Re: [PATCH] cifs: fix credits leak for SMB1 oplock breaks

[ronnie sahlberg <ronniesahlberg@gmail.com>]

On Sat, Apr 27, 2019 at 2:38 AM Pavel Shilovsky <piastryyy@gmail.com> wrote:
>
> чт, 25 апр. 2019 г. в 18:43, Ronnie Sahlberg <lsahlber@redhat.com>:
> >
> > Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
> > ---
> >  fs/cifs/cifsglob.h  |  1 +
> >  fs/cifs/cifssmb.c   |  2 +-
> >  fs/cifs/transport.c | 10 +++++-----
> >  3 files changed, 7 insertions(+), 6 deletions(-)
> >
> > diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
> > index 621640195713..7a65124f70f9 100644
> > --- a/fs/cifs/cifsglob.h
> > +++ b/fs/cifs/cifsglob.h
> > @@ -1701,6 +1701,7 @@ static inline bool is_retryable_error(int error)
> >
> >  #define   CIFS_HAS_CREDITS 0x0400    /* already has credits */
> >  #define   CIFS_TRANSFORM_REQ 0x0800    /* transform request before sending */
> > +#define   CIFS_NO_SRV_RSP    0x1000    /* there is no server response */
> >
> >  /* Security Flags: indicate type of session setup needed */
> >  #define   CIFSSEC_MAY_SIGN     0x00001
> > diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
> > index f43747c062a7..6050851edcb8 100644
> > --- a/fs/cifs/cifssmb.c
> > +++ b/fs/cifs/cifssmb.c
> > @@ -2540,7 +2540,7 @@ CIFSSMBLock(const unsigned int xid, struct cifs_tcon *tcon,
> >
> >         if (lockType == LOCKING_ANDX_OPLOCK_RELEASE) {
> >                 /* no response expected */
> > -               flags = CIFS_ASYNC_OP | CIFS_OBREAK_OP;
> > +               flags = CIFS_NO_SRV_RSP | CIFS_ASYNC_OP | CIFS_OBREAK_OP;
> >                 pSMB->Timeout = 0;
> >         } else if (waitFlag) {
> >                 flags = CIFS_BLOCKING_OP; /* blocking operation, no timeout */
> > diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
> > index 5c59c498f56a..5573e38b13f3 100644
> > --- a/fs/cifs/transport.c
> > +++ b/fs/cifs/transport.c
> > @@ -1073,8 +1073,11 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
> >
> >         mutex_unlock(&ses->server->srv_mutex);
> >
> > -       if (rc < 0) {
> > -               /* Sending failed for some reason - return credits back */
> > +       /*
> > +        * If sending failed for some reason or it is an oplock break that we
>
> probably indicate that it is SMB1 oplock break?
>
> > +        * will not receive a response to - return credits back
> > +        */
> > +       if (rc < 0 || (flags & CIFS_NO_SRV_RSP)) {
> >                 for (i = 0; i < num_rqst; i++)
> >                         add_credits(ses->server, &credits[i], optype);
>
> A no-op callback is still needed to be set here or above for
> CIFS_NO_SRV_RSP requests. Otherwise we may end up adding credits
> twice: here and in the demultiplex thread.

I don't think we need one. Since there will never be a reply we will
never invoke the callback from the demultiplex thread.


>
> >                 goto out;
> > @@ -1095,9 +1098,6 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
> >                 smb311_update_preauth_hash(ses, rqst[0].rq_iov,
> >                                            rqst[0].rq_nvec);
> >
> > -       if ((flags & CIFS_TIMEOUT_MASK) == CIFS_ASYNC_OP)
> > -               goto out;
> > -
> >         for (i = 0; i < num_rqst; i++) {
> >                 rc = wait_for_response(ses->server, midQ[i]);
> >                 if (rc != 0)
> > --
> > 2.13.6
> >
>
>
> --
> Best regards,
> Pavel Shilovsky