ext4: check ext2/3 compatibility outside handle_mount_opt()

At the parsing phase of mount in the new mount api sb will not be
available so move ext2/3 compatibility check outside handle_mount_opt().
Unfortunately we will lose the ability to show exactly which option is
not compatible.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Link: https://lore.kernel.org/r/20211027141857.33657-8-lczerner@redhat.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/super.c

@@ -89,8 +89,8 @@ static void ext4_clear_request_list(void);
 static struct inode *ext4_get_journal_inode(struct super_block *sb,
 					    unsigned int journal_inum);
 static int ext4_validate_options(struct fs_context *fc);
-static int ext4_check_quota_consistency(struct fs_context *fc,
-					struct super_block *sb);
+static int ext4_check_opt_consistency(struct fs_context *fc,
+				      struct super_block *sb);
 static void ext4_apply_quota_options(struct fs_context *fc,
 				     struct super_block *sb);
 
@@ -2199,6 +2199,7 @@ struct ext4_fs_context {
 	unsigned long	journal_devnum;
 	unsigned int	journal_ioprio;
 	int 		mb_optimize_scan;
+	unsigned int	opt_flags;	/* MOPT flags */
 };
 
 #ifdef CONFIG_QUOTA
@@ -2329,25 +2330,14 @@ static int handle_mount_opt(struct fs_context *fc, struct fs_parameter *param)
 		if (token == m->token)
 			break;
 
+	ctx->opt_flags |= m->flags;
+
 	if (m->token == Opt_err) {
 		ext4_msg(NULL, KERN_ERR, "Unrecognized mount option \"%s\" "
 			 "or missing value", param->key);
 		return -EINVAL;
 	}
 
-	if ((m->flags & MOPT_NO_EXT2) && IS_EXT2_SB(sb)) {
-		ext4_msg(NULL, KERN_ERR,
-			 "Mount option \"%s\" incompatible with ext2",
-			 param->key);
-		return -EINVAL;
-	}
-	if ((m->flags & MOPT_NO_EXT3) && IS_EXT3_SB(sb)) {
-		ext4_msg(NULL, KERN_ERR,
-			 "Mount option \"%s\" incompatible with ext3",
-			 param->key);
-		return -EINVAL;
-	}
-
 	if (m->flags & MOPT_EXPLICIT) {
 		if (m->mount_opt & EXT4_MOUNT_DELALLOC) {
 			set_opt2(sb, EXPLICIT_DELALLOC);
@@ -2630,7 +2620,7 @@ static int parse_options(char *options, struct super_block *sb,
 	if (ret < 0)
 		return 0;
 
-	ret = ext4_check_quota_consistency(&fc, sb);
+	ret = ext4_check_opt_consistency(&fc, sb);
 	if (ret < 0)
 		return 0;
 
@@ -2724,6 +2714,25 @@ static int ext4_check_quota_consistency(struct fs_context *fc,
 #endif
 }
 
+static int ext4_check_opt_consistency(struct fs_context *fc,
+				      struct super_block *sb)
+{
+	struct ext4_fs_context *ctx = fc->fs_private;
+
+	if ((ctx->opt_flags & MOPT_NO_EXT2) && IS_EXT2_SB(sb)) {
+		ext4_msg(NULL, KERN_ERR,
+			 "Mount option(s) incompatible with ext2");
+		return -EINVAL;
+	}
+	if ((ctx->opt_flags & MOPT_NO_EXT3) && IS_EXT3_SB(sb)) {
+		ext4_msg(NULL, KERN_ERR,
+			 "Mount option(s) incompatible with ext3");
+		return -EINVAL;
+	}
+
+	return ext4_check_quota_consistency(fc, sb);
+}
+
 static int ext4_validate_options(struct fs_context *fc)
 {
 	struct ext4_sb_info *sbi = fc->s_fs_info;