From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 92231C433F5 for ; Wed, 6 Oct 2021 18:20:04 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id BE027610E5 for ; Wed, 6 Oct 2021 18:20:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org BE027610E5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:37516 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mYBWM-0007QN-O8 for qemu-devel@archiver.kernel.org; Wed, 06 Oct 2021 14:20:02 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60426) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mYBUH-0006bc-IM for qemu-devel@nongnu.org; Wed, 06 Oct 2021 14:17:53 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:46925) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mYBUD-0002E4-Hh for qemu-devel@nongnu.org; Wed, 06 Oct 2021 14:17:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1633544268; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=cV9PQyRfPo4/37Y+Yhu8RZJf5aFCAZsQ7R6SZXWLCmM=; b=RUxflq90yyJOkOwG20NfMM9o8GoQAh1aPOQL28/LyXjFZUtXQGPN0CwhxJXi/4v8EcBEfa Jv1qdNF8kiIBNnQGzrz6+gG+URXFM6vCc+6WA9fXjEG0OCPYTvSMGJuOEt0pHX0zn7fzA0 coirpco5vRWoPfkPIchtH24u5Ky6s8o= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-461-lwe_8TbfNGKHMHQJOyKwOA-1; Wed, 06 Oct 2021 14:17:47 -0400 X-MC-Unique: lwe_8TbfNGKHMHQJOyKwOA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EA6CA19251A0; Wed, 6 Oct 2021 18:17:45 +0000 (UTC) Received: from horse.redhat.com (unknown [10.22.17.87]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2BBD05D9C6; Wed, 6 Oct 2021 18:17:28 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id A2264220BDB; Wed, 6 Oct 2021 14:17:27 -0400 (EDT) Date: Wed, 6 Oct 2021 14:17:27 -0400 From: Vivek Goyal To: Christophe de Dinechin Subject: Re: [Virtio-fs] [PATCH 12/13] virtiofsd: Implement blocking posix locks Message-ID: References: <20210930153037.1194279-1-vgoyal@redhat.com> <20210930153037.1194279-13-vgoyal@redhat.com> MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=vgoyal@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=vgoyal@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.05, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: virtio-fs@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com, miklos@szeredi.hu Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Oct 06, 2021 at 05:34:59PM +0200, Christophe de Dinechin wrote: > > On 2021-09-30 at 11:30 -04, Vivek Goyal wrote... > > As of now we don't support fcntl(F_SETLKW) and if we see one, we return > > -EOPNOTSUPP. > > > > Change that by accepting these requests and returning a reply > > immediately asking caller to wait. Once lock is available, send a > > notification to the waiter indicating lock is available. > > > > In response to lock request, we are returning error value as "1", which > > signals to client to queue the lock request internally and later client > > will get a notification which will signal lock is taken (or error). And > > then fuse client should wake up the guest process. > > > > Signed-off-by: Vivek Goyal > > Signed-off-by: Ioannis Angelakopoulos > > --- > > tools/virtiofsd/fuse_lowlevel.c | 37 ++++++++++++++++- > > tools/virtiofsd/fuse_lowlevel.h | 26 ++++++++++++ > > tools/virtiofsd/fuse_virtio.c | 50 ++++++++++++++++++++--- > > tools/virtiofsd/passthrough_ll.c | 70 ++++++++++++++++++++++++++++---- > > 4 files changed, 167 insertions(+), 16 deletions(-) > > > > diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c > > index e4679c73ab..2e7f4b786d 100644 > > --- a/tools/virtiofsd/fuse_lowlevel.c > > +++ b/tools/virtiofsd/fuse_lowlevel.c > > @@ -179,8 +179,8 @@ int fuse_send_reply_iov_nofree(fuse_req_t req, int error, struct iovec *iov, > > .unique = req->unique, > > .error = error, > > }; > > - > > - if (error <= -1000 || error > 0) { > > + /* error = 1 has been used to signal client to wait for notificaiton */ > > + if (error <= -1000 || error > 1) { > > What about adding a #define for that special value 1? Will do. Miklos wants that as well. > > (and while we are at it, the -1000 does not look too good either, that could > be a separate cleanup patch) Hmm..., that's an unrelated cleanup. May be for some other day. > > > fuse_log(FUSE_LOG_ERR, "fuse: bad error value: %i\n", error); > > out.error = -ERANGE; > > } > > @@ -290,6 +290,11 @@ int fuse_reply_err(fuse_req_t req, int err) > > return send_reply(req, -err, NULL, 0); > > } > > > > +int fuse_reply_wait(fuse_req_t req) > > +{ > > + return send_reply(req, 1, NULL, 0); > > ... to be used here too. Yes. Wil use new define here too. > > > +} > > + > > void fuse_reply_none(fuse_req_t req) > > { > > fuse_free_req(req); > > @@ -2165,6 +2170,34 @@ static void do_destroy(fuse_req_t req, fuse_ino_t nodeid, > > send_reply_ok(req, NULL, 0); > > } > > > > +static int send_notify_iov(struct fuse_session *se, int notify_code, > > + struct iovec *iov, int count) > > +{ > > + struct fuse_out_header out; > > + if (!se->got_init) { > > + return -ENOTCONN; > > + } > > + out.unique = 0; > > + out.error = notify_code; > > + iov[0].iov_base = &out; > > + iov[0].iov_len = sizeof(struct fuse_out_header); > > + return fuse_send_msg(se, NULL, iov, count); > > +} > > + > > +int fuse_lowlevel_notify_lock(struct fuse_session *se, uint64_t unique, > > + int32_t error) > > +{ > > + struct fuse_notify_lock_out outarg = {0}; > > + struct iovec iov[2]; > > + > > + outarg.unique = unique; > > + outarg.error = -error; > > + > > + iov[1].iov_base = &outarg; > > + iov[1].iov_len = sizeof(outarg); > > + return send_notify_iov(se, FUSE_NOTIFY_LOCK, iov, 2); > > +} > > This may be just me, but I find it odd that you fill iov[0] and iov[1] in > two separate functions, one of them being static and AFAICT only used once. > I understand that you are trying to split the notify logic from the lock. > But the logic is not fully isolated, e.g. the caller needs to know to add > one to the count, start filling at 1, etc. > > Just a matter of taste, I guess ;-) I thought that multiple notification types can use common code send_notify_iov() because it requires filling common fuse_out_header. So if in future I introduce another notification say, FUSE_NOTIFY_FOO, then I can just define one function fuse_lowlevel_notify_foo() and it can also use send_notify_iov(). I think that's the thought I had in mind. > > > + > > int fuse_lowlevel_notify_store(struct fuse_session *se, fuse_ino_t ino, > > off_t offset, struct fuse_bufvec *bufv) > > { > > diff --git a/tools/virtiofsd/fuse_lowlevel.h b/tools/virtiofsd/fuse_lowlevel.h > > index c55c0ca2fc..64624b48dc 100644 > > --- a/tools/virtiofsd/fuse_lowlevel.h > > +++ b/tools/virtiofsd/fuse_lowlevel.h > > @@ -1251,6 +1251,22 @@ struct fuse_lowlevel_ops { > > */ > > int fuse_reply_err(fuse_req_t req, int err); > > > > +/** > > + * Ask caller to wait for lock. > > + * > > + * Possible requests: > > + * setlkw > > + * > > + * If caller sends a blocking lock request (setlkw), then reply to caller > > + * that wait for lock to be available. Once lock is available caller will > > + * receive a notification with request's unique id. Notification will > > + * carry info whether lock was successfully obtained or not. > > + * > > + * @param req request handle > > + * @return zero for success, -errno for failure to send reply > > + */ > > +int fuse_reply_wait(fuse_req_t req); > > + > > /** > > * Don't send reply > > * > > @@ -1685,6 +1701,16 @@ int fuse_lowlevel_notify_delete(struct fuse_session *se, fuse_ino_t parent, > > int fuse_lowlevel_notify_store(struct fuse_session *se, fuse_ino_t ino, > > off_t offset, struct fuse_bufvec *bufv); > > > > +/** > > + * Notify event related to previous lock request > > + * > > + * @param se the session object > > + * @param unique the unique id of the request which requested setlkw > > + * @param error