = cpu_to_le16(ar.len);
+	/* Mark unwritten */
+	if (flags & EXT4_GET_BLOCKS_UNWRIT_EXT) {
+		ext4_ext_mark_unwritten(&newex);
+		map->m_flags |= EXT4_MAP_UNWRITTEN;
+	}
+
+	path = ext4_ext_insert_extent(handle, inode, path, &newex, flags);
+	if (IS_ERR(path)) {
+		err = PTR_ERR(path);
+		if (allocated_clusters) {
+			int fb_flags = 0;
+
+			/*
+			 * free data blocks we just allocated.
+			 * not a good idea to call discard here directly,
+			 * but otherwise we'd need to call it every free().
+			 */
+			ext4_discard_preallocations(inode);
+			if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
+				fb_flags = EXT4_FREE_BLOCKS_NO_QUOT_UPDATE;
+			ext4_free_blocks(handle, inode, NULL, newblock,
+					 EXT4_C2B(sbi, allocated_clusters),
+					 fb_flags);
+		}
+		goto out;
+	}
+
+	/*
+	 * Cache the extent and update transaction to commit on fdatasync only
+	 * when it is _not_ an unwritten extent.
+	 */
+	if ((flags & EXT4_GET_BLOCKS_UNWRIT_EXT) == 0)
+		ext4_update_inode_fsync_trans(handle, inode, 1);
+	else
+		ext4_update_inode_fsync_trans(handle, inode, 0);
+
+	map->m_flags |= (EXT4_MAP_NEW | EXT4_MAP_MAPPED);
+	map->m_pblk = pblk;
+	map->m_len = ar.len;
+	allocated = map->m_len;
+	ext4_ext_show_leaf(inode, path);
+out:
+	/*
+	 * We never use EXT4_GET_BLOCKS_QUERY_LAST_IN_LEAF with CREATE flag.
+	 * So we know that the depth used here is correct, since there was no
+	 * block allocation done if EXT4_GET_BLOCKS_QUERY_LAST_IN_LEAF is set.
+	 * If tomorrow we start using this QUERY flag with CREATE, then we will
+	 * need to re-calculate the depth as it might have changed due to block
+	 * allocation.
+	 */
+	if (flags & EXT4_GET_BLOCKS_QUERY_LAST_IN_LEAF) {
+		WARN_ON_ONCE(flags & EXT4_GET_BLOCKS_CREATE);
+		if (!err && ex && (ex == EXT_LAST_EXTENT(path[depth].p_hdr)))
+			map->m_flags |= EXT4_MAP_QUERY_LAST_IN_LEAF;
+	}
+
+	ext4_free_ext_path(path);
+
+	trace_ext4_ext_map_blocks_exit(inode, flags, map,
+				       err ? err : allocated);
+	return err ? err : allocated;
+}
+
+int ext4_ext_truncate(handle_t *handle, struct inode *inode)
+{
+	struct super_block *sb = inode->i_sb;
+	ext4_lblk_t last_block;
+	int err = 0;
+
+	/*
+	 * TODO: optimization is possible here.
+	 * Probably we need not scan at all,
+	 * because page truncation is enough.
+	 */
+
+	/* we have to know where to truncate from in crash case */
+	EXT4_I(inode)->i_disksize = inode->i_size;
+	err = ext4_mark_inode_dirty(handle, inode);
+	if (err)
+		return err;
+
+	last_block = (inode->i_size + sb->s_blocksize - 1)
+			>> EXT4_BLOCK_SIZE_BITS(sb);
+	ext4_es_remove_extent(inode, last_block, EXT_MAX_BLOCKS - last_block);
+
+retry_remove_space:
+	err = ext4_ext_remove_space(inode, last_block, EXT_MAX_BLOCKS - 1);
+	if (err == -ENOMEM) {
+		memalloc_retry_wait(GFP_ATOMIC);
+		goto retry_remove_space;
+	}
+	return err;
+}
+
+static int ext4_alloc_file_blocks(struct file *file, ext4_lblk_t offset,
+				  ext4_lblk_t len, loff_t new_size,
+				  int flags)
+{
+	struct inode *inode = file_inode(file);
+	handle_t *handle;
+	int ret = 0, ret2 = 0, ret3 = 0;
+	int retries = 0;
+	int depth = 0;
+	struct ext4_map_blocks map;
+	unsigned int credits;
+	loff_t epos, old_size = i_size_read(inode);
+	unsigned int blkbits = inode->i_blkbits;
+	bool alloc_zero = false;
+
+	BUG_ON(!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS));
+	map.m_lblk = offset;
+	map.m_len = len;
+	/*
+	 * Don't normalize the request if it can fit in one extent so
+	 * that it doesn't get unnecessarily split into multiple
+	 * extents.
+	 */
+	if (len <= EXT_UNWRITTEN_MAX_LEN)
+		flags |= EXT4_GET_BLOCKS_NO_NORMALIZE;
+
+	/*
+	 * Do the actual write zero during a running journal transaction
+	 * costs a lot. First allocate an unwritten extent and then
+	 * convert it to written after zeroing it out.
+	 */
+	if (flags & EXT4_GET_BLOCKS_ZERO) {
+		flags &= ~EXT4_GET_BLOCKS_ZERO;
+		flags |= EXT4_GET_BLOCKS_UNWRIT_EXT;
+		alloc_zero = true;
+	}
+
+	/*
+	 * credits to insert 1 extent into extent tree
+	 */
+	credits = ext4_chunk_trans_blocks(inode, len);
+	depth = ext_depth(inode);
+
+retry:
+	while (len) {
+		/*
+		 * Recalculate credits when extent tree depth changes.
+		 */
+		if (depth != ext_depth(inode)) {
+			credits = ext4_chunk_trans_blocks(inode, len);
+			depth = ext_depth(inode);
+		}
+
+		handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS,
+					    credits);
+		if (IS_ERR(handle)) {
+			ret = PTR_ERR(handle);
+			break;
+		}
+		ret = ext4_map_blocks(handle, inode, &map, flags);
+		if (ret <= 0) {
+			ext4_debug("inode #%lu: block %u: len %u: "
+				   "ext4_ext_map_blocks returned %d",
+				   inode->i_ino, map.m_lblk,
+				   map.m_len, ret);
+			ext4_mark_inode_dirty(handle, inode);
+			ext4_journal_stop(handle);
+			break;
+		}
+		/*
+		 * allow a full retry cycle for any remaining allocations
+		 */
+		retries = 0;
+		epos = (loff_t)(map.m_lblk + ret) << blkbits;
+		inode_set_ctime_current(inode);
+		if (new_size) {
+			if (epos > new_size)
+				epos = new_size;
+			if (ext4_update_inode_size(inode, epos) & 0x1)
+				inode_set_mtime_to_ts(inode,
+						      inode_get_ctime(inode));
+			if (epos > old_size) {
+				pagecache_isize_extended(inode, old_size, epos);
+				ext4_zero_partial_blocks(handle, inode,
+						     old_size, epos - old_size);
+			}
+		}
+		ret2 = ext4_mark_inode_dirty(handle, inode);
+		ext4_update_inode_fsync_trans(handle, inode, 1);
+		ret3 = ext4_journal_stop(handle);
+		ret2 = ret3 ? ret3 : ret2;
+		if (unlikely(ret2))
+			break;
+
+		if (alloc_zero &&
+		    (map.m_flags & (EXT4_MAP_MAPPED | EXT4_MAP_UNWRITTEN))) {
+			ret2 = ext4_issue_zeroout(inode, map.m_lblk, map.m_pblk,
+						  map.m_len);
+			if (likely(!ret2))
+				ret2 = ext4_convert_unwritten_extents(NULL,
+					inode, (loff_t)map.m_lblk << blkbits,
+					(loff_t)map.m_len << blkbits);
+			if (ret2)
+				break;
+		}
+
+		map.m_lblk += ret;
+		map.m_len = len = len - ret;
+	}
+	if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
+		goto retry;
+
+	return ret > 0 ? ret2 : ret;
+}
+
+static int ext4_collapse_range(struct file *file, loff_t offset, loff_t len);
+
+static int ext4_insert_range(struct file *file, loff_t offset, loff_t len);
+
+static long ext4_zero_range(struct file *file, loff_t offset,
+			    loff_t len, int mode)
+{
+	struct inode *inode = file_inode(file);
+	handle_t *handle = NULL;
+	loff_t new_size = 0;
+	loff_t end = offset + len;
+	ext4_lblk_t start_lblk, end_lblk;
+	unsigned int blocksize = i_blocksize(inode);
+	unsigned int blkbits = inode->i_blkbits;
+	int ret, flags, credits;
+
+	trace_ext4_zero_range(inode, offset, len, mode);
+	WARN_ON_ONCE(!inode_is_locked(inode));
