btrfs: handle null fs_info in btrfs_panic()

At least backref_tree_panic() can apparently pass
in a null fs_info, so handle that in __btrfs_panic
to get the message out on the console.

The btrfs_panic macro also uses fs_info, but that's
largely pointless; it's testing to see if
BTRFS_MOUNT_PANIC_ON_FATAL_ERROR is not set.
But if it *were* set, __btrfs_panic() would have,
well, paniced and we wouldn't be here, testing it!
So just BUG() at this point.

And since we only use fs_info once now, just use it
directly.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index fd6a07c30ee9..06537d217419 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -289,7 +289,7 @@ void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
         vaf.va = &args;
 
         errstr = btrfs_decode_error(errno, nbuf);
-        if (fs_info->mount_opt & BTRFS_MOUNT_PANIC_ON_FATAL_ERROR)
+        if (fs_info && (fs_info->mount_opt & BTRFS_MOUNT_PANIC_ON_FATAL_ERROR))
                 panic(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (%s)\n",
                         s_id, function, line, &vaf, errstr);