Retire z_nr_znodes

Added in ab26409db753 ("Linux 3.1 compat, super_block->s_shrink"), with
the only consumer which needed the count getting retired in 066e82522101
("Linux compat: Minimum kernel version 3.10").

The counter gets in the way of not maintaining the list to begin with.

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Alexander Motin <[email protected]>
Signed-off-by: Mateusz Guzik <[email protected]>
Closes #15274 

7 files changed, 6 insertions, 16 deletions

diff --git a/include/os/freebsd/zfs/sys/zfs_vfsops_os.h b/include/os/freebsd/zfs/sys/zfs_vfsops_os.h
index f765d38db..24bb03575 100644
--- a/include/os/freebsd/zfs/sys/zfs_vfsops_os.h
+++ b/include/os/freebsd/zfs/sys/zfs_vfsops_os.h
@@ -93,7 +93,6 @@ struct zfsvfs {
 	zfs_teardown_lock_t z_teardown_lock;
 	zfs_teardown_inactive_lock_t z_teardown_inactive_lock;
 	list_t		z_all_znodes;	/* all vnodes in the fs */
-	uint64_t	z_nr_znodes;	/* number of znodes in the fs */
 	kmutex_t	z_znodes_lock;	/* lock for z_all_znodes */
 	struct zfsctl_root	*z_ctldir;	/* .zfs directory pointer */
 	boolean_t	z_show_ctldir;	/* expose .zfs in the root dir */
diff --git a/include/os/linux/zfs/sys/zfs_vfsops_os.h b/include/os/linux/zfs/sys/zfs_vfsops_os.h
index e320b8de4..b4d5db21f 100644
--- a/include/os/linux/zfs/sys/zfs_vfsops_os.h
+++ b/include/os/linux/zfs/sys/zfs_vfsops_os.h
@@ -105,7 +105,6 @@ struct zfsvfs {
 	rrmlock_t	z_teardown_lock;
 	krwlock_t	z_teardown_inactive_lock;
 	list_t		z_all_znodes;	/* all znodes in the fs */
-	uint64_t	z_nr_znodes;	/* number of znodes in the fs */
 	unsigned long	z_rollback_time; /* last online rollback time */
 	unsigned long	z_snap_defer_time; /* last snapshot unmount deferral */
 	kmutex_t	z_znodes_lock;	/* lock for z_all_znodes */
diff --git a/module/os/freebsd/zfs/zfs_vfsops.c b/module/os/freebsd/zfs/zfs_vfsops.c
index 33759fa26..e8b9ada13 100644
--- a/module/os/freebsd/zfs/zfs_vfsops.c
+++ b/module/os/freebsd/zfs/zfs_vfsops.c
@@ -1154,7 +1154,6 @@ zfsvfs_free(zfsvfs_t *zfsvfs)
 
 	mutex_destroy(&zfsvfs->z_znodes_lock);
 	mutex_destroy(&zfsvfs->z_lock);
-	ASSERT3U(zfsvfs->z_nr_znodes, ==, 0);
 	list_destroy(&zfsvfs->z_all_znodes);
 	ZFS_TEARDOWN_DESTROY(zfsvfs);
 	ZFS_TEARDOWN_INACTIVE_DESTROY(zfsvfs);
@@ -1558,12 +1557,11 @@ zfsvfs_teardown(zfsvfs_t *zfsvfs, boolean_t unmounting)
 		 * may add the parents of dir-based xattrs to the taskq
 		 * so we want to wait for these.
 		 *
-		 * We can safely read z_nr_znodes without locking because the
-		 * VFS has already blocked operations which add to the
-		 * z_all_znodes list and thus increment z_nr_znodes.
+		 * We can safely check z_all_znodes for being empty because the
+		 * VFS has already blocked operations which add to it.
 		 */
 		int round = 0;
-		while (zfsvfs->z_nr_znodes > 0) {
+		while (!list_is_empty(&zfsvfs->z_all_znodes)) {
 			taskq_wait_outstanding(dsl_pool_zrele_taskq(
 			    dmu_objset_pool(zfsvfs->z_os)), 0);
 			if (++round > 1 && !unmounting)
diff --git a/module/os/freebsd/zfs/zfs_znode.c b/module/os/freebsd/zfs/zfs_znode.c
index c4f2b722e..0d4c94555 100644
--- a/module/os/freebsd/zfs/zfs_znode.c
+++ b/module/os/freebsd/zfs/zfs_znode.c
@@ -537,7 +537,6 @@ zfs_znode_alloc(zfsvfs_t *zfsvfs, dmu_buf_t *db, int blksz,
 