zero for success, -errno for the failure > > + */ > > +int fuse_lowlevel_notify_lock(struct fuse_session *se, uint64_t unique, > > + int32_t error); > > + > > /* > > * Utility functions > > */ > > diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c > > index a87e88e286..bb2d4456fc 100644 > > --- a/tools/virtiofsd/fuse_virtio.c > > +++ b/tools/virtiofsd/fuse_virtio.c > > @@ -273,6 +273,23 @@ static void vq_send_element(struct fv_QueueInfo *qi, VuVirtqElement *elem, > > vu_dispatch_unlock(qi->virtio_dev); > > } > > > > +/* Returns NULL if queue is empty */ > > +static FVRequest *vq_pop_notify_elem(struct fv_QueueInfo *qi) > > +{ > > + struct fuse_session *se = qi->virtio_dev->se; > > + VuDev *dev = &se->virtio_dev->dev; > > + VuVirtq *q = vu_get_queue(dev, qi->qidx); > > + FVRequest *req; > > + > > + vu_dispatch_rdlock(qi->virtio_dev); > > + pthread_mutex_lock(&qi->vq_lock); > > + /* Pop an element from queue */ > > + req = vu_queue_pop(dev, q, sizeof(FVRequest)); > > + pthread_mutex_unlock(&qi->vq_lock); > > + vu_dispatch_unlock(qi->virtio_dev); > > + return req; > > +} > > + > > /* > > * Called back by ll whenever it wants to send a reply/message back > > * The 1st element of the iov starts with the fuse_out_header > > @@ -281,9 +298,9 @@ static void vq_send_element(struct fv_QueueInfo *qi, VuVirtqElement *elem, > > int virtio_send_msg(struct fuse_session *se, struct fuse_chan *ch, > > struct iovec *iov, int count) > > { > > - FVRequest *req = container_of(ch, FVRequest, ch); > > - struct fv_QueueInfo *qi = ch->qi; > > - VuVirtqElement *elem = &req->elem; > > + FVRequest *req; > > + struct fv_QueueInfo *qi; > > + VuVirtqElement *elem; > > int ret = 0; > > > > assert(count >= 1); > > @@ -294,8 +311,30 @@ int virtio_send_msg(struct fuse_session *se, struct fuse_chan *ch, > > > > size_t tosend_len = iov_size(iov, count); > > > > - /* unique == 0 is notification, which we don't support */ > > - assert(out->unique); > > + /* unique == 0 is notification */ > > + if (!out->unique) { > > + if (!se->notify_enabled) { > > + return -EOPNOTSUPP; > > + } > > + /* If notifications are enabled, queue index 1 is notification queue */ > > + qi = se->virtio_dev->qi[1]; > > + req = vq_pop_notify_elem(qi); > > + if (!req) { > > + /* > > + * TODO: Implement some sort of ring buffer and queue notifications > > + * on that and send these later when notification queue has space > > + * available. > > + */ > > Maybe add a trace / message here to debug more easily if we hit that case? Maybe I could add a pr_debug() message. But now this code will probably change. Stefan wants me to wait on some conditional variable for descriptors to become available (instead of returning -ENOSPC to the caller. And be woken up when new descriptors are available (through queue kick path). In new structure, a message might not be needed. Thanks Vivek > > > + return -ENOSPC; > > + } > > + req->reply_sent = false; > > + } else { > > + assert(ch); > > + req = container_of(ch, FVRequest, ch); > > + qi = ch->qi; > > + } > > + > > + elem = &req->elem; > > assert(!req->reply_sent); > > > > /* The 'in' part of the elem is to qemu */ > > @@ -985,6 +1024,7 @@ static int fv_get_config(VuDev *dev, uint8_t *config, uint32_t len) > > struct fuse_notify_delete_out delete_out; > > struct fuse_notify_store_out store_out; > > struct fuse_notify_retrieve_out retrieve_out; > > + struct fuse_notify_lock_out lock_out; > > }; > > > > notify_size = sizeof(struct fuse_out_header) + > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > > index 6928662e22..277f74762b 100644 > > --- a/tools/virtiofsd/passthrough_ll.c > > +++ b/tools/virtiofsd/passthrough_ll.c > > @@ -2131,13 +2131,35 @@ out: > > } > > } > > > > +static void setlk_send_notification(struct fuse_session *se, uint64_t unique, > > + int saverr) > > +{ > > + int ret; > > + > > + do { > > + ret = fuse_lowlevel_notify_lock(se, unique, saverr); > > + /* > > + * Retry