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block/blkio: do not use open flags in qemu_open() 

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>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-id: 20230726074807.14041-1-sgarzare@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
master
Stefano Garzarella 2023-07-26 09:48:07 +02:00 committed by Stefan Hajnoczi
parent 9359c45988
commit a5942c177b
1 changed files with 12 additions and 9 deletions
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21
block/blkio.c
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@ -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;
}