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| author | Marcos Paulo de Souza <mpdesouza@suse.com> | 2020-08-21 16:54:44 +0200 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2020-08-27 13:37:54 +0200 |
| commit | e3e39c72b99f93bbd0420d38c858e7c4a061bb63 (patch) | |
| tree | cf500248ff53d9145c4a7f752720cdd3cc863a3d /fs/btrfs/free-space-tree.c | |
| parent | btrfs: detect nocow for swap after snapshot delete (diff) | |
| download | linux-e3e39c72b99f93bbd0420d38c858e7c4a061bb63.tar.xz linux-e3e39c72b99f93bbd0420d38c858e7c4a061bb63.zip | |
btrfs: block-group: fix free-space bitmap threshold
[BUG]
After commit 9afc66498a0b ("btrfs: block-group: refactor how we read one
block group item"), cache->length is being assigned after calling
btrfs_create_block_group_cache. This causes a problem since
set_free_space_tree_thresholds calculates the free-space threshold to
decide if the free-space tree should convert from extents to bitmaps.
The current code calls set_free_space_tree_thresholds with cache->length
being 0, which then makes cache->bitmap_high_thresh zero. This implies
the system will always use bitmap instead of extents, which is not
desired if the block group is not fragmented.
This behavior can be seen by a test that expects to repair systems
with FREE_SPACE_EXTENT and FREE_SPACE_BITMAP, but the current code only
created FREE_SPACE_BITMAP.
[FIX]
Call set_free_space_tree_thresholds after setting cache->length. There
is now a WARN_ON in set_free_space_tree_thresholds to help preventing
the same mistake to happen again in the future.
Link: https://github.com/kdave/btrfs-progs/issues/251
Fixes: 9afc66498a0b ("btrfs: block-group: refactor how we read one block group item")
CC: stable@vger.kernel.org # 5.8+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/free-space-tree.c')
| -rw-r--r-- | fs/btrfs/free-space-tree.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/fs/btrfs/free-space-tree.c b/fs/btrfs/free-space-tree.c index 8b1f5c8897b7..6b9faf3b0e96 100644 --- a/fs/btrfs/free-space-tree.c +++ b/fs/btrfs/free-space-tree.c @@ -22,6 +22,10 @@ void set_free_space_tree_thresholds(struct btrfs_block_group *cache) size_t bitmap_size; u64 num_bitmaps, total_bitmap_size; + if (WARN_ON(cache->length == 0)) + btrfs_warn(cache->fs_info, "block group %llu length is zero", + cache->start); + /* * We convert to bitmaps when the disk space required for using extents * exceeds that required for using bitmaps. |