sending notification if notification queue does not have > > + * free descriptor yet, otherwise break out of loop. Either we > > + * successfully sent notifiation or some other error occurred. > > + */ > > + if (ret != -ENOSPC) { > > + break; > > + } > > + usleep(10000); > > + } while (1); > > +} > > + > > static void lo_setlk(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi, > > struct flock *lock, int sleep) > > { > > struct lo_data *lo = lo_data(req); > > struct lo_inode *inode; > > struct lo_inode_plock *plock; > > - int ret, saverr = 0; > > + int ret, saverr = 0, ofd; > > + uint64_t unique; > > + struct fuse_session *se = req->se; > > + bool blocking_lock = false; > > > > fuse_log(FUSE_LOG_DEBUG, > > "lo_setlk(ino=%" PRIu64 ", flags=%d)" > > @@ -2151,11 +2173,6 @@ static void lo_setlk(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi, > > return; > > } > > > > - if (sleep) { > > - fuse_reply_err(req, EOPNOTSUPP); > > - return; > > - } > > - > > inode = lo_inode(req, ino); > > if (!inode) { > > fuse_reply_err(req, EBADF); > > @@ -2168,21 +2185,56 @@ static void lo_setlk(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi, > > > > if (!plock) { > > saverr = ret; > > + pthread_mutex_unlock(&inode->plock_mutex); > > goto out; > > } > > > > + /* > > + * plock is now released when inode is going away. We already have > > + * a reference on inode, so it is guaranteed that plock->fd is > > + * still around even after dropping inode->plock_mutex lock > > + */ > > + ofd = plock->fd; > > + pthread_mutex_unlock(&inode->plock_mutex); > > + > > + /* > > + * If this lock request can block, request caller to wait for > > + * notification. Do not access req after this. Once lock is > > + * available, send a notification instead. > > + */ > > + if (sleep && lock->l_type != F_UNLCK) { > > + /* > > + * If notification queue is not enabled, can't support async > > + * locks. > > + */ > > + if (!se->notify_enabled) { > > + saverr = EOPNOTSUPP; > > + goto out; > > + } > > + blocking_lock = true; > > + unique = req->unique; > > + fuse_reply_wait(req); > > + } > > + > > /* TODO: Is it alright to modify flock? */ > > lock->l_pid = 0; > > - ret = fcntl(plock->fd, F_OFD_SETLK, lock); > > + if (blocking_lock) { > > + ret = fcntl(ofd, F_OFD_SETLKW, lock); > > + } else { > > + ret = fcntl(ofd, F_OFD_SETLK, lock); > > + } > > if (ret == -1) { > > saverr = errno; > > } > > > > out: > > - pthread_mutex_unlock(&inode->plock_mutex); > > lo_inode_put(lo, &inode); > > > > - fuse_reply_err(req, saverr); > > + if (!blocking_lock) { > > + fuse_reply_err(req, saverr); > > + } else { > > + setlk_send_notification(se, unique, saverr); > > + } > > } > > > > static void lo_fsyncdir(fuse_req_t req, fuse_ino_t ino, int datasync, > > > -- > Cheers, > Christophe de Dinechin (IRC c3d) > From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 6 Oct 2021 14:17:27 -0400 From: Vivek Goyal Message-ID: References: <20210930153037.1194279-1-vgoyal@redhat.com> <20210930153037.1194279-13-vgoyal@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Virtio-fs] [PATCH 12/13] virtiofsd: Implement blocking posix locks List-Id: Development discussions about virtio-fs List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Christophe de Dinechin Cc: virtio-fs@redhat.com, qemu-devel@nongnu.org, miklos@szeredi.hu On Wed, Oct 06, 2021 at 05:34:59PM +0200, Christophe de Dinechin wrote: > > On 2021-09-30 at 11:30 -04, Vivek Goyal wrote... > > As of now we don't support fcntl(F_SETLKW) and if we see one, we return > > -EOPNOTSUPP. > > > > Change that by accepting these requests and returning a reply > > immediately asking caller to wait. Once lock is available, send a > > notification to the waiter indicating lock is available. > > > > In response to lock request, we are returning error value as "1", which > > signals to client to queue the lock