[PATCH] xfs: don't send null bp to xfs_trans_brelse()

[Eric Sandeen <sandeen@xxxxxxxxxx>]

In this case, if bp is null, error is set, and we send
bp to xfs_trans_brelse, which will try to dereference it.

Test whether we actualy have a buffer before we try to
free it.

Coverity spotted this.

Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
---

diff --git a/fs/xfs/xfs_da_btree.c b/fs/xfs/xfs_da_btree.c
index 6cc5f67..41f7a42 100644
--- a/fs/xfs/xfs_da_btree.c
+++ b/fs/xfs/xfs_da_btree.c
@@ -2571,7 +2571,8 @@ xfs_da_get_buf(
                                    mapp, nmap, 0);
        error = bp ? bp->b_error : XFS_ERROR(EIO);
        if (error) {
-               xfs_trans_brelse(trans, bp);
+               if (bp)
+                       xfs_trans_brelse(trans, bp);
                goto out_free;
        }