Re: [PATCH] cifs: Make echo interval tunable.

[Sachin Prabhu <sprabhu-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On Wed, 2015-12-16 at 22:37 -0600, Steve French wrote:
> Why restrict the echo interval to such a narrow range?  If tunable
> might as well allow a larger range, maybe 1 to 600 (ten minutes)?  I
> am not certain of the range of possible future uses - maybe a
> pseudo-real type workload connected to a really fast server wants
> something really low (a few seconds?) and maybe very poor network
> connections want something longer?  Not a strong objection, but seems
> like we could allow a broader range without confusing the user.
> 
> Many years ago, Windows and OS/2 had an oplock break time (which also
> controlled how long to wait for acks to come back from the server) -
> and it ranged from 34 to 127 seconds for acks and 35 to 640 for
> oplock
> break timeouts.     Don't see any reason to limit it less than that
> (that was really old and networks vary a lot in performance now).
> 
> Thoughts?

the numbers I chose were arbitrary. I have no objections to changing
the min and max values. Do you want me to send a new patch with those
values?

Sachin Prabhu

> 
> On Mon, Dec 14, 2015 at 6:47 AM, Sachin Prabhu <sprabhu-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> wrote:
> > Currently the echo interval is set to 60 seconds using a macro.
> > This
> > setting determines the interval at which echo requests are sent to
> > the
> > server on an idling connection. This setting also affects the time
> > required for a connection to an unresponsive server to timeout.
> > 
> > Making this setting a tunable allows users to control the echo
> > interval
> > times as well as control the time after which the connecting to an
> > unresponsive server times out.
> > 
> > Signed-off-by: Sachin Prabhu <sprabhu-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> > ---
> >  fs/cifs/cifsfs.c   |  2 ++
> >  fs/cifs/cifsglob.h |  8 ++++++--
> >  fs/cifs/connect.c  | 33 +++++++++++++++++++++++++++------
> >  3 files changed, 35 insertions(+), 8 deletions(-)
> > 
> > diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> > index cbc0f4b..eab2de6 100644
> > --- a/fs/cifs/cifsfs.c
> > +++ b/fs/cifs/cifsfs.c
> > @@ -507,6 +507,8 @@ cifs_show_options(struct seq_file *s, struct
> > dentry *root)
> > 
> >         seq_printf(s, ",rsize=%u", cifs_sb->rsize);
> >         seq_printf(s, ",wsize=%u", cifs_sb->wsize);
> > +       seq_printf(s, ",echo_interval=%lu",
> > +                       tcon->ses->server->echo_interval / HZ);
> >         /* convert actimeo and display it in seconds */
> >         seq_printf(s, ",actimeo=%lu", cifs_sb->actimeo / HZ);
> > 
> > diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
> > index 2b510c5..56d3698 100644
> > --- a/fs/cifs/cifsglob.h
> > +++ b/fs/cifs/cifsglob.h
> > @@ -70,8 +70,10 @@
> >  #define SERVER_NAME_LENGTH 40
> >  #define SERVER_NAME_LEN_WITH_NULL     (SERVER_NAME_LENGTH + 1)
> > 
> > -/* SMB echo "timeout" -- FIXME: tunable? */
> > -#define SMB_ECHO_INTERVAL (60 * HZ)
> > +/* echo interval in seconds */
> > +#define SMB_ECHO_INTERVAL_MIN 10
> > +#define SMB_ECHO_INTERVAL_MAX 120
> > +#define SMB_ECHO_INTERVAL_DEFAULT 60
> > 
> >  #include "cifspdu.h"
> > 
> > @@ -507,6 +509,7 @@ struct smb_vol {
> >         struct sockaddr_storage dstaddr; /* destination address */
> >         struct sockaddr_storage srcaddr; /* allow binding to a
> > local IP */
> >         struct nls_table *local_nls;
> > +       unsigned int echo_interval; /* echo interval in secs */
> >  };
> > 
> >  #define CIFS_MOUNT_MASK (CIFS_MOUNT_NO_PERM | CIFS_MOUNT_SET_UID |
> > \
> > @@ -628,6 +631,7 @@ struct TCP_Server_Info {
> >         unsigned int    max_read;
> >         unsigned int    max_write;
> >  #endif /* CONFIG_CIFS_SMB2 */
> > +       unsigned long echo_interval;
> >  };
> > 
> >  static inline unsigned int
> > diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> > index ecb0803..3b44e9e 100644
> > --- a/fs/cifs/connect.c
> > +++ b/fs/cifs/connect.c
> > @@ -95,6 +95,7 @@ enum {
> >         Opt_cruid, Opt_gid, Opt_file_mode,
> >         Opt_dirmode, Opt_port,
> >         Opt_rsize, Opt_wsize, Opt_actimeo,
> > +       Opt_echo_interval,
> > 
> >         /* Mount options which take string value */
> >         Opt_user, Opt_pass, Opt_ip,
> > @@ -188,6 +189,7 @@ static const match_table_t
> > cifs_mount_option_tokens = {
> >         { Opt_rsize, "rsize=%s" },