+
+	/* Indirect files do not support unwritten extents */
+	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
+		return -EOPNOTSUPP;
+
+	if (!(mode & FALLOC_FL_KEEP_SIZE) &&
+	    (end > inode->i_size || end > EXT4_I(inode)->i_disksize)) {
+		new_size = end;
+		ret = inode_newsize_ok(inode, new_size);
+		if (ret)
+			return ret;
+	}
+
+	flags = EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT;
+	/* Preallocate the range including the unaligned edges */
+	if (!IS_ALIGNED(offset | end, blocksize)) {
+		ext4_lblk_t alloc_lblk = offset >> blkbits;
+		ext4_lblk_t len_lblk = EXT4_MAX_BLOCKS(len, offset, blkbits);
+
+		ret = ext4_alloc_file_blocks(file, alloc_lblk, len_lblk,
+					     new_size, flags);
+		if (ret)
+			return ret;
+	}
+
+	ret = ext4_update_disksize_before_punch(inode, offset, len);
+	if (ret)
+		return ret;
+
+	/* Now release the pages and zero block aligned part of pages */
+	ret = ext4_truncate_page_cache_block_range(inode, offset, end);
+	if (ret)
+		return ret;
+
+	/* Zero range excluding the unaligned edges */
+	start_lblk = EXT4_B_TO_LBLK(inode, offset);
+	end_lblk = end >> blkbits;
+	if (end_lblk > start_lblk) {
+		ext4_lblk_t zero_blks = end_lblk - start_lblk;
+
+		if (mode & FALLOC_FL_WRITE_ZEROES)
+			flags = EXT4_GET_BLOCKS_CREATE_ZERO | EXT4_EX_NOCACHE;
+		else
+			flags |= (EXT4_GET_BLOCKS_CONVERT_UNWRITTEN |
+				  EXT4_EX_NOCACHE);
+		ret = ext4_alloc_file_blocks(file, start_lblk, zero_blks,
+					     new_size, flags);
+		if (ret)
+			return ret;
+	}
+	/* Finish zeroing out if it doesn't contain partial block */
+	if (IS_ALIGNED(offset | end, blocksize))
+		return ret;
+
+	/*
+	 * In worst case we have to writeout two nonadjacent unwritten
+	 * blocks and update the inode
+	 */
+	credits = (2 * ext4_ext_index_trans_blocks(inode, 2)) + 1;
+	if (ext4_should_journal_data(inode))
+		credits += 2;
+	handle = ext4_journal_start(inode, EXT4_HT_MISC, credits);
+	if (IS_ERR(handle)) {
+		ret = PTR_ERR(handle);
+		ext4_std_error(inode->i_sb, ret);
+		return ret;
+	}
+
+	/* Zero out partial block at the edges of the range */
+	ret = ext4_zero_partial_blocks(handle, inode, offset, len);
+	if (ret)
+		goto out_handle;
+
+	if (new_size)
+		ext4_update_inode_size(inode, new_size);
+	ret = ext4_mark_inode_dirty(handle, inode);
+	if (unlikely(ret))
+		goto out_handle;
+
+	ext4_update_inode_fsync_trans(handle, inode, 1);
+	if (file->f_flags & O_SYNC)
+		ext4_handle_sync(handle);
+
+out_handle:
+	ext4_journal_stop(handle);
+	return ret;
+}
+
+static long ext4_do_fallocate(struct file *file, loff_t offset,
+			      loff_t len, int mode)
+{
+	struct inode *inode = file_inode(file);
+	loff_t end = offset + len;
+	loff_t new_size = 0;
+	ext4_lblk_t start_lblk, len_lblk;
+	int ret;
+
+	trace_ext4_fallocate_enter(inode, offset, len, mode);
+	WARN_ON_ONCE(!inode_is_locked(inode));
+
+	start_lblk = offset >> inode->i_blkbits;
+	len_lblk = EXT4_MAX_BLOCKS(len, offset, inode->i_blkbits);
+
+	/* We only support preallocation for extent-based files only. */
+	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
+		ret = -EOPNOTSUPP;
+		goto out;
+	}
+
+	if (!(mode & FALLOC_FL_KEEP_SIZE) &&
+	    (end > inode->i_size || end > EXT4_I(inode)->i_disksize)) {
+		new_size = end;
+		ret = inode_newsize_ok(inode, new_size);
+		if (ret)
+			goto out;
+	}
+
+	ret = ext4_alloc_file_blocks(file, start_lblk, len_lblk, new_size,
+				     EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT);
+	if (ret)
+		goto out;
+
+	if (file->f_flags & O_SYNC && EXT4_SB(inode->i_sb)->s_journal) {
+		ret = ext4_fc_commit(EXT4_SB(inode->i_sb)->s_journal,
+					EXT4_I(inode)->i_sync_tid);
+	}
+out:
+	trace_ext4_fallocate_exit(inode, offset, len_lblk, ret);
+	return ret;
+}
+
+/*
+ * preallocate space for a file. This implements ext4's fallocate file
+ * operation, which gets called from sys_fallocate system call.
+ * For block-mapped files, posix_fallocate should fall back to the method
+ * of writing zeroes to the required new blocks (the same behavior which is
+ * expected for file systems which do not support fallocate() system call).
+ */
+long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
+{
+	struct inode *inode = file_inode(file);
+	struct address_space *mapping = file->f_mapping;
+	int ret;
+
+	/*
+	 * Encrypted inodes can't handle collapse range or insert
+	 * range since we would need to re-encrypt blocks with a
+	 * different IV or XTS tweak (which are based on the logical
+	 * block number).
+	 */
+	if (IS_ENCRYPTED(inode) &&
+	    (mode & (FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_INSERT_RANGE)))
+		return -EOPNOTSUPP;
+	/*
+	 * Don't allow writing zeroes if the underlying device does not
+	 * enable the unmap write zeroes operation.
+	 */
+	if ((mode & FALLOC_FL_WRITE_ZEROES) &&
+	    !bdev_write_zeroes_unmap_sectors(inode->i_sb->s_bdev))
+		return -EOPNOTSUPP;
+
+	/* Return error if mode is not supported */
+	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
+		     FALLOC_FL_ZERO_RANGE | FALLOC_FL_COLLAPSE_RANGE |
+		     FALLOC_FL_INSERT_RANGE | FALLOC_FL_WRITE_ZEROES))
+		return -EOPNOTSUPP;
+
+	inode_lock(inode);
+	ret = ext4_convert_inline_data(inode);
+	if (ret)
+		goto out_inode_lock;
+
+	/* Wait all existing dio workers, newcomers will block on i_rwsem */
+	inode_dio_wait(inode);
+
+	ret = file_modified(file);
+	if (ret)
+		goto out_inode_lock;
+
+	if ((mode & FALLOC_FL_MODE_MASK) == FALLOC_FL_ALLOCATE_RANGE) {
+		ret = ext4_do_fallocate(file, offset, len, mode);
+		goto out_inode_lock;
+	}
+
+	/*
+	 * Follow-up operations will drop page cache, hold invalidate lock
+	 * to prevent page faults from reinstantiating pages we have
+	 * released from page cache.
+	 */
+	filemap_invalidate_lock(mapping);
+
+	ret = ext4_break_layouts(inode);
+	if (ret)
+		goto out_invalidate_lock;
+
+	switch (mode & FALLOC_FL_MODE_MASK) {
+	case FALLOC_FL_PUNCH_HOLE:
+		ret = ext4_punch_hole(file, offset, len);
+		break;
+	case FALLOC_FL_COLLAPSE_RANGE:
+		ret = ext4_collapse_range(file, offset, len);
+		break;
+	case FALLOC_FL_INSERT_RANGE:
+		ret = ext4_insert_range(file, offset, len);
+		break;
+	case FALLOC_FL_ZERO_RANGE:
+	case FALLOC_FL_WRITE_ZEROES:
+		ret = ext4_zero_range(file, offset, len, mode);
+		break;
+	default:
+		ret = -EOPNOTSUPP;
+	}
+
+out_invalidate_lock:
+	filemap_invalidate_unlock(mapping);
+out_inode_lock:
+	inode_unlock(inode);
+	return ret;
+}
+
+/*
+ * This function converts a range of blocks to written extents. The caller of
+ * this function will pass the start offset and the size. all unwritten extents
+ * within this range will be converted to written extents.
