| Message ID | 20230726074807.14041-1-sgarzare@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] block/blkio: do not use open flags in qemu_open() | expand |
On Wed, Jul 26, 2023 at 09:48:07AM +0200, Stefano Garzarella wrote: > 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 <qinwang@redhat.com> > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> > --- > > Notes: > v2: > - added comment on top of qemu_open() [Daniel] > > v1: https://lore.kernel.org/qemu-devel/20230725111155.85426-1-sgarzare@redhat.com/ > > block/blkio.c | 21 ++++++++++++--------- > 1 file changed, 12 insertions(+), 9 deletions(-) Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> With regards, Daniel
On Wed, Jul 26, 2023 at 09:48:07AM +0200, Stefano Garzarella wrote: > 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 <qinwang@redhat.com> > Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> > --- > > Notes: > v2: > - added comment on top of qemu_open() [Daniel] > > v1: https://lore.kernel.org/qemu-devel/20230725111155.85426-1-sgarzare@redhat.com/ > > block/blkio.c | 21 ++++++++++++--------- > 1 file changed, 12 insertions(+), 9 deletions(-) Thanks, applied to my block tree: https://gitlab.com/stefanha/qemu/commits/block Stefan
diff --git a/block/blkio.c b/block/blkio.c index 1798648134..cd6d2e55e7 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; }
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 <qinwang@redhat.com> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> --- Notes: v2: - added comment on top of qemu_open() [Daniel] v1: https://lore.kernel.org/qemu-devel/20230725111155.85426-1-sgarzare@redhat.com/ block/blkio.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-)