From a5942c177b7bcc1357e496b7d68668befcfc2bb9 Mon Sep 17 00:00:00 2001 From: Stefano Garzarella Date: Wed, 26 Jul 2023 09:48:07 +0200 Subject: [PATCH] block/blkio: do not use open flags in qemu_open() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit qemu_open() in blkio_virtio_blk_common_open() is used to open the character device (e.g. /dev/vhost-vdpa-0 or /dev/vfio/vfio) or in the future eventually the unix socket. In all these cases we cannot open the path in read-only mode, when the `read-only` option of blockdev is on, because the exchange of IOCTL commands for example will fail. In order to open the device read-only, we have to use the `read-only` property of the libblkio driver as we already do in blkio_file_open(). Fixes: cad2ccc395 ("block/blkio: use qemu_open() to support fd passing for virtio-blk") Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2225439 Reported-by: Qing Wang Signed-off-by: Stefano Garzarella Reviewed-by: Daniel P. Berrangé Message-id: 20230726074807.14041-1-sgarzare@redhat.com Signed-off-by: Stefan Hajnoczi --- block/blkio.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/block/blkio.c b/block/blkio.c index bc1fac48b7..7eb1b94820 100644 --- a/block/blkio.c +++ b/block/blkio.c @@ -686,15 +686,18 @@ static int blkio_virtio_blk_common_open(BlockDriverState *bs, * 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); + /* + * `path` can contain the path of a character device + * (e.g. /dev/vhost-vdpa-0 or /dev/vfio/vfio) or a unix socket. + * + * So, we should always open it with O_RDWR flag, also if BDRV_O_RDWR + * is not set in the open flags, because the exchange of IOCTL commands + * for example will fail. + * + * In order to open the device read-only, we are using the `read-only` + * property of the libblkio driver in blkio_file_open(). + */ + fd = qemu_open(path, O_RDWR, errp); if (fd < 0) { return -EINVAL; } -- 2.30.2