ext4: refactor ext4_move_extents code base

ext4_move_extents is too complex for review. It has duplicate almost
each function available in the rest of other codebase. It has useless
artificial restriction orig_offset == donor_offset. But in fact logic
of ext4_move_extents is very simple:

Iterate extents one by one (similar to ext4_fill_fiemap_extents)
   ->Iterate each page covered extent (similar to generic_perform_write)
     ->swap extents for covered by page (can be shared with IOC_MOVE_DATA)

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

3 files changed, 338 insertions, 891 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 420c9be9f7ae..cf3ad75d3015 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2740,10 +2740,15 @@ extern int ext4_find_delalloc_range(struct inode *inode,
 				    ext4_lblk_t lblk_start,
 				    ext4_lblk_t lblk_end);
 extern int ext4_find_delalloc_cluster(struct inode *inode, ext4_lblk_t lblk);
+extern ext4_lblk_t ext4_ext_next_allocated_block(struct ext4_ext_path *path);
 extern int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 			__u64 start, __u64 len);
 extern int ext4_ext_precache(struct inode *inode);
 extern int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len);
+extern 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 mark_unwritten,int *err);
 
 /* move_extent.c */
 extern void ext4_double_down_write_data_sem(struct inode *first,
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 1b768343ddf1..73d9ae9a16db 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -291,6 +291,19 @@ static inline int ext4_ext_space_root_idx(struct inode *inode, int check)
 	return size;
 }
 
+static inline int
+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);
+
+	return ext4_split_extent_at(handle, inode, path, lblk, unwritten ?
+			EXT4_EXT_MARK_UNWRIT1|EXT4_EXT_MARK_UNWRIT2 : 0,
+			EXT4_EX_NOCACHE | EXT4_GET_BLOCKS_PRE_IO |
+			(nofail ? EXT4_GET_BLOCKS_METADATA_NOFAIL:0));
+}
+
 /*
  * Calculate the number of metadata blocks needed
  * to allocate @blocks
@@ -1559,7 +1572,7 @@ found_extent:
  * allocated block. Thus, index entries have to be consistent
  * with leaves.
  */
-static ext4_lblk_t
+ext4_lblk_t
 ext4_ext_next_allocated_block(struct ext4_ext_path *path)
 {
 	int depth;
@@ -2854,24 +2867,14 @@ again:
 		 */
 		if (end >= ee_block &&
 		    end < ee_block + ext4_ext_get_actual_len(ex) - 1) {
-			int split_flag = 0;
-
-			if (ext4_ext_is_unwritten(ex))
-				split_flag = EXT4_EXT_MARK_UNWRIT1 |
-					     EXT4_EXT_MARK_UNWRIT2;
-
 			/*
 			 * 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.
 			 */
-			err = ext4_split_extent_at(handle, inode, path,
-					end + 1, split_flag,
-					EXT4_EX_NOCACHE |
-					EXT4_GET_BLOCKS_PRE_IO |
-					EXT4_GET_BLOCKS_METADATA_NOFAIL);
-
+			err = ext4_force_split_extent_at(handle, inode, path,
+							 end + 1, 1);
 			if (err < 0)
 				goto out;
 		}
@@ -5506,3 +5509,208 @@ out_mutex:
 	mutex_unlock(&inode->i_mutex);
 	return ret;
 }
+
+/**
+ * ext4_swap_extents - Swap extents between two inodes
+ *
+ * @inode1:	First inode
+ * @inode2:	Second inode
+ * @lblk1:	Start block for first inode
+ * @lblk2:	Start block for second inode
+ * @count:	Number of blocks to swap
+ * @mark_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_mutex 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(!mutex_is_locked(&inode1->i_mutex));
+	BUG_ON(!mutex_is_locked(&inode1->i_mutex));
+
+	*erp = ext4_es_remove_extent(inode1, lblk1, count);
+	if (*erp)
+		return 0;
+	*erp = ext4_es_remove_extent(inode2, lblk2, count);
+	if (*erp)
+		return 0;
+
+	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_ext_find_extent(inode1, lblk1, NULL, EXT4_EX_NOCACHE);
+		if (IS_ERR(path1)) {
+			*erp = PTR_ERR(path1);
+			break;
+		}
+		path2 = ext4_ext_find_extent(inode2, lblk2, NULL, EXT4_EX_NOCACHE);
+		if (IS_ERR(path2)) {
+			*erp = PTR_ERR(path2);
+			break;
+		}
+		ex1 = path1[path1->p_depth].p_ext;
+		ex2 = path2[path2->p_depth].p_ext;
+		/* Do we have somthing to swap ? */
+		if (unlikely(!ex2 || !ex1))
+			break;
+
+		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 = e1_blk;
+			/* Do we have something to swap */
+			if (next1 == EXT_MAX_BLOCKS || next2 == EXT_MAX_BLOCKS)
+				break;
+			/* 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;
+			goto repeat;
+		}
+
+		/* Prepare left boundary */
+		if (e1_blk < lblk1) {
+			split = 1;
+			*erp = ext4_force_split_extent_at(handle, inode1,
+						path1, lblk1, 0);
+			if (*erp)
+				break;
+		}
+		if (e2_blk < lblk2) {
+			split = 1;
+			*erp = ext4_force_split_extent_at(handle, inode2,
+						path2,  lblk2, 0);
+			if (*erp)
+				break;
+		}
+		/* ext4_split_extent_at() may retult in leaf extent split,
+		 * path must to be revalidated. */
+		if (split)
+			goto repeat;
+
+		/* 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;
+			*erp = ext4_force_split_extent_at(handle, inode1,
+						path1, lblk1 + len, 0);
+			if (*erp)
+				break;
+		}
+		if (len != e2_len) {
+			split = 1;
+			*erp = ext4_force_split_extent_at(handle, inode2,
+						path2, lblk2 + len, 0);
+			if (*erp)
+				break;
+		}
+		/* ext4_split_extent_at() may retult in leaf extent split,
+		 * path must to be revalidated. */
+		if (split)
+			goto repeat;
+
+		BUG_ON(e2_len != e1_len);
+		*erp = ext4_ext_get_access(handle, inode1, path1 + path1->p_depth);
+		if (*erp)
+			break;
+		*erp = ext4_ext_get_access(handle, inode2, path2 + path2->p_depth);
+		if (*erp)
+			break;
+
+		/* 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 (*erp)
+			break;
+		*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 (*erp)
+			break;
+		lblk1 += len;
+		lblk2 += len;
+		replaced_count += len;
+		count -= len;
+
+	repeat:
+		if (path1) {
+			ext4_ext_drop_refs(path1);
+			kfree(path1);
+			path1 = NULL;
+		}
+		if (path2) {
+			ext4_ext_drop_refs(path2);
+			kfree(path2);
+			path2 = NULL;
+		}
+	}
+	if (path1) {
+		ext4_ext_drop_refs(path1);
+		kfree(path1);
+	}
+	if (path2) {
+		ext4_ext_drop_refs(path2);
+		kfree(path2);
+	}
+	return replaced_count;
+}
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index 123a51b05965..c8f895b410f6 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -49,101 +49,6 @@ get_ext_path(struct inode *inode, ext4_lblk_t lblock,
 }
 
