Rename zvol kernel module parameters sysctls on FreeBSD side

Make 'zvol_threads', 'zvol_num_taskqs' and 'zvol_request_sync' names
compatible with FreeBSD sysctl naming convention. Now the sysctls are
have a next form:

$ sysctl vfs.zfs.vol.threads
vfs.zfs.vol.threads: 0

$ sysctl vfs.zfs.vol.num_taskqs
vfs.zfs.vol.num_taskqs: 0

$ sysctl vfs.zfs.vol.request_sync
vfs.zfs.vol.request_sync: 0

Sponsored-by: vStack, Inc.
Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Alexander Motin <[email protected]>
Signed-off-by: Fedor Uporov <[email protected]>
Closes #17406

Author: fuporovvStack

module/zfs/zvol.c

@@ -2156,9 +2156,9 @@ zvol_fini_impl(void)
 
 ZFS_MODULE_PARAM(zfs_vol, zvol_, inhibit_dev, UINT, ZMOD_RW,
 	"Do not create zvol device nodes");
-ZFS_MODULE_PARAM(zfs, , zvol_threads, UINT, ZMOD_RW,
+ZFS_MODULE_PARAM(zfs_vol, zvol_, threads, UINT, ZMOD_RW,
 	"Number of threads for I/O requests. Set to 0 to use all active CPUs");
-ZFS_MODULE_PARAM(zfs, , zvol_num_taskqs, UINT, ZMOD_RW,
+ZFS_MODULE_PARAM(zfs_vol, zvol_, num_taskqs, UINT, ZMOD_RW,
 	"Number of zvol taskqs");
-ZFS_MODULE_PARAM(zfs, , zvol_request_sync, UINT, ZMOD_RW,
+ZFS_MODULE_PARAM(zfs_vol, zvol_, request_sync, UINT, ZMOD_RW,
 	"Synchronously handle bio requests");

tests/zfs-tests/include/tunables.cfg

@@ -102,7 +102,7 @@ VDEV_VALIDATE_SKIP		vdev.validate_skip		vdev_validate_skip
 VOL_INHIBIT_DEV			vol.inhibit_dev			zvol_inhibit_dev
 VOL_MODE			vol.mode			zvol_volmode
 VOL_RECURSIVE			vol.recursive			UNSUPPORTED
-VOL_REQUEST_SYNC		zvol_request_sync		zvol_request_sync
+VOL_REQUEST_SYNC		vol.request_sync		zvol_request_sync
 VOL_USE_BLK_MQ			UNSUPPORTED			zvol_use_blk_mq
 BCLONE_ENABLED			bclone_enabled			zfs_bclone_enabled
 BCLONE_WAIT_DIRTY		bclone_wait_dirty		zfs_bclone_wait_dirty