zvol: Hold the zvol state writer lock when renaming

Otherwise nothing serializes updates to the global zvol hash table.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <alexander.motin@TrueNAS.com>
Signed-off-by: Mark Johnston <markj@FreeBSD.org>
Closes #18191

module/os/freebsd/zfs/zvol_os.c

@@ -1249,7 +1249,7 @@ zvol_os_rename_minor(zvol_state_t *zv, const char *newname)
 {
 	int error = 0;
 
-	ASSERT(RW_LOCK_HELD(&zvol_state_lock));
+	ASSERT(RW_WRITE_HELD(&zvol_state_lock));
 	ASSERT(MUTEX_HELD(&zv->zv_state_lock));
 
 	/* Move to a new hashtable entry.  */

module/os/linux/zfs/zvol_os.c

@@ -1796,7 +1796,7 @@ zvol_os_rename_minor(zvol_state_t *zv, const char *newname)
 {
 	int readonly = get_disk_ro(zv->zv_zso->zvo_disk);
 
-	ASSERT(RW_LOCK_HELD(&zvol_state_lock));
+	ASSERT(RW_WRITE_HELD(&zvol_state_lock));
 	ASSERT(MUTEX_HELD(&zv->zv_state_lock));
 
 	strlcpy(zv->zv_name, newname, sizeof (zv->zv_name));

module/zfs/zvol.c

@@ -1827,7 +1827,7 @@ zvol_rename_minors_impl(zvol_task_t *task)
 
 	oldnamelen = strlen(oldname);
 
-	rw_enter(&zvol_state_lock, RW_READER);
+	rw_enter(&zvol_state_lock, RW_WRITER);
 
 	for (zv = list_head(&zvol_state_list); zv != NULL; zv = zv_next) {
 		zv_next = list_next(&zvol_state_list, zv);