Re: [libvirt] [PATCH 7/8 v8] qemu: Set unpriv_sgio when attaching disk
On 2012年12月15日 06:05, Eric Blake wrote:
On 12/14/2012 08:45 AM, Osier Yang wrote:
> Just like for domain starting, this sets the disk's unpriv_sgio
> if cdbfilter is specified when attaching disk.
> ---
> src/qemu/qemu_driver.c | 23 +++++++++++++++++------
> 1 files changed, 17 insertions(+), 6 deletions(-)
> +
> + /* Set sysfs unpriv_sgio if cdbfilter is specified. */
> + if (disk->cdbfilter) {
> + if (virSetDeviceUnprivSGIO(disk->src, NULL,
> + (disk->cdbfilter ==
> + VIR_DOMAIN_DISK_CDB_FILTER_NO)
> + ? 1 : 0)< 0) {
> + VIR_WARN("Failed to set unpriv_sgio of disk '%s'",
disk->src);
> + goto end;
> + }
> + }
Again, does this do the right thing if some other domain already had
cdbfilter='no' (aka kernel allows SG_IO) but this domain omitted the
cdbfilter attribute (which defaults to cdbfilter='yes' but does not
satisfy the if(disk->cdbfilter) condition)?
I think it does the right thing, because not specifying "cdbfilter"
should mean it doesn't care about what the kernel setting is, not
means cdbfiler="yes" instead. Assuming that one used rawio="yes"
for a domain, and if we defaults cdbfilter to "yes", it will cause
regression, as the user still expects SG_IO commands can be executed
on the disk, however, it's disabled by cdbfilter="yes".
I suspect that will be
worked out when you rework things to use a tri-state rawio.
Of course, this is based on we use a separate XML tag like cdbfilter,
it won't stand anymore if we finally use a tri-state rawio.
Regards,
Osier