cifs: fix reconnect on smb3 mount types

cifs.ko defines two file system types: cifs & smb3, and
__cifs_get_super() was not including smb3 file system type when
looking up superblocks, therefore failing to reconnect tcons in
cifs_tree_connect().

Fix this by calling iterate_supers_type() on both file system types.

Link: https://lore.kernel.org/r/CAFrh3J9soC36+BVuwHB=g9z_KB5Og2+p2_W+BBoBOZveErz14w@mail.gmail.com
Cc: stable@vger.kernel.org
Tested-by: Satadru Pramanik <satadru@gmail.com>
Reported-by: Satadru Pramanik <satadru@gmail.com>
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/cifsfs.c

@@ -1086,7 +1086,7 @@ struct file_system_type cifs_fs_type = {
 };
 MODULE_ALIAS_FS("cifs");
 
-static struct file_system_type smb3_fs_type = {
+struct file_system_type smb3_fs_type = {
 	.owner = THIS_MODULE,
 	.name = "smb3",
 	.init_fs_context = smb3_init_fs_context,

fs/cifs/cifsfs.h

@@ -38,7 +38,7 @@ static inline unsigned long cifs_get_time(struct dentry *dentry)
 	return (unsigned long) dentry->d_fsdata;
 }
 
-extern struct file_system_type cifs_fs_type;
+extern struct file_system_type cifs_fs_type, smb3_fs_type;
 extern const struct address_space_operations cifs_addr_ops;
 extern const struct address_space_operations cifs_addr_ops_smallbuf;
 

fs/cifs/misc.c

@@ -1211,18 +1211,23 @@ static struct super_block *__cifs_get_super(void (*f)(struct super_block *, void
 		.data = data,
 		.sb = NULL,
 	};
+	struct file_system_type **fs_type = (struct file_system_type *[]) {
+		&cifs_fs_type, &smb3_fs_type, NULL,
+	};
 
-	iterate_supers_type(&cifs_fs_type, f, &sd);
-
-	if (!sd.sb)
-		return ERR_PTR(-EINVAL);
-	/*
-	 * Grab an active reference in order to prevent automounts (DFS links)
-	 * of expiring and then freeing up our cifs superblock pointer while
-	 * we're doing failover.
-	 */
-	cifs_sb_active(sd.sb);
-	return sd.sb;
+	for (; *fs_type; fs_type++) {
+		iterate_supers_type(*fs_type, f, &sd);
+		if (sd.sb) {
+			/*
+			 * Grab an active reference in order to prevent automounts (DFS links)
+			 * of expiring and then freeing up our cifs superblock pointer while
+			 * we're doing failover.
+			 */
+			cifs_sb_active(sd.sb);
+			return sd.sb;
+		}
+	}
+	return ERR_PTR(-EINVAL);
 }
 
 static void __cifs_put_super(struct super_block *sb)