 /**
- * copy_extent_status - Copy the extent's initialization status
- *
- * @src:	an extent for getting initialize status
- * @dest:	an extent to be set the status
- */
-static void
-copy_extent_status(struct ext4_extent *src, struct ext4_extent *dest)
-{
-	if (ext4_ext_is_unwritten(src))
-		ext4_ext_mark_unwritten(dest);
-	else
-		dest->ee_len = cpu_to_le16(ext4_ext_get_actual_len(dest));
-}
-
-/**
- * mext_next_extent - Search for the next extent and set it to "extent"
- *
- * @inode:	inode which is searched
- * @path:	this will obtain data for the next extent
- * @extent:	pointer to the next extent we have just gotten
- *
- * Search the next extent in the array of ext4_ext_path structure (@path)
- * and set it to ext4_extent structure (@extent). In addition, the member of
- * @path (->p_ext) also points the next extent. Return 0 on success, 1 if
- * ext4_ext_path structure refers to the last extent, or a negative error
- * value on failure.
- */
-static int
-mext_next_extent(struct inode *inode, struct ext4_ext_path *path,
-		      struct ext4_extent **extent)
-{
-	struct ext4_extent_header *eh;
-	int ppos, leaf_ppos = path->p_depth;
-
-	ppos = leaf_ppos;
-	if (EXT_LAST_EXTENT(path[ppos].p_hdr) > path[ppos].p_ext) {
-		/* leaf block */
-		*extent = ++path[ppos].p_ext;
-		path[ppos].p_block = ext4_ext_pblock(path[ppos].p_ext);
-		return 0;
-	}
-
-	while (--ppos >= 0) {
-		if (EXT_LAST_INDEX(path[ppos].p_hdr) >
-		    path[ppos].p_idx) {
-			int cur_ppos = ppos;
-
-			/* index block */
-			path[ppos].p_idx++;
-			path[ppos].p_block = ext4_idx_pblock(path[ppos].p_idx);
-			if (path[ppos+1].p_bh)
-				brelse(path[ppos+1].p_bh);
-			path[ppos+1].p_bh =
-				sb_bread(inode->i_sb, path[ppos].p_block);
-			if (!path[ppos+1].p_bh)
-				return -EIO;
-			path[ppos+1].p_hdr =
-				ext_block_hdr(path[ppos+1].p_bh);
-
-			/* Halfway index block */
-			while (++cur_ppos < leaf_ppos) {
-				path[cur_ppos].p_idx =
-					EXT_FIRST_INDEX(path[cur_ppos].p_hdr);
-				path[cur_ppos].p_block =
-					ext4_idx_pblock(path[cur_ppos].p_idx);
-				if (path[cur_ppos+1].p_bh)
-					brelse(path[cur_ppos+1].p_bh);
-				path[cur_ppos+1].p_bh = sb_bread(inode->i_sb,
-					path[cur_ppos].p_block);
-				if (!path[cur_ppos+1].p_bh)
-					return -EIO;
-				path[cur_ppos+1].p_hdr =
-					ext_block_hdr(path[cur_ppos+1].p_bh);
-			}
-
-			path[leaf_ppos].p_ext = *extent = NULL;
-
-			eh = path[leaf_ppos].p_hdr;
-			if (le16_to_cpu(eh->eh_entries) == 0)
-				/* empty leaf is found */
-				return -ENODATA;
-
-			/* leaf block */
-			path[leaf_ppos].p_ext = *extent =
-				EXT_FIRST_EXTENT(path[leaf_ppos].p_hdr);
-			path[leaf_ppos].p_block =
-					ext4_ext_pblock(path[leaf_ppos].p_ext);
-			return 0;
-		}
-	}
-	/* We found the last extent */
-	return 1;
-}
-
-/**
  * ext4_double_down_write_data_sem - Acquire two inodes' write lock
  *                                   of i_data_sem
  *
@@ -178,417 +83,6 @@ ext4_double_up_write_data_sem(struct inode *orig_inode,
 }
 
