Unify arc_prune_async() code

There is no sense to have separate implementations for FreeBSD and
Linux.  Make Linux code shared as more functional and just register
FreeBSD-specific prune callback with arc_add_prune_callback() API.

Aside of code cleanup this should fix excessive pruning on FreeBSD:
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=274698

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Mark Johnston <[email protected]>
Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
Closes #15456 

2 files changed, 1 insertions, 52 deletions

diff --git a/module/os/linux/zfs/arc_os.c b/module/os/linux/zfs/arc_os.c
index 381563476..55cdbba5b 100644
--- a/module/os/linux/zfs/arc_os.c
+++ b/module/os/linux/zfs/arc_os.c
@@ -495,56 +495,5 @@ arc_unregister_hotplug(void)
 }
 #endif /* _KERNEL */
 
-/*
- * Helper function for arc_prune_async() it is responsible for safely
- * handling the execution of a registered arc_prune_func_t.
- */
-static void
-arc_prune_task(void *ptr)
-{
-	arc_prune_t *ap = (arc_prune_t *)ptr;
-	arc_prune_func_t *func = ap->p_pfunc;
-
-	if (func != NULL)
-		func(ap->p_adjust, ap->p_private);
-
-	zfs_refcount_remove(&ap->p_refcnt, func);
-}
-
-/*
- * Notify registered consumers they must drop holds on a portion of the ARC
- * buffered they reference.  This provides a mechanism to ensure the ARC can
- * honor the metadata limit and reclaim otherwise pinned ARC buffers.  This
- * is analogous to dnlc_reduce_cache() but more generic.
- *
- * This operation is performed asynchronously so it may be safely called
- * in the context of the arc_reclaim_thread().  A reference is taken here
- * for each registered arc_prune_t and the arc_prune_task() is responsible
- * for releasing it once the registered arc_prune_func_t has completed.
- */
-void
-arc_prune_async(uint64_t adjust)
-{
-	arc_prune_t *ap;
-
-	mutex_enter(&arc_prune_mtx);
-	for (ap = list_head(&arc_prune_list); ap != NULL;
-	    ap = list_next(&arc_prune_list, ap)) {
-
-		if (zfs_refcount_count(&ap->p_refcnt) >= 2)
-			continue;
-
-		zfs_refcount_add(&ap->p_refcnt, ap->p_pfunc);
-		ap->p_adjust = adjust;
-		if (taskq_dispatch(arc_prune_taskq, arc_prune_task,
-		    ap, TQ_SLEEP) == TASKQID_INVALID) {
-			zfs_refcount_remove(&ap->p_refcnt, ap->p_pfunc);
-			continue;
-		}
-		ARCSTAT_BUMP(arcstat_prune);
-	}
-	mutex_exit(&arc_prune_mtx);
-}
-
 ZFS_MODULE_PARAM(zfs_arc, zfs_arc_, shrinker_limit, INT, ZMOD_RW,
 	"Limit on number of pages that ARC shrinker can reclaim at once");
diff --git a/module/os/linux/zfs/zpl_super.c b/module/os/linux/zfs/zpl_super.c
index ad52a11aa..d98d32c1f 100644
--- a/module/os/linux/zfs/zpl_super.c
+++ b/module/os/linux/zfs/zpl_super.c
@@ -375,7 +375,7 @@ zpl_kill_sb(struct super_block *sb)
 }
 
 void
-zpl_prune_sb(int64_t nr_to_scan, void *arg)
+zpl_prune_sb(uint64_t nr_to_scan, void *arg)
 {
 	struct super_block *sb = (struct super_block *)arg;
 	int objects = 0;