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

On Thu, Aug 18, 2011 at 04:25:55PM +0200, Michal Privoznik wrote: > 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. thanks for the explanation, ACK then ! Daniel