ext4: journal_path mount options should follow links

Before the commit 461c3af045 ("ext4: Change handle_mount_opt() to use
fs_parameter") ext4 mount option journal_path did follow links in the
provided path.

Bring this behavior back by allowing to pass pathwalk flags to
fs_lookup_param().

Fixes: 461c3af045 ("ext4: Change handle_mount_opt() to use fs_parameter")
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20221004135803.32283-1-lczerner@redhat.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org

Documentation/filesystems/mount_api.rst

@@ -814,6 +814,7 @@ process the parameters it is given.
        int fs_lookup_param(struct fs_context *fc,
 			   struct fs_parameter *value,
 			   bool want_bdev,
+			   unsigned int flags,
 			   struct path *_path);
 
      This takes a parameter that carries a string or filename type and attempts

fs/ext4/super.c

@@ -2247,7 +2247,7 @@ static int ext4_parse_param(struct fs_context *fc, struct fs_parameter *param)
 			return -EINVAL;
 		}
 
-		error = fs_lookup_param(fc, param, 1, &path);
+		error = fs_lookup_param(fc, param, 1, LOOKUP_FOLLOW, &path);
 		if (error) {
 			ext4_msg(NULL, KERN_ERR, "error: could not find "
 				 "journal device path");

fs/fs_parser.c

@@ -138,15 +138,16 @@ EXPORT_SYMBOL(__fs_parse);
  * @fc: The filesystem context to log errors through.
  * @param: The parameter.
  * @want_bdev: T if want a blockdev
+ * @flags: Pathwalk flags passed to filename_lookup()
  * @_path: The result of the lookup
  */
 int fs_lookup_param(struct fs_context *fc,
 		    struct fs_parameter *param,
 		    bool want_bdev,
+		    unsigned int flags,
 		    struct path *_path)
 {
 	struct filename *f;
-	unsigned int flags = 0;
 	bool put_f;
 	int ret;
 

include/linux/fs_parser.h

@@ -76,6 +76,7 @@ static inline int fs_parse(struct fs_context *fc,
 extern int fs_lookup_param(struct fs_context *fc,
 			   struct fs_parameter *param,
 			   bool want_bdev,
+			   unsigned int flags,
 			   struct path *_path);
 
 extern int lookup_constant(const struct constant_table tbl[], const char *name, int not_found);