Messages in this thread | | | From | David Howells <> | Subject | Re: [PATCH] cifs: Fix reacquisition of volume cookie on still-live connection | Date | Wed, 17 Apr 2024 14:41:50 +0100 |
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Paulo Alcantara <pc@manguebit.com> wrote:
> > [!] 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. > > Agreed.
Looking over the code again, I'm not sure whether is actually necessary - or whether it is necessary and will be a bit nasty to implement as it will require read locking also.
Firstly, reset_cifs_unix_caps() seems to re-set tcon->fsUnixInfo.Capability and tcon->unix_ext, which it would presumably set to the same things - which is probably fine.
However, cifs_qfs_tcon() makes RPC operations that reloads tcon->fsDevInfo and tcon->fsAttrInfo - both of which may be being accessed without locks.
smb2_qfs_tcon() and smb3_qfs_tcon() alters everything cifs_qfs_tcon() does, plus a bunch of extra tcon members. Can this locally cached information change over time on the server whilst we have a connection to it?
David
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