linux-ext4 - [PATCH v2 5/8] ext4: Set the case-insensitive dentry operations through ->s_d

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Message-ID: <20231215211608.6449-6-krisman@suse.de>
Date: Fri, 15 Dec 2023 16:16:05 -0500
From: Gabriel Krisman Bertazi <krisman@...e.de>
To: viro@...iv.linux.org.uk,
	ebiggers@...nel.org,
	jaegeuk@...nel.org,
	tytso@....edu
Cc: linux-f2fs-devel@...ts.sourceforge.net,
	linux-ext4@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	Gabriel Krisman Bertazi <krisman@...e.de>
Subject: [PATCH v2 5/8] ext4: Set the case-insensitive dentry operations through ->s_d_op

All dentries in a case-insensitive filesystem have the same set of
dentry operations.  Therefore, we should let VFS propagate them from
sb->s_d_op d_alloc instead of setting at lookup time.

This was already the case before commit bb9cd9106b22 ("fscrypt: Have
filesystems handle their d_ops"), but it was changed to set at
lookup-time to facilitate the integration with fscrypt.  But it's a
problem because dentries that don't get created through ->lookup() won't
have any visibility of the operations.  Let's revert to the previous
implementation.

Suggested-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Gabriel Krisman Bertazi <krisman@...e.de>

---
changes since v1:
  - Fix CONFIG_UNICODE=n build (lkp)
---
 fs/ext4/namei.c | 6 +++++-
 fs/ext4/super.c | 5 +++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index d252935f9c8a..463e73fb5bf0 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1762,7 +1762,11 @@ static struct buffer_head *ext4_lookup_entry(struct inode *dir,
 	struct buffer_head *bh;
 
 	err = ext4_fname_prepare_lookup(dir, dentry, &fname);
-	generic_set_encrypted_ci_d_ops(dentry);
+
+	/* Case-insensitive volumes set dentry ops through sb->s_d_op. */
+	if (!dir->i_sb->s_d_op)
+		generic_set_encrypted_ci_d_ops(dentry);
+
 	if (err == -ENOENT)
 		return NULL;
 	if (err)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index c5fcf377ab1f..e0680d0641aa 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -5493,6 +5493,11 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
 		goto failed_mount4;
 	}
 
+#if IS_ENABLED(CONFIG_UNICODE)
+	if (sb->s_encoding)
+		sb->s_d_op = &generic_ci_dentry_ops;
+#endif
+
 	sb->s_root = d_make_root(root);
 	if (!sb->s_root) {
 		ext4_msg(sb, KERN_ERR, "get root dentry failed");
-- 
2.43.0