| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.4 105/108] btrfs: compression: dont try to compress if we dont have enough pages | Date | Mon, 26 Jul 2021 17:39:46 +0200 |
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From: David Sterba <dsterba@suse.com>
commit f2165627319ffd33a6217275e5690b1ab5c45763 upstream
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> [sudip: adjust context] Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- fs/btrfs/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -543,7 +543,7 @@ again: * inode has not been flagged as nocompress. This flag can * change at any time if we discover bad compression ratios. */ - if (inode_need_compress(inode, start, end)) { + if (nr_pages > 1 && inode_need_compress(inode, start, end)) { WARN_ON(pages); pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS); if (!pages) {
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