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Btrfs: fix to search one more bitmap for cluster setup

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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>
This commit is contained in:
Li Zefan 2011-11-20 07:33:38 -05:00 committed by Chris Mason
parent 32240a913d
commit 0f0fbf1d0e
1 changed files with 12 additions and 0 deletions
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12
fs/btrfs/free-space-cache.c
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@ -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.