From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 17 May 2021 08:48:29 -0400 From: Vivek Goyal Message-ID: <20210517124829.GA546943@horse.lan> References: <20210215095410.85607-1-stefanha@redhat.com> <20210512223637.GA6241@rsjd01523.et2sqa> MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Subject: Re: [Virtio-fs] [virtio-dev] [PATCH v2 0/2] virtio-fs: add notification queue List-Id: Development discussions about virtio-fs List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: virtio-fs@redhat.com, virtio-dev@lists.oasis-open.org On Thu, May 13, 2021 at 02:44:42PM +0100, Stefan Hajnoczi wrote: > On Thu, May 13, 2021 at 06:36:37AM +0800, Liu Bo wrote: > > Hi Stefan, > > > > On Tue, May 11, 2021 at 09:22:24AM +0100, Stefan Hajnoczi wrote: > > > On Mon, Feb 15, 2021 at 09:54:08AM +0000, Stefan Hajnoczi wrote: > > > > v2: > > > > * Document empty virtqueue behavior for FUSE_NOTIFY_LOCK messages > > > > > > > > This patch series adds the notification queue to the VIRTIO specification. > > > > This new virtqueue carries device->driver FUSE notify messages. They are > > > > currently unused but will be necessary for file locking, which can block for an > > > > unbounded amount of time and therefore needs a asynchronous completion event > > > > instead of a request/response buffer that consumes space in the request > > > > virtqueue until the operation completes. > > > > > > > > Patch 1 corrects an oversight I noticed: the file system device was not added > > > > to the Conformance chapter. > > > > > > > > Stefan Hajnoczi (2): > > > > virtio-fs: add file system device to Conformance chapter > > > > virtio-fs: add notification queue > > > > > > > > conformance.tex | 23 ++++++++++++++++ > > > > virtio-fs.tex | 71 ++++++++++++++++++++++++++++++++++++++++++------- > > > > 2 files changed, 84 insertions(+), 10 deletions(-) > > > > > > Reminder to anyone who needs the virtio-fs notification queue: please > > > review this series. > > > > > > > Besides using notification queue to provide posix lock support, I've > > also managed to invalidate dentry/inode's cache with notification > > queue, it worked well. > > Thank you! > > Are you using dentry/inode cache invalidation to reduce the number of > file descriptors that virtiofsd needs to hold open, Using notifications to invalidate client's dentry/inode cache sounds interesting. Will like to see an actual implementation though. Various races w.r.t opening the same file for which server is trying to invalidate the dentry/inode might be little tricky. Thanks Vivek