 /**
- * mext_insert_across_blocks - Insert extents across leaf block
- *
- * @handle:		journal handle
- * @orig_inode:		original inode
- * @o_start:		first original extent to be changed
- * @o_end:		last original extent to be changed
- * @start_ext:		first new extent to be inserted
- * @new_ext:		middle of new extent to be inserted
- * @end_ext:		last new extent to be inserted
- *
- * Allocate a new leaf block and insert extents into it. Return 0 on success,
- * or a negative error value on failure.
- */
-static int
-mext_insert_across_blocks(handle_t *handle, struct inode *orig_inode,
-		struct ext4_extent *o_start, struct ext4_extent *o_end,
-		struct ext4_extent *start_ext, struct ext4_extent *new_ext,
-		struct ext4_extent *end_ext)
-{
-	struct ext4_ext_path *orig_path = NULL;
-	ext4_lblk_t eblock = 0;
-	int new_flag = 0;
-	int end_flag = 0;
-	int err = 0;
-
-	if (start_ext->ee_len && new_ext->ee_len && end_ext->ee_len) {
-		if (o_start == o_end) {
-
-			/*       start_ext   new_ext    end_ext
-			 * donor |---------|-----------|--------|
-			 * orig  |------------------------------|
-			 */
-			end_flag = 1;
-		} else {
-
-			/*       start_ext   new_ext   end_ext
-			 * donor |---------|----------|---------|
-			 * orig  |---------------|--------------|
-			 */
-			o_end->ee_block = end_ext->ee_block;
-			o_end->ee_len = end_ext->ee_len;
-			ext4_ext_store_pblock(o_end, ext4_ext_pblock(end_ext));
-		}
-
-		o_start->ee_len = start_ext->ee_len;
-		eblock = le32_to_cpu(start_ext->ee_block);
-		new_flag = 1;
-
-	} else if (start_ext->ee_len && new_ext->ee_len &&
-		   !end_ext->ee_len && o_start == o_end) {
-
-		/*	 start_ext	new_ext
-		 * donor |--------------|---------------|
-		 * orig  |------------------------------|
-		 */
-		o_start->ee_len = start_ext->ee_len;
-		eblock = le32_to_cpu(start_ext->ee_block);
-		new_flag = 1;
-
-	} else if (!start_ext->ee_len && new_ext->ee_len &&
-		   end_ext->ee_len && o_start == o_end) {
-
-		/*	  new_ext	end_ext
-		 * donor |--------------|---------------|
-		 * orig  |------------------------------|
-		 */
-		o_end->ee_block = end_ext->ee_block;
-		o_end->ee_len = end_ext->ee_len;
-		ext4_ext_store_pblock(o_end, ext4_ext_pblock(end_ext));
-
-		/*
-		 * Set 0 to the extent block if new_ext was
-		 * the first block.
-		 */
-		if (new_ext->ee_block)
-			eblock = le32_to_cpu(new_ext->ee_block);
-
-		new_flag = 1;
-	} else {
-		ext4_debug("ext4 move extent: Unexpected insert case\n");
-		return -EIO;
-	}
-
-	if (new_flag) {
-		err = get_ext_path(orig_inode, eblock, &orig_path);
-		if (err)
-			goto out;
-
-		if (ext4_ext_insert_extent(handle, orig_inode,
-					orig_path, new_ext, 0))
-			goto out;
-	}
-
-	if (end_flag) {
-		err = get_ext_path(orig_inode,
-				le32_to_cpu(end_ext->ee_block) - 1, &orig_path);
-		if (err)
-			goto out;
-
-		if (ext4_ext_insert_extent(handle, orig_inode,
-					   orig_path, end_ext, 0))
-			goto out;
-	}
-out:
-	if (orig_path) {
-		ext4_ext_drop_refs(orig_path);
-		kfree(orig_path);
-	}
-
-	return err;
-
-}
-
-/**
- * mext_insert_inside_block - Insert new extent to the extent block
- *
- * @o_start:		first original extent to be moved
- * @o_end:		last original extent to be moved
- * @start_ext:		first new extent to be inserted
- * @new_ext:		middle of new extent to be inserted
- * @end_ext:		last new extent to be inserted
- * @eh:			extent header of target leaf block
- * @range_to_move:	used to decide how to insert extent
- *
- * Insert extents into the leaf block. The extent (@o_start) is overwritten
- * by inserted extents.
- */
-static void
-mext_insert_inside_block(struct ext4_extent *o_start,
-			      struct ext4_extent *o_end,
-			      struct ext4_extent *start_ext,
-			      struct ext4_extent *new_ext,
-			      struct ext4_extent *end_ext,
-			      struct ext4_extent_header *eh,
-			      int range_to_move)
-{
-	int i = 0;
-	unsigned long len;
-
-	/* Move the existing extents */
-	if (range_to_move && o_end < EXT_LAST_EXTENT(eh)) {
-		len = (unsigned long)(EXT_LAST_EXTENT(eh) + 1) -
-			(unsigned long)(o_end + 1);
-		memmove(o_end + 1 + range_to_move, o_end + 1, len);
-	}
-
-	/* Insert start entry */
-	if (start_ext->ee_len)
-		o_start[i++].ee_len = start_ext->ee_len;
-
-	/* Insert new entry */
-	if (new_ext->ee_len) {
-		o_start[i] = *new_ext;
-		ext4_ext_store_pblock(&o_start[i++], ext4_ext_pblock(new_ext));
-	}
-
-	/* Insert end entry */
-	if (end_ext->ee_len)
-		o_start[i] = *end_ext;
-
-	/* Increment the total entries counter on the extent block */
-	le16_add_cpu(&eh->eh_entries, range_to_move);
-}
-
-/**
- * mext_insert_extents - Insert new extent
- *
- * @handle:	journal handle
- * @orig_inode:	original inode
- * @orig_path:	path indicates first extent to be changed
- * @o_start:	first original extent to be changed
- * @o_end:	last original extent to be changed
- * @start_ext:	first new extent to be inserted
- * @new_ext:	middle of new extent to be inserted
- * @end_ext:	last new extent to be inserted
- *
- * Call the function to insert extents. If we cannot add more extents into
- * the leaf block, we call mext_insert_across_blocks() to create a
- * new leaf block. Otherwise call mext_insert_inside_block(). Return 0
- * on success, or a negative error value on failure.
- */
-static int
-mext_insert_extents(handle_t *handle, struct inode *orig_inode,
