Commit 170607eb authored Jun 06, 2017 by Timofey Titovets Committed by David Sterba Jun 19, 2017

Btrfs: compression must free at least one sector size



We already skip storing data where compression does not make the result
at least one byte less.  Let's make the logic better and check
that compression frees at least one sector size of bytes, otherwise it's
not that useful.

Signed-off-by: Timofey Titovets <nefelim4ag@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ changelog updated ]
Signed-off-by: David Sterba <dsterba@suse.com>

parent c5e4c3d7

fs/btrfs/inode.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -607,12 +607,11 @@ static noinline void compress_file_range(struct inode *inode,

		/*
		* one last check to make sure the compression is really a
		* win, compare the page count read with the blocks on disk
		* win, compare the page count read with the blocks on disk,
		* compression must free at least one sector size
		*/
		total_in = ALIGN(total_in, PAGE_SIZE);
		if (total_compressed >= total_in) {
		will_compress = 0;
		} else {
		if (total_compressed + blocksize <= total_in) {
		num_bytes = total_in;
		*num_added += 1;