+ *
+ * This function is called from the direct IO end io call back function for
+ * atomic writes, to convert the unwritten extents after IO is completed.
+ *
+ * Note that the requirement for atomic writes is that all conversion should
+ * happen atomically in a single fs journal transaction. We mainly only allocate
+ * unwritten extents either on a hole on a pre-exiting unwritten extent range in
+ * ext4_map_blocks_atomic_write(). The only case where we can have multiple
+ * unwritten extents in a range [offset, offset+len) is when there is a split
+ * unwritten extent between two leaf nodes which was cached in extent status
+ * cache during ext4_iomap_alloc() time. That will allow
+ * ext4_map_blocks_atomic_write() to return the unwritten extent range w/o going
+ * into the slow path. That means we might need a loop for conversion of this
+ * unwritten extent split across leaf block within a single journal transaction.
+ * Split extents across leaf nodes is a rare case, but let's still handle that
+ * to meet the requirements of multi-fsblock atomic writes.
+ *
+ * Returns 0 on success.
+ */
+int ext4_convert_unwritten_extents_atomic(handle_t *handle, struct inode *inode,
+					  loff_t offset, ssize_t len)
+{
+	unsigned int max_blocks;
+	int ret = 0, ret2 = 0, ret3 = 0;
+	struct ext4_map_blocks map;
+	unsigned int blkbits = inode->i_blkbits;
+	unsigned int credits = 0;
+	int flags = EXT4_GET_BLOCKS_IO_CONVERT_EXT | EXT4_EX_NOCACHE;
+
+	map.m_lblk = offset >> blkbits;
+	max_blocks = EXT4_MAX_BLOCKS(len, offset, blkbits);
+
+	if (!handle) {
+		/*
+		 * TODO: An optimization can be added later by having an extent
+		 * status flag e.g. EXTENT_STATUS_SPLIT_LEAF. If we query that
+		 * it can tell if the extent in the cache is a split extent.
+		 * But for now let's assume pextents as 2 always.
+		 */
+		credits = ext4_meta_trans_blocks(inode, max_blocks, 2);
+	}
+
+	if (credits) {
+		handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, credits);
+		if (IS_ERR(handle)) {
+			ret = PTR_ERR(handle);
+			return ret;
+		}
+	}
+
+	while (ret >= 0 && ret < max_blocks) {
+		map.m_lblk += ret;
+		map.m_len = (max_blocks -= ret);
+		ret = ext4_map_blocks(handle, inode, &map, flags);
+		if (ret != max_blocks)
+			ext4_msg(inode->i_sb, KERN_INFO,
+				     "inode #%lu: block %u: len %u: "
+				     "split block mapping found for atomic write, "
+				     "ret = %d",
+				     inode->i_ino, map.m_lblk,
+				     map.m_len, ret);
+		if (ret <= 0)
+			break;
+	}
+
+	ret2 = ext4_mark_inode_dirty(handle, inode);
+
+	if (credits) {
+		ret3 = ext4_journal_stop(handle);
+		if (unlikely(ret3))
+			ret2 = ret3;
+	}
+
+	if (ret <= 0 || ret2)
+		ext4_warning(inode->i_sb,
+			     "inode #%lu: block %u: len %u: "
+			     "returned %d or %d",
+			     inode->i_ino, map.m_lblk,
+			     map.m_len, ret, ret2);
+
+	return ret > 0 ? ret2 : ret;
+}
+
+/*
+ * This function convert a range of blocks to written extents
+ * The caller of this function will pass the start offset and the size.
+ * all unwritten extents within this range will be converted to
+ * written extents.
+ *
+ * This function is called from the direct IO end io call back
+ * function, to convert the fallocated extents after IO is completed.
+ * Returns 0 on success.
+ */
+int ext4_convert_unwritten_extents(handle_t *handle, struct inode *inode,
+				   loff_t offset, ssize_t len)
+{
+	unsigned int max_blocks;
+	int ret = 0, ret2 = 0, ret3 = 0;
+	struct ext4_map_blocks map;
+	unsigned int blkbits = inode->i_blkbits;
+	unsigned int credits = 0;
+
+	map.m_lblk = offset >> blkbits;
+	max_blocks = EXT4_MAX_BLOCKS(len, offset, blkbits);
+
+	if (!handle) {
+		/*
+		 * credits to insert 1 extent into extent tree
+		 */
+		credits = ext4_chunk_trans_blocks(inode, max_blocks);
+	}
+	while (ret >= 0 && ret < max_blocks) {
+		map.m_lblk += ret;
+		map.m_len = (max_blocks -= ret);
+		if (credits) {
+			handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS,
+						    credits);
+			if (IS_ERR(handle)) {
+				ret = PTR_ERR(handle);
+				break;
+			}
+		}
+		/*
+		 * Do not cache any unrelated extents, as it does not hold the
+		 * i_rwsem or invalidate_lock, which could corrupt the extent
+		 * status tree.
+		 */
+		ret = ext4_map_blocks(handle, inode, &map,
+				      EXT4_GET_BLOCKS_IO_CONVERT_EXT |
+				      EXT4_EX_NOCACHE);
+		if (ret <= 0)
+			ext4_warning(inode->i_sb,
+				     "inode #%lu: block %u: len %u: "
+				     "ext4_ext_map_blocks returned %d",
+				     inode->i_ino, map.m_lblk,
+				     map.m_len, ret);
+		ret2 = ext4_mark_inode_dirty(handle, inode);
+		if (credits) {
+			ret3 = ext4_journal_stop(handle);
+			if (unlikely(ret3))
+				ret2 = ret3;
+		}
+
+		if (ret <= 0 || ret2)
+			break;
+	}
+	return ret > 0 ? ret2 : ret;
+}
+
+int ext4_convert_unwritten_io_end_vec(handle_t *handle, ext4_io_end_t *io_end)
+{
+	int ret = 0, err = 0;
+	struct ext4_io_end_vec *io_end_vec;
+
+	/*
+	 * This is somewhat ugly but the idea is clear: When transaction is
+	 * reserved, everything goes into it. Otherwise we rather start several
+	 * smaller transactions for conversion of each extent separately.
+	 */
+	if (handle) {
+		handle = ext4_journal_start_reserved(handle,
+						     EXT4_HT_EXT_CONVERT);
+		if (IS_ERR(handle))
+			return PTR_ERR(handle);
+	}
+
+	list_for_each_entry(io_end_vec, &io_end->list_vec, list) {
+		ret = ext4_convert_unwritten_extents(handle, io_end->inode,
+						     io_end_vec->offset,
+						     io_end_vec->size);
+		if (ret)
+			break;
+	}
+
+	if (handle)
+		err = ext4_journal_stop(handle);
+
+	return ret < 0 ? ret : err;
+}
+
+static int ext4_iomap_xattr_fiemap(struct inode *inode, struct iomap *iomap)
+{
+	__u64 physical = 0;
+	__u64 length = 0;
+	int blockbits = inode->i_sb->s_blocksize_bits;
+	int error = 0;
+	u16 iomap_type;
+
+	/* in-inode? */
+	if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
+		struct ext4_iloc iloc;
+		int offset;	/* offset of xattr in inode */
+
+		error = ext4_get_inode_loc(inode, &iloc);
+		if (error)
+			return error;
+		physical = (__u64)iloc.bh->b_blocknr << blockbits;
+		offset = EXT4_GOOD_OLD_INODE_SIZE +
+				EXT4_I(inode)->i_extra_isize;
+		physical += offset;
+		length = EXT4_SB(inode->i_sb)->s_inode_size - offset;
+		brelse(iloc.bh);
+		iomap_type = IOMAP_INLINE;
+	} else if (EXT4_I(inode)->i_file_acl) { /* external block */
+		physical = (__u64)EXT4_I(inode)->i_file_acl << blockbits;
+		length = inode->i_sb->s_blocksize;
+		iomap_type = IOMAP_MAPPED;
+	} else {
+		/* no in-inode or external block for xattr, so return -ENOENT */
+		error = -ENOENT;
+		goto out;
+	}
+
+	iomap->addr = physical;
+	iomap->offset = 0;
+	iomap->length = length;
+	iomap->type = iomap_type;
+	iomap->flags = 0;
+out:
+	return error;
+}
+
+static int ext4_iomap_xattr_begin(struct inode *inode, loff_t offset,
+				  loff_t length, unsigned flags,
+				  struct iomap *iomap, struct iomap *srcmap)
+{
+	int error;
+
+	error = ext4_iomap_xattr_fiemap(inode, iomap);
+	if (error == 0 && (offset >= iomap->length))
+		error = -ENOENT;
+	return error;
+}
+
+static const struct iomap_ops ext4_iomap_xattr_ops = {
+	.iomap_begin		= ext4_iomap_xattr_begin,
+};
+
+static int ext4_fiemap_check_ranges(struct inode *inode, u64 start, u64 *len)
+{
+	u64 maxbytes = ext4_get_maxbytes(inode);
+
+	if (*len == 0)
+		return -EINVAL;
+	if (start > maxbytes)
+		return -EFBIG;
+
+	/*
+	 * Shrink request scope to what the fs can actually handle.