-			 struct ext4_ext_path *orig_path,
-			 struct ext4_extent *o_start,
-			 struct ext4_extent *o_end,
-			 struct ext4_extent *start_ext,
-			 struct ext4_extent *new_ext,
-			 struct ext4_extent *end_ext)
-{
-	struct  ext4_extent_header *eh;
-	unsigned long need_slots, slots_range;
-	int	range_to_move, depth, ret;
-
-	/*
-	 * The extents need to be inserted
-	 * start_extent + new_extent + end_extent.
-	 */
-	need_slots = (start_ext->ee_len ? 1 : 0) + (end_ext->ee_len ? 1 : 0) +
-		(new_ext->ee_len ? 1 : 0);
-
-	/* The number of slots between start and end */
-	slots_range = ((unsigned long)(o_end + 1) - (unsigned long)o_start + 1)
-		/ sizeof(struct ext4_extent);
-
-	/* Range to move the end of extent */
-	range_to_move = need_slots - slots_range;
-	depth = orig_path->p_depth;
-	orig_path += depth;
-	eh = orig_path->p_hdr;
-
-	if (depth) {
-		/* Register to journal */
-		BUFFER_TRACE(orig_path->p_bh, "get_write_access");
-		ret = ext4_journal_get_write_access(handle, orig_path->p_bh);
-		if (ret)
-			return ret;
-	}
-
-	/* Expansion */
-	if (range_to_move > 0 &&
-		(range_to_move > le16_to_cpu(eh->eh_max)
-			- le16_to_cpu(eh->eh_entries))) {
-
-		ret = mext_insert_across_blocks(handle, orig_inode, o_start,
-					o_end, start_ext, new_ext, end_ext);
-		if (ret < 0)
-			return ret;
-	} else
-		mext_insert_inside_block(o_start, o_end, start_ext, new_ext,
-						end_ext, eh, range_to_move);
-
-	return ext4_ext_dirty(handle, orig_inode, orig_path);
-}
-
-/**
- * mext_leaf_block - Move one leaf extent block into the inode.
- *
- * @handle:		journal handle
- * @orig_inode:		original inode
- * @orig_path:		path indicates first extent to be changed
- * @dext:		donor extent
- * @from:		start offset on the target file
- *
- * In order to insert extents into the leaf block, we must divide the extent
- * in the leaf block into three extents. The one is located to be inserted
- * extents, and the others are located around it.
- *
- * Therefore, this function creates structures to save extents of the leaf
- * block, and inserts extents by calling mext_insert_extents() with
- * created extents. Return 0 on success, or a negative error value on failure.
- */
-static int
-mext_leaf_block(handle_t *handle, struct inode *orig_inode,
-		     struct ext4_ext_path *orig_path, struct ext4_extent *dext,
-		     ext4_lblk_t *from)
-{
-	struct ext4_extent *oext, *o_start, *o_end, *prev_ext;
-	struct ext4_extent new_ext, start_ext, end_ext;
-	ext4_lblk_t new_ext_end;
-	int oext_alen, new_ext_alen, end_ext_alen;
-	int depth = ext_depth(orig_inode);
-	int ret;
-
-	start_ext.ee_block = end_ext.ee_block = 0;
-	o_start = o_end = oext = orig_path[depth].p_ext;
-	oext_alen = ext4_ext_get_actual_len(oext);
-	start_ext.ee_len = end_ext.ee_len = 0;
-
-	new_ext.ee_block = cpu_to_le32(*from);
-	ext4_ext_store_pblock(&new_ext, ext4_ext_pblock(dext));
-	new_ext.ee_len = dext->ee_len;
-	new_ext_alen = ext4_ext_get_actual_len(&new_ext);
-	new_ext_end = le32_to_cpu(new_ext.ee_block) + new_ext_alen - 1;
-
-	/*
-	 * Case: original extent is first
-	 * oext      |--------|
-	 * new_ext      |--|
-	 * start_ext |--|
-	 */
-	if (le32_to_cpu(oext->ee_block) < le32_to_cpu(new_ext.ee_block) &&
-		le32_to_cpu(new_ext.ee_block) <
-		le32_to_cpu(oext->ee_block) + oext_alen) {
-		start_ext.ee_len = cpu_to_le16(le32_to_cpu(new_ext.ee_block) -
-					       le32_to_cpu(oext->ee_block));
-		start_ext.ee_block = oext->ee_block;
-		copy_extent_status(oext, &start_ext);
-	} else if (oext > EXT_FIRST_EXTENT(orig_path[depth].p_hdr)) {
-		prev_ext = oext - 1;
-		/*
-		 * We can merge new_ext into previous extent,
-		 * if these are contiguous and same extent type.
-		 */
-		if (ext4_can_extents_be_merged(orig_inode, prev_ext,
-					       &new_ext)) {
-			o_start = prev_ext;
-			start_ext.ee_len = cpu_to_le16(
-				ext4_ext_get_actual_len(prev_ext) +
-				new_ext_alen);
-			start_ext.ee_block = oext->ee_block;
-			copy_extent_status(prev_ext, &start_ext);
-			new_ext.ee_len = 0;
-		}
-	}
-
-	/*
-	 * Case: new_ext_end must be less than oext
-	 * oext      |-----------|
-	 * new_ext       |-------|
-	 */
-	if (le32_to_cpu(oext->ee_block) + oext_alen - 1 < new_ext_end) {
-		EXT4_ERROR_INODE(orig_inode,
-			"new_ext_end(%u) should be less than or equal to "
-			"oext->ee_block(%u) + oext_alen(%d) - 1",
-			new_ext_end, le32_to_cpu(oext->ee_block),
-			oext_alen);
-		ret = -EIO;
-		goto out;
-	}
-
-	/*
-	 * Case: new_ext is smaller than original extent
-	 * oext    |---------------|
-	 * new_ext |-----------|
-	 * end_ext             |---|
-	 */
-	if (le32_to_cpu(oext->ee_block) <= new_ext_end &&
-		new_ext_end < le32_to_cpu(oext->ee_block) + oext_alen - 1) {
-		end_ext.ee_len =
-			cpu_to_le16(le32_to_cpu(oext->ee_block) +
-			oext_alen - 1 - new_ext_end);
-		copy_extent_status(oext, &end_ext);
-		end_ext_alen = ext4_ext_get_actual_len(&end_ext);
-		ext4_ext_store_pblock(&end_ext,
-			(ext4_ext_pblock(o_end) + oext_alen - end_ext_alen));
-		end_ext.ee_block =
-			cpu_to_le32(le32_to_cpu(o_end->ee_block) +
-			oext_alen - end_ext_alen);
-	}
-
-	ret = mext_insert_extents(handle, orig_inode, orig_path, o_start,
-				o_end, &start_ext, &new_ext, &end_ext);
-out:
-	return ret;
-}
-
-/**
- * mext_calc_swap_extents - Calculate extents for extent swapping.
- *
- * @tmp_dext:		the extent that will belong to the original inode
