From 29d77d1a64d4d6f1ee0dbf7c205393aa49269531 Mon Sep 17 00:00:00 2001 From: Peter Krempa Date: Mon, 3 Feb 2025 15:45:49 +0100 Subject: [PATCH] qemu: snapshot: Limit scope of checkpoint-snapshot interlock MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 'qemuDomainSupportsCheckpointsBlockjobs()' should really be used only with active VMs based on the scope of interlocking it does. This means that the inactive snapshot code path needs to do the interlocking based on what's supported: - external snapshot support was not implemented yet (bitmaps need to be propagated to the new overlay image) - internal snapshot support can be deferred to qemu Move the check inside qemuSnapshotPrepare() which has knowledge about the snapshot type and implement an explicit check for the inactive case. See: https://gitlab.com/libvirt/libvirt/-/issues/739 Signed-off-by: Peter Krempa Reviewed-by: Ján Tomko --- src/qemu/qemu_snapshot.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/src/qemu/qemu_snapshot.c b/src/qemu/qemu_snapshot.c index ed140dd41c..f7d6272907 100644 --- a/src/qemu/qemu_snapshot.c +++ b/src/qemu/qemu_snapshot.c @@ -39,6 +39,7 @@ #include "domain_audit.h" #include "locking/domain_lock.h" #include "virdomainsnapshotobjlist.h" +#include "virdomaincheckpointobjlist.h" #include "virqemu.h" #include "storage_source.h" @@ -1080,6 +1081,23 @@ qemuSnapshotPrepare(virDomainObj *vm, } + /* Handle interlocking with 'checkpoints': + * - if the VM is online use qemuDomainSupportsCheckpointsBlockjobs + * - if the VM is offline disallow external snapshots as the support for + * propagating bitmaps into the would-be-created overlay is not yet implemented + */ + if (!active) { + if (external && + virDomainListCheckpoints(vm->checkpoints, NULL, NULL, NULL, 0) > 0) { + virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s", + _("support for offline external snapshots while checkpoint exists was not yet implemented")); + return -1; + } + } else { + if (qemuDomainSupportsCheckpointsBlockjobs(vm) < 0) + return -1; + } + /* Alter flags to let later users know what we learned. */ if (external && !active) *flags |= VIR_DOMAIN_SNAPSHOT_CREATE_DISK_ONLY; @@ -2147,9 +2165,6 @@ qemuSnapshotCreateXML(virDomainPtr domain, VIR_DOMAIN_SNAPSHOT_CREATE_REDEFINE, NULL); - if (qemuDomainSupportsCheckpointsBlockjobs(vm) < 0) - return NULL; - if (!vm->persistent && (flags & VIR_DOMAIN_SNAPSHOT_CREATE_HALT)) { virReportError(VIR_ERR_OPERATION_INVALID, "%s", _("cannot halt after transient domain snapshot"));