+	 */
+	if (*len > maxbytes || (maxbytes - *len) < start)
+		*len = maxbytes - start;
+	return 0;
+}
+
+int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
+		u64 start, u64 len)
+{
+	int error = 0;
+
+	inode_lock_shared(inode);
+	if (fieinfo->fi_flags & FIEMAP_FLAG_CACHE) {
+		error = ext4_ext_precache(inode);
+		if (error)
+			goto unlock;
+		fieinfo->fi_flags &= ~FIEMAP_FLAG_CACHE;
+	}
+
+	/*
+	 * For bitmap files the maximum size limit could be smaller than
+	 * s_maxbytes, so check len here manually instead of just relying on the
+	 * generic check.
+	 */
+	error = ext4_fiemap_check_ranges(inode, start, &len);
+	if (error)
+		goto unlock;
+
+	if (fieinfo->fi_flags & FIEMAP_FLAG_XATTR) {
+		fieinfo->fi_flags &= ~FIEMAP_FLAG_XATTR;
+		error = iomap_fiemap(inode, fieinfo, start, len,
+				     &ext4_iomap_xattr_ops);
+	} else {
+		error = iomap_fiemap(inode, fieinfo, start, len,
+				     &ext4_iomap_report_ops);
+	}
+unlock:
+	inode_unlock_shared(inode);
+	return error;
+}
+
+int ext4_get_es_cache(struct inode *inode, struct fiemap_extent_info *fieinfo,
+		      __u64 start, __u64 len)
+{
+	ext4_lblk_t start_blk, len_blks;
+	__u64 last_blk;
+	int error = 0;
+
+	if (ext4_has_inline_data(inode)) {
+		int has_inline;
+
+		down_read(&EXT4_I(inode)->xattr_sem);
+		has_inline = ext4_has_inline_data(inode);
+		up_read(&EXT4_I(inode)->xattr_sem);
+		if (has_inline)
+			return 0;
+	}
+
+	if (fieinfo->fi_flags & FIEMAP_FLAG_CACHE) {
+		inode_lock_shared(inode);
+		error = ext4_ext_precache(inode);
+		inode_unlock_shared(inode);
+		if (error)
+			return error;
+		fieinfo->fi_flags &= ~FIEMAP_FLAG_CACHE;
+	}
+
+	error = fiemap_prep(inode, fieinfo, start, &len, 0);
+	if (error)
+		return error;
+
+	error = ext4_fiemap_check_ranges(inode, start, &len);
+	if (error)
+		return error;
+
+	start_blk = start >> inode->i_sb->s_blocksize_bits;
+	last_blk = (start + len - 1) >> inode->i_sb->s_blocksize_bits;
+	if (last_blk >= EXT_MAX_BLOCKS)
+		last_blk = EXT_MAX_BLOCKS-1;
+	len_blks = ((ext4_lblk_t) last_blk) - start_blk + 1;
+
+	/*
+	 * Walk the extent tree gathering extent information
+	 * and pushing extents back to the user.
+	 */
+	return ext4_fill_es_cache_info(inode, start_blk, len_blks, fieinfo);
+}
+
+/*
+ * ext4_ext_shift_path_extents:
+ * Shift the extents of a path structure lying between path[depth].p_ext
+ * and EXT_LAST_EXTENT(path[depth].p_hdr), by @shift blocks. @SHIFT tells
+ * if it is right shift or left shift operation.
+ */
+static int
+ext4_ext_shift_path_extents(struct ext4_ext_path *path, ext4_lblk_t shift,
+			    struct inode *inode, handle_t *handle,
+			    enum SHIFT_DIRECTION SHIFT)
+{
+	int depth, err = 0;
+	struct ext4_extent *ex_start, *ex_last;
+	bool update = false;
+	int credits, restart_credits;
+	depth = path->p_depth;
+
+	while (depth >= 0) {
+		if (depth == path->p_depth) {
+			ex_start = path[depth].p_ext;
+			if (!ex_start)
+				return -EFSCORRUPTED;
+
+			ex_last = EXT_LAST_EXTENT(path[depth].p_hdr);
+			/* leaf + sb + inode */
+			credits = 3;
+			if (ex_start == EXT_FIRST_EXTENT(path[depth].p_hdr)) {
+				update = true;
+				/* extent tree + sb + inode */
+				credits = depth + 2;
+			}
+
+			restart_credits = ext4_chunk_trans_extent(inode, 0);
+			err = ext4_datasem_ensure_credits(handle, inode, credits,
+					restart_credits, 0);
+			if (err) {
+				if (err > 0)
+					err = -EAGAIN;
+				goto out;
+			}
+
+			err = ext4_ext_get_access(handle, inode, path + depth);
+			if (err)
+				goto out;
+
+			while (ex_start <= ex_last) {
+				if (SHIFT == SHIFT_LEFT) {
+					le32_add_cpu(&ex_start->ee_block,
+						-shift);
+					/* Try to merge to the left. */
+					if ((ex_start >
+					    EXT_FIRST_EXTENT(path[depth].p_hdr))
+					    &&
+					    ext4_ext_try_to_merge_right(inode,
+					    path, ex_start - 1))
+						ex_last--;
+					else
+						ex_start++;
+				} else {
+					le32_add_cpu(&ex_last->ee_block, shift);
+					ext4_ext_try_to_merge_right(inode, path,
+						ex_last);
+					ex_last--;
+				}
+			}
+			err = ext4_ext_dirty(handle, inode, path + depth);
+			if (err)
+				goto out;
+
+			if (--depth < 0 || !update)
+				break;
+		}
+
+		/* Update index too */
+		err = ext4_ext_get_access(handle, inode, path + depth);
+		if (err)
+			goto out;
+
+		if (SHIFT == SHIFT_LEFT)
+			le32_add_cpu(&path[depth].p_idx->ei_block, -shift);
+		else
+			le32_add_cpu(&path[depth].p_idx->ei_block, shift);
+		err = ext4_ext_dirty(handle, inode, path + depth);
+		if (err)
+			goto out;
+
+		/* we are done if current index is not a starting index */
+		if (path[depth].p_idx != EXT_FIRST_INDEX(path[depth].p_hdr))
+			break;
+
+		depth--;
+	}
+
+out:
+	return err;
+}
+
+/*
+ * ext4_ext_shift_extents:
+ * All the extents which lies in the range from @start to the last allocated
+ * block for the @inode are shifted either towards left or right (depending
+ * upon @SHIFT) by @shift blocks.
+ * On success, 0 is returned, error otherwise.
