linux-kernel - [PATCH v4 6/9] ovl: Set case-insensitive dentry operations for ovl sb

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Message-Id: <20250813-tonyk-overlayfs-v4-6-357ccf2e12ad@igalia.com>
Date: Wed, 13 Aug 2025 19:36:42 -0300
From: André Almeida <andrealmeid@...lia.com>
To: Miklos Szeredi <miklos@...redi.hu>, Amir Goldstein <amir73il@...il.com>, 
 Theodore Tso <tytso@....edu>, Gabriel Krisman Bertazi <krisman@...nel.org>
Cc: linux-unionfs@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-fsdevel@...r.kernel.org, Alexander Viro <viro@...iv.linux.org.uk>, 
 Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, 
 kernel-dev@...lia.com, 
 André Almeida <andrealmeid@...lia.com>
Subject: [PATCH v4 6/9] ovl: Set case-insensitive dentry operations for ovl
 sb

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@...lia.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