request internally and later client > > will get a notification which will signal lock is taken (or error). And > > then fuse client should wake up the guest process. > > > > Signed-off-by: Vivek Goyal > > Signed-off-by: Ioannis Angelakopoulos > > --- > > tools/virtiofsd/fuse_lowlevel.c | 37 ++++++++++++++++- > > tools/virtiofsd/fuse_lowlevel.h | 26 ++++++++++++ > > tools/virtiofsd/fuse_virtio.c | 50 ++++++++++++++++++++--- > > tools/virtiofsd/passthrough_ll.c | 70 ++++++++++++++++++++++++++++---- > > 4 files changed, 167 insertions(+), 16 deletions(-) > > > > diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c > > index e4679c73ab..2e7f4b786d 100644 > > --- a/tools/virtiofsd/fuse_lowlevel.c > > +++ b/tools/virtiofsd/fuse_lowlevel.c > > @@ -179,8 +179,8 @@ int fuse_send_reply_iov_nofree(fuse_req_t req, int error, struct iovec *iov, > > .unique = req->unique, > > .error = error, > > }; > > - > > - if (error <= -1000 || error > 0) { > > + /* error = 1 has been used to signal client to wait for notificaiton */ > > + if (error <= -1000 || error > 1) { > > What about adding a #define for that special value 1? Will do. Miklos wants that as well. > > (and while we are at it, the -1000 does not look too good either, that could > be a separate cleanup patch) Hmm..., that's an unrelated cleanup. May be for some other day. > > > fuse_log(FUSE_LOG_ERR, "fuse: bad error value: %i\n", error); > > out.error = -ERANGE; > > } > > @@ -290,6 +290,11 @@ int fuse_reply_err(fuse_req_t req, int err) > > return send_reply(req, -err, NULL, 0); > > } > > > > +int fuse_reply_wait(fuse_req_t req) > > +{ > > + return send_reply(req, 1, NULL, 0); > > ... to be used here too. Yes. Wil use new define here too. > > > +} > > + > > void fuse_reply_none(fuse_req_t req) > > { > > fuse_free_req(req); > > @@ -2165,6 +2170,34 @@ static void do_destroy(fuse_req_t req, fuse_ino_t nodeid, > > send_reply_ok(req, NULL, 0); > > } > > > > +static int send_notify_iov(struct fuse_session *se, int notify_code, > > + struct iovec *iov, int count) > > +{ > > + struct fuse_out_header out; > > + if (!se->got_init) { > > + return -ENOTCONN; > > + } > > + out.unique = 0; > > + out.error = notify_code; > > + iov[0].iov_base = &out; > > + iov[0].iov_len = sizeof(struct fuse_out_header); > > + return fuse_send_msg(se, NULL, iov, count); > > +} > > + > > +int fuse_lowlevel_notify_lock(struct fuse_session *se, uint64_t unique, > > + int32_t error) > > +{ > > + struct fuse_notify_lock_out outarg = {0}; > > + struct iovec iov[2]; > > + > > + outarg.unique = unique; > > + outarg.error = -error; > > + > > + iov[1].iov_base = &outarg; > > + iov[1].iov_len = sizeof(outarg); > > + return send_notify_iov(se, FUSE_NOTIFY_LOCK, iov, 2); > > +} > > This may be just me, but I find it odd that you fill iov[0] and iov[1] in > two separate functions, one of them being static and AFAICT only used once. > I understand that you are trying to split the notify logic from the lock. > But the logic is not fully isolated, e.g. the caller needs to know to add > one to the count, start filling at 1, etc. > > Just a matter of taste, I guess ;-) I thought that multiple notification types can use common code send_notify_iov() because it requires filling common fuse_out_header. So if in future I introduce another notification say, FUSE_NOTIFY_FOO, then I can just define one function fuse_lowlevel_notify_foo() and it can also use send_notify_iov(). I think that's the thought I had in mind. > > > + > > int fuse_lowlevel_notify_store(struct fuse_session *se, fuse_ino_t ino, > > off_t offset, struct fuse_bufvec *bufv) > > { > > diff --git a/tools/virtiofsd/fuse_lowlevel.h b/tools/virtiofsd/fuse_lowlevel.h > > index c55c0ca2fc..64624b48dc 100644 > > --- a/tools/virtiofsd/fuse_lowlevel.h > > +++ b/tools/virtiofsd/fuse_lowlevel.h > > @@ -1251,6 +1251,22 @@ struct fuse_lowlevel_ops { > > */ > > int fuse_reply_err(fuse_req_t