From fd57241cf0f8c2906fa56118f8da1e65a5b1e4d8 Mon Sep 17 00:00:00 2001 From: Stefano Garzarella Date: Tue, 30 May 2023 09:19:40 +0200 Subject: [PATCH 3/5] block/blkio: use qemu_open() to support fd passing for virtio-blk RH-Author: Stefano Garzarella RH-MergeRequest: 169: block/blkio: support fd passing for virtio-blk-vhost-vdpa driver RH-Bugzilla: 2180076 RH-Acked-by: Miroslav Rezanina RH-Acked-by: Stefan Hajnoczi RH-Commit: [1/2] 9ff1a1510500db101648341207a36318a0c41c5a (sgarzarella/qemu-kvm-c-9-s) 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. Reviewed-by: Stefan Hajnoczi Signed-off-by: Stefano Garzarella Message-id: 20230530071941.8954-2-sgarzare@redhat.com Signed-off-by: Stefan Hajnoczi (cherry picked from commit cad2ccc395c7113fb30bc9390774b67b34f06c68) Signed-off-by: Stefano Garzarella --- 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; } -- 2.39.3