updated patch (had minor merge conflict) and added the two reviewed-by
and tentatively merged into cifs-2.6.git
On Tue, Feb 2, 2021 at 3:37 PM Tom Talpey <tom@xxxxxxxxxx> wrote:
>
> Updated comment looks good!
>
> Reviewed-By: Tom Talpey <tom@xxxxxxxxxx>
>
> On 2/2/2021 2:55 PM, Pavel Shilovsky wrote:
> > Currently we try to guess if a compound request is going to succeed
> > waiting for credits or not based on the number of requests in flight.
> > This approach doesn't work correctly all the time because there may
> > be only one request in flight which is going to bring multiple credits
> > satisfying the compound request.
> >
> > Change the behavior to fail a request only if there are no requests
> > in flight at all and proceed waiting for credits otherwise.
> >
> > Cc: <stable@xxxxxxxxxxxxxxx> # 5.1+
> > Signed-off-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
> > ---
> > fs/cifs/transport.c | 18 +++++++++++++++---
> > 1 file changed, 15 insertions(+), 3 deletions(-)
> >
> > diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
> > index 4ffbf8f965814..eab7940bfebef 100644
> > --- a/fs/cifs/transport.c
> > +++ b/fs/cifs/transport.c
> > @@ -659,10 +659,22 @@ wait_for_compound_request(struct TCP_Server_Info *server, int num,
> > spin_lock(&server->req_lock);
> > if (*credits < num) {
> > /*
> > - * Return immediately if not too many requests in flight since
> > - * we will likely be stuck on waiting for credits.
> > + * If the server is tight on resources or just gives us less
> > + * credits for other reasons (e.g. requests are coming out of
> > + * order and the server delays granting more credits until it
> > + * processes a missing mid) and we exhausted most available
> > + * credits there may be situations when we try to send
> > + * a compound request but we don't have enough credits. At this
> > + * point the client needs to decide if it should wait for
> > + * additional credits or fail the request. If at least one
> > + * request is in flight there is a high probability that the
> > + * server will return enough credits to satisfy this compound
> > + * request.
> > + *
> > + * Return immediately if no requests in flight since we will be
> > + * stuck on waiting for credits.
> > */
> > - if (server->in_flight < num - *credits) {
> > + if (server->in_flight == 0) {
> > spin_unlock(&server->req_lock);
> > return -ENOTSUPP;
> > }
> >
--
Thanks,
Steve
