Re: [bug report] Inconsistent state with CIFS mount after interrupted process in Linux 5.10

[Steve French <smfrench@gmail.com>]

Pavel's explanation looks plausible.


On Wed, Jan 13, 2021 at 10:31 AM Pavel Shilovsky <piastryyy@gmail.com> wrote:
>
> Thanks for reporting the issue.
>
> The problem is with the recent fix which changes the error code from
> -EINTR to -ERESTARTSYS:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/fs/cifs/transport.c?id=6988a619f5b79e4efadea6e19dcfe75fbcd350b5
>
> and this problem happens here:
>
> https://git.samba.org/sfrench/?p=sfrench/cifs-2.6.git;a=blob;f=fs/cifs/smb2pdu.c;h=067eb44c7baa863c1e7ccd2c2f599be0b067f320;hb=236237ab6de1cde004b0ab3e348fc530334270d5#l3251
>
> So, interrupted close commands don't get restarted by the client and
> the client leaks open handles on the server. The offending patch was
> tagged stable, so the fix seems quite urgent. The fix itself should be
> simple: replace -EINTR with -ERESTARTSYS in the IF condition or even
> amend it with "||".
>
> Adding Paulo and Steve to comment.
>
> --
> Best regards,
> Pavel Shilovsky
>
> ср, 13 янв. 2021 г. в 04:31, Aurélien Aptel <aaptel@suse.com>:
> >
> > Duncan Findlay <duncf@duncf.ca> writes:
> > > There seems to be a problem with the CIFS module in Linux 5.10. Files
> > > that are opened and not cleanly closed end up in an inconsistent
> > > state. This can be triggered by writing to a file and interrupting the
> > > writer with Ctrl-C. Once this happens, attempting to delete the file
> > > causes access to the mount to hang. Afterwards, the files are visible
> > > to ls, but cannot be accessed or deleted.
> > >
> > > I'm running Debian unstable with a Debian unstable kernel
> > > (5.10.5-1). I attempted to but could not reproduce this with a 4.19 kernel.
> > >
> > >
> > > Repro steps:
> > >
> > > $ sudo mount -t cifs //test/share /mnt/test --verbose -o
> > > rw,user,auto,nosuid,uid=user,gid=user,vers=3.1.1,credentials=/home/user/tmp/creds
> > > $ mkdir /mnt/test/subdir
> > > $ cat > /mnt/test/subdir/foo
> > > [ Hit Ctrl-C to interrupt ]
> > > $ ls /mnt/test/subdir/
> > > foo
> > > $ rm /mnt/test/subdir/foo
> > > [ Hangs for 35 seconds, errors in dmesg log -- see below ]
> > > $ ls /mnt/test/subdir/
> > > foo
> > > $ stat /mnt/test/subdir/foo
> > > stat: cannot statx '/mnt/test/subdir/foo': No such file or directory
> > >
> > > At this point, the file still exists on the server side, and
> > > restarting the server causes it to be deleted.
> > >
> > > I can provide pcaps if necessary. It looks like with 4.19, when the
> > > cat command is killed, the client sends a Close Request, and on 5.10
> > > no commands are sent.
> >
> > I can reproduce this on Steve's current for-next branch but only against
> > a Samba server.
> >
> > On Windows server, doing ^C kills cat properly but the output file is
> > never created, which is also a bug.
> >
> > Cheers,
> > --
> > Aurélien Aptel / SUSE Labs Samba Team
> > GPG: 1839 CB5F 9F5B FB9B AA97  8C99 03C8 A49B 521B D5D3
> > SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg, DE
> > GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 247165 (AG München)
> >



--
Thanks,

Steve