> >         { Opt_wsize, "wsize=%s" },
> >         { Opt_actimeo, "actimeo=%s" },
> > +       { Opt_echo_interval, "echo_interval=%s" },
> > 
> >         { Opt_blank_user, "user=" },
> >         { Opt_blank_user, "username=" },
> > @@ -418,6 +420,7 @@ cifs_echo_request(struct work_struct *work)
> >         int rc;
> >         struct TCP_Server_Info *server = container_of(work,
> >                                         struct TCP_Server_Info,
> > echo.work);
> > +       unsigned long echo_interval = server->echo_interval;
> > 
> >         /*
> >          * We cannot send an echo if it is disabled or until the
> > @@ -427,7 +430,7 @@ cifs_echo_request(struct work_struct *work)
> >          */
> >         if (!server->ops->need_neg || server->ops->need_neg(server) 
> > ||
> >             (server->ops->can_echo && !server->ops-
> > >can_echo(server)) ||
> > -           time_before(jiffies, server->lstrp + SMB_ECHO_INTERVAL
> > - HZ))
> > +           time_before(jiffies, server->lstrp + echo_interval -
> > HZ))
> >                 goto requeue_echo;
> > 
> >         rc = server->ops->echo ? server->ops->echo(server) :
> > -ENOSYS;
> > @@ -436,7 +439,7 @@ cifs_echo_request(struct work_struct *work)
> >                          server->hostname);
> > 
> >  requeue_echo:
> > -       queue_delayed_work(cifsiod_wq, &server->echo,
> > SMB_ECHO_INTERVAL);
> > +       queue_delayed_work(cifsiod_wq, &server->echo,
> > echo_interval);
> >  }
> > 
> >  static bool
> > @@ -487,9 +490,9 @@ server_unresponsive(struct TCP_Server_Info
> > *server)
> >          *     a response in >60s.
> >          */
> >         if (server->tcpStatus == CifsGood &&
> > -           time_after(jiffies, server->lstrp + 2 *
> > SMB_ECHO_INTERVAL)) {
> > -               cifs_dbg(VFS, "Server %s has not responded in %d
> > seconds. Reconnecting...\n",
> > -                        server->hostname, (2 * SMB_ECHO_INTERVAL)
> > / HZ);
> > +           time_after(jiffies, server->lstrp + 2 * server-
> > >echo_interval)) {
> > +               cifs_dbg(VFS, "Server %s has not responded in %lu
> > seconds. Reconnecting...\n",
> > +                        server->hostname, (2 * server-
> > >echo_interval) / HZ);
> >                 cifs_reconnect(server);
> >                 wake_up(&server->response_q);
> >                 return true;
> > @@ -1624,6 +1627,14 @@ cifs_parse_mount_options(const char
> > *mountdata, const char *devname,
> >                                 goto cifs_parse_mount_err;
> >                         }
> >                         break;
> > +               case Opt_echo_interval:
> > +                       if (get_option_ul(args, &option)) {
> > +                               cifs_dbg(VFS, "%s: Invalid echo
> > interval value\n",
> > +                                        __func__);
> > +                               goto cifs_parse_mount_err;
> > +                       }
> > +                       vol->echo_interval = option;
> > +                       break;
> > 
> >                 /* String Arguments */
> > 
> > @@ -2089,6 +2100,9 @@ static int match_server(struct
> > TCP_Server_Info *server, struct smb_vol *vol)
> >         if (!match_security(server, vol))
> >                 return 0;
> > 
> > +       if (server->echo_interval != vol->echo_interval)
> > +               return 0;
> > +
> >         return 1;
> >  }
> > 
> > @@ -2208,6 +2222,13 @@ cifs_get_tcp_session(struct smb_vol
> > *volume_info)
> >         tcp_ses->tcpStatus = CifsNew;
> >         ++tcp_ses->srv_count;
> > 
> > +       /* echo interval should be between 10 and 120 secs */
> > +       if (volume_info->echo_interval > SMB_ECHO_INTERVAL_MIN ||
> > +               volume_info->echo_interval < SMB_ECHO_INTERVAL_MAX)
> > +               tcp_ses->echo_interval = volume_info->echo_interval 
> > * HZ;
> > +       else
> > +               tcp_ses->echo_interval = SMB_ECHO_INTERVAL_DEFAULT
> > * HZ;
> > +
> >         rc = ip_connect(tcp_ses);
> >         if (rc < 0) {
> >                 cifs_dbg(VFS, "Error connecting to socket. Aborting
> > operation.\n");
> > @@ -2237,7 +2258,7 @@ cifs_get_tcp_session(struct smb_vol
> > *volume_info)
> >         cifs_fscache_get_client_cookie(tcp_ses);
> > 
> >         /* queue echo request delayed work */
> > -       queue_delayed_work(cifsiod_wq, &tcp_ses->echo,
> > SMB_ECHO_INTERVAL);
> > +       queue_delayed_work(cifsiod_wq, &tcp_ses->echo, tcp_ses-
> > >echo_interval);
> > 
> >         return tcp_ses;
> > 
> > --
> > 2.4.3
> > 
> 
> 
>