btrfs: assign error values to the correct bio structs

BugLink: http://bugs.launchpad.net/bugs/1637501

commit 14155ca upstream.

Fixes: 4246a0b ("block: add a bi_error field to struct bio")
Signed-off-by: Junjie Mao <junjie.mao@enight.me>
Acked-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

fs/btrfs/compression.c

@@ -694,7 +694,7 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 			ret = btrfs_map_bio(root, READ, comp_bio,
 					    mirror_num, 0);
 			if (ret) {
-				bio->bi_error = ret;
+				comp_bio->bi_error = ret;
 				bio_endio(comp_bio);
 			}
 
@@ -723,7 +723,7 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 
 	ret = btrfs_map_bio(root, READ, comp_bio, mirror_num, 0);
 	if (ret) {
-		bio->bi_error = ret;
+		comp_bio->bi_error = ret;
 		bio_endio(comp_bio);
 	}