xfs: support a tag-based inode_ag_iterator

Genericize xfs_inode_ag_walk() to support an optional radix tree tag
and args argument for the execute function. Create a new wrapper
called xfs_inode_ag_iterator_tag() that performs a tag based walk
of perag's and inodes.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

fs/xfs/xfs_qm_syscalls.c

@@ -846,7 +846,8 @@ STATIC int
 xfs_dqrele_inode(
 	struct xfs_inode	*ip,
 	struct xfs_perag	*pag,
-	int			flags)
+	int			flags,
+	void			*args)
 {
 	/* skip quota inodes */
 	if (ip == ip->i_mount->m_quotainfo->qi_uquotaip ||
@@ -882,5 +883,5 @@ xfs_qm_dqrele_all_inodes(
 	uint		 flags)
 {
 	ASSERT(mp->m_quotainfo);
-	xfs_inode_ag_iterator(mp, xfs_dqrele_inode, flags);
+	xfs_inode_ag_iterator(mp, xfs_dqrele_inode, flags, NULL);
 }