linux-kernel - CIFS: Rename bug on servers not supporting inode numbers

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Date:	Thu, 3 Nov 2011 15:20:17 +0000
From:	Anton Altaparmakov <aia21@....ac.uk>
To:	Steve French <sfrench@...ba.org>
Cc:	linux-cifs@...r.kernel.org, samba-technical@...ts.samba.org,
	LKML <linux-kernel@...r.kernel.org>,
	Unix Support <unix-support@....cam.ac.uk>
Subject: CIFS: Rename bug on servers not supporting inode numbers

Hi,

Our CIFS server problems seem to have no end…  The Novell CIFS server does not support server inode numbers (when I try the mount option I get the message it is being turned off as server does not support it) and thus each inode gets a different number each time it is accessed and it gets a different number again for each readdir call.

The fun happens with rename() when the rename source and target only differ in case, e.g.

	touch foo
	mv foo Foo

The result?  Because of the difference in inode numbers, the request gets through to the CIFS module which promptly does:

	cifs_unlink(target_dir, target_dentry)
	rc = cifs_do_rename(…)

And because the cifs_unlink() just removed the source of the rename (as it is the same as the target), "rc" comes back as -ENOENT.

And indeed the file is gone so we just lost the user's file for ever.  )-:

We are tossing around ideas how to fix this but we would be interested in your input as to what you think the fix should be.

In any case this probably should be fixed in the standard kernel CIFS module, too, and not just for us locally as this presumably affects anyone who is using the CIFS module against case-insensitive, non-server-inode-number-supporting CIFS servers...

Best regards,

	Anton
-- 
Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)
Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK
Linux NTFS maintainer, http://www.linux-ntfs.org/

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