For filesystems with encoding (i.e. with case-insensitive support), set
the dentry operations for the super block as ovl_dentry_ci_operations.

Signed-off-by: André Almeida <andrealmeid@igalia.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
---
Changes from v3:
- new helper ovl_set_d_op()
- encoding flags are now set in a step earlier

Changes from v2:
- Create ovl_dentry_ci_operations to not override dentry ops set by
  ovl_dentry_operations
- Create a new function for this
- Instead of setting encoding just when there's a upper layer, set it
  for any first layer (ofs->fs[0].sb), regardless of it being upper or
  not.
---
 fs/overlayfs/super.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index b1dbd3c79961094d00c7f99cc622e515d544d22f..a99c77802efa1a6d96c43019728d3517fccdc16a 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -161,6 +161,16 @@ static const struct dentry_operations ovl_dentry_operations = {
 	.d_weak_revalidate = ovl_dentry_weak_revalidate,
 };
 
+#if IS_ENABLED(CONFIG_UNICODE)
+static const struct dentry_operations ovl_dentry_ci_operations = {
+	.d_real = ovl_d_real,
+	.d_revalidate = ovl_dentry_revalidate,
+	.d_weak_revalidate = ovl_dentry_weak_revalidate,
+	.d_hash = generic_ci_d_hash,
+	.d_compare = generic_ci_d_compare,
+};
+#endif
+
 static struct kmem_cache *ovl_inode_cachep;
 
 static struct inode *ovl_alloc_inode(struct super_block *sb)
@@ -1332,6 +1342,19 @@ static struct dentry *ovl_get_root(struct super_block *sb,
 	return root;
 }
 
+static void ovl_set_d_op(struct super_block *sb)
+{
+	struct ovl_fs *ofs = sb->s_fs_info;
+
+#if IS_ENABLED(CONFIG_UNICODE)
+	if (ofs->casefold) {
+		set_default_d_op(sb, &ovl_dentry_ci_operations);
+		return;
+	}
+#endif
+	set_default_d_op(sb, &ovl_dentry_operations);
+}
+
 int ovl_fill_super(struct super_block *sb, struct fs_context *fc)
 {
 	struct ovl_fs *ofs = sb->s_fs_info;
@@ -1443,6 +1466,8 @@ int ovl_fill_super(struct super_block *sb, struct fs_context *fc)
 	if (IS_ERR(oe))
 		goto out_err;
 
+	ovl_set_d_op(sb);
+
 	/* If the upper fs is nonexistent, we mark overlayfs r/o too */
 	if (!ovl_upper_mnt(ofs))
 		sb->s_flags |= SB_RDONLY;

-- 
2.50.1

Hi André,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 0cc53520e68bea7fb80fdc6bdf8d226d1b6a98d9]

url:    https://github.com/intel-lab-lkp/linux/commits/Andr-Almeida/fs-Create-sb_encoding-helper/20250815-013213
base:   0cc53520e68bea7fb80fdc6bdf8d226d1b6a98d9
patch link:    https://lore.kernel.org/r/20250814-tonyk-overlayfs-v5-6-c5b80a909cbd%40igalia.com
patch subject: [PATCH v5 6/9] ovl: Set case-insensitive dentry operations for ovl sb
config: i386-buildonly-randconfig-003-20250815 (https://download.01.org/0day-ci/archive/20250815/202508151941.VDMlemUG-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250815/202508151941.VDMlemUG-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202508151941.VDMlemUG-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> fs/overlayfs/super.c:1347:17: warning: unused variable 'ofs' [-Wunused-variable]
    1347 |         struct ovl_fs *ofs = sb->s_fs_info;
         |                        ^~~
   1 warning generated.


vim +/ofs +1347 fs/overlayfs/super.c

  1344	
  1345	static void ovl_set_d_op(struct super_block *sb)
  1346	{
> 1347		struct ovl_fs *ofs = sb->s_fs_info;
  1348	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki