Am 13.08.2012 09:54, schrieb Kevin Wolf:
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.
Kevin, would you like to resend this as a proper patch with a Signed-off-by line? If you like, you can also add a dinfo->bdrv->open_flags = snapshot ? BDRV_O_SNAPSHOT : 0. This would fix the second bug I mentioned above, that snapshot=on is lost on empty drives. Kevin