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Commit 197217a5 authored by Yongqiang Yang's avatar Yongqiang Yang Committed by Theodore Ts'o
Browse files

ext4: add a function merging extents right and left 



1) Rename ext4_ext_try_to_merge() to ext4_ext_try_to_merge_right().

2) Add a new function ext4_ext_try_to_merge() which tries to merge
   an extent both left and right.

3) Use the new function in ext4_ext_convert_unwritten_endio() and
   ext4_ext_insert_extent().

Signed-off-by: default avatarYongqiang Yang <xiaoqiangnk@gmail.com>
Tested-by: default avatarAllison Henderson <achender@linux.vnet.ibm.com>
parent df5e6223

fs/ext4/extents.c

+36 −29
Original line number Diff line number Diff line
@@ -1563,7 +1563,7 @@ ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1, 
 * 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(struct inode *inode,

static int ext4_ext_try_to_merge_right(struct inode *inode,

				 struct ext4_ext_path *path,

				 struct ext4_extent *ex)

{
@@ -1602,6 +1602,31 @@ static int ext4_ext_try_to_merge(struct inode *inode, 
	return merge_done;

}



/*

 * This function tries to merge the @ex extent to neighbours in the tree.

 * return 1 if merge left else 0.

 */

static int ext4_ext_try_to_merge(struct inode *inode,

				  struct ext4_ext_path *path,

				  struct ext4_extent *ex) {

	struct ext4_extent_header *eh;

	unsigned int depth;

	int merge_done = 0;

	int ret = 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)

		ret = ext4_ext_try_to_merge_right(inode, path, ex);



	return ret;

}



/*

 * check if a portion of the "newext" extent overlaps with an

 * existing extent.
@@ -3039,6 +3064,7 @@ static int ext4_split_unwritten_extents(handle_t *handle, 
	ext4_ext_dirty(handle, inode, path + depth);

	return err;

}



static int ext4_convert_unwritten_extents_endio(handle_t *handle,

					      struct inode *inode,

					      struct ext4_ext_path *path)
@@ -3047,46 +3073,27 @@ static int ext4_convert_unwritten_extents_endio(handle_t *handle, 
	struct ext4_extent_header *eh;

	int depth;

	int err = 0;

	int ret = 0;



	depth = ext_depth(inode);

	eh = path[depth].p_hdr;

	ex = path[depth].p_ext;



	ext_debug("ext4_convert_unwritten_extents_endio: inode %lu, logical"

		"block %llu, max_blocks %u\n", inode->i_ino,

		(unsigned long long)le32_to_cpu(ex->ee_block),

		ext4_ext_get_actual_len(ex));



	err = ext4_ext_get_access(handle, inode, path + depth);

	if (err)

		goto out;

	/* first mark the extent as initialized */

	ext4_ext_mark_initialized(ex);



	/*

	 * We have to see if it can be merged with the extent

	 * on the left.

	 */

	if (ex > EXT_FIRST_EXTENT(eh)) {

		/*

		 * To merge left, pass "ex - 1" to try_to_merge(),

		 * since it merges towards right _only_.

	/* note: ext4_ext_correct_indexes() isn't needed here because

	 * borders are not changed

	 */

		ret = ext4_ext_try_to_merge(inode, path, ex - 1);

		if (ret) {

			err = ext4_ext_correct_indexes(handle, inode, path);

			if (err)

				goto out;

			depth = ext_depth(inode);

			ex--;

		}

	}

	/*

	 * Try to Merge towards right.

	 */

	ret = ext4_ext_try_to_merge(inode, path, ex);

	if (ret) {

		err = ext4_ext_correct_indexes(handle, inode, path);

		if (err)

			goto out;

		depth = ext_depth(inode);

	}

	ext4_ext_try_to_merge(inode, path, ex);



	/* Mark modified extent as dirty */

	err = ext4_ext_dirty(handle, inode, path + depth);

out: