[libvirt] [PATCH] disk: Fixup error handling path for devmapper when part_separator='yes'

[John Ferlan]

ping?

Thanks -

John

On 12/03/2016 09:06 AM, John Ferlan wrote:
> 
> ping?
> 
> Tks -
> 
> John
> 
> On 11/17/2016 09:55 AM, John Ferlan wrote:
>> https://bugzilla.redhat.com/show_bug.cgi?id=1346566
>>
>> If libvirt_parthelper is erroneously told to append the partition
>> separator 'p' onto the generated output for a disk pool using device
>> mapper that has 'user_friendly_names' set to true, then the error
>> recovery path will fail to find volume resulting in the pool being
>> in an unusable state.
>>
>> So, augment the documentation to provide the better hint that the
>> part_separator='yes' should be set when user_friendly_names are not
>> being used. Additionally, once we're in the error path where the
>> returned name doesn't match the expected partition name try to see
>> if the reason is because the 'p' was erroneosly added. If so alter
>> the about to be removed vol->target.path so that the DiskDeleteVol
>> code can find the partition that was created and remove it.
>>
>> Signed-off-by: John Ferlan <jferlan at redhat.com>
>> ---
>>  docs/formatstorage.html.in         |  5 ++++-
>>  src/storage/storage_backend_disk.c | 23 +++++++++++++++++++++++
>>  2 files changed, 27 insertions(+), 1 deletion(-)
>>
>> diff --git a/docs/formatstorage.html.in b/docs/formatstorage.html.in
>> index ed1f0d1..7690114 100644
>> --- a/docs/formatstorage.html.in
>> +++ b/docs/formatstorage.html.in
>> @@ -138,7 +138,10 @@
>>          causes libvirt to attempt to generate and find target volume path's
>>          using a "p" separator. The default algorithm used by device mapper
>>          is to add the "p" separator only when the source device path ends
>> -        with a number.
>> +        with a number; however, it's possible to configure the devmapper
>> +        device to not use 'user_friendly_names' thus creating partitions
>> +        with the "p" separator even when the device source path does not
>> +        end with a number.
>>          <span class="since">Since 1.3.1</span></p></dd>
>>        <dt><code>dir</code></dt>
>>        <dd>Provides the source for pools backed by directories (pool
>> diff --git a/src/storage/storage_backend_disk.c b/src/storage/storage_backend_disk.c
>> index 666ad03..07a04f1 100644
>> --- a/src/storage/storage_backend_disk.c
>> +++ b/src/storage/storage_backend_disk.c
>> @@ -95,6 +95,29 @@ virStorageBackendDiskMakeDataVol(virStoragePoolObjPtr pool,
>>          virReportError(VIR_ERR_INVALID_ARG,
>>                         _("invalid partition name '%s', expected '%s'"),
>>                         vol->name, partname);
>> +
>> +        /* Let's see if we by chance parthelper created a name that won't be
>> +         * found later when we try to delete. We tell parthelper to add a 'p'
>> +         * to the output via the part_separator flag, but if devmapper has
>> +         * user_friendly_names set, the creation won't happen that way, thus
>> +         * our deletion will fail because the name we generated is wrong.
>> +         * Check for our conditions and see if the generated name is the
>> +         * same as StablePath returns and has the 'p' in it */
>> +        if (pool->def->source.devices[0].part_separator ==
>> +            VIR_TRISTATE_BOOL_YES &&
>> +            !virIsDevMapperDevice(vol->target.path) &&
>> +            STREQ(groups[0], vol->target.path) &&
>> +            (tmp = strrchr(groups[0], 'p'))) {
>> +
>> +            /* If we remove the 'p' from groups[0] and the resulting
>> +             * device is a devmapper device, then we know parthelper
>> +             * was told to create the wrong name based on the results.
>> +             * So just remove the 'p' from the vol->target.path too. */
>> +            memmove(tmp, tmp + 1, strlen(tmp));
>> +            if (virIsDevMapperDevice(groups[0]) &&
>> +                (tmp = strrchr(vol->target.path, 'p')))
>> +                memmove(tmp, tmp + 1, strlen(tmp));
>> +        }
>>          return -1;
>>      }
>>  
>>
> 
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