xfs: Fix uninitialized return value in xfs_alloc_fix_freelist()

xfs_alloc_fix_freelist() can sometimes jump to out_agbp_relse
without ever setting value of 'error' variable which is then
returned. This can happen e.g. when pag->pagf_init is set but AG is
for metadata and we want to allocate user data.

Fix the problem by initializing 'error' to 0, which is the desired
return value when we decide to skip this group.

CC: xfs@oss.sgi.com
Coverity-id: 1309714
Signed-off-by: NJan Kara <jack@suse.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

fs/xfs/libxfs/xfs_alloc.c

@@ -1937,7 +1937,7 @@ xfs_alloc_fix_freelist(
 	struct xfs_alloc_arg	targs;	/* local allocation arguments */
 	xfs_agblock_t		bno;	/* freelist block */
 	xfs_extlen_t		need;	/* total blocks needed in freelist */
-	int			error;
+	int			error = 0;
 
 	if (!pag->pagf_init) {
 		error = xfs_alloc_read_agf(mp, tp, args->agno, flags, &agbp);