linux-stable/fs/smb
David Howells dad80c6bff cifs: Fix reacquisition of volume cookie on still-live connection
During mount, cifs_mount_get_tcon() gets a tcon resource connection record
and then attaches an fscache volume cookie to it.  However, it does this
irrespective of whether or not the tcon returned from cifs_get_tcon() is a
new record or one that's already in use.  This leads to a warning about a
volume cookie collision and a leaked volume cookie because tcon->fscache
gets reset.

Fix this be adding a mutex and a "we've already tried this" flag and only
doing it once for the lifetime of the tcon.

[!] Note: Looking at cifs_mount_get_tcon(), a more general solution may
actually be required.  Reacquiring the volume cookie isn't the only thing
that function does: it also partially reinitialises the tcon record without
any locking - which may cause live filesystem ops already using the tcon
through a previous mount to malfunction.

This can be reproduced simply by something like:

    mount //example.com/test /xfstest.test -o user=shares,pass=xxx,fsc
    mount //example.com/test /mnt -o user=shares,pass=xxx,fsc

Fixes: 70431bfd82 ("cifs: Support fscache indexing rewrite")
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
cc: Shyam Prasad N <sprasad@microsoft.com>
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
2024-04-19 15:37:47 -05:00
..
client cifs: Fix reacquisition of volume cookie on still-live connection 2024-04-19 15:37:47 -05:00
common smb311: additional compression flag defined in updated protocol spec 2024-03-20 11:49:44 -05:00
server ksmbd: do not set SMB2_GLOBAL_CAP_ENCRYPTION for SMB 3.1.1 2024-04-02 09:21:25 -05:00
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