xfs: return the busy generation from xfs_extent_busy_list_empty

This avoid having to poke into the internals of the busy tracking in
xrep_setup_ag_allocbt.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Author: Christoph Hellwig

fs/xfs/scrub/alloc_repair.c

@@ -132,16 +132,12 @@ int
 xrep_setup_ag_allocbt(
 	struct xfs_scrub	*sc)
 {
-	unsigned int		busy_gen;
-
 	/*
 	 * Make sure the busy extent list is clear because we can't put extents
 	 * on there twice.
 	 */
-	busy_gen = READ_ONCE(sc->sa.pag->pagb_gen);
-	if (xfs_extent_busy_list_empty(sc->sa.pag))
+	if (xfs_extent_busy_list_empty(sc->sa.pag, &busy_gen))
 		return 0;
-
 	return xfs_extent_busy_flush(sc->tp, sc->sa.pag, busy_gen, 0);
 }
 
@@ -849,6 +845,7 @@ xrep_allocbt(
 {
 	struct xrep_abt		*ra;
 	struct xfs_mount	*mp = sc->mp;
+	unsigned int		busy_gen;
 	char			*descr;
 	int			error;
 
@@ -869,7 +866,7 @@ xrep_allocbt(
 	 * on there twice.  In theory we cleared this before we started, but
 	 * let's not risk the filesystem.
 	 */
-	if (!xfs_extent_busy_list_empty(sc->sa.pag)) {
+	if (!xfs_extent_busy_list_empty(sc->sa.pag, &busy_gen)) {
 		error = -EDEADLOCK;
 		goto out_ra;
 	}

fs/xfs/xfs_extent_busy.c

@@ -667,12 +667,14 @@ xfs_extent_busy_ag_cmp(
 /* Are there any busy extents in this AG? */
 bool
 xfs_extent_busy_list_empty(
-	struct xfs_perag	*pag)
+	struct xfs_perag	*pag,
+	unsigned		*busy_gen)
 {
 	bool			res;
 
 	spin_lock(&pag->pagb_lock);
 	res = RB_EMPTY_ROOT(&pag->pagb_tree);
+	*busy_gen = READ_ONCE(pag->pagb_gen);
 	spin_unlock(&pag->pagb_lock);
 	return res;
 }

fs/xfs/xfs_extent_busy.h

@@ -83,6 +83,6 @@ static inline void xfs_extent_busy_sort(struct list_head *list)
 	list_sort(NULL, list, xfs_extent_busy_ag_cmp);
 }
 
-bool xfs_extent_busy_list_empty(struct xfs_perag *pag);
+bool xfs_extent_busy_list_empty(struct xfs_perag *pag, unsigned int *busy_gen);
 
 #endif /* __XFS_EXTENT_BUSY_H__ */