- * @tmp_oext:		the extent that will belong to the donor inode
- * @orig_off:		block offset of original inode
- * @donor_off:		block offset of donor inode
- * @max_count:		the maximum length of extents
- *
- * Return 0 on success, or a negative error value on failure.
- */
-static int
-mext_calc_swap_extents(struct ext4_extent *tmp_dext,
-			      struct ext4_extent *tmp_oext,
-			      ext4_lblk_t orig_off, ext4_lblk_t donor_off,
-			      ext4_lblk_t max_count)
-{
-	ext4_lblk_t diff, orig_diff;
-	struct ext4_extent dext_old, oext_old;
-
-	BUG_ON(orig_off != donor_off);
-
-	/* original and donor extents have to cover the same block offset */
-	if (orig_off < le32_to_cpu(tmp_oext->ee_block) ||
-	    le32_to_cpu(tmp_oext->ee_block) +
-			ext4_ext_get_actual_len(tmp_oext) - 1 < orig_off)
-		return -ENODATA;
-
-	if (orig_off < le32_to_cpu(tmp_dext->ee_block) ||
-	    le32_to_cpu(tmp_dext->ee_block) +
-			ext4_ext_get_actual_len(tmp_dext) - 1 < orig_off)
-		return -ENODATA;
-
-	dext_old = *tmp_dext;
-	oext_old = *tmp_oext;
-
-	/* When tmp_dext is too large, pick up the target range. */
-	diff = donor_off - le32_to_cpu(tmp_dext->ee_block);
-
-	ext4_ext_store_pblock(tmp_dext, ext4_ext_pblock(tmp_dext) + diff);
-	le32_add_cpu(&tmp_dext->ee_block, diff);
-	le16_add_cpu(&tmp_dext->ee_len, -diff);
-
-	if (max_count < ext4_ext_get_actual_len(tmp_dext))
-		tmp_dext->ee_len = cpu_to_le16(max_count);
-
-	orig_diff = orig_off - le32_to_cpu(tmp_oext->ee_block);
-	ext4_ext_store_pblock(tmp_oext, ext4_ext_pblock(tmp_oext) + orig_diff);
-
-	/* Adjust extent length if donor extent is larger than orig */
-	if (ext4_ext_get_actual_len(tmp_dext) >
-	    ext4_ext_get_actual_len(tmp_oext) - orig_diff)
-		tmp_dext->ee_len = cpu_to_le16(le16_to_cpu(tmp_oext->ee_len) -
-						orig_diff);
-
-	tmp_oext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(tmp_dext));
-
-	copy_extent_status(&oext_old, tmp_dext);
-	copy_extent_status(&dext_old, tmp_oext);
-
-	return 0;
-}
-
-/**
  * mext_check_coverage - Check that all extents in range has the same type
  *
  * @inode:		inode in question
@@ -647,129 +141,6 @@ out:
  *
  * Return replaced block count.
  */
-static int
-mext_replace_branches(handle_t *handle, struct inode *orig_inode,
-			   struct inode *donor_inode, ext4_lblk_t from,
-			   ext4_lblk_t count, int *err)
-{
-	struct ext4_ext_path *orig_path = NULL;
-	struct ext4_ext_path *donor_path = NULL;
-	struct ext4_extent *oext, *dext;
-	struct ext4_extent tmp_dext, tmp_oext;
-	ext4_lblk_t orig_off = from, donor_off = from;
-	int depth;
-	int replaced_count = 0;
-	int dext_alen;
-
-	*err = ext4_es_remove_extent(orig_inode, from, count);
-	if (*err)
-		goto out;
-
-	*err = ext4_es_remove_extent(donor_inode, from, count);
-	if (*err)
-		goto out;
-
-	/* Get the original extent for the block "orig_off" */
-	*err = get_ext_path(orig_inode, orig_off, &orig_path);
-	if (*err)
-		goto out;
-
-	/* Get the donor extent for the head */
-	*err = get_ext_path(donor_inode, donor_off, &donor_path);
-	if (*err)
-		goto out;
-	depth = ext_depth(orig_inode);
-	oext = orig_path[depth].p_ext;
-	tmp_oext = *oext;
-
-	depth = ext_depth(donor_inode);
-	dext = donor_path[depth].p_ext;
-	if (unlikely(!dext))
-		goto missing_donor_extent;
-	tmp_dext = *dext;
-
-	*err = mext_calc_swap_extents(&tmp_dext, &tmp_oext, orig_off,
-				      donor_off, count);
-	if (*err)
-		goto out;
-
-	/* Loop for the donor extents */
-	while (1) {
-		/* The extent for donor must be found. */
-		if (unlikely(!dext)) {
-		missing_donor_extent:
-			EXT4_ERROR_INODE(donor_inode,
-				   "The extent for donor must be found");
-			*err = -EIO;
-			goto out;
-		} else if (donor_off != le32_to_cpu(tmp_dext.ee_block)) {
-			EXT4_ERROR_INODE(donor_inode,
-				"Donor offset(%u) and the first block of donor "
-				"extent(%u) should be equal",
-				donor_off,
-				le32_to_cpu(tmp_dext.ee_block));
-			*err = -EIO;
-			goto out;
-		}
-
-		/* Set donor extent to orig extent */
-		*err = mext_leaf_block(handle, orig_inode,
-					   orig_path, &tmp_dext, &orig_off);
-		if (*err)
-			goto out;
-
-		/* Set orig extent to donor extent */
-		*err = mext_leaf_block(handle, donor_inode,
-					   donor_path, &tmp_oext, &donor_off);
-		if (*err)
-			goto out;
-
-		dext_alen = ext4_ext_get_actual_len(&tmp_dext);
-		replaced_count += dext_alen;
-		donor_off += dext_alen;
-		orig_off += dext_alen;
-
-		BUG_ON(replaced_count > count);
-		/* Already moved the expected blocks */
-		if (replaced_count >= count)
-			break;
-
-		if (orig_path)
-			ext4_ext_drop_refs(orig_path);
-		*err = get_ext_path(orig_inode, orig_off, &orig_path);
-		if (*err)
-			goto out;
-		depth = ext_depth(orig_inode);
-		oext = orig_path[depth].p_ext;
-		tmp_oext = *oext;
-
-		if (donor_path)
-			ext4_ext_drop_refs(donor_path);
-		*err = get_ext_path(donor_inode, donor_off, &donor_path);
-		if (*err)
-			goto out;
-		depth = ext_depth(donor_inode);
-		dext = donor_path[depth].p_ext;
-		tmp_dext = *dext;
-
-		*err = mext_calc_swap_extents(&tmp_dext, &tmp_oext, orig_off,
-					   donor_off, count - replaced_count);
-		if (*err)
-			goto out;
-	}
-
-out:
-	if (orig_path) {
-		ext4_ext_drop_refs(orig_path);
-		kfree(orig_path);
-	}
-	if (donor_path) {
-		ext4_ext_drop_refs(donor_path);
-		kfree(donor_path);
-	}
-
-	return replaced_count;
-}
 
