Re: [libvirt] [Qemu-devel] [PATCH] block: Set cdrom device read only flag

Am 12.08.2012 04:48, schrieb Kevin Shanahan: > So qmp_change_blockdev uses bdrv_is_read_only() to check whether to > try and open the backing file read only, which uses the ->read_only > member of struct BlockDriverState to decide whether to pass the > BDRV_O_RDRW flag to qmp_bdrv_open_encypted() and then bdrv_open(). > > I would assume we want to set this flag in drive_init() when the block > driver state is initialised. How about a patch like this instead? > > diff --git a/blockdev.c b/blockdev.c > index 8669142..ba22064 100644 > --- a/blockdev.c > +++ b/blockdev.c > @@ -526,6 +526,7 @@ DriveInfo *drive_init(QemuOpts *opts, int default_to_scsi) > if_name[type], mediastr, unit_id); > } > dinfo->bdrv = bdrv_new(dinfo->id); > + dinfo->bdrv->read_only = ro; > dinfo->devaddr = devaddr; > dinfo->type = type; > dinfo->bus = bus_id; Ah, yes, this looks much more like the proper fix. Basically we need to set everything that is retained after a 'change' command. We have this code in qmp_change_blockdev(): bdrv_flags = bdrv_is_read_only(bs) ? 0 : BDRV_O_RDWR; bdrv_flags |= bdrv_is_snapshot(bs) ? BDRV_O_SNAPSHOT : 0; qmp_bdrv_open_encrypted(bs, filename, bdrv_flags, drv, NULL, errp); bdrv_is_read_only() is covered by your patch, bdrv_is_snapshot() additionally requires bs->open_flags to be right.