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Commit 1988b51e authored by Alex Tomas's avatar Alex Tomas Committed by Theodore Ts'o
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ext4: Add new functions for searching extent tree 



Add the functions ext4_ext_search_left() and ext4_ext_search_right(),
which are used by mballoc during ext4_ext_get_blocks to decided whether
to merge extent information.

Signed-off-by: default avatarAlex Tomas <alex@clusterfs.com>
Signed-off-by: default avatarAndreas Dilger <adilger@clusterfs.com>
Signed-off-by: default avatarJohann Lombardi <johann@clusterfs.com>
Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent aa02ad67

fs/ext4/extents.c

+142 −0
Original line number Diff line number Diff line
@@ -1016,6 +1016,148 @@ static int ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode, 
	return 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

 */

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;



	BUG_ON(path == NULL);

	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;

	if (*logical < le32_to_cpu(ex->ee_block)) {

		BUG_ON(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex);

		while (--depth >= 0) {

			ix = path[depth].p_idx;

			BUG_ON(ix != EXT_FIRST_INDEX(path[depth].p_hdr));

		}

		return 0;

	}



	BUG_ON(*logical < le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len));



	*logical = le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len) - 1;

	*phys = ext_pblock(ex) + le16_to_cpu(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 *logical is the smallest allocated block, the function

 * returns 0 at @phys

 * return value contains 0 (success) or error code

 */

int

ext4_ext_search_right(struct inode *inode, struct ext4_ext_path *path,

			ext4_lblk_t *logical, ext4_fsblk_t *phys)

{

	struct buffer_head *bh = NULL;

	struct ext4_extent_header *eh;

	struct ext4_extent_idx *ix;

	struct ext4_extent *ex;

	ext4_fsblk_t block;

	int depth;



	BUG_ON(path == NULL);

	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;

	if (*logical < le32_to_cpu(ex->ee_block)) {

		BUG_ON(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex);

		while (--depth >= 0) {

			ix = path[depth].p_idx;

			BUG_ON(ix != EXT_FIRST_INDEX(path[depth].p_hdr));

		}

		*logical = le32_to_cpu(ex->ee_block);

		*phys = ext_pblock(ex);

		return 0;

	}



	BUG_ON(*logical < le32_to_cpu(ex->ee_block) + le16_to_cpu(ex->ee_len));



	if (ex != EXT_LAST_EXTENT(path[depth].p_hdr)) {

		/* next allocated block in this leaf */

		ex++;

		*logical = le32_to_cpu(ex->ee_block);

		*phys = ext_pblock(ex);

		return 0;

	}



	/* 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))

			break;

	}



	if (depth < 0) {

		/* we've gone up to the root and

		 * found no index to the right */

		return 0;

	}



	/* we've found index to the right, let's

	 * follow it and find the closest allocated

	 * block to the right */

	ix++;

	block = idx_pblock(ix);

	while (++depth < path->p_depth) {

		bh = sb_bread(inode->i_sb, block);

		if (bh == NULL)

			return -EIO;

		eh = ext_block_hdr(bh);

		if (ext4_ext_check_header(inode, eh, depth)) {

			put_bh(bh);

			return -EIO;

		}

		ix = EXT_FIRST_INDEX(eh);

		block = idx_pblock(ix);

		put_bh(bh);

	}



	bh = sb_bread(inode->i_sb, block);

	if (bh == NULL)

		return -EIO;

	eh = ext_block_hdr(bh);

	if (ext4_ext_check_header(inode, eh, path->p_depth - depth)) {

		put_bh(bh);

		return -EIO;

	}

	ex = EXT_FIRST_EXTENT(eh);

	*logical = le32_to_cpu(ex->ee_block);

	*phys = ext_pblock(ex);

	put_bh(bh);

	return 0;



}



/*

 * ext4_ext_next_allocated_block:

 * returns allocated block in subsequent extent or EXT_MAX_BLOCK.

include/linux/ext4_fs_extents.h

+4 −0
Original line number Diff line number Diff line
@@ -223,5 +223,9 @@ extern unsigned int ext4_ext_check_overlap(struct inode *, struct ext4_extent *, 
extern int ext4_ext_insert_extent(handle_t *, struct inode *, struct ext4_ext_path *, struct ext4_extent *);

extern struct ext4_ext_path *ext4_ext_find_extent(struct inode *, ext4_lblk_t,

							struct ext4_ext_path *);

extern int ext4_ext_search_left(struct inode *, struct ext4_ext_path *,

						ext4_lblk_t *, ext4_fsblk_t *);

extern int ext4_ext_search_right(struct inode *, struct ext4_ext_path *,

						ext4_lblk_t *, ext4_fsblk_t *);

#endif /* _LINUX_EXT4_EXTENTS */