Btrfs: Fix the multi-bio code to save the original bio for completion

The multi-bio code is responsible for duplicating blocks in raid1 and
single spindle duplication.  It has counters to make sure all of
the locations for a given extent are properly written before io completion
is returned to the higher layers.

But, it didn't always complete the same bio it was given, sometimes a
clone was completed instead.  This lead to problems with the async
work queues because they saved a pointer to the bio in a struct off
bi_private.

The fix is to remember the original bio and only complete that one.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 48a44f7a9385..c50e50580b51 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -95,6 +95,7 @@ struct btrfs_bio_stripe {
 struct btrfs_multi_bio {
         atomic_t stripes_pending;
         bio_end_io_t *end_io;
+        struct bio *orig_bio;
         void *private;
         atomic_t error;
         int max_errors;