Ack On Tue, Oct 1, 2024 at 1:11 PM Liu Kui <kui....@virtuozzo.com> wrote: > > Currently krpc would report to userspace to be in work state immediately > after connect, even though kernel rpc may not be in work state. Userspace > will start sending msg immediately after connect while kernel is still > establishing the underlying connection. It's not uncommon that it may take > very long time for a connection to be fully established. When this happens, > userspace may abort the connection due to timeout. However krpc abort needs > to acquire rpc's mutex lock, which could have been held for connection > establishment, thus blocking the userspace evloop process. > > To avoid above problem, a proper krpc state transition on connect is > implemented here. It now blocks userspace from transiting to work state > on connect until the underlying kernel rpc transits to work state. > Userspace can abort the krpc connection without being blocked while kernel > rpc is still in establishment phrase. > > https://virtuozzo.atlassian.net/browse/VSTOR-93162 > > Signed-off-by: Liu Kui <kui....@virtuozzo.com> > --- > fs/fuse/kio/pcs/pcs_krpc.c | 63 ++++++++++++++++++++++++++++++++++---- > fs/fuse/kio/pcs/pcs_krpc.h | 7 +++++ > 2 files changed, 64 insertions(+), 6 deletions(-) > > diff --git a/fs/fuse/kio/pcs/pcs_krpc.c b/fs/fuse/kio/pcs/pcs_krpc.c > index 0ef33b730204..ee88bc17e6d9 100644 > --- a/fs/fuse/kio/pcs/pcs_krpc.c > +++ b/fs/fuse/kio/pcs/pcs_krpc.c > @@ -474,6 +474,8 @@ static int pcs_krpc_abort(struct pcs_krpc *krpc) > spin_lock(&krpc->lock); > > if (krpc->state != PCS_KRPC_STATE_CONNECTED) { > + if (krpc->state == PCS_KRPC_STATE_CONNECT) > + krpc->state = PCS_KRPC_STATE_UNCONN; > spin_unlock(&krpc->lock); > return 0; > } > @@ -723,6 +725,38 @@ int pcs_krpc_update_addr(struct pcs_krpc_set *krpcs, > PCS_NODE_ID_T *id, > > return 0; > } > + > +static void krpc_connect_done(struct pcs_msg *msg) > +{ > + struct krpc_connect_req *req = container_of(msg, struct > krpc_connect_req, msg); > + struct pcs_krpc *krpc = req->krpc; > + __poll_t pollflags = EPOLLHUP; > + > + if (msg->rpc) { > + pcs_rpc_put(msg->rpc); > + msg->rpc = NULL; > + } > + > + spin_lock(&krpc->lock); > + /* from a stale session, do nothing */ > + if (req->gen != krpc->gen || krpc->state != PCS_KRPC_STATE_CONNECT) { > + spin_unlock(&krpc->lock); > + goto out; > + } > + > + if (!pcs_if_error(&msg->error)) { > + krpc->state = PCS_KRPC_STATE_CONNECTED; > + pollflags = EPOLLOUT; > + } > + spin_unlock(&krpc->lock); > + > + wake_up_poll(&krpc->poll_wait, pollflags); > + > +out: > + pcs_krpc_put(krpc); > + kfree(req); > +} > + > /* > * Connect to a pcs_krpc, return a valid fd on success. > */ > @@ -732,6 +766,8 @@ int pcs_krpc_connect(struct pcs_krpc_set *krpcs, > PCS_NODE_ID_T *id) > int fd; > struct file *file; > struct pcs_krpc_context *ctx; > + struct krpc_connect_req *connect_req; > + struct pcs_msg *msg; > > krpc = pcs_krpc_lookup(krpcs, id); > if (!krpc) > @@ -741,18 +777,26 @@ int pcs_krpc_connect(struct pcs_krpc_set *krpcs, > PCS_NODE_ID_T *id) > krpc->state == PCS_KRPC_STATE_DESTROYED) > return -EPERM; > > + connect_req = kzalloc(sizeof(*connect_req), GFP_KERNEL); > + if (!connect_req) > + return -ENOMEM; > + > ctx = kmalloc(sizeof(*ctx), GFP_KERNEL); > - if (!ctx) > + if (!ctx) { > + kfree(connect_req); > return -ENOMEM; > + } > > fd = get_unused_fd_flags(O_CLOEXEC); > if (fd < 0) { > + kfree(connect_req); > kfree(ctx); > return fd; > } > > file = anon_inode_getfile("[pcs_krpc]", &pcs_krpc_fops, ctx, 0); > if (IS_ERR(file)) { > + kfree(connect_req); > kfree(ctx); > put_unused_fd(fd); > fd = PTR_ERR(file); > @@ -764,13 +808,20 @@ int pcs_krpc_connect(struct pcs_krpc_set *krpcs, > PCS_NODE_ID_T *id) > spin_lock(&krpc->lock); > ctx->gen = ++krpc->gen; > ctx->krpc = pcs_krpc_get(krpc); > - /* > - * the krpc should always be connected regardless state of > - * underlying RPC > - */ > - krpc->state = PCS_KRPC_STATE_CONNECTED; > + connect_req->gen = krpc->gen; > + connect_req->krpc = pcs_krpc_get(krpc); > + krpc->state = PCS_KRPC_STATE_CONNECT; > spin_unlock(&krpc->lock); > > + /* Send a zero-size msg which should be completed after the rpc > enters work state */ > + msg = &connect_req->msg; > + msg->size = 0; > + msg->timeout = 0; > + msg->rpc = NULL; > + msg->done = krpc_connect_done; > + pcs_clear_error(&msg->error); > + pcs_rpc_queue(krpc->rpc, msg); > + > return fd; > } > > diff --git a/fs/fuse/kio/pcs/pcs_krpc.h b/fs/fuse/kio/pcs/pcs_krpc.h > index 8100dfb2629d..db13b71f6357 100644 > --- a/fs/fuse/kio/pcs/pcs_krpc.h > +++ b/fs/fuse/kio/pcs/pcs_krpc.h > @@ -37,11 +37,18 @@ struct pcs_krpc_set { > > enum { > PCS_KRPC_STATE_UNCONN, > + PCS_KRPC_STATE_CONNECT, > PCS_KRPC_STATE_CONNECTED, > PCS_KRPC_STATE_ABORTED, > PCS_KRPC_STATE_DESTROYED, > }; > > +struct krpc_connect_req { > + struct pcs_msg msg; > + struct pcs_krpc *krpc; > + u32 gen; > +}; > + > struct pcs_krpc { > struct hlist_node hlist; > struct list_head link; > -- > 2.39.3 (Apple Git-146)
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