Merge tag 'ovl-update-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs

Pull overlayfs updates from Amir Goldstein:

 - Work by André Almeida to support case-insensitive overlayfs

   Underlying case-insensitive filesystems casefolding is per directory,
   but for overlayfs it is all-or-nothing. It supports layers where all
   directories are casefolded (with same encoding) or layers where no
   directories are casefolded.

 - A fix for a "bug" in Neil's ovl directory lock changes, which only
   manifested itself with casefold enabled layers which may return an
   unhashed negative dentry from lookup.

* tag 'ovl-update-6.18' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs:
  ovl: make sure that ovl_create_real() returns a hashed dentry
  ovl: Support mounting case-insensitive enabled layers
  ovl: Check for casefold consistency when creating new dentries
  ovl: Add S_CASEFOLD as part of the inode flag to be copied
  ovl: Set case-insensitive dentry operations for ovl sb
  ovl: Ensure that all layers have the same encoding
  ovl: Create ovl_casefold() to support casefolded strncmp()
  ovl: Prepare for mounting case-insensitive enabled layers
  fs: Create sb_same_encoding() helper
  fs: Create sb_encoding() helper

1 files changed, 25 insertions, 2 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index caa8e8879f4b..1f4a1c570a2a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3739,12 +3739,35 @@ 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
 }