On Sun, Jun 13, 2021 at 12:16 PM Trond Myklebust
<trondmy@xxxxxxxxxxxxxxx> wrote:
>
> On Thu, 2021-06-03 at 18:59 -0400, Olga Kornievskaia wrote:
> > From: Olga Kornievskaia <kolga@xxxxxxxxxx>
> >
> > Using sysfs's xprt_state attribute, mark a particular transport
> > offline.
> > It will not be picked during the round-robin selection. It's not
> > allowed
> > to take the main (1st created transport associated with the
> > rpc_client)
> > offline.
> >
> > Signed-off-by: Olga Kornievskaia <kolga@xxxxxxxxxx>
> > ---
> > include/linux/sunrpc/xprt.h | 2 ++
> > net/sunrpc/clnt.c | 1 +
> > net/sunrpc/sysfs.c | 42 +++++++++++++++++++++++++++++++++--
> > --
> > net/sunrpc/xprtmultipath.c | 3 ++-
> > 4 files changed, 43 insertions(+), 5 deletions(-)
> >
> > diff --git a/include/linux/sunrpc/xprt.h
> > b/include/linux/sunrpc/xprt.h
> > index 13a4eaf385cf..72a858f032c7 100644
> > --- a/include/linux/sunrpc/xprt.h
> > +++ b/include/linux/sunrpc/xprt.h
> > @@ -293,6 +293,7 @@ struct rpc_xprt {
> > struct rcu_head rcu;
> > const struct xprt_class *xprt_class;
> > struct rpc_sysfs_xprt *xprt_sysfs;
> > + bool main; /* marked if it's the 1st
> > transport */
> > };
> >
> > #if defined(CONFIG_SUNRPC_BACKCHANNEL)
> > @@ -426,6 +427,7 @@
> > void xprt_release_write(struct rpc_xprt *,
> > struct rpc_task *);
> > #define XPRT_BOUND (4)
> > #define XPRT_BINDING (5)
> > #define XPRT_CLOSING (6)
> > +#define XPRT_OFFLINE (7)
> > #define XPRT_CONGESTED (9)
> > #define XPRT_CWND_WAIT (10)
> > #define XPRT_WRITE_SPACE (11)
> > diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
> > index 9bf820bad84c..408618765aa5 100644
> > --- a/net/sunrpc/clnt.c
> > +++ b/net/sunrpc/clnt.c
> > @@ -412,6 +412,7 @@ static struct rpc_clnt * rpc_new_client(const
> > struct rpc_create_args *args,
> > }
> >
> > rpc_clnt_set_transport(clnt, xprt, timeout);
> > + xprt->main = true;
> > xprt_iter_init(&clnt->cl_xpi, xps);
> > xprt_switch_put(xps);
> >
> > diff --git a/net/sunrpc/sysfs.c b/net/sunrpc/sysfs.c
> > index ec06c9257c07..02c918c5061b 100644
> > --- a/net/sunrpc/sysfs.c
> > +++ b/net/sunrpc/sysfs.c
> > @@ -118,7 +118,7 @@ static ssize_t rpc_sysfs_xprt_state_show(struct
> > kobject *kobj,
> > struct rpc_xprt *xprt = rpc_sysfs_xprt_kobj_get_xprt(kobj);
> > ssize_t ret;
> > int locked, connected, connecting, close_wait, bound,
> > binding,
> > - closing, congested, cwnd_wait, write_space;
> > + closing, congested, cwnd_wait, write_space, offline;
> >
> > if (!xprt)
> > return 0;
> > @@ -136,8 +136,9 @@ static ssize_t rpc_sysfs_xprt_state_show(struct
> > kobject *kobj,
> > congested = test_bit(XPRT_CONGESTED, &xprt->state);
> > cwnd_wait = test_bit(XPRT_CWND_WAIT, &xprt->state);
> > write_space = test_bit(XPRT_WRITE_SPACE, &xprt-
> > >state);
> > + offline = test_bit(XPRT_OFFLINE, &xprt->state);
> >
> > - ret = sprintf(buf, "state=%s %s %s %s %s %s %s %s %s
> > %s\n",
