Re: [libvirt] [PATCH] qemu: update disk chain in vm->newDef when block job compeleted

On 11/10/14 05:15, weiwei li wrote: > A bug will be hitted with libvirt+qemu+kvm when doing follow steps: > 1.initial status :vm = base+z(z is a snapshot) > 2. call snapshotCreateXML( ): vm = base+z +z' > 3. call blockRebase( ): vm = base+z''(z rebase to z') > 4.(after rebasing work done) vm shutdown and then start > > an error occured like this: > "unable to set user and group to '0:0' on ' > /path/to/disk': No such file or directory > > A second start may sucess. > > The error message reported by virSecurityDACSetSecurityDiskLabel > when the disk chain is misused(that is base+z +z', after rebase, > but z' was deleted yet).virSecurityDACSetSecurityDiskLabel used > an old disk chain after rebasing. > In qemuProcessHandleBlockJob when rebase complete, the disk chain > in vm->def is updated but vm->newDef is not(when vm->newDef is not > null). In shutdown( actrully in qemuProcessStop ), if vm->newDef > is not null , vm->def will be replaced by vm->newDef, which > contains a wrong disk chain!!! Then the next start will failed with > above message. > To fix it, update disk chain in vm->newDef in qemuProcessHandleBlockJob. > > Signed-off-by: Weiwei Li <nuonuoli(a)tencent.com > <mailto:nuonuoli@tencent.com>> > --- > src/qemu/qemu_process.c | 27 +++++++++++++++++++++++++++ > 1 files changed, 27 insertions(+), 0 deletions(-) Since commit: commit fe7ef7b112b3b4d6f9c9edf499a79683fb0b7edb Author: Peter Krempa <pkrempa(a)redhat.com&gt; AuthorDate: Thu Sep 25 17:30:28 2014 +0200 Commit: Peter Krempa <pkrempa(a)redhat.com&gt; CommitDate: Fri Sep 26 09:35:33 2014 +0200 qemu: Always re-detect backing chain Since 363e9a68 we track backing chain metadata when creating snapshots the right way even for the inactive configuration. As we did not yet update other code paths that modify the backing chain (blockpull) the newDef backing chain gets out of sync. After stopping of a VM the new definition gets copied to the next start one. The new VM then has incorrect backing chain info. This patch switches the backing chain detector to always purge the existing backing chain and forces re-detection to avoid this issue until we'll have full backing chain tracking support. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1144922 diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index 11145d1..76fccce 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -2540,7 +2540,7 @@ qemuDomainCheckDiskPresence(virQEMUDriverPtr driver, virFileExists(virDomainDiskGetSource(disk))) continue; - if (qemuDomainDetermineDiskChain(driver, vm, disk, false, true) >= 0) + if (qemuDomainDetermineDiskChain(driver, vm, disk, true, true) >= 0) continue; if (disk->startupPolicy && thus your symptoms shouldn't show up. Could you please verify that the situation you've described happens