On 09/12/2012 09:22 AM, Guannan Ren wrote:
After failure of qemu transaction command, the snapshot file still be there with non-zero in size. In order to unlink the file, the patch removes the file size checking.
Can you give some exact steps to reproduce this, so that I know who is making the file have non-zero size? I'm worried that unlinking a non-empty file is discarding data, so the commit message needs a lot more details about how we are proving that the only way the file can be non-zero size is because qemu happened to put data into a previously empty file prior to the failed 'transaction' attempt. That is, after re-reading context code just now, I'm fairly confident that this code can only be reached when qemu supports the 'transaction' monitor command, and libvirt's --reuse-ext flag was not specified, and therefore libvirt must have just created the file. But I want that in the commit message rather than having to re-read the code every time I visit this commit in future reads of the git log. It may also be that qemu has a bug in that the 'transaction' command is modifying files even when it fails, so even while this works around the bug, I'm cc'ing Jeff to see if qemu also needs a bug fix.
--- src/qemu/qemu_driver.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 8e8e00c..1fedfb8 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -10833,7 +10833,7 @@ qemuDomainSnapshotUndoSingleDiskActive(struct qemud_driver *driver, if (virDomainLockDiskDetach(driver->lockManager, vm, disk) < 0) VIR_WARN("Unable to release lock on %s", disk->src); if (need_unlink && stat(disk->src, &st) == 0 && - st.st_size == 0 && S_ISREG(st.st_mode) && unlink(disk->src) < 0) + S_ISREG(st.st_mode) && unlink(disk->src) < 0) VIR_WARN("Unable to remove just-created %s", disk->src);
/* Update vm in place to match changes. */
-- Eric Blake eblake@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org