From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 13 Jan 2022 10:59:15 +0100 From: Greg Kurz Message-ID: <20220113105915.0f46dbb6@bahia> In-Reply-To: <20220111181043.435915-1-sebastian.hasler@stuvus.uni-stuttgart.de> References: <20220111181043.435915-1-sebastian.hasler@stuvus.uni-stuttgart.de> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Virtio-fs] [PATCH] virtiofsd: Do not support blocking flock List-Id: Development discussions about virtio-fs List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Sebastian Hasler Cc: virtio-fs@redhat.com, qemu-devel@nongnu.org On Tue, 11 Jan 2022 19:10:43 +0100 Sebastian Hasler wrote: > With the current implementation, blocking flock can lead to > deadlock. Thus, it's better to return EOPNOTSUPP if a user attempts > to perform a blocking flock request. > > Signed-off-by: Sebastian Hasler > --- > tools/virtiofsd/passthrough_ll.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > index 64b5b4fbb1..f3cc307f6d 100644 > --- a/tools/virtiofsd/passthrough_ll.c > +++ b/tools/virtiofsd/passthrough_ll.c > @@ -2442,6 +2442,12 @@ static void lo_flock(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi, > int res; > (void)ino; > > + if (!(op & LOCK_NB)) { > + /* Blocking flock is not supported */ This paraphrases the code. It would be more informative to provide an explanation, something like /* Blocking flock can deadlock */ . No big deal. Reviewed-by: Greg Kurz > + fuse_reply_err(req, EOPNOTSUPP); > + return; > + } > + > res = flock(lo_fi_fd(req, fi), op); > > fuse_reply_err(req, res == -1 ? errno : 0);