linux/super: match vfs_t lifetime to fs_context

vfs_t is initially just parameters for the mount or remount operation,
so match them to the lifetime of the fs_context that represents that
operation.

When we actually execute the operation (calling .get_tree or .reconfigure),
transfer ownership of those options to the associated zfsvfs_t.

Sponsored-by: TrueNAS
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <rob.norris@truenas.com>
Closes #18377

include/os/linux/zfs/sys/zfs_vfsops_os.h

@@ -76,7 +76,7 @@ typedef struct vfs {
 
 typedef struct zfs_mnt {
 	const char	*mnt_osname;	/* Objset name */
-	char		*mnt_data;	/* Raw mount options */
+	vfs_t		*mnt_opts;	/* Parsed options */
 } zfs_mnt_t;
 
 struct zfsvfs {