btrfs: fix missing increment of bi_remaining

In btrfs_end_bio(), we increment bi_remaining if is_orig_bio. If not,
we restore the orig_bio but failed to increment bi_remaining for
orig_bio, which triggers a BUG_ON later when bio_endio is called. Fix
is to increment bi_remaining when we restore the orig bio as well.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
CC: Kent Overstreet <kmo@daterainc.com>
Signed-off-by: Muthukumar Ratty <muthur@gmail.com>
Reviewed-by: Chris Mason <clm@fb.com>
Tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 7 insertions, 2 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 37972d5db737..54d2685a3071 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -5297,9 +5297,14 @@ static void btrfs_end_bio(struct bio *bio, int err)
                 if (!is_orig_bio) {
                         bio_put(bio);
                         bio = bbio->orig_bio;
-                } else {
-                        atomic_inc(&bio->bi_remaining);
                 }
+
+                /*
+                 * We have original bio now. So increment bi_remaining to
+                 * account for it in endio
+                 */
+                atomic_inc(&bio->bi_remaining);
+
                 bio->bi_private = bbio->private;
                 bio->bi_end_io = bbio->end_io;
                 btrfs_io_bio(bio)->mirror_num = bbio->mirror_num;