 /**
  * mext_page_double_lock - Grab and lock pages on both @inode1 and @inode2
@@ -783,7 +154,7 @@ out:
  */
 static int
 mext_page_double_lock(struct inode *inode1, struct inode *inode2,
-		      pgoff_t index, struct page *page[2])
+		      pgoff_t index1, pgoff_t index2, struct page *page[2])
 {
 	struct address_space *mapping[2];
 	unsigned fl = AOP_FLAG_NOFS;
@@ -793,15 +164,18 @@ mext_page_double_lock(struct inode *inode1, struct inode *inode2,
 		mapping[0] = inode1->i_mapping;
 		mapping[1] = inode2->i_mapping;
 	} else {
+		pgoff_t tmp = index1;
+		index1 = index2;
+		index2 = tmp;
 		mapping[0] = inode2->i_mapping;
 		mapping[1] = inode1->i_mapping;
 	}
 
-	page[0] = grab_cache_page_write_begin(mapping[0], index, fl);
+	page[0] = grab_cache_page_write_begin(mapping[0], index1, fl);
 	if (!page[0])
 		return -ENOMEM;
 
-	page[1] = grab_cache_page_write_begin(mapping[1], index, fl);
+	page[1] = grab_cache_page_write_begin(mapping[1], index2, fl);
 	if (!page[1]) {
 		unlock_page(page[0]);
 		page_cache_release(page[0]);
@@ -905,13 +279,14 @@ out:
  */
 static int
 move_extent_per_page(struct file *o_filp, struct inode *donor_inode,
-		  pgoff_t orig_page_offset, int data_offset_in_page,
-		  int block_len_in_page, int unwritten, int *err)
+		     pgoff_t orig_page_offset, pgoff_t donor_page_offset,
+		     int data_offset_in_page,
+		     int block_len_in_page, int unwritten, int *err)
 {
 	struct inode *orig_inode = file_inode(o_filp);
 	struct page *pagep[2] = {NULL, NULL};
 	handle_t *handle;
-	ext4_lblk_t orig_blk_offset;
+	ext4_lblk_t orig_blk_offset, donor_blk_offset;
 	unsigned long blocksize = orig_inode->i_sb->s_blocksize;
 	unsigned int w_flags = 0;
 	unsigned int tmp_data_size, data_size, replaced_size;
@@ -939,6 +314,9 @@ again:
 	orig_blk_offset = orig_page_offset * blocks_per_page +
 		data_offset_in_page;
 
+	donor_blk_offset = donor_page_offset * blocks_per_page +
+		data_offset_in_page;
+
 	/* Calculate data_size */
 	if ((orig_blk_offset + block_len_in_page - 1) ==
 	    ((orig_inode->i_size - 1) >> orig_inode->i_blkbits)) {
@@ -959,7 +337,7 @@ again:
 	replaced_size = data_size;
 
 	*err = mext_page_double_lock(orig_inode, donor_inode, orig_page_offset,
-				     pagep);
+				     donor_page_offset, pagep);
 	if (unlikely(*err < 0))
 		goto stop_journal;
 	/*
@@ -978,7 +356,7 @@ again:
 		if (*err)
 			goto drop_data_sem;
 
-		unwritten &= mext_check_coverage(donor_inode, orig_blk_offset,
+		unwritten &= mext_check_coverage(donor_inode, donor_blk_offset,
 						 block_len_in_page, 1, err);
 		if (*err)
 			goto drop_data_sem;
@@ -994,9 +372,10 @@ again:
 			*err = -EBUSY;
 			goto drop_data_sem;
 		}
-		replaced_count = mext_replace_branches(handle, orig_inode,
-						donor_inode, orig_blk_offset,
-						block_len_in_page, err);
+		replaced_count = ext4_swap_extents(handle, orig_inode,
+						   donor_inode, orig_blk_offset,
+						   donor_blk_offset,
+						   block_len_in_page, 1, err);
 	drop_data_sem:
 		ext4_double_up_write_data_sem(orig_inode, donor_inode);
 		goto unlock_pages;
@@ -1014,9 +393,9 @@ data_copy:
 		goto unlock_pages;
 	}
 	ext4_double_down_write_data_sem(orig_inode, donor_inode);
-	replaced_count = mext_replace_branches(handle, orig_inode, donor_inode,
-					       orig_blk_offset,
-					       block_len_in_page, err);
+	replaced_count = ext4_swap_extents(handle, orig_inode, donor_inode,
+					       orig_blk_offset, donor_blk_offset,
+					   block_len_in_page, 1, err);
 	ext4_double_up_write_data_sem(orig_inode, donor_inode);
 	if (*err) {
 		if (replaced_count) {
@@ -1061,9 +440,9 @@ repair_branches:
 	 * Try to swap extents to it's original places
 	 */
 	ext4_double_down_write_data_sem(orig_inode, donor_inode);
-	replaced_count = mext_replace_branches(handle, donor_inode, orig_inode,
-					       orig_blk_offset,
-					       block_len_in_page, &err2);
+	replaced_count = ext4_swap_extents(handle, donor_inode, orig_inode,
+					       orig_blk_offset, donor_blk_offset,
+					   block_len_in_page, 0, &err2);
 	ext4_double_up_write_data_sem(orig_inode, donor_inode);
 	if (replaced_count != block_len_in_page) {
 		EXT4_ERROR_INODE_BLOCK(orig_inode, (sector_t)(orig_blk_offset),
@@ -1093,10 +472,14 @@ mext_check_arguments(struct inode *orig_inode,
 		     struct inode *donor_inode, __u64 orig_start,
 		     __u64 donor_start, __u64 *len)
 {
-	ext4_lblk_t orig_blocks, donor_blocks;
+	__u64 orig_eof, donor_eof;
 	unsigned int blkbits = orig_inode->i_blkbits;
 	unsigned int blocksize = 1 << blkbits;
 
+	orig_eof = (i_size_read(orig_inode) + blocksize - 1) >> blkbits;
+	donor_eof = (i_size_read(donor_inode) + blocksize - 1) >> blkbits;
+
+
 	if (donor_inode->i_mode & (S_ISUID|S_ISGID)) {
 		ext4_debug("ext4 move extent: suid or sgid is set"
 			   " to donor file [ino:orig %lu, donor %lu]\n",
@@ -1112,7 +495,7 @@ mext_check_arguments(struct inode *orig_inode,
 		ext4_debug("ext4 move extent: The argument files should "
 			"not be swapfile [ino:orig %lu, donor %lu]\n",
 			orig_inode->i_ino, donor_inode->i_ino);
-		return -EINVAL;
+		return -EBUSY;
 	}
 
 	/* Ext4 move extent supports only extent based file */
@@ -1132,67 +515,28 @@ mext_check_arguments(struct inode *orig_inode,
 	}
 
 	/* Start offset should be same */
-	if (orig_start != donor_start) {
+	if ((orig_start & ~(PAGE_MASK >> orig_inode->i_blkbits)) !=
+	    (donor_start & ~(PAGE_MASK >> orig_inode->i_blkbits))) {
 		ext4_debug("ext4 move extent: orig and donor's start "
-			"offset are not same [ino:orig %lu, donor %lu]\n",
+			"offset are not alligned [ino:orig %lu, donor %lu]\n",
 			orig_inode->i_ino, donor_inode->i_ino);
 		return -EINVAL;
 	}
 