req, int err); > > > > +/** > > + * Ask caller to wait for lock. > > + * > > + * Possible requests: > > + * setlkw > > + * > > + * If caller sends a blocking lock request (setlkw), then reply to caller > > + * that wait for lock to be available. Once lock is available caller will > > + * receive a notification with request's unique id. Notification will > > + * carry info whether lock was successfully obtained or not. > > + * > > + * @param req request handle > > + * @return zero for success, -errno for failure to send reply > > + */ > > +int fuse_reply_wait(fuse_req_t req); > > + > > /** > > * Don't send reply > > * > > @@ -1685,6 +1701,16 @@ int fuse_lowlevel_notify_delete(struct fuse_session *se, fuse_ino_t parent, > > int fuse_lowlevel_notify_store(struct fuse_session *se, fuse_ino_t ino, > > off_t offset, struct fuse_bufvec *bufv); > > > > +/** > > + * Notify event related to previous lock request > > + * > > + * @param se the session object > > + * @param unique the unique id of the request which requested setlkw > > + * @param error zero for success, -errno for the failure > > + */ > > +int fuse_lowlevel_notify_lock(struct fuse_session *se, uint64_t unique, > > + int32_t error); > > + > > /* > > * Utility functions > > */ > > diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c > > index a87e88e286..bb2d4456fc 100644 > > --- a/tools/virtiofsd/fuse_virtio.c > > +++ b/tools/virtiofsd/fuse_virtio.c > > @@ -273,6 +273,23 @@ static void vq_send_element(struct fv_QueueInfo *qi, VuVirtqElement *elem, > > vu_dispatch_unlock(qi->virtio_dev); > > } > > > > +/* Returns NULL if queue is empty */ > > +static FVRequest *vq_pop_notify_elem(struct fv_QueueInfo *qi) > > +{ > > + struct fuse_session *se = qi->virtio_dev->se; > > + VuDev *dev = &se->virtio_dev->dev; > > + VuVirtq *q = vu_get_queue(dev, qi->qidx); > > + FVRequest *req; > > + > > + vu_dispatch_rdlock(qi->virtio_dev); > > + pthread_mutex_lock(&qi->vq_lock); > > + /* Pop an element from queue */ > > + req = vu_queue_pop(dev, q, sizeof(FVRequest)); > > + pthread_mutex_unlock(&qi->vq_lock); > > + vu_dispatch_unlock(qi->virtio_dev); > > + return req; > > +} > > + > > /* > > * Called back by ll whenever it wants to send a reply/message back > > * The 1st element of the iov starts with the fuse_out_header > > @@ -281,9 +298,9 @@ static void vq_send_element(struct fv_QueueInfo *qi, VuVirtqElement *elem, > > int virtio_send_msg(struct fuse_session *se, struct fuse_chan *ch, > > struct iovec *iov, int count) > > { > > - FVRequest *req = container_of(ch, FVRequest, ch); > > - struct fv_QueueInfo *qi = ch->qi; > > - VuVirtqElement *elem = &req->elem; > > + FVRequest *req; > > + struct fv_QueueInfo *qi; > > + VuVirtqElement *elem; > > int ret = 0; > > > > assert(count >= 1); > > @@ -294,8 +311,30 @@ int virtio_send_msg(struct fuse_session *se, struct fuse_chan *ch, > > > > size_t tosend_len = iov_size(iov, count); > > > > - /* unique == 0 is notification, which we don't support */ > > - assert(out->unique); > > + /* unique == 0 is notification */ > > + if (!out->unique) { > > + if (!se->notify_enabled) { > > + return -EOPNOTSUPP; > > + } > > + /* If notifications are enabled, queue index 1 is notification queue */ > > + qi = se->virtio_dev->qi[1]; > > + req = vq_pop_notify_elem(qi); > > + if (!req) { > > + /* > > + * TODO: Implement some sort of ring buffer and queue notifications > > + * on that and send these later when notification queue has space > > + * available. > > + */ > > Maybe add a trace / message here to debug more easily if we hit that case? Maybe I could add a pr_debug() message. But now this code will probably change. Stefan wants me to wait on some conditional variable for descriptors to become available (instead of returning -ENOSPC to the caller. And be woken up when new descriptors are available (through queue kick path). In new structure, a message might not