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Thu, 11 May 2023 02:15:37 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ6qw2EHquUoXuvnOU6bPvR3WzBrpbM3/oCu/2/pMc8QkMtkZcGnbzV/iSpsXaMkSSIqxD1tHw== X-Received: by 2002:adf:ef47:0:b0:2f0:e287:1fbc with SMTP id c7-20020adfef47000000b002f0e2871fbcmr13518491wrp.11.1683796536749; Thu, 11 May 2023 02:15:36 -0700 (PDT) From: Stefano Garzarella To: qemu-devel@nongnu.org Cc: Kevin Wolf , Stefan Hajnoczi , Jonathon Jongsma , qemu-block@nongnu.org, Hanna Reitz , Stefano Garzarella Subject: [PATCH v3 1/1] block/blkio: use qemu_open() to support fd passing for virtio-blk Date: Thu, 11 May 2023 11:15:27 +0200 Message-Id: <20230511091527.46620-2-sgarzare@redhat.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230511091527.46620-1-sgarzare@redhat.com> References: <20230511091527.46620-1-sgarzare@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; 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, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1683796638898100001 Content-Type: text/plain; charset="utf-8" The virtio-blk-vhost-vdpa driver in libblkio 1.3.0 supports the new 'fd' property. Let's expose this to the user, so the management layer can pass the file descriptor of an already opened vhost-vdpa character device. This is useful especially when the device can only be accessed with certain privileges. 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 --- Notes: 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(BlockDriverSt= ate *bs, { const char *path =3D qdict_get_try_str(options, "path"); BDRVBlkioState *s =3D bs->opaque; - int ret; + bool fd_supported =3D false; + int fd, ret; =20 if (!path) { error_setg(errp, "missing 'path' option"); return -EINVAL; } =20 - ret =3D 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=3Doff is not supported"); return -EINVAL; } + + if (blkio_get_int(s->blkio, "fd", &fd) =3D=3D 0) { + fd_supported =3D true; + } + + /* + * If the libblkio driver supports fd passing, let's always use qemu_o= pen() + * 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 =3D O_RDWR; + } else { + open_flags =3D O_RDONLY; + } + + fd =3D qemu_open(path, open_flags, errp); + if (fd < 0) { + return -EINVAL; + } + + ret =3D 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 =3D 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; } =20 --=20 2.40.1