From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 399B31FBC8C; Sat, 25 Oct 2025 02:50:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.3 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761360611; cv=none; b=VNEOb6Y44FHaGaAx0I11VgT3/FTKDjPeQYd+6zj74OVZviMBJiJXe7HLZRLQmvjaGlnIpXab9b1OUKjBu+4oVO0MveIwyaFfaGwDJPGXEm0pcBi0TzAAYIWBNdJVYJAKIkH8s8QPNYeWNKntrmVozsuoa/IfAz1qpBUQ6iTkwbU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761360611; c=relaxed/simple; bh=IthRKqaXYla/GIkqCMwx+59tGaJNkOv0wDQqAyF/piY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=hcDXG94TVKTMH6YaWLqGc4egR25p2qCNurGZhcKU1efhStjFToAzh0GMw/jP/CqY5mkHgmhU/3m9zZajKAhHE4NFmVrkqrwgPScrs6OWrPVYZhYrEslHGyeEgLDFU9cQa6DsvNc9hOP5ya2MrvWzCc3kuCMMq2GAmbUwYcRZp3c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=ZvtftmRN; arc=none smtp.client-ip=220.197.31.3 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="ZvtftmRN" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=/J 5o70XA/obLpt91BZcECXr4vrBe6G5ePfm/spl+71w=; b=ZvtftmRN5u2bWYrP/X zrSrAm1511uFYWF160nmSoEQFnyWfno5HgsC9OcWlxHevIFXGEPDk5QqUYdHNExr X96T6PF2GDhGD5ZcpVTfnaG5OFWyArVBNnh8Fteqyi6qOKEn2QQaWOsY0zWVS0Hv O1XyquM2og7/5taDm94IpbMpE= Received: from MS-CMFLBWVCLQRG.localdomain (unknown []) by gzga-smtp-mtada-g0-1 (Coremail) with SMTP id _____wD3HzzAOvxoLsBsCg--.59453S2; Sat, 25 Oct 2025 10:49:38 +0800 (CST) From: GuangFei Luo To: viro@zeniv.linux.org.uk Cc: brauner@kernel.org, jack@suse.cz, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, GuangFei Luo , stable@vger.kernel.org Subject: [PATCH] mount: fix duplicate mounts using the new mount API Date: Sat, 25 Oct 2025 10:49:34 +0800 Message-ID: <20251025024934.1350492-1-luogf2025@163.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:_____wD3HzzAOvxoLsBsCg--.59453S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7Zr1UKFy8Zw45GFWxGF4xXrb_yoW8XF1xpF 1FyF9xGrn3Gr43Xw4xZFZ5KrW3Ars5Z3Z0gF15uw1YyryIgF93Xas29F4SvF4UtFWUWF9r ZF4xtr17C3sFgF7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0p_9a9rUUUUU= X-CM-SenderInfo: poxrwwisqskqqrwthudrp/1tbizQrxmWj8MyhzWgAAsJ When using the new mount API, invoking the same mount command multiple times such as: mount /dev/mapper/mydevice /mnt/mydisk2 results in multiple identical mount entries being created: /dev/mapper/mydevice on /mnt/mydisk2 type ext4 (rw,relatime) /dev/mapper/mydevice on /mnt/mydisk2 type ext4 (rw,relatime) /dev/mapper/mydevice on /mnt/mydisk2 type ext4 (rw,relatime) ... Fixes: 2db154b3ea8e ("vfs: syscall: Add move_mount(2) to move mounts around") Signed-off-by: GuangFei Luo Cc: # 5.2+ --- fs/namespace.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/fs/namespace.c b/fs/namespace.c index d82910f33dc4..9436471955ce 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -4427,6 +4427,7 @@ SYSCALL_DEFINE5(move_mount, { struct path to_path __free(path_put) = {}; struct path from_path __free(path_put) = {}; + struct path path __free(path_put) = {}; struct filename *to_name __free(putname) = NULL; struct filename *from_name __free(putname) = NULL; unsigned int lflags, uflags; @@ -4472,6 +4473,14 @@ SYSCALL_DEFINE5(move_mount, return ret; } + ret = user_path_at(AT_FDCWD, to_pathname, LOOKUP_FOLLOW, &path); + if (ret) + return ret; + + /* Refuse the same filesystem on the same mount point */ + if (path.mnt->mnt_sb == to_path.mnt->mnt_sb && path_mounted(&path)) + return -EBUSY; + uflags = 0; if (flags & MOVE_MOUNT_F_EMPTY_PATH) uflags = AT_EMPTY_PATH; -- 2.43.0