+ */
+static int
+ext4_ext_shift_extents(struct inode *inode, handle_t *handle,
+		       ext4_lblk_t start, ext4_lblk_t shift,
+		       enum SHIFT_DIRECTION SHIFT)
+{
+	struct ext4_ext_path *path;
+	int ret = 0, depth;
+	struct ext4_extent *extent;
+	ext4_lblk_t stop, *iterator, ex_start, ex_end;
+	ext4_lblk_t tmp = EXT_MAX_BLOCKS;
+
+	/* Let path point to the last extent */
+	path = ext4_find_extent(inode, EXT_MAX_BLOCKS - 1, NULL,
+				EXT4_EX_NOCACHE);
+	if (IS_ERR(path))
+		return PTR_ERR(path);
+
+	depth = path->p_depth;
+	extent = path[depth].p_ext;
+	if (!extent)
+		goto out;
+
+	stop = le32_to_cpu(extent->ee_block);
+
+       /*
+	* For left shifts, make sure the hole on the left is big enough to
+	* accommodate the shift.  For right shifts, make sure the last extent
+	* won't be shifted beyond EXT_MAX_BLOCKS.
+	*/
+	if (SHIFT == SHIFT_LEFT) {
+		path = ext4_find_extent(inode, start - 1, path,
+					EXT4_EX_NOCACHE);
+		if (IS_ERR(path))
+			return PTR_ERR(path);
+		depth = path->p_depth;
+		extent =  path[depth].p_ext;
+		if (extent) {
+			ex_start = le32_to_cpu(extent->ee_block);
+			ex_end = le32_to_cpu(extent->ee_block) +
+				ext4_ext_get_actual_len(extent);
+		} else {
+			ex_start = 0;
+			ex_end = 0;
+		}
+
+		if ((start == ex_start && shift > ex_start) ||
+		    (shift > start - ex_end)) {
+			ret = -EINVAL;
+			goto out;
+		}
+	} else {
+		if (shift > EXT_MAX_BLOCKS -
+		    (stop + ext4_ext_get_actual_len(extent))) {
+			ret = -EINVAL;
+			goto out;
+		}
+	}
+
+	/*
+	 * In case of left shift, iterator points to start and it is increased
+	 * till we reach stop. In case of right shift, iterator points to stop
+	 * and it is decreased till we reach start.
+	 */
+again:
+	ret = 0;
+	if (SHIFT == SHIFT_LEFT)
+		iterator = &start;
+	else
+		iterator = &stop;
+
+	if (tmp != EXT_MAX_BLOCKS)
+		*iterator = tmp;
+
+	/*
+	 * Its safe to start updating extents.  Start and stop are unsigned, so
+	 * in case of right shift if extent with 0 block is reached, iterator
+	 * becomes NULL to indicate the end of the loop.
+	 */
+	while (iterator && start <= stop) {
+		path = ext4_find_extent(inode, *iterator, path,
+					EXT4_EX_NOCACHE);
+		if (IS_ERR(path))
+			return PTR_ERR(path);
+		depth = path->p_depth;
+		extent = path[depth].p_ext;
+		if (!extent) {
+			EXT4_ERROR_INODE(inode, "unexpected hole at %lu",
+					 (unsigned long) *iterator);
+			return -EFSCORRUPTED;
+		}
+		if (SHIFT == SHIFT_LEFT && *iterator >
+		    le32_to_cpu(extent->ee_block)) {
+			/* Hole, move to the next extent */
+			if (extent < EXT_LAST_EXTENT(path[depth].p_hdr)) {
+				path[depth].p_ext++;
+			} else {
+				*iterator = ext4_ext_next_allocated_block(path);
+				continue;
+			}
+		}
+
+		tmp = *iterator;
+		if (SHIFT == SHIFT_LEFT) {
+			extent = EXT_LAST_EXTENT(path[depth].p_hdr);
+			*iterator = le32_to_cpu(extent->ee_block) +
+					ext4_ext_get_actual_len(extent);
+		} else {
+			extent = EXT_FIRST_EXTENT(path[depth].p_hdr);
+			if (le32_to_cpu(extent->ee_block) > start)
+				*iterator = le32_to_cpu(extent->ee_block) - 1;
+			else if (le32_to_cpu(extent->ee_block) == start)
+				iterator = NULL;
+			else {
+				extent = EXT_LAST_EXTENT(path[depth].p_hdr);
+				while (le32_to_cpu(extent->ee_block) >= start)
+					extent--;
+
+				if (extent == EXT_LAST_EXTENT(path[depth].p_hdr))
+					break;
+
+				extent++;
+				iterator = NULL;
+			}
+			path[depth].p_ext = extent;
+		}
+		ret = ext4_ext_shift_path_extents(path, shift, inode,
+				handle, SHIFT);
+		/* iterator can be NULL which means we should break */
+		if (ret == -EAGAIN)
+			goto again;
+		if (ret)
+			break;
+	}
+out:
+	ext4_free_ext_path(path);
+	return ret;
+}
+
+/*
+ * ext4_collapse_range:
+ * This implements the fallocate's collapse range functionality for ext4
+ * Returns: 0 and non-zero on error.
+ */
+static int ext4_collapse_range(struct file *file, loff_t offset, loff_t len)
+{
+	struct inode *inode = file_inode(file);
+	struct super_block *sb = inode->i_sb;
+	struct address_space *mapping = inode->i_mapping;
+	loff_t end = offset + len;
+	ext4_lblk_t start_lblk, end_lblk;
+	handle_t *handle;
+	unsigned int credits;
+	loff_t start, new_size;
+	int ret;
+
+	trace_ext4_collapse_range(inode, offset, len);
+	WARN_ON_ONCE(!inode_is_locked(inode));
+
+	/* Currently just for extent based files */
+	if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+		return -EOPNOTSUPP;
+	/* Collapse range works only on fs cluster size aligned regions. */
+	if (!IS_ALIGNED(offset | len, EXT4_CLUSTER_SIZE(sb)))
+		return -EINVAL;
+	/*
+	 * There is no need to overlap collapse range with EOF, in which case
+	 * it is effectively a truncate operation
+	 */
+	if (end >= inode->i_size)
+		return -EINVAL;
+
+	/*
+	 * Write tail of the last page before removed range and data that
+	 * will be shifted since they will get removed from the page cache
+	 * below. We are also protected from pages becoming dirty by
+	 * i_rwsem and invalidate_lock.
+	 * Need to round down offset to be aligned with page size boundary
+	 * for page size > block size.
+	 */
+	start = round_down(offset, PAGE_SIZE);
+	ret = filemap_write_and_wait_range(mapping, start, offset);
+	if (!ret)
+		ret = filemap_write_and_wait_range(mapping, end, LLONG_MAX);
+	if (ret)
+		return ret;
+
+	truncate_pagecache(inode, start);
+
+	credits = ext4_chunk_trans_extent(inode, 0);
+	handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
+	if (IS_ERR(handle))
+		return PTR_ERR(handle);
+
+	ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_FALLOC_RANGE, handle);
+
+	start_lblk = offset >> inode->i_blkbits;
+	end_lblk = (offset + len) >> inode->i_blkbits;
+
+	ext4_check_map_extents_env(inode);
+
+	down_write(&EXT4_I(inode)->i_data_sem);
+	ext4_discard_preallocations(inode);
+	ext4_es_remove_extent(inode, start_lblk, EXT_MAX_BLOCKS - start_lblk);
+
+	ret = ext4_ext_remove_space(inode, start_lblk, end_lblk - 1);
+	if (ret) {
+		up_write(&EXT4_I(inode)->i_data_sem);
+		goto out_handle;
+	}
+	ext4_discard_preallocations(inode);
+
+	ret = ext4_ext_shift_extents(inode, handle, end_lblk,
+				     end_lblk - start_lblk, SHIFT_LEFT);
+	if (ret) {
+		up_write(&EXT4_I(inode)->i_data_sem);
+		goto out_handle;
+	}
+
+	new_size = inode->i_size - len;
+	i_size_write(inode, new_size);
+	EXT4_I(inode)->i_disksize = new_size;
+
+	up_write(&EXT4_I(inode)->i_data_sem);
+	ret = ext4_mark_inode_dirty(handle, inode);
+	if (ret)
+		goto out_handle;
+
+	ext4_update_inode_fsync_trans(handle, inode, 1);
+	if (IS_SYNC(inode))
+		ext4_handle_sync(handle);
+
+out_handle:
+	ext4_journal_stop(handle);
+	return ret;
+}
+
+/*
+ * ext4_insert_range:
+ * This function implements the FALLOC_FL_INSERT_RANGE flag of fallocate.
+ * The data blocks starting from @offset to the EOF are shifted by @len
+ * towards right to create a hole in the @inode. Inode size is increased
+ * by len bytes.
