Commit 0f0fbf1d authored Nov 20, 2011 by Li Zefan Committed by Chris Mason Nov 20, 2011

Btrfs: fix to search one more bitmap for cluster setup



Suppose there are two bitmaps [0, 256], [256, 512] and one extent
[100, 120] in the free space cache, and we want to setup a cluster
with offset=100, bytes=50.

In this case, there will be only one bitmap [256, 512] in the temporary
bitmaps list, and then setup_cluster_bitmap() won't search bitmap [0, 256].

The cause is, the list is constructed in setup_cluster_no_bitmap(),
and only bitmaps with bitmap_entry->offset >= offset will be added
into the list, and the very bitmap that convers offset has
bitmap_entry->offset <= offset.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

parent 32240a91

fs/btrfs/free-space-cache.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -2453,10 +2453,22 @@ setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
		struct btrfs_free_space *entry;
		struct rb_node *node;
		int ret = -ENOSPC;
		u64 bitmap_offset = offset_to_bitmap(ctl, offset);

		if (ctl->total_bitmaps == 0)
		return -ENOSPC;

		/*
		* The bitmap that covers offset won't be in the list unless offset
		* is just its start offset.
		*/
		entry = list_first_entry(bitmaps, struct btrfs_free_space, list);
		if (entry->offset != bitmap_offset) {
		entry = tree_search_offset(ctl, bitmap_offset, 1, 0);
		if (entry && list_empty(&entry->list))
		list_add(&entry->list, bitmaps);
		}

		/*
		* First check our cached list of bitmaps and see if there is an entry
		* here that will work.

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