resovled it, this is because in the kernel 2.6.32; the 9pfs doesn't implement the fsync function. just back port the code from higher version, can resolve it.
like this patch https://gitorious.org/linux- gemini/mainline/commit/7a4439c406c21b1e900ed497cec1a79d05b38c07 ** Changed in: qemu Assignee: (unassigned) => chchen (cc272309126) -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1280961 Title: editing the file when mount the file system using 9pfs. it will report fsync failed. Status in QEMU: New Bug description: I have get a fsync error when I use the 9pfs on the kvm guest. it appears when I use vi editor and sysbench. I have not found the reason yet. can you tell something about it? the attache is the picture. and there is no any log which I can provide. My qemu version is qemu-kvm-0.13.0, and my host linux distributions is 2.6.32-431.el6.x86_64 and the guest vm is the same version which enable 9pfs and 9pnet support. I use the string of "mount -t 9p -o trans=virtio test_mount /tmp/shared/ -oversion=9p2000.L,posixacl" to get the file system. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1280961/+subscriptions