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[87.12.25.16]) by smtp.gmail.com with ESMTPSA id bl17-20020a170906c25100b0094e4eabb402sm2239995ejb.128.2023.05.26.08.03.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 26 May 2023 08:03:10 -0700 (PDT) From: Stefano Garzarella To: qemu-devel@nongnu.org Cc: Hanna Reitz , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= , Jonathon Jongsma , Paolo Bonzini , =?utf-8?q?Marc-Andr=C3=A9_Lureau?= , Eric Blake , Kevin Wolf , qemu-block@nongnu.org, Thomas Huth , =?utf-8?q?Daniel_P?= =?utf-8?q?=2E_Berrang=C3=A9?= , Markus Armbruster , Stefan Hajnoczi , Stefano Garzarella Subject: [PATCH v4 1/2] block/blkio: use qemu_open() to support fd passing for virtio-blk Date: Fri, 26 May 2023 17:03:03 +0200 Message-Id: <20230526150304.158206-2-sgarzare@redhat.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230526150304.158206-1-sgarzare@redhat.com> References: <20230526150304.158206-1-sgarzare@redhat.com> MIME-Version: 1.0 Content-type: text/plain Received-SPF: pass client-ip=170.10.129.124; envelope-from=sgarzare@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Some virtio-blk drivers (e.g. virtio-blk-vhost-vdpa) supports the fd passing. Let's expose this to the user, so the management layer can pass the file descriptor of an already opened path. If the libblkio virtio-blk driver supports fd passing, let's always use qemu_open() to open the `path`, so we can handle fd passing from the management layer through the "/dev/fdset/N" special path. Signed-off-by: Stefano Garzarella Reviewed-by: Stefan Hajnoczi --- Notes: v4: - modified commit description v3: - use qemu_open() on `path` to simplify libvirt code [Jonathon] block/blkio.c | 53 ++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 44 insertions(+), 9 deletions(-) diff --git a/block/blkio.c b/block/blkio.c index 0cdc99a729..6a6f20f923 100644 --- a/block/blkio.c +++ b/block/blkio.c @@ -672,25 +672,60 @@ static int blkio_virtio_blk_common_open(BlockDriverState *bs, { const char *path = qdict_get_try_str(options, "path"); BDRVBlkioState *s = bs->opaque; - int ret; + bool fd_supported = false; + int fd, ret; if (!path) { error_setg(errp, "missing 'path' option"); return -EINVAL; } - ret = blkio_set_str(s->blkio, "path", path); - qdict_del(options, "path"); - if (ret < 0) { - error_setg_errno(errp, -ret, "failed to set path: %s", - blkio_get_error_msg()); - return ret; - } - if (!(flags & BDRV_O_NOCACHE)) { error_setg(errp, "cache.direct=off is not supported"); return -EINVAL; } + + if (blkio_get_int(s->blkio, "fd", &fd) == 0) { + fd_supported = true; + } + + /* + * If the libblkio driver supports fd passing, let's always use qemu_open() + * to open the `path`, so we can handle fd passing from the management + * layer through the "/dev/fdset/N" special path. + */ + if (fd_supported) { + int open_flags; + + if (flags & BDRV_O_RDWR) { + open_flags = O_RDWR; + } else { + open_flags = O_RDONLY; + } + + fd = qemu_open(path, open_flags, errp); + if (fd < 0) { + return -EINVAL; + } + + ret = blkio_set_int(s->blkio, "fd", fd); + if (ret < 0) { + error_setg_errno(errp, -ret, "failed to set fd: %s", + blkio_get_error_msg()); + qemu_close(fd); + return ret; + } + } else { + ret = blkio_set_str(s->blkio, "path", path); + if (ret < 0) { + error_setg_errno(errp, -ret, "failed to set path: %s", + blkio_get_error_msg()); + return ret; + } + } + + qdict_del(options, "path"); + return 0; }