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Commit 1b16da77 authored by Yongqiang Yang's avatar Yongqiang Yang Committed by Theodore Ts'o
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ext4: teach ext4_ext_split to calculate extents efficiently 



Make ext4_ext_split() get extents to be moved by calculating in a statement
instead of counting in a loop.

Signed-off-by: default avatarYongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent ae24f28d

fs/ext4/extents.c

+46 −38
Original line number Diff line number Diff line
@@ -482,9 +482,43 @@ static void ext4_ext_show_leaf(struct inode *inode, struct ext4_ext_path *path) 
	}

	ext_debug("\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("%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("move %d:%llu:[%d]%d in new leaf %llu\n",

				le32_to_cpu(ex->ee_block),

				ext4_ext_pblock(ex),

				ext4_ext_is_uninitialized(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



void ext4_ext_drop_refs(struct ext4_ext_path *path)
@@ -808,7 +842,6 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode, 
	int depth = ext_depth(inode);

	struct ext4_extent_header *neh;

	struct ext4_extent_idx *fidx;

	struct ext4_extent *ex;

	int i = at, k, m, a;

	ext4_fsblk_t newblock, oldblock;

	__le32 border;
@@ -885,7 +918,6 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode, 
	neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0));

	neh->eh_magic = EXT4_EXT_MAGIC;

	neh->eh_depth = 0;

	ex = EXT_FIRST_EXTENT(neh);



	/* move remainder of path[depth] to the new leaf */

	if (unlikely(path[depth].p_hdr->eh_entries !=
@@ -897,25 +929,12 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode, 
		goto cleanup;

	}

	/* start copy from next extent */

	/* TODO: we could do it by single memmove */

	m = 0;

	path[depth].p_ext++;

	while (path[depth].p_ext <=

			EXT_MAX_EXTENT(path[depth].p_hdr)) {

		ext_debug("move %d:%llu:[%d]%d in new leaf %llu\n",

				le32_to_cpu(path[depth].p_ext->ee_block),

				ext4_ext_pblock(path[depth].p_ext),

				ext4_ext_is_uninitialized(path[depth].p_ext),

				ext4_ext_get_actual_len(path[depth].p_ext),

				newblock);

		/*memmove(ex++, path[depth].p_ext++,

				sizeof(struct ext4_extent));

		neh->eh_entries++;*/

		path[depth].p_ext++;

		m++;

	}

	m = EXT_MAX_EXTENT(path[depth].p_hdr) - path[depth].p_ext++;

	ext4_ext_show_move(inode, path, newblock, depth);

	if (m) {

		memmove(ex, path[depth].p_ext-m, sizeof(struct ext4_extent)*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);

	}
@@ -977,12 +996,8 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode, 


		ext_debug("int.index at %d (block %llu): %u -> %llu\n",

				i, newblock, le32_to_cpu(border), oldblock);

		/* copy indexes */

		m = 0;

		path[i].p_idx++;



		ext_debug("cur 0x%p, last 0x%p\n", path[i].p_idx,

				EXT_MAX_INDEX(path[i].p_hdr));

		/* 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,
@@ -991,20 +1006,13 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode, 
			err = -EIO;

			goto cleanup;

		}

		while (path[i].p_idx <= EXT_MAX_INDEX(path[i].p_hdr)) {

			ext_debug("%d: move %d:%llu in new index %llu\n", i,

					le32_to_cpu(path[i].p_idx->ei_block),

					ext4_idx_pblock(path[i].p_idx),

					newblock);

			/*memmove(++fidx, path[i].p_idx++,

					sizeof(struct ext4_extent_idx));

			neh->eh_entries++;

			BUG_ON(neh->eh_entries > neh->eh_max);*/

			path[i].p_idx++;

			m++;

		}

		/* start copy indexes */

		m = EXT_MAX_INDEX(path[i].p_hdr) - path[i].p_idx++;

		ext_debug("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 - m,

			memmove(++fidx, path[i].p_idx,

				sizeof(struct ext4_extent_idx) * m);

			le16_add_cpu(&neh->eh_entries, m);

		}