 	mutex_enter(&zfsvfs->z_znodes_lock);
 	list_insert_tail(&zfsvfs->z_all_znodes, zp);
-	zfsvfs->z_nr_znodes++;
 	zp->z_zfsvfs = zfsvfs;
 	mutex_exit(&zfsvfs->z_znodes_lock);
 
@@ -1286,7 +1285,6 @@ zfs_znode_free(znode_t *zp)
 	mutex_enter(&zfsvfs->z_znodes_lock);
 	POINTER_INVALIDATE(&zp->z_zfsvfs);
 	list_remove(&zfsvfs->z_all_znodes, zp);
-	zfsvfs->z_nr_znodes--;
 	mutex_exit(&zfsvfs->z_znodes_lock);
 
 #if __FreeBSD_version >= 1300139
diff --git a/module/os/linux/zfs/zfs_ctldir.c b/module/os/linux/zfs/zfs_ctldir.c
index c45a3eb5a..02cb379ea 100644
--- a/module/os/linux/zfs/zfs_ctldir.c
+++ b/module/os/linux/zfs/zfs_ctldir.c
@@ -537,7 +537,6 @@ zfsctl_inode_alloc(zfsvfs_t *zfsvfs, uint64_t id,
 
 	mutex_enter(&zfsvfs->z_znodes_lock);
 	list_insert_tail(&zfsvfs->z_all_znodes, zp);
-	zfsvfs->z_nr_znodes++;
 	membar_producer();
 	mutex_exit(&zfsvfs->z_znodes_lock);
 
diff --git a/module/os/linux/zfs/zfs_vfsops.c b/module/os/linux/zfs/zfs_vfsops.c
index 464c12e11..a1db5c57c 100644
--- a/module/os/linux/zfs/zfs_vfsops.c
+++ b/module/os/linux/zfs/zfs_vfsops.c
@@ -1330,12 +1330,11 @@ zfsvfs_teardown(zfsvfs_t *zfsvfs, boolean_t unmounting)
 		 * may add the parents of dir-based xattrs to the taskq
 		 * so we want to wait for these.
 		 *
-		 * We can safely read z_nr_znodes without locking because the
-		 * VFS has already blocked operations which add to the
-		 * z_all_znodes list and thus increment z_nr_znodes.
+		 * We can safely check z_all_znodes for being empty because the
+		 * VFS has already blocked operations which add to it.
 		 */
 		int round = 0;
-		while (zfsvfs->z_nr_znodes > 0) {
+		while (!list_is_empty(&zfsvfs->z_all_znodes)) {
 			taskq_wait_outstanding(dsl_pool_zrele_taskq(
 			    dmu_objset_pool(zfsvfs->z_os)), 0);
 			if (++round > 1 && !unmounting)
diff --git a/module/os/linux/zfs/zfs_znode.c b/module/os/linux/zfs/zfs_znode.c
index 335ae3460..52c8e51df 100644
--- a/module/os/linux/zfs/zfs_znode.c
+++ b/module/os/linux/zfs/zfs_znode.c
@@ -390,7 +390,6 @@ zfs_inode_destroy(struct inode *ip)
 	mutex_enter(&zfsvfs->z_znodes_lock);
 	if (list_link_active(&zp->z_link_node)) {
 		list_remove(&zfsvfs->z_all_znodes, zp);
-		zfsvfs->z_nr_znodes--;
 	}
 	mutex_exit(&zfsvfs->z_znodes_lock);
 
@@ -641,7 +640,6 @@ zfs_znode_alloc(zfsvfs_t *zfsvfs, dmu_buf_t *db, int blksz,
 
 	mutex_enter(&zfsvfs->z_znodes_lock);
 	list_insert_tail(&zfsvfs->z_all_znodes, zp);
-	zfsvfs->z_nr_znodes++;
 	mutex_exit(&zfsvfs->z_znodes_lock);
 
 	if (links > 0)