xfs: switch to NOFS allocation under i_lock in xfs_dir_cilookup_result

xfs_dir_cilookup_result is always called with i_lock held, but i_lock is taken
in reclaim context so all allocations under it must avoid recursions into the
filesystem.

Reported by the new reclaim context tracing in lockdep.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Felix Blyakher <felixb@sgi.com>
Signed-off-by: Felix Blyakher <felixb@sgi.com>

fs/xfs/xfs_dir2.c

@@ -256,7 +256,7 @@ xfs_dir_cilookup_result(
 					!(args->op_flags & XFS_DA_OP_CILOOKUP))
 		return EEXIST;
 
-	args->value = kmem_alloc(len, KM_MAYFAIL);
+	args->value = kmem_alloc(len, KM_NOFS | KM_MAYFAIL);
 	if (!args->value)
 		return ENOMEM;