[libvirt] [PATCH] qemu: add a value check for granularity

[lhuang]

On 04/01/2015 04:12 PM, Michal Privoznik wrote:
> On 27.03.2015 10:56, Luyao Huang wrote:
>> https://bugzilla.redhat.com/show_bug.cgi?id=1206479
>>
>> >From our manual of virsh and qemu side code, we know this
>> value must be power of 2, so instead of let qemu output error,
>> we can add a check when we file this value in qemuDomainBlockCopy.
>>
>> Signed-off-by: Luyao Huang <lhuang at redhat.com>
>> ---
>>   src/qemu/qemu_driver.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
>> index 2c55fb0..6d63317 100644
>> --- a/src/qemu/qemu_driver.c
>> +++ b/src/qemu/qemu_driver.c
>> @@ -16871,6 +16871,11 @@ qemuDomainBlockCopy(virDomainPtr dom, const char *disk, const char *destxml,
>>               }
>>               bandwidth = param->value.ul;
>>           } else if (STREQ(param->field, VIR_DOMAIN_BLOCK_COPY_GRANULARITY)) {
>> +            if (param->value.ui != VIR_ROUND_UP_POWER_OF_TWO(param->value.ui)) {
>> +                virReportError(VIR_ERR_INVALID_ARG, "%s",
>> +                               _("granularity must be power of 2"));
>> +                goto cleanup;
>> +            }
>>               granularity = param->value.ui;
>>           } else if (STREQ(param->field, VIR_DOMAIN_BLOCK_COPY_BUF_SIZE)) {
>>               buf_size = param->value.ul;
>>
> In fact, the virsh man page is not as precise as it could be either:
>
> diff --git a/tools/virsh.pod b/tools/virsh.pod
> index 63325ff..5d52761 100644
> --- a/tools/virsh.pod
> +++ b/tools/virsh.pod
> @@ -1039,10 +1039,10 @@ unlimited, but more likely would overflow; it is safer to use 0 for that
> purpose.  Specifying I<granularity> allows fine-tuning of the granularity that
> will be copied when a dirty region is detected; larger values trigger less
> I/O overhead but may end up copying more data overall (the default value is
> usually correct); {+hypervisors may restrict+} this [-value must-]{+to+} be a power of [-two.-]{+two or fall+}
> {+within a certain range.+} Specifying I<buf-size> will control how much data can
> be simultaneously in-flight during the copy; larger values use more memory but
> may allow faster completion (the default value is usually correct).
>
> =item B<blockpull> I<domain> I<path> [I<bandwidth>] [I<base>]
> [I<--wait> [I<--verbose>] [I<--timeout> B<seconds>] [I<--async>]]
>
> I'm fixing the man page too, rewording the commit message a bit and ACKing. Will push after the release.

Oh, thanks a lot for your remind and your fix for man page looks good 
for me.

Thanks for your review.

> Michal

Luyao