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



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 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.

Michal


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