be needed. Thanks Vivek > > > + return -ENOSPC; > > + } > > + req->reply_sent = false; > > + } else { > > + assert(ch); > > + req = container_of(ch, FVRequest, ch); > > + qi = ch->qi; > > + } > > + > > + elem = &req->elem; > > assert(!req->reply_sent); > > > > /* The 'in' part of the elem is to qemu */ > > @@ -985,6 +1024,7 @@ static int fv_get_config(VuDev *dev, uint8_t *config, uint32_t len) > > struct fuse_notify_delete_out delete_out; > > struct fuse_notify_store_out store_out; > > struct fuse_notify_retrieve_out retrieve_out; > > + struct fuse_notify_lock_out lock_out; > > }; > > > > notify_size = sizeof(struct fuse_out_header) + > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > > index 6928662e22..277f74762b 100644 > > --- a/tools/virtiofsd/passthrough_ll.c > > +++ b/tools/virtiofsd/passthrough_ll.c > > @@ -2131,13 +2131,35 @@ out: > > } > > } > > > > +static void setlk_send_notification(struct fuse_session *se, uint64_t unique, > > + int saverr) > > +{ > > + int ret; > > + > > + do { > > + ret = fuse_lowlevel_notify_lock(se, unique, saverr); > > + /* > > + * Retry sending notification if notification queue does not have > > + * free descriptor yet, otherwise break out of loop. Either we > > + * successfully sent notifiation or some other error occurred. > > + */ > > + if (ret != -ENOSPC) { > > + break; > > + } > > + usleep(10000); > > + } while (1); > > +} > > + > > static void lo_setlk(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi, > > struct flock *lock, int sleep) > > { > > struct lo_data *lo = lo_data(req); > > struct lo_inode *inode; > > struct lo_inode_plock *plock; > > - int ret, saverr = 0; > > + int ret, saverr = 0, ofd; > > + uint64_t unique; > > + struct fuse_session *se = req->se; > > + bool blocking_lock = false; > > > > fuse_log(FUSE_LOG_DEBUG, > > "lo_setlk(ino=%" PRIu64 ", flags=%d)" > > @@ -2151,11 +2173,6 @@ static void lo_setlk(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi, > > return; > > } > > > > - if (sleep) { > > - fuse_reply_err(req, EOPNOTSUPP); > > - return; > > - } > > - > > inode = lo_inode(req, ino); > > if (!inode) { > > fuse_reply_err(req, EBADF); > > @@ -2168,21 +2185,56 @@ static void lo_setlk(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi, > > > > if (!plock) { > > saverr = ret; > > + pthread_mutex_unlock(&inode->plock_mutex); > > goto out; > > } > > > > + /* > > + * plock is now released when inode is going away. We already have > > + * a reference on inode, so it is guaranteed that plock->fd is > > + * still around even after dropping inode->plock_mutex lock > > + */ > > + ofd = plock->fd; > > + pthread_mutex_unlock(&inode->plock_mutex); > > + > > + /* > > + * If this lock request can block, request caller to wait for > > + * notification. Do not access req after this. Once lock is > > + * available, send a notification instead. > > + */ > > + if (sleep && lock->l_type != F_UNLCK) { > > + /* > > + * If notification queue is not enabled, can't support async > > + * locks. > > + */ > > + if (!se->notify_enabled) { > > + saverr = EOPNOTSUPP; > > + goto out; > > + } > > + blocking_lock = true; > > + unique = req->unique; > > + fuse_reply_wait(req); > > + } > > + > > /* TODO: Is it alright to modify flock? */ > > lock->l_pid = 0; > > - ret = fcntl(plock->fd, F_OFD_SETLK, lock); > > + if (blocking_lock) { > > + ret = fcntl(ofd, F_OFD_SETLKW, lock); > > + } else { > > + ret = fcntl(ofd, F_OFD_SETLK, lock); > > + } > > if (ret == -1) { > > saverr = errno; > > } > > > > out: > > - pthread_mutex_unlock(&inode->plock_mutex); > > lo_inode_put(lo, &inode); > > > > - fuse_reply_err(req, saverr); > > + if (!blocking_lock) { > > + fuse_reply_err(req, saverr); > > + } else { > > + setlk_send_notification(se, unique, saverr); > > + } > > } > > > > static void lo_fsyncdir(fuse_req_t req, fuse_ino_t ino, int datasync, > > > -- > Cheers, > Christophe de Dinechin (IRC c3d) >