 	if ((orig_start >= EXT_MAX_BLOCKS) ||
+	    (donor_start >= EXT_MAX_BLOCKS) ||
 	    (*len > EXT_MAX_BLOCKS) ||
+	    (donor_start + *len >= EXT_MAX_BLOCKS) ||
 	    (orig_start + *len >= EXT_MAX_BLOCKS))  {
 		ext4_debug("ext4 move extent: Can't handle over [%u] blocks "
 			"[ino:orig %lu, donor %lu]\n", EXT_MAX_BLOCKS,
 			orig_inode->i_ino, donor_inode->i_ino);
 		return -EINVAL;
 	}
-
-	if (orig_inode->i_size > donor_inode->i_size) {
-		donor_blocks = (donor_inode->i_size + blocksize - 1) >> blkbits;
-		/* TODO: eliminate this artificial restriction */
-		if (orig_start >= donor_blocks) {
-			ext4_debug("ext4 move extent: orig start offset "
-			"[%llu] should be less than donor file blocks "
-			"[%u] [ino:orig %lu, donor %lu]\n",
-			orig_start, donor_blocks,
-			orig_inode->i_ino, donor_inode->i_ino);
-			return -EINVAL;
-		}
-
-		/* TODO: eliminate this artificial restriction */
-		if (orig_start + *len > donor_blocks) {
-			ext4_debug("ext4 move extent: End offset [%llu] should "
-				"be less than donor file blocks [%u]."
-				"So adjust length from %llu to %llu "
-				"[ino:orig %lu, donor %lu]\n",
-				orig_start + *len, donor_blocks,
-				*len, donor_blocks - orig_start,
-				orig_inode->i_ino, donor_inode->i_ino);
-			*len = donor_blocks - orig_start;
-		}
-	} else {
-		orig_blocks = (orig_inode->i_size + blocksize - 1) >> blkbits;
-		if (orig_start >= orig_blocks) {
-			ext4_debug("ext4 move extent: start offset [%llu] "
-				"should be less than original file blocks "
-				"[%u] [ino:orig %lu, donor %lu]\n",
-				 orig_start, orig_blocks,
-				orig_inode->i_ino, donor_inode->i_ino);
-			return -EINVAL;
-		}
-
-		if (orig_start + *len > orig_blocks) {
-			ext4_debug("ext4 move extent: Adjust length "
-				"from %llu to %llu. Because it should be "
-				"less than original file blocks "
-				"[ino:orig %lu, donor %lu]\n",
-				*len, orig_blocks - orig_start,
-				orig_inode->i_ino, donor_inode->i_ino);
-			*len = orig_blocks - orig_start;
-		}
-	}
-
+	if (orig_eof < orig_start + *len - 1)
+		*len = orig_eof - orig_start;
+	if (donor_eof < donor_start + *len - 1)
+		*len = donor_eof - donor_start;
 	if (!*len) {
 		ext4_debug("ext4 move extent: len should not be 0 "
 			"[ino:orig %lu, donor %lu]\n", orig_inode->i_ino,
@@ -1245,23 +589,16 @@ mext_check_arguments(struct inode *orig_inode,
  * 7:Return 0 on success, or a negative error value on failure.
  */
 int
-ext4_move_extents(struct file *o_filp, struct file *d_filp,
-		 __u64 orig_start, __u64 donor_start, __u64 len,
-		 __u64 *moved_len)
+ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
+		  __u64 donor_blk, __u64 len, __u64 *moved_len)
 {
 	struct inode *orig_inode = file_inode(o_filp);
 	struct inode *donor_inode = file_inode(d_filp);
-	struct ext4_ext_path *orig_path = NULL, *holecheck_path = NULL;
-	struct ext4_extent *ext_prev, *ext_cur, *ext_dummy;
-	ext4_lblk_t block_start = orig_start;
-	ext4_lblk_t block_end, seq_start, add_blocks, file_end, seq_blocks = 0;
-	ext4_lblk_t rest_blocks;
-	pgoff_t orig_page_offset = 0, seq_end_page;
-	int ret, depth, last_extent = 0;
+	struct ext4_ext_path *path = NULL;
 	int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;
-	int data_offset_in_page;
-	int block_len_in_page;
-	int unwritten;
+	ext4_lblk_t o_end, o_start = orig_blk;
+	ext4_lblk_t d_start = donor_blk;
+	int ret;
 
 	if (orig_inode->i_sb != donor_inode->i_sb) {
 		ext4_debug("ext4 move extent: The argument files "
@@ -1303,121 +640,58 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
 	/* Protect extent tree against block allocations via delalloc */
 	ext4_double_down_write_data_sem(orig_inode, donor_inode);
 	/* Check the filesystem environment whether move_extent can be done */
-	ret = mext_check_arguments(orig_inode, donor_inode, orig_start,
-				    donor_start, &len);
+	ret = mext_check_arguments(orig_inode, donor_inode, orig_blk,
+				    donor_blk, &len);
 	if (ret)
 		goto out;
+	o_end = o_start + len;
 
-	file_end = (i_size_read(orig_inode) - 1) >> orig_inode->i_blkbits;
-	block_end = block_start + len - 1;
-	if (file_end < block_end)
-		len -= block_end - file_end;
-
-	ret = get_ext_path(orig_inode, block_start, &orig_path);
-	if (ret)
-		goto out;
-
-	/* Get path structure to check the hole */
-	ret = get_ext_path(orig_inode, block_start, &holecheck_path);
-	if (ret)
-		goto out;
+	while (o_start < o_end) {
+		struct ext4_extent *ex;
+		ext4_lblk_t cur_blk, next_blk;
+		pgoff_t orig_page_index, donor_page_index;
+		int offset_in_page;
+		int unwritten, cur_len;
 
