[libvirt] [PATCH] storage: Flush host cache after write

[Michal Privoznik]

On 18.08.2011 15:55, Eric Blake wrote:
> On 08/18/2011 07:44 AM, Michal Privoznik wrote:
>> Although we are flushing cache after some critical writes (e.g.
>> volume creation), after some others we do not (e.g. volume cloning).
>> This patch fix this issue. That is for volume cloning, writing
>> header of logical volume, and storage wipe.
>> ---
>>   src/storage/storage_backend.c         |    8 ++++++++
>>   src/storage/storage_backend_logical.c |    7 +++++++
>>   src/storage/storage_driver.c          |    8 ++++++++
>>   3 files changed, 23 insertions(+), 0 deletions(-)
>>
>> diff --git a/src/storage/storage_backend.c
>> b/src/storage/storage_backend.c
>> index 6243d1e..889f530 100644
>> --- a/src/storage/storage_backend.c
>> +++ b/src/storage/storage_backend.c
>> @@ -208,6 +208,14 @@ virStorageBackendCopyToFD(virStorageVolDefPtr vol,
>>           } while ((amtleft -= interval)>  0);
>>       }
>>
>> +    if (fdatasync(fd)<  0) {
> 
> Why fdatasync here,
Here we need to flush data but not metadata.
> 
> 
>> +++ b/src/storage/storage_backend_logical.c
>> @@ -424,6 +424,13 @@ virStorageBackendLogicalBuildPool(virConnectPtr
>> conn ATTRIBUTE_UNUSED,
>>               VIR_FORCE_CLOSE(fd);
>>               goto cleanup;
>>           }
>> +        if (fsync(fd)<  0) {
> 
> but only fsync here?
>
Here we are accessing logical volume where we want to make sure anybody
(including LVM) will read data & metadata.