+ * Returns 0 on success, error otherwise.
+ */
+static int ext4_insert_range(struct file *file, loff_t offset, loff_t len)
+{
+	struct inode *inode = file_inode(file);
+	struct super_block *sb = inode->i_sb;
+	struct address_space *mapping = inode->i_mapping;
+	handle_t *handle;
+	struct ext4_ext_path *path;
+	struct ext4_extent *extent;
+	ext4_lblk_t start_lblk, len_lblk, ee_start_lblk = 0;
+	unsigned int credits, ee_len;
+	int ret, depth, split_flag = 0;
+	loff_t start;
+
+	trace_ext4_insert_range(inode, offset, len);
+	WARN_ON_ONCE(!inode_is_locked(inode));
+
+	/* Currently just for extent based files */
+	if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+		return -EOPNOTSUPP;
+	/* Insert range works only on fs cluster size aligned regions. */
+	if (!IS_ALIGNED(offset | len, EXT4_CLUSTER_SIZE(sb)))
+		return -EINVAL;
+	/* Offset must be less than i_size */
+	if (offset >= inode->i_size)
+		return -EINVAL;
+	/* Check whether the maximum file size would be exceeded */
+	if (len > inode->i_sb->s_maxbytes - inode->i_size)
+		return -EFBIG;
+
+	/*
+	 * Write out all dirty pages. Need to round down to align start offset
+	 * to page size boundary for page size > block size.
+	 */
+	start = round_down(offset, PAGE_SIZE);
+	ret = filemap_write_and_wait_range(mapping, start, LLONG_MAX);
+	if (ret)
+		return ret;
+
+	truncate_pagecache(inode, start);
+
+	credits = ext4_chunk_trans_extent(inode, 0);
+	handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
+	if (IS_ERR(handle))
+		return PTR_ERR(handle);
+
+	ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_FALLOC_RANGE, handle);
+
+	/* Expand file to avoid data loss if there is error while shifting */
+	inode->i_size += len;
+	EXT4_I(inode)->i_disksize += len;
+	ret = ext4_mark_inode_dirty(handle, inode);
+	if (ret)
+		goto out_handle;
+
+	start_lblk = offset >> inode->i_blkbits;
+	len_lblk = len >> inode->i_blkbits;
+
+	ext4_check_map_extents_env(inode);
+
+	down_write(&EXT4_I(inode)->i_data_sem);
+	ext4_discard_preallocations(inode);
+
+	path = ext4_find_extent(inode, start_lblk, NULL, 0);
+	if (IS_ERR(path)) {
+		up_write(&EXT4_I(inode)->i_data_sem);
+		ret = PTR_ERR(path);
+		goto out_handle;
+	}
+
+	depth = ext_depth(inode);
+	extent = path[depth].p_ext;
+	if (extent) {
+		ee_start_lblk = le32_to_cpu(extent->ee_block);
+		ee_len = ext4_ext_get_actual_len(extent);
+
+		/*
+		 * If start_lblk is not the starting block of extent, split
+		 * the extent @start_lblk
+		 */
+		if ((start_lblk > ee_start_lblk) &&
+				(start_lblk < (ee_start_lblk + ee_len))) {
+			if (ext4_ext_is_unwritten(extent))
+				split_flag = EXT4_EXT_MARK_UNWRIT1 |
+					EXT4_EXT_MARK_UNWRIT2;
+			path = ext4_split_extent_at(handle, inode, path,
+					start_lblk, split_flag,
+					EXT4_EX_NOCACHE |
+					EXT4_GET_BLOCKS_PRE_IO |
+					EXT4_GET_BLOCKS_METADATA_NOFAIL);
+		}
+
+		if (IS_ERR(path)) {
+			up_write(&EXT4_I(inode)->i_data_sem);
+			ret = PTR_ERR(path);
+			goto out_handle;
+		}
+	}
+
+	ext4_free_ext_path(path);
+	ext4_es_remove_extent(inode, start_lblk, EXT_MAX_BLOCKS - start_lblk);
+
+	/*
+	 * if start_lblk lies in a hole which is at start of file, use
+	 * ee_start_lblk to shift extents
+	 */
+	ret = ext4_ext_shift_extents(inode, handle,
+		max(ee_start_lblk, start_lblk), len_lblk, SHIFT_RIGHT);
+	up_write(&EXT4_I(inode)->i_data_sem);
+	if (ret)
+		goto out_handle;
+
+	ext4_update_inode_fsync_trans(handle, inode, 1);
+	if (IS_SYNC(inode))
+		ext4_handle_sync(handle);
+
+out_handle:
+	ext4_journal_stop(handle);
+	return ret;
+}
+
+/**
+ * ext4_swap_extents() - Swap extents between two inodes
+ * @handle: handle for this transaction
+ * @inode1:	First inode
+ * @inode2:	Second inode
+ * @lblk1:	Start block for first inode
+ * @lblk2:	Start block for second inode
+ * @count:	Number of blocks to swap
+ * @unwritten: Mark second inode's extents as unwritten after swap
+ * @erp:	Pointer to save error value
+ *
+ * This helper routine does exactly what is promise "swap extents". All other
+ * stuff such as page-cache locking consistency, bh mapping consistency or
+ * extent's data copying must be performed by caller.
+ * Locking:
+ *		i_rwsem is held for both inodes
+ * 		i_data_sem is locked for write for both inodes
+ * Assumptions:
+ *		All pages from requested range are locked for both inodes
+ */
+int
+ext4_swap_extents(handle_t *handle, struct inode *inode1,
+		  struct inode *inode2, ext4_lblk_t lblk1, ext4_lblk_t lblk2,
+		  ext4_lblk_t count, int unwritten, int *erp)
+{
+	struct ext4_ext_path *path1 = NULL;
+	struct ext4_ext_path *path2 = NULL;
+	int replaced_count = 0;
+
+	BUG_ON(!rwsem_is_locked(&EXT4_I(inode1)->i_data_sem));
+	BUG_ON(!rwsem_is_locked(&EXT4_I(inode2)->i_data_sem));
+	BUG_ON(!inode_is_locked(inode1));
+	BUG_ON(!inode_is_locked(inode2));
+
+	ext4_es_remove_extent(inode1, lblk1, count);
+	ext4_es_remove_extent(inode2, lblk2, count);
+
+	while (count) {
+		struct ext4_extent *ex1, *ex2, tmp_ex;
+		ext4_lblk_t e1_blk, e2_blk;
+		int e1_len, e2_len, len;
+		int split = 0;
+
+		path1 = ext4_find_extent(inode1, lblk1, path1, EXT4_EX_NOCACHE);
+		if (IS_ERR(path1)) {
+			*erp = PTR_ERR(path1);
+			goto errout;
+		}
+		path2 = ext4_find_extent(inode2, lblk2, path2, EXT4_EX_NOCACHE);
+		if (IS_ERR(path2)) {
+			*erp = PTR_ERR(path2);
+			goto errout;
+		}
+		ex1 = path1[path1->p_depth].p_ext;
+		ex2 = path2[path2->p_depth].p_ext;
+		/* Do we have something to swap ? */
+		if (unlikely(!ex2 || !ex1))
+			goto errout;
+
+		e1_blk = le32_to_cpu(ex1->ee_block);
+		e2_blk = le32_to_cpu(ex2->ee_block);
+		e1_len = ext4_ext_get_actual_len(ex1);
+		e2_len = ext4_ext_get_actual_len(ex2);
+
+		/* Hole handling */
+		if (!in_range(lblk1, e1_blk, e1_len) ||
+		    !in_range(lblk2, e2_blk, e2_len)) {
+			ext4_lblk_t next1, next2;
+
+			/* if hole after extent, then go to next extent */
+			next1 = ext4_ext_next_allocated_block(path1);
+			next2 = ext4_ext_next_allocated_block(path2);
+			/* If hole before extent, then shift to that extent */
+			if (e1_blk > lblk1)
+				next1 = e1_blk;