-	depth = ext_depth(orig_inode);
-	ext_cur = holecheck_path[depth].p_ext;
-
-	/*
-	 * Get proper starting location of block replacement if block_start was
-	 * within the hole.
-	 */
-	if (le32_to_cpu(ext_cur->ee_block) +
-		ext4_ext_get_actual_len(ext_cur) - 1 < block_start) {
-		/*
-		 * The hole exists between extents or the tail of
-		 * original file.
-		 */
-		last_extent = mext_next_extent(orig_inode,
-					holecheck_path, &ext_cur);
-		if (last_extent < 0) {
-			ret = last_extent;
-			goto out;
-		}
-		last_extent = mext_next_extent(orig_inode, orig_path,
-							&ext_dummy);
-		if (last_extent < 0) {
-			ret = last_extent;
+		ret = get_ext_path(orig_inode, o_start, &path);
+		if (ret)
 			goto out;
+		ex = path[path->p_depth].p_ext;
+		next_blk = ext4_ext_next_allocated_block(path);
+		cur_blk = le32_to_cpu(ex->ee_block);
+		cur_len = ext4_ext_get_actual_len(ex);
+		/* Check hole before the start pos */
+		if (cur_blk + cur_len - 1 < o_start) {
+			if (next_blk == EXT_MAX_BLOCKS) {
+				o_start = o_end;
+				ret = -ENODATA;
+				goto out;
+			}
+			d_start += next_blk - o_start;
+			o_start = next_blk;
+			goto repeat;
+		/* Check hole after the start pos */
+		} else if (cur_blk > o_start) {
+			/* Skip hole */
+			d_start += cur_blk - o_start;
+			o_start = cur_blk;
+			/* Extent inside requested range ?*/
+			if (cur_blk >= o_end)
+				goto out;
+		} else { /* in_range(o_start, o_blk, o_len) */
+			cur_len += cur_blk - o_start;
 		}
-		seq_start = le32_to_cpu(ext_cur->ee_block);
-	} else if (le32_to_cpu(ext_cur->ee_block) > block_start)
-		/* The hole exists at the beginning of original file. */
-		seq_start = le32_to_cpu(ext_cur->ee_block);
-	else
-		seq_start = block_start;
-
-	/* No blocks within the specified range. */
-	if (le32_to_cpu(ext_cur->ee_block) > block_end) {
-		ext4_debug("ext4 move extent: The specified range of file "
-							"may be the hole\n");
-		ret = -EINVAL;
-		goto out;
-	}
-
-	/* Adjust start blocks */
-	add_blocks = min(le32_to_cpu(ext_cur->ee_block) +
-			 ext4_ext_get_actual_len(ext_cur), block_end + 1) -
-		     max(le32_to_cpu(ext_cur->ee_block), block_start);
-
-	while (!last_extent && le32_to_cpu(ext_cur->ee_block) <= block_end) {
-		seq_blocks += add_blocks;
-
-		/* Adjust tail blocks */
-		if (seq_start + seq_blocks - 1 > block_end)
-			seq_blocks = block_end - seq_start + 1;
-
-		ext_prev = ext_cur;
-		last_extent = mext_next_extent(orig_inode, holecheck_path,
-						&ext_cur);
-		if (last_extent < 0) {
-			ret = last_extent;
-			break;
-		}
-		add_blocks = ext4_ext_get_actual_len(ext_cur);
-
-		/*
-		 * Extend the length of contiguous block (seq_blocks)
-		 * if extents are contiguous.
-		 */
-		if (ext4_can_extents_be_merged(orig_inode,
-					       ext_prev, ext_cur) &&
-		    block_end >= le32_to_cpu(ext_cur->ee_block) &&
-		    !last_extent)
-			continue;
-
-		/* Is original extent is unwritten */
-		unwritten = ext4_ext_is_unwritten(ext_prev);
-
-		data_offset_in_page = seq_start % blocks_per_page;
-
-		/*
-		 * Calculate data blocks count that should be swapped
-		 * at the first page.
-		 */
-		if (data_offset_in_page + seq_blocks > blocks_per_page) {
-			/* Swapped blocks are across pages */
-			block_len_in_page =
-					blocks_per_page - data_offset_in_page;
-		} else {
-			/* Swapped blocks are in a page */
-			block_len_in_page = seq_blocks;
-		}
-
-		orig_page_offset = seq_start >>
-				(PAGE_CACHE_SHIFT - orig_inode->i_blkbits);
-		seq_end_page = (seq_start + seq_blocks - 1) >>
-				(PAGE_CACHE_SHIFT - orig_inode->i_blkbits);
-		seq_start = le32_to_cpu(ext_cur->ee_block);
-		rest_blocks = seq_blocks;
-
+		unwritten = ext4_ext_is_unwritten(ex);
+		if (o_end - o_start < cur_len)
+			cur_len = o_end - o_start;
+
+		orig_page_index = o_start >> (PAGE_CACHE_SHIFT -
+					       orig_inode->i_blkbits);
+		donor_page_index = d_start >> (PAGE_CACHE_SHIFT -
+					       donor_inode->i_blkbits);
+		offset_in_page = o_start % blocks_per_page;
+		if (cur_len > blocks_per_page- offset_in_page)
+			cur_len = blocks_per_page - offset_in_page;
 		/*
 		 * Up semaphore to avoid following problems:
 		 * a. transaction deadlock among ext4_journal_start,
@@ -1426,76 +700,36 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
 		 *    in move_extent_per_page
 		 */
 		ext4_double_up_write_data_sem(orig_inode, donor_inode);
-
-		while (orig_page_offset <= seq_end_page) {
-
-			/* Swap original branches with new branches */
-			block_len_in_page = move_extent_per_page(
-						o_filp, donor_inode,
-						orig_page_offset,
-						data_offset_in_page,
-						block_len_in_page,
-						unwritten, &ret);
-
-			/* Count how many blocks we have exchanged */
-			*moved_len += block_len_in_page;
-			if (ret < 0)
-				break;
-			if (*moved_len > len) {
-				EXT4_ERROR_INODE(orig_inode,
-					"We replaced blocks too much! "
-					"sum of replaced: %llu requested: %llu",
-					*moved_len, len);
-				ret = -EIO;
-				break;
-			}
-
-			orig_page_offset++;
-			data_offset_in_page = 0;
-			rest_blocks -= block_len_in_page;
-			if (rest_blocks > blocks_per_page)
-				block_len_in_page = blocks_per_page;
-			else
-				block_len_in_page = rest_blocks;
-		}
-
+		/* Swap original branches with new branches */
+		move_extent_per_page(o_filp, donor_inode,
+				     orig_page_index, donor_page_index,
+				     offset_in_page, cur_len,
+				     unwritten, &ret);
 		ext4_double_down_write_data_sem(orig_inode, donor_inode);
 		if (ret < 0)
 			break;
-
-		/* Decrease buffer counter */
-		if (holecheck_path)
-			ext4_ext_drop_refs(holecheck_path);
-		ret = get_ext_path(orig_inode, seq_start, &holecheck_path);
-		if (ret)
-			break;
-		depth = holecheck_path->p_depth;
-
-		/* Decrease buffer counter */
-		if (orig_path)
-			ext4_ext_drop_refs(orig_path);
-		ret = get_ext_path(orig_inode, seq_start, &orig_path);
-		if (ret)
-			break;
-
-		ext_cur = holecheck_path[depth].p_ext;
-		add_blocks = ext4_ext_get_actual_len(ext_cur);
-		seq_blocks = 0;
-
+		o_start += cur_len;
+		d_start += cur_len;
+	repeat:
+		if (path) {
+			ext4_ext_drop_refs(path);
+			kfree(path);
+			path = NULL;
+		}
 	}
+	*moved_len = o_start - orig_blk;
+	if (*moved_len > len)
+		*moved_len = len;
+
 out:
 	if (*moved_len) {
 		ext4_discard_preallocations(orig_inode);
 		ext4_discard_preallocations(donor_inode);
 	}
 
-	if (orig_path) {
-		ext4_ext_drop_refs(orig_path);
-		kfree(orig_path);
-	}
-	if (holecheck_path) {
-		ext4_ext_drop_refs(holecheck_path);
-		kfree(holecheck_path);
+	if (path) {
+		ext4_ext_drop_refs(path);
+		kfree(path);
 	}
 	ext4_double_up_write_data_sem(orig_inode, donor_inode);
 	ext4_inode_resume_unlocked_dio(orig_inode);