btrfs: raid56: properly handle the error when unable to find the missing stripe

In raid56_alloc_missing_rbio(), if we can not determine where the
missing device is inside the full stripe, we just BUG_ON().

This is not necessary especially the only caller inside scrub.c is
already properly checking the return value, and will treat it as a
memory allocation failure.

Fix the error handling by:

- Add an extra warning for the reason
  Although personally speaking it may be better to be an ASSERT().

- Properly free the allocated rbio

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index f6395e8..892005f 100644 (file)
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -2742,8 +2742,10 @@ raid56_alloc_missing_rbio(struct bio *bio, struct btrfs_io_context *bioc)
 
        rbio->faila = find_logical_bio_stripe(rbio, bio);
        if (rbio->faila == -1) {
-               BUG();
-               kfree(rbio);
+               btrfs_warn_rl(fs_info,
+       "can not determine the failed stripe number for full stripe %llu",
+                             bioc->raid_map[0]);
+               __free_raid_bio(rbio);
                return NULL;
        }