[PATCH v6] Btrfs: compression must free at least one sector size

[Timofey Titovets <nefelim4ag@gmail.com>]

Btrfs already skip store of data where compression didn't
free at least one byte. Let's make logic better and make check
that compression free at least one sector size
because in another case it useless to store this data compressed

Signed-off-by: Timofey Titovets <nefelim4ag@gmail.com>
Cc: David Sterba <dsterba@suse.cz>
---
 fs/btrfs/inode.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 17cbe930..7646f46b 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -609,11 +609,10 @@ 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
+		 * 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;

--
2.13.0