autofs: validate protocol version

Move the protocol parameter validation into a seperate function.
Signed-off-by: Ian Kent <raven@themaw.net>
Reviewed-by: Bill O'Donnell <bodonnel@redhat.com>
Message-Id: <20230922041215.13675-7-raven@themaw.net>
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs/autofs/inode.c

@@ -287,6 +287,28 @@ static struct autofs_sb_info *autofs_alloc_sbi(void)
 	return sbi;
 }
 
+static int autofs_validate_protocol(struct autofs_sb_info *sbi)
+{
+	/* Test versions first */
+	if (sbi->max_proto < AUTOFS_MIN_PROTO_VERSION ||
+	    sbi->min_proto > AUTOFS_MAX_PROTO_VERSION) {
+		pr_err("kernel does not match daemon version "
+		       "daemon (%d, %d) kernel (%d, %d)\n",
+		       sbi->min_proto, sbi->max_proto,
+		       AUTOFS_MIN_PROTO_VERSION, AUTOFS_MAX_PROTO_VERSION);
+		return -EINVAL;
+	}
+
+	/* Establish highest kernel protocol version */
+	if (sbi->max_proto > AUTOFS_MAX_PROTO_VERSION)
+		sbi->version = AUTOFS_MAX_PROTO_VERSION;
+	else
+		sbi->version = sbi->max_proto;
+	sbi->sub_version = AUTOFS_PROTO_SUBVERSION;
+
+	return 0;
+}
+
 int autofs_fill_super(struct super_block *s, void *data, int silent)
 {
 	struct inode *root_inode;
@@ -335,22 +357,8 @@ int autofs_fill_super(struct super_block *s, void *data, int silent)
 		goto fail_dput;
 	}
 
-	/* Test versions first */
-	if (sbi->max_proto < AUTOFS_MIN_PROTO_VERSION ||
-	    sbi->min_proto > AUTOFS_MAX_PROTO_VERSION) {
-		pr_err("kernel does not match daemon version "
-		       "daemon (%d, %d) kernel (%d, %d)\n",
-		       sbi->min_proto, sbi->max_proto,
-		       AUTOFS_MIN_PROTO_VERSION, AUTOFS_MAX_PROTO_VERSION);
+	if (autofs_validate_protocol(sbi))
 		goto fail_dput;
-	}
-
-	/* Establish highest kernel protocol version */
-	if (sbi->max_proto > AUTOFS_MAX_PROTO_VERSION)
-		sbi->version = AUTOFS_MAX_PROTO_VERSION;
-	else
-		sbi->version = sbi->max_proto;
-	sbi->sub_version = AUTOFS_PROTO_SUBVERSION;
 
 	if (pgrp_set) {
 		sbi->oz_pgrp = find_get_pid(pgrp);