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Commit bea495e5 authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: Tune readahead during defrag to avoid reading too much at once 



Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent d1310b2e

fs/btrfs/extent-tree.c

+28 −13
Original line number Diff line number Diff line
@@ -1856,27 +1856,44 @@ static int noinline drop_leaf_ref(struct btrfs_trans_handle *trans, 
}



static void noinline reada_walk_down(struct btrfs_root *root,

				     struct extent_buffer *node)

				     struct extent_buffer *node,

				     int slot)

{

	int i;

	u32 nritems;

	u64 bytenr;

	int ret;

	u64 last = 0;

	u32 nritems;

	u32 refs;

	int level;

	u32 blocksize;

	int ret;

	int i;

	int level;

	int skipped = 0;



	nritems = btrfs_header_nritems(node);

	level = btrfs_header_level(node);

	for (i = 0; i < nritems; i++) {

	if (level)

		return;



	for (i = slot; i < nritems && skipped < 32; i++) {

		bytenr = btrfs_node_blockptr(node, i);

		if (last && ((bytenr > last && bytenr - last > 32 * 1024) ||

			     (last > bytenr && last - bytenr > 32 * 1024))) {

			skipped++;

			continue;

		}

		blocksize = btrfs_level_size(root, level - 1);

		ret = lookup_extent_ref(NULL, root, bytenr, blocksize, &refs);

		if (i != slot) {

			ret = lookup_extent_ref(NULL, root, bytenr,

						blocksize, &refs);

			BUG_ON(ret);

		if (refs != 1)

			if (refs != 1) {

				skipped++;

				continue;

			}

		}

		mutex_unlock(&root->fs_info->fs_mutex);

		ret = readahead_tree_block(root, bytenr, blocksize);

		last = bytenr + blocksize;

		cond_resched();

		mutex_lock(&root->fs_info->fs_mutex);

		if (ret)
@@ -1919,9 +1936,6 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans, 
		WARN_ON(*level >= BTRFS_MAX_LEVEL);

		cur = path->nodes[*level];



		if (*level > 0 && path->slots[*level] == 0)

			reada_walk_down(root, cur);



		if (btrfs_header_level(cur) != *level)

			WARN_ON(1);
@@ -1951,6 +1965,7 @@ static int noinline walk_down_tree(struct btrfs_trans_handle *trans, 
		next = btrfs_find_tree_block(root, bytenr, blocksize);

		if (!next || !btrfs_buffer_uptodate(next)) {

			free_extent_buffer(next);

			reada_walk_down(root, cur, path->slots[*level]);

			mutex_unlock(&root->fs_info->fs_mutex);

			next = read_tree_block(root, bytenr, blocksize);

			mutex_lock(&root->fs_info->fs_mutex);