> > + ret = sprintf(buf, "state=%s %s %s %s %s %s %s %s %s
> > %s %s\n",
> > locked ? "LOCKED" : "",
> > connected ? "CONNECTED" : "",
> > connecting ? "CONNECTING" : "",
> > @@ -147,7 +148,8 @@ static ssize_t rpc_sysfs_xprt_state_show(struct
> > kobject *kobj,
> > closing ? "CLOSING" : "",
> > congested ? "CONGESTED" : "",
> > cwnd_wait ? "CWND_WAIT" : "",
> > - write_space ? "WRITE_SPACE" : "");
> > + write_space ? "WRITE_SPACE" : "",
> > + offline ? "OFFLINE" : "");
> > }
> >
> > xprt_put(xprt);
> > @@ -223,6 +225,38 @@ static ssize_t
> > rpc_sysfs_xprt_dstaddr_store(struct kobject *kobj,
> > goto out;
> > }
> >
> > +static ssize_t rpc_sysfs_xprt_state_change(struct kobject *kobj,
> > + struct kobj_attribute
> > *attr,
> > + const char *buf, size_t
> > count)
> > +{
> > + struct rpc_xprt *xprt = rpc_sysfs_xprt_kobj_get_xprt(kobj);
> > + int offline = 0;
> > +
> > + if (!xprt)
> > + return 0;
> > +
> > + if (!strncmp(buf, "offline", 7))
> > + offline = 1;
> > + else
> > + return -EINVAL;
> > +
> > + if (wait_on_bit_lock(&xprt->state, XPRT_LOCKED,
> > TASK_KILLABLE)) {
> > + count = -EINTR;
> > + goto out_put;
> > + }
> > + if (offline) {
> > + if (xprt->main)
> > + count = -EINVAL;
> > + else
> > + set_bit(XPRT_OFFLINE, &xprt->state);
> > + }
>
> Is there any way to put the transport back online? What say the problem
> with the downed IP address gets fixed?
I will add this in v2. Originally the thought was that offlining a
transport was just a middle step before removing it and not something
in its own right. I would like to know if it's appropriate to also
then decrement the xps_nactive counter when the xprt is offline?
>
> > +
> > + xprt_release_write(xprt, NULL);
> > +out_put:
> > + xprt_put(xprt);
> > + return count;
> > +}
> > +
> > int rpc_sysfs_init(void)
> > {
> > rpc_sunrpc_kset = kset_create_and_add("sunrpc", NULL,
> > kernel_kobj);
> > @@ -293,7 +327,7 @@ static struct kobj_attribute rpc_sysfs_xprt_info
> > = __ATTR(xprt_info,
> > 0444, rpc_sysfs_xprt_info_show, NULL);
> >
> > static struct kobj_attribute rpc_sysfs_xprt_change_state =
> > __ATTR(xprt_state,
> > - 0644, rpc_sysfs_xprt_state_show, NULL);
> > + 0644, rpc_sysfs_xprt_state_show,
> > rpc_sysfs_xprt_state_change);
> >
> > static struct attribute *rpc_sysfs_xprt_attrs[] = {
> > &rpc_sysfs_xprt_dstaddr.attr,
> > diff --git a/net/sunrpc/xprtmultipath.c b/net/sunrpc/xprtmultipath.c
> > index 07e76ae1028a..39551b794b80 100644
> > --- a/net/sunrpc/xprtmultipath.c
> > +++ b/net/sunrpc/xprtmultipath.c
> > @@ -230,7 +230,8 @@ void xprt_iter_default_rewind(struct
> > rpc_xprt_iter *xpi)
> > static
> > bool xprt_is_active(const struct rpc_xprt *xprt)
> > {
> > - return kref_read(&xprt->kref) != 0;
> > + return (kref_read(&xprt->kref) != 0 &&
> > + !test_bit(XPRT_OFFLINE, &xprt->state));
> > }
> >
> > static
>
> --
> Trond Myklebust
> Linux NFS client maintainer, Hammerspace
> trond.myklebust@xxxxxxxxxxxxxxx
>
>
