The early check if we should attempt compression does not take into account the number of input pages. It can happen that there's only one page, eg. a tail page after some ranges of the BTRFS_MAX_UNCOMPRESSED have been processed, or an isolated page that won't be converted to an inline extent.
The single page would be compressed but a later check would drop it again because the result size must be at least one block shorter than the input. That can never work with just one page.
CC: stable@vger.kernel.org # 4.4+ Signed-off-by: David Sterba dsterba@suse.com --- fs/btrfs/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index a2494c645681..e6eb20987351 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -629,7 +629,7 @@ static noinline int compress_file_range(struct async_chunk *async_chunk) * inode has not been flagged as nocompress. This flag can * change at any time if we discover bad compression ratios. */ - if (inode_need_compress(BTRFS_I(inode), start, end)) { + if (nr_pages > 1 && inode_need_compress(BTRFS_I(inode), start, end)) { WARN_ON(pages); pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS); if (!pages) {