From c9c9405687b78713b913c09113697fcadec1cdba Mon Sep 17 00:00:00 2001 Message-ID: From: Pavel Hrdina Date: Wed, 26 Feb 2025 11:04:52 +0100 Subject: [PATCH] qemu: snapshot: error out early when reverting snapshot for VM with non-file disk Before this patch the code would start the revert process by destroying the VM and preparing to revert where it would fail with following error: error: unsupported configuration: source for disk 'sdb' is not a regular file; refusing to generate external snapshot name and leaving user with offline VM even if it was running. Make the check before we start the revert process to not destroy VMs. Resolves: https://issues.redhat.com/browse/RHEL-30971 Resolves: https://issues.redhat.com/browse/RHEL-79928 Signed-off-by: Pavel Hrdina Reviewed-by: Peter Krempa (cherry picked from commit 278b8334eb26aa9495f6d37e4f72471cbc8739a6) Signed-off-by: Pavel Hrdina --- src/qemu/qemu_snapshot.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/src/qemu/qemu_snapshot.c b/src/qemu/qemu_snapshot.c index 3a8510c69e..16d3aaf6e7 100644 --- a/src/qemu/qemu_snapshot.c +++ b/src/qemu/qemu_snapshot.c @@ -2190,6 +2190,8 @@ qemuSnapshotRevertValidate(virDomainObj *vm, virDomainSnapshotDef *snapdef, unsigned int flags) { + size_t i; + if (!vm->persistent && snapdef->state != VIR_DOMAIN_SNAPSHOT_RUNNING && snapdef->state != VIR_DOMAIN_SNAPSHOT_PAUSED && @@ -2217,6 +2219,22 @@ qemuSnapshotRevertValidate(virDomainObj *vm, } } + /* Reverting to external snapshot creates overlay files for every disk and + * it would fail for non-file based disks. + * See qemuSnapshotRevertExternalPrepare for more details. */ + if (virDomainSnapshotIsExternal(snap)) { + for (i = 0; i < snap->def->dom->ndisks; i++) { + virDomainDiskDef *disk = snap->def->dom->disks[i]; + + if (disk->src->type != VIR_STORAGE_TYPE_FILE) { + virReportError(VIR_ERR_OPERATION_UNSUPPORTED, + _("source disk for '%1$s' is not a regular file, reverting to snapshot is not supported"), + disk->dst); + return -1; + } + } + } + return 0; } @@ -2368,6 +2386,9 @@ qemuSnapshotRevertExternalPrepare(virDomainObj *vm, if (virDomainMomentDefPostParse(&tmpsnapdef->parent) < 0) return -1; + /* Force default location to be external in order to create overlay files + * for every disk. In qemuSnapshotRevertValidate we make sure that each + * disk is regular file otherwise this would fail. */ if (virDomainSnapshotAlignDisks(tmpsnapdef, domdef, VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL, false, true) < 0) { -- 2.48.1