1 files changed, 32 insertions, 4 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index caa8e8879f4b..540004970ad5 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1192,6 +1192,8 @@ static inline int ra_has_index(struct file_ra_state *ra, pgoff_t index)
  * @f_cred: stashed credentials of creator/opener
  * @f_owner: file owner
  * @f_path: path of the file
+ * @__f_path: writable alias for @f_path; *ONLY* for core VFS and only before
+ *   the file gets open
  * @f_pos_lock: lock protecting file position
  * @f_pipe: specific to pipes
  * @f_pos: file position
@@ -1217,7 +1219,10 @@ struct file {
 	const struct cred		*f_cred;
 	struct fown_struct		*f_owner;
 	/* --- cacheline 1 boundary (64 bytes) --- */
-	struct path			f_path;
+	union {
+		const struct path	f_path;
+		struct path		__f_path;
+	};
 	union {
 		/* regular files (with FMODE_ATOMIC_POS) and directories */
 		struct mutex		f_pos_lock;
@@ -2877,7 +2882,7 @@ struct file *dentry_open_nonotify(const struct path *path, int flags,
 				  const struct cred *cred);
 struct file *dentry_create(const struct path *path, int flags, umode_t mode,
 			   const struct cred *cred);
-struct path *backing_file_user_path(const struct file *f);
+const struct path *backing_file_user_path(const struct file *f);
 
 /*
  * When mmapping a file on a stackable filesystem (e.g., overlayfs), the file
@@ -3739,12 +3744,35 @@ static inline bool generic_ci_validate_strict_name(struct inode *dir,
 }
 #endif
 
+static inline struct unicode_map *sb_encoding(const struct super_block *sb)
+{
+#if IS_ENABLED(CONFIG_UNICODE)
+	return sb->s_encoding;
+#else
+	return NULL;
+#endif
+}
+
 static inline bool sb_has_encoding(const struct super_block *sb)
 {
+	return !!sb_encoding(sb);
+}
+
+/*
+ * Compare if two super blocks have the same encoding and flags
+ */
+static inline bool sb_same_encoding(const struct super_block *sb1,
+				    const struct super_block *sb2)
+{
 #if IS_ENABLED(CONFIG_UNICODE)
-	return !!sb->s_encoding;
+	if (sb1->s_encoding == sb2->s_encoding)
+		return true;
+
+	return (sb1->s_encoding && sb2->s_encoding &&
+	       (sb1->s_encoding->version == sb2->s_encoding->version) &&
+	       (sb1->s_encoding_flags == sb2->s_encoding_flags));
 #else
-	return false;
+	return true;
 #endif
 }