[libvirt] [PATCH 01/12] qemu: Add a hash table for the shared disks

[Osier Yang]

On 2012年12月13日 01:09, Daniel P. Berrange wrote:
> On Tue, Dec 11, 2012 at 09:37:18PM +0800, Osier Yang wrote:
>> This introduces a hash table for qemu driver, to store the shared
>> disk's info as (@disk_path, {@ref_count, @orig_cdbfilter}). @ref_count
>> is the number of domains which shares the disk. @orig_cdbfilter is
>> the original cdbfilter setting of the shared disk, it will be used
>> to restore the the disk's cdbfilter setting to original value by
>> later patches.
>>
>> * src/qemu/qemu_conf.h: (Add member 'sharedDisks' of type
>>                           virHashTablePtr; New struct qemuSharedDiskEntry;
>>                           Declare helpers qemuAddSharedDisk,
>>                           qemuRemoveSharedDisk)
>> * src/qemu/qemu_conf.c (Implement the two helpers)
>> * src/qemu/qemu_process.c (Update 'sharedDisks' when domain
>>                             starting and shutdown)
>> * src/qemu/qemu_driver.c (Update 'sharedDisks' when attaching
>>                            or detaching disk).
>>
>> 0 is passed for orig_cdbfilter temporarily, later patches will update
>> it.
>> ---
>>   src/qemu/qemu_conf.c    |   48 +++++++++++++++++++++++++++++++++++++++++++++++
>>   src/qemu/qemu_conf.h    |   18 +++++++++++++++++
>>   src/qemu/qemu_driver.c  |   17 ++++++++++++++++
>>   src/qemu/qemu_process.c |   17 +++++++++++++++-
>>   4 files changed, 99 insertions(+), 1 deletions(-)
>>
>> diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
>> index 8d380a1..2b21186 100644
>> --- a/src/qemu/qemu_conf.c
>> +++ b/src/qemu/qemu_conf.c
>> @@ -556,3 +556,51 @@ qemuDriverCloseCallbackRunAll(virQEMUDriverPtr driver,
>>
>>       virHashForEach(driver->closeCallbacks, qemuDriverCloseCallbackRun,&data);
>>   }
>> +
>> +/* Increase ref count if the entry already exists, otherwise
>> + * add a new entry.
>> + */
>> +int
>> +qemuAddSharedDisk(virHashTablePtr sharedDisks,
>> +                  const char *disk_path,
>> +                  int orig_cdbfilter)
>> +{
>> +    qemuSharedDiskEntryPtr entry = NULL;
>> +
>> +    if ((entry = virHashLookup(sharedDisks, disk_path))) {
>> +        entry->ref++;
>> +    } else {
>> +        if (VIR_ALLOC(entry)<  0)
>> +            return -1;
>> +
>> +        entry->ref = 1;
>> +        entry->orig_cdbfilter = orig_cdbfilter;
>> +
>> +        if (virHashAddEntry(sharedDisks, disk_path, entry))
>> +            return -1;
>
> Leaking 'entry' in failure path.

Okay, it's missed when changing the hash value from
only 'ref' count to a struct containing the original
cdbfilter value.

>
>> @@ -6035,6 +6039,12 @@ qemuDomainAttachDeviceDiskLive(virConnectPtr conn,
>>               VIR_WARN("Failed to teardown cgroup for disk path %s",
>>                        NULLSTR(disk->src));
>>       }
>> +
>> +    if (ret == 0&&  disk->shared) {
>> +        if (qemuAddSharedDisk(driver->sharedDisks, disk->src, 0)<  0)
>> +            VIR_WARN("Failed to add disk '%s' to shared disk table",
>> +                     disk->src);
>> +    }
>
> You are not allowed to reference 'disk->src' unless you've validate
> disk->type is FILE or BLOCK.
>
> We only need to track this for TYPE_BLOCK in any case

Oh, right, okay.

>
>
>>   end:
>>       if (cgroup)
>>           virCgroupFree(&cgroup);
>> @@ -6149,6 +6159,13 @@ qemuDomainDetachDeviceDiskLive(virQEMUDriverPtr driver,
>>                          virDomainDiskDeviceTypeToString(disk->type));
>>           break;
>>       }
>> +
>> +    if (ret == 0&&  disk->shared) {
>> +        if (qemuRemoveSharedDisk(driver->sharedDisks, disk->src)<  0)
>> +             VIR_WARN("Failed to remove disk '%s' from shared disk table",
>> +                      disk->src);
>> +    }
>
> Same crash problem here
>
>
>> +
>>       return ret;
>>   }
>>
>> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
>> index ab04599..89152b8 100644
>> --- a/src/qemu/qemu_process.c
>> +++ b/src/qemu/qemu_process.c
>> @@ -3706,8 +3706,15 @@ int qemuProcessStart(virConnectPtr conn,
>>
>>       /* in case a certain disk is desirous of CAP_SYS_RAWIO, add this */
>>       for (i = 0; i<  vm->def->ndisks; i++) {
>> -        if (vm->def->disks[i]->rawio == 1)
>> +        virDomainDiskDefPtr disk = vm->def->disks[i];
>> +
>> +        if (disk->rawio == 1)
>>               virCommandAllowCap(cmd, CAP_SYS_RAWIO);
>> +
>> +        if (disk->shared) {
>> +            if (qemuAddSharedDisk(driver->sharedDisks, disk->src, 0)<  0)
>> +                goto cleanup;
>> +        }
>
>
> And here
>
>>       }
>>
>>       virCommandSetPreExecHook(cmd, qemuProcessHook,&hookData);
>> @@ -4104,6 +4111,14 @@ void qemuProcessStop(virQEMUDriverPtr driver,
>>                                             flags&  VIR_QEMU_PROCESS_STOP_MIGRATED);
>>       virSecurityManagerReleaseLabel(driver->securityManager, vm->def);
>>
>> +    for (i = 0; i<  vm->def->ndisks; i++) {
>> +        virDomainDiskDefPtr disk = vm->def->disks[i];
>> +
>> +        if (disk->shared) {
>> +            ignore_value(qemuRemoveSharedDisk(driver->sharedDisks, disk->src));
>> +        }
>> +    }
>
> And here
>
> Daniel