+			if (e2_blk > lblk2)
+				next2 = e2_blk;
+			/* Do we have something to swap */
+			if (next1 == EXT_MAX_BLOCKS || next2 == EXT_MAX_BLOCKS)
+				goto errout;
+			/* Move to the rightest boundary */
+			len = next1 - lblk1;
+			if (len < next2 - lblk2)
+				len = next2 - lblk2;
+			if (len > count)
+				len = count;
+			lblk1 += len;
+			lblk2 += len;
+			count -= len;
+			continue;
+		}
+
+		/* Prepare left boundary */
+		if (e1_blk < lblk1) {
+			split = 1;
+			path1 = ext4_force_split_extent_at(handle, inode1,
+							   path1, lblk1, 0);
+			if (IS_ERR(path1)) {
+				*erp = PTR_ERR(path1);
+				goto errout;
+			}
+		}
+		if (e2_blk < lblk2) {
+			split = 1;
+			path2 = ext4_force_split_extent_at(handle, inode2,
+							   path2, lblk2, 0);
+			if (IS_ERR(path2)) {
+				*erp = PTR_ERR(path2);
+				goto errout;
+			}
+		}
+		/* ext4_split_extent_at() may result in leaf extent split,
+		 * path must to be revalidated. */
+		if (split)
+			continue;
+
+		/* Prepare right boundary */
+		len = count;
+		if (len > e1_blk + e1_len - lblk1)
+			len = e1_blk + e1_len - lblk1;
+		if (len > e2_blk + e2_len - lblk2)
+			len = e2_blk + e2_len - lblk2;
+
+		if (len != e1_len) {
+			split = 1;
+			path1 = ext4_force_split_extent_at(handle, inode1,
+							path1, lblk1 + len, 0);
+			if (IS_ERR(path1)) {
+				*erp = PTR_ERR(path1);
+				goto errout;
+			}
+		}
+		if (len != e2_len) {
+			split = 1;
+			path2 = ext4_force_split_extent_at(handle, inode2,
+							path2, lblk2 + len, 0);
+			if (IS_ERR(path2)) {
+				*erp = PTR_ERR(path2);
+				goto errout;
+			}
+		}
+		/* ext4_split_extent_at() may result in leaf extent split,
+		 * path must to be revalidated. */
+		if (split)
+			continue;
+
+		BUG_ON(e2_len != e1_len);
+		*erp = ext4_ext_get_access(handle, inode1, path1 + path1->p_depth);
+		if (unlikely(*erp))
+			goto errout;
+		*erp = ext4_ext_get_access(handle, inode2, path2 + path2->p_depth);
+		if (unlikely(*erp))
+			goto errout;
+
+		/* Both extents are fully inside boundaries. Swap it now */
+		tmp_ex = *ex1;
+		ext4_ext_store_pblock(ex1, ext4_ext_pblock(ex2));
+		ext4_ext_store_pblock(ex2, ext4_ext_pblock(&tmp_ex));
+		ex1->ee_len = cpu_to_le16(e2_len);
+		ex2->ee_len = cpu_to_le16(e1_len);
+		if (unwritten)
+			ext4_ext_mark_unwritten(ex2);
+		if (ext4_ext_is_unwritten(&tmp_ex))
+			ext4_ext_mark_unwritten(ex1);
+
+		ext4_ext_try_to_merge(handle, inode2, path2, ex2);
+		ext4_ext_try_to_merge(handle, inode1, path1, ex1);
+		*erp = ext4_ext_dirty(handle, inode2, path2 +
+				      path2->p_depth);
+		if (unlikely(*erp))
+			goto errout;
+		*erp = ext4_ext_dirty(handle, inode1, path1 +
+				      path1->p_depth);
+		/*
+		 * Looks scarry ah..? second inode already points to new blocks,
+		 * and it was successfully dirtied. But luckily error may happen
+		 * only due to journal error, so full transaction will be
+		 * aborted anyway.
+		 */
+		if (unlikely(*erp))
+			goto errout;
+
+		lblk1 += len;
+		lblk2 += len;
+		replaced_count += len;
+		count -= len;
+	}
+
+errout:
+	ext4_free_ext_path(path1);
+	ext4_free_ext_path(path2);
+	return replaced_count;
+}
+
+/*
+ * ext4_clu_mapped - determine whether any block in a logical cluster has
+ *                   been mapped to a physical cluster
+ *
+ * @inode - file containing the logical cluster
+ * @lclu - logical cluster of interest
+ *
+ * Returns 1 if any block in the logical cluster is mapped, signifying
+ * that a physical cluster has been allocated for it.  Otherwise,
+ * returns 0.  Can also return negative error codes.  Derived from
+ * ext4_ext_map_blocks().
+ */
+int ext4_clu_mapped(struct inode *inode, ext4_lblk_t lclu)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	struct ext4_ext_path *path;
+	int depth, mapped = 0, err = 0;
+	struct ext4_extent *extent;
+	ext4_lblk_t first_lblk, first_lclu, last_lclu;
+
+	/*
+	 * if data can be stored inline, the logical cluster isn't
+	 * mapped - no physical clusters have been allocated, and the
+	 * file has no extents
+	 */
+	if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) ||
+	    ext4_has_inline_data(inode))
+		return 0;
+
+	/* search for the extent closest to the first block in the cluster */
+	path = ext4_find_extent(inode, EXT4_C2B(sbi, lclu), NULL, 0);
+	if (IS_ERR(path))
+		return PTR_ERR(path);
+
+	depth = ext_depth(inode);
+
+	/*
+	 * A consistent leaf must not be empty.  This situation is possible,
+	 * though, _during_ tree modification, and it's why an assert can't
+	 * be put in ext4_find_extent().
+	 */
+	if (unlikely(path[depth].p_ext == NULL && depth != 0)) {
+		EXT4_ERROR_INODE(inode,
+		    "bad extent address - lblock: %lu, depth: %d, pblock: %lld",
+				 (unsigned long) EXT4_C2B(sbi, lclu),
+				 depth, path[depth].p_block);
+		err = -EFSCORRUPTED;
+		goto out;
+	}
+
+	extent = path[depth].p_ext;
+
+	/* can't be mapped if the extent tree is empty */
+	if (extent == NULL)
+		goto out;
+
+	first_lblk = le32_to_cpu(extent->ee_block);
+	first_lclu = EXT4_B2C(sbi, first_lblk);
+
+	/*
+	 * Three possible outcomes at this point - found extent spanning
+	 * the target cluster, to the left of the target cluster, or to the
+	 * right of the target cluster.  The first two cases are handled here.
+	 * The last case indicates the target cluster is not mapped.
+	 */
+	if (lclu >= first_lclu) {
+		last_lclu = EXT4_B2C(sbi, first_lblk +
+				     ext4_ext_get_actual_len(extent) - 1);
+		if (lclu <= last_lclu) {
+			mapped = 1;
+		} else {
+			first_lblk = ext4_ext_next_allocated_block(path);
+			first_lclu = EXT4_B2C(sbi, first_lblk);
+			if (lclu == first_lclu)
+				mapped = 1;
+		}
+	}
+
+out:
+	ext4_free_ext_path(path);
+
+	return err ? err : mapped;
+}
+
+/*
+ * Updates physical block address and unwritten status of extent
+ * starting at lblk start and of len. If such an extent doesn't exist,
+ * this function splits the extent tree appropriately to create an
+ * extent like this.  This function is called in the fast commit
+ * replay path.  Returns 0 on success and error on failure.
+ */
+int ext4_ext_replay_update_ex(struct inode *inode, ext4_lblk_t start,
+			      int len, int unwritten, ext4_fsblk_t pblk)
+{
+	struct ext4_ext_path *path;
+	struct ext4_extent *ex;
+	int ret;
+
+	path = ext4_find_extent(inode, start, NULL, 0);
+	if (IS_ERR(path))
+		return PTR_ERR(path);
+	ex = path[path->p_depth].p_ext;
+	if (!ex) {
+		ret = -EFSCORRUPTED;
+		goto out;
+	}
+
+	if (le32_to_cpu(ex->ee_block) != start ||
+		ext4_ext_get_actual_len(ex) != len) {
+		/* We need to split this extent to match our extent first */
+		down_write(&EXT4_I(inode)->i_data_sem);
+		path = ext4_force_split_extent_at(NULL, inode, path, start, 1);
+		up_write(&EXT4_I(inode)->i_data_sem);
+		if (IS_ERR(path)) {
+			ret = PTR_ERR(path);
+			goto out;
+		}
+
+		path = ext4_find_extent(inode, start, path, 0);
+		if (IS_ERR(path))
+			return PTR_ERR(path);
+
+		ex = path[path->p_depth].p_ext;
+		WARN_ON(le32_to_cpu(ex->ee_block) != start);
+
+		if (ext4_ext_get_actual_len(ex) != len) {
+			down_write(&EXT4_I(inode)->i_data_sem);
+			path = ext4_force_split_extent_at(NULL, inode, path,
+							  start + len, 1);
+			up_write(&EXT4_I(inode)->i_data_sem);
+			if (IS_ERR(path)) {
+				ret = PTR_ERR(path);
+				goto out;
+			}
+
+			path = ext4_find_extent(inode, start, path, 0);
+			if (IS_ERR(path))
+				return PTR_ERR(path);
+			ex = path[path->p_depth].p_ext;
+		}
+	}
+	if (unwritten)
+		ext4_ext_mark_unwritten(ex);
+	else
+		ext4_ext_mark_initialized(ex);
+	ext4_ext_store_pblock(ex, pblk);
+	down_write(&EXT4_I(inode)->i_data_sem);
+	ret = ext4_ext_dirty(NULL, inode, &path[path->p_depth]);
+	up_write(&EXT4_I(inode)->i_data_sem);
+out:
+	ext4_free_ext_path(path);
+	ext4_mark_inode_dirty(NULL, inode);
+	return ret;
+}
+
+/* Try to shrink the extent tree */
+void ext4_ext_replay_shrink_inode(struct inode *inode, ext4_lblk_t end)
+{
+	struct ext4_ext_path *path = NULL;
+	struct ext4_extent *ex;
+	ext4_lblk_t old_cur, cur = 0;
+
+	while (cur < end) {
+		path = ext4_find_extent(inode, cur, NULL, 0);
+		if (IS_ERR(path))
+			return;
+		ex = path[path->p_depth].p_ext;
+		if (!ex) {
+			ext4_free_ext_path(path);
+			ext4_mark_inode_dirty(NULL, inode);
+			return;
+		}
+		old_cur = cur;
+		cur = le32_to_cpu(ex->ee_block) + ext4_ext_get_actual_len(ex);
+		if (cur <= old_cur)
+			cur = old_cur + 1;
+		ext4_ext_try_to_merge(NULL, inode, path, ex);
+		down_write(&EXT4_I(inode)->i_data_sem);
+		ext4_ext_dirty(NULL, inode, &path[path->p_depth]);
+		up_write(&EXT4_I(inode)->i_data_sem);
+		ext4_mark_inode_dirty(NULL, inode);
+		ext4_free_ext_path(path);
+	}
+}
+
+/* Check if *cur is a hole and if it is, skip it */
+static int skip_hole(struct inode *inode, ext4_lblk_t *cur)
+{
+	int ret;
+	struct ext4_map_blocks map;
+
+	map.m_lblk = *cur;
+	map.m_len = ((inode->i_size) >> inode->i_sb->s_blocksize_bits) - *cur;
+
+	ret = ext4_map_blocks(NULL, inode, &map, 0);
+	if (ret < 0)
+		return ret;
+	if (ret != 0)
+		return 0;
+	*cur = *cur + map.m_len;
+	return 0;
+}
+
+/* Count number of blocks used by this inode and update i_blocks */
+int ext4_ext_replay_set_iblocks(struct inode *inode)
+{
+	struct ext4_ext_path *path = NULL, *path2 = NULL;
+	struct ext4_extent *ex;
+	ext4_lblk_t cur = 0, end;
+	int numblks = 0, i, ret = 0;
+	ext4_fsblk_t cmp1, cmp2;
+	struct ext4_map_blocks map;
+
+	/* Determin the size of the file first */
+	path = ext4_find_extent(inode, EXT_MAX_BLOCKS - 1, NULL,
+					EXT4_EX_NOCACHE);
+	if (IS_ERR(path))
+		return PTR_ERR(path);
+	ex = path[path->p_depth].p_ext;
+	if (!ex)
+		goto out;
+	end = le32_to_cpu(ex->ee_block) + ext4_ext_get_actual_len(ex);
+
+	/* Count the number of data blocks */
+	cur = 0;
+	while (cur < end) {
+		map.m_lblk = cur;
+		map.m_len = end - cur;
+		ret = ext4_map_blocks(NULL, inode, &map, 0);
+		if (ret < 0)
+			break;
+		if (ret > 0)
+			numblks += ret;
+		cur = cur + map.m_len;
+	}
+
+	/*
+	 * Count the number of extent tree blocks. We do it by looking up
+	 * two successive extents and determining the difference between
+	 * their paths. When path is different for 2 successive extents
+	 * we compare the blocks in the path at each level and increment
+	 * iblocks by total number of differences found.
+	 */
+	cur = 0;
+	ret = skip_hole(inode, &cur);
+	if (ret < 0)
+		goto out;
+	path = ext4_find_extent(inode, cur, path, 0);
+	if (IS_ERR(path))
+		goto out;
+	numblks += path->p_depth;
+	while (cur < end) {
+		path = ext4_find_extent(inode, cur, path, 0);
+		if (IS_ERR(path))
+			break;
+		ex = path[path->p_depth].p_ext;
+		if (!ex)
+			goto cleanup;
+
+		cur = max(cur + 1, le32_to_cpu(ex->ee_block) +
+					ext4_ext_get_actual_len(ex));
+		ret = skip_hole(inode, &cur);
+		if (ret < 0)
+			break;
+
+		path2 = ext4_find_extent(inode, cur, path2, 0);
+		if (IS_ERR(path2))
+			break;
+
+		for (i = 0; i <= max(path->p_depth, path2->p_depth); i++) {
+			cmp1 = cmp2 = 0;
+			if (i <= path->p_depth)
+				cmp1 = path[i].p_bh ?
+					path[i].p_bh->b_blocknr : 0;
+			if (i <= path2->p_depth)
+				cmp2 = path2[i].p_bh ?
+					path2[i].p_bh->b_blocknr : 0;
+			if (cmp1 != cmp2 && cmp2 != 0)
+				numblks++;
+		}
+	}
+
+out:
+	inode->i_blocks = numblks << (inode->i_sb->s_blocksize_bits - 9);
+	ext4_mark_inode_dirty(NULL, inode);
+cleanup:
+	ext4_free_ext_path(path);
+	ext4_free_ext_path(path2);
+	return 0;
+}
+
+int ext4_ext_clear_bb(struct inode *inode)
+{
+	struct ext4_ext_path *path = NULL;
+	struct ext4_extent *ex;
+	ext4_lblk_t cur = 0, end;
+	int j, ret = 0;
+	struct ext4_map_blocks map;
+
+	if (ext4_test_inode_flag(inode, EXT4_INODE_INLINE_DATA))
+		return 0;
+
+	/* Determin the size of the file first */
+	path = ext4_find_extent(inode, EXT_MAX_BLOCKS - 1, NULL,
+					EXT4_EX_NOCACHE);
+	if (IS_ERR(path))
+		return PTR_ERR(path);
+	ex = path[path->p_depth].p_ext;
+	if (!ex)
+		goto out;
+	end = le32_to_cpu(ex->ee_block) + ext4_ext_get_actual_len(ex);
+
+	cur = 0;
+	while (cur < end) {
+		map.m_lblk = cur;
+		map.m_len = end - cur;
+		ret = ext4_map_blocks(NULL, inode, &map, 0);
+		if (ret < 0)
+			break;
+		if (ret > 0) {
+			path = ext4_find_extent(inode, map.m_lblk, path, 0);
+			if (!IS_ERR(path)) {
+				for (j = 0; j < path->p_depth; j++) {
+					ext4_mb_mark_bb(inode->i_sb,
+							path[j].p_block, 1, false);
+					ext4_fc_record_regions(inode->i_sb, inode->i_ino,
+							0, path[j].p_block, 1, 1);
+				}
+			} else {
+				path = NULL;
+			}
+			ext4_mb_mark_bb(inode->i_sb, map.m_pblk, map.m_len, false);
+			ext4_fc_record_regions(inode->i_sb, inode->i_ino,
+					map.m_lblk, map.m_pblk, map.m_len, 1);
+		}
+		cur = cur + map.m_len;
+	}
+
+out:
+	ext4_free_ext_path(path);
+	return 0;
+}
-- 
2.43.0

    