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Thu, 12 Nov 2020 13:24:28 -0500 (EST) From: Vivek Goyal To: qemu-devel@nongnu.org, virtio-fs@redhat.com Subject: [PATCH v2 1/2] virtiofsd: Save error code early at the failure callsite Date: Thu, 12 Nov 2020 13:24:17 -0500 Message-Id: <20201112182418.25395-2-vgoyal@redhat.com> In-Reply-To: <20201112182418.25395-1-vgoyal@redhat.com> References: <20201112182418.25395-1-vgoyal@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 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-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII" Received-SPF: pass client-ip=216.205.24.124; envelope-from=vgoyal@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/11/12 08:00:44 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=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: mszeredi@redhat.com, dgilbert@redhat.com, vgoyal@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Change error code handling slightly in lo_setattr(). Right now we seem to jump to out_err and assume that "errno" is valid and use that to send reply. But if caller has to do some other operations before jumping to out_err, then it does the dance of first saving errno to saverr and the restore errno before jumping to out_err. This makes it more confusing. I am about to make more changes where caller will have to do some work after error before jumping to out_err. I found it easier to change the convention a bit. That is caller saves error in "saverr" before jumping to out_err. And out_err uses "saverr" to send error back and does not rely on "errno" having actual error. Signed-off-by: Vivek Goyal --- tools/virtiofsd/passthrough_ll.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index ec1008bceb..6407b1a2e1 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -686,6 +686,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, res = fchmodat(lo->proc_self_fd, procname, attr->st_mode, 0); } if (res == -1) { + saverr = errno; goto out_err; } } @@ -695,6 +696,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, res = fchownat(ifd, "", uid, gid, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW); if (res == -1) { + saverr = errno; goto out_err; } } @@ -707,15 +709,15 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, sprintf(procname, "%i", ifd); truncfd = openat(lo->proc_self_fd, procname, O_RDWR); if (truncfd < 0) { + saverr = errno; goto out_err; } } res = ftruncate(truncfd, attr->st_size); + saverr = res == -1 ? errno : 0; if (!fi) { - saverr = errno; close(truncfd); - errno = saverr; } if (res == -1) { goto out_err; @@ -748,6 +750,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, res = utimensat(lo->proc_self_fd, procname, tv, 0); } if (res == -1) { + saverr = errno; goto out_err; } } @@ -756,7 +759,6 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, return lo_getattr(req, ino, fi); out_err: - saverr = errno; lo_inode_put(lo, &inode); fuse_reply_err(req, saverr); } -- 2.25.4 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vivek Goyal Date: Thu, 12 Nov 2020 13:24:17 -0500 Message-Id: <20201112182418.25395-2-vgoyal@redhat.com> In-Reply-To: <20201112182418.25395-1-vgoyal@redhat.com> References: <20201112182418.25395-1-vgoyal@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: [Virtio-fs] [PATCH v2 1/2] virtiofsd: Save error code early at the failure callsite List-Id: Development discussions about virtio-fs List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, virtio-fs@redhat.com Cc: vgoyal@redhat.com Change error code handling slightly in lo_setattr(). Right now we seem to jump to out_err and assume that "errno" is valid and use that to send reply. But if caller has to do some other operations before jumping to out_err, then it does the dance of first saving errno to saverr and the restore errno before jumping to out_err. This makes it more confusing. I am about to make more changes where caller will have to do some work after error before jumping to out_err. I found it easier to change the convention a bit. That is caller saves error in "saverr" before jumping to out_err. And out_err uses "saverr" to send error back and does not rely on "errno" having actual error. Signed-off-by: Vivek Goyal --- tools/virtiofsd/passthrough_ll.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index ec1008bceb..6407b1a2e1 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -686,6 +686,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, res = fchmodat(lo->proc_self_fd, procname, attr->st_mode, 0); } if (res == -1) { + saverr = errno; goto out_err; } } @@ -695,6 +696,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, res = fchownat(ifd, "", uid, gid, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW); if (res == -1) { + saverr = errno; goto out_err; } } @@ -707,15 +709,15 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, sprintf(procname, "%i", ifd); truncfd = openat(lo->proc_self_fd, procname, O_RDWR); if (truncfd < 0) { + saverr = errno; goto out_err; } } res = ftruncate(truncfd, attr->st_size); + saverr = res == -1 ? errno : 0; if (!fi) { - saverr = errno; close(truncfd); - errno = saverr; } if (res == -1) { goto out_err; @@ -748,6 +750,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, res = utimensat(lo->proc_self_fd, procname, tv, 0); } if (res == -1) { + saverr = errno; goto out_err; } } @@ -756,7 +759,6 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, return lo_getattr(req, ino, fi); out_err: - saverr = errno; lo_inode_put(lo, &inode); fuse_reply_err(req, saverr); } -- 2.25.4