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Commit 52621cb6 authored by Li Zefan's avatar Li Zefan Committed by Chris Mason
Browse files

Btrfs: avoid unnecessary bitmap search for cluster setup 



setup_cluster_no_bitmap() searches all the extents and bitmaps starting
from offset. Therefore if it returns -ENOSPC, all the bitmaps starting
from offset are in the bitmaps list, so it's sufficient to search from
this list in setup_cluser_bitmap().

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 0f0fbf1d

fs/btrfs/free-space-cache.c

+4 −38
Original line number Diff line number Diff line
@@ -2451,7 +2451,6 @@ setup_cluster_bitmap(struct btrfs_block_group_cache *block_group, 
{

	struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;

	struct btrfs_free_space *entry;

	struct rb_node *node;

	int ret = -ENOSPC;

	u64 bitmap_offset = offset_to_bitmap(ctl, offset);
@@ -2469,10 +2468,6 @@ setup_cluster_bitmap(struct btrfs_block_group_cache *block_group, 
			list_add(&entry->list, bitmaps);

	}



	/*

	 * First check our cached list of bitmaps and see if there is an entry

	 * here that will work.

	 */

	list_for_each_entry(entry, bitmaps, list) {

		if (entry->bytes < min_bytes)

			continue;
@@ -2483,38 +2478,10 @@ setup_cluster_bitmap(struct btrfs_block_group_cache *block_group, 
	}



	/*

	 * If we do have entries on our list and we are here then we didn't find

	 * anything, so go ahead and get the next entry after the last entry in

	 * this list and start the search from there.

	 * The bitmaps list has all the bitmaps that record free space

	 * starting after offset, so no more search is required.

	 */

	if (!list_empty(bitmaps)) {

		entry = list_entry(bitmaps->prev, struct btrfs_free_space,

				   list);

		node = rb_next(&entry->offset_index);

		if (!node)

	return -ENOSPC;

		entry = rb_entry(node, struct btrfs_free_space, offset_index);

		goto search;

	}



	entry = tree_search_offset(ctl, offset_to_bitmap(ctl, offset), 0, 1);

	if (!entry)

		return -ENOSPC;



search:

	node = &entry->offset_index;

	do {

		entry = rb_entry(node, struct btrfs_free_space, offset_index);

		node = rb_next(&entry->offset_index);

		if (!entry->bitmap)

			continue;

		if (entry->bytes < min_bytes)

			continue;

		ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,

					   bytes, min_bytes);

	} while (ret && node);



	return ret;

}



/*
@@ -2532,8 +2499,8 @@ int btrfs_find_space_cluster(struct btrfs_trans_handle *trans, 
			     u64 offset, u64 bytes, u64 empty_size)

{

	struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;

	struct list_head bitmaps;

	struct btrfs_free_space *entry, *tmp;

	LIST_HEAD(bitmaps);

	u64 min_bytes;

	int ret;
@@ -2572,7 +2539,6 @@ int btrfs_find_space_cluster(struct btrfs_trans_handle *trans, 
		goto out;

	}



	INIT_LIST_HEAD(&bitmaps);

	ret = setup_cluster_no_bitmap(block_group, cluster, &bitmaps, offset,

				      bytes, min_bytes);

	if (ret)