Commit f2165627 authored by David Sterba's avatar David Sterba
Browse files

btrfs: compression: don't try to compress if we don't have enough pages 



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: default avatarDavid Sterba <dsterba@suse.com>
parent 44365827

fs/btrfs/inode.c

+1 −1
Original line number Diff line number Diff line
@@ -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) {