linux-kernel - [PATCH v4 05/10] libfs: Check for casefold dirs on simple

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Message-ID: <20240911144502.115260-6-andrealmeid@igalia.com>
Date: Wed, 11 Sep 2024 11:44:57 -0300
From: André Almeida <andrealmeid@...lia.com>
To: Hugh Dickins <hughd@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>,
	Jan Kara <jack@...e.cz>,
	krisman@...nel.org
Cc: linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	kernel-dev@...lia.com,
	Daniel Rosenberg <drosen@...gle.com>,
	smcv@...labora.com,
	Christoph Hellwig <hch@....de>,
	Theodore Ts'o <tytso@....edu>,
	André Almeida <andrealmeid@...lia.com>
Subject: [PATCH v4 05/10] libfs: Check for casefold dirs on simple_lookup()

On simple_lookup(), do not create dentries for casefold directories.
Currently, VFS does not support case-insensitive negative dentries and
can create inconsistencies in the filesystem. Prevent such dentries to
being created in the first place.

Signed-off-by: André Almeida <andrealmeid@...lia.com>
---
 fs/libfs.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/libfs.c b/fs/libfs.c
index 99fb36b48708..838524314b1b 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -77,6 +77,10 @@ struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned
 		return ERR_PTR(-ENAMETOOLONG);
 	if (!dentry->d_sb->s_d_op)
 		d_set_d_op(dentry, &simple_dentry_operations);
+
+	if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
+		return NULL;
+
 	d_add(dentry, NULL);
 	return NULL;
 }
-- 
2.46.0