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qemu: snapshot: Improve approach to deal with snapshot metadata

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Until now we were changing information about the disk source via
multiple steps of copying data. Now that we changed to a pointer to
store the disk source we might use it to change the approach to track
the data.

Additionally this will allow proper tracking of the backing chain.
This commit is contained in:
Peter Krempa 2014-06-12 16:57:43 +02:00
parent 4cc1f1a01f
commit 363e9a68d4
1 changed files with 35 additions and 89 deletions
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124
src/qemu/qemu_driver.c
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@ -12836,14 +12836,11 @@ qemuDomainSnapshotCreateSingleDiskActive(virQEMUDriverPtr driver,
qemuDomainAsyncJob asyncJob)
{
qemuDomainObjPrivatePtr priv = vm->privateData;
virStorageSourcePtr newDiskSrc = NULL;
virStorageSourcePtr persistDiskSrc = NULL;
char *device = NULL;
char *source = NULL;
char *newsource = NULL;
virStorageNetHostDefPtr newhosts = NULL;
virStorageNetHostDefPtr persistHosts = NULL;
int format = snap->src->format;
const char *formatStr = NULL;
char *persistSource = NULL;
int ret = -1;
int fd = -1;
bool need_unlink = false;
@ -12857,26 +12854,27 @@ qemuDomainSnapshotCreateSingleDiskActive(virQEMUDriverPtr driver,
if (virAsprintf(&device, "drive-%s", disk