Hi Daniel, On Thu, Jul 16, 2009 at 7:46 PM, Daniel P. Berrange <berrange@redhat.com>wrote:
On Thu, Jul 16, 2009 at 06:06:25AM -0700, Harshavardhana wrote:
New option index added to support -o options for various netfs. Currently added an option for glusterfs.
What effect does it have ? Or why do we want/need it
Options could be required for filesystem to have few enhaced handling at the site where they will be under use. Correct approach for a configurable will be a new "XML" option in this case. Regarding current patch: This is required for the glusterfs to work properly with VM's. Right now there is a problem/difficulty in using direct-io based mechanism in the fuse kernel module when used with "XEN" in its "tap:aio" framework, we have seen xen vms hang over glusterfs or any fuse based filesystem due to fact that fuse module doesn't yet support "aio" with O_DIRECT internally as a kernel module. To have a work around fix we have to hardcode this value due to its usage in case of VM's. We are currently fixing this problem by fixing directly O_DIRECT problem in fuse. Which will be available in later releases for kernel. So its just a glusterfs specific case.
@@ -670,6 +692,12 @@ virStorageBackendFileSystemMount(virConnectPtr conn, }
if (pool->def->type == VIR_STORAGE_POOL_NETFS) { + if (pool->def->source.format = VIR_STORAGE_POOL_NETFS_GLUSTERFS) { + if (virAsprintf(&options, "direct-io-mode=1") == -1) { + virReportOOMError(conn); + return -1; + } + }
Normally direct-IO mode is something you'd let apps set on a per file basis as they desire. QEMU / Xen both know todo this, so I'm not convinced we should force it on for the whole mount point.
Regards, Daniel -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/:| |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org:| |: http://autobuild.org -o- http://search.cpan.org/~danberr/<http://search.cpan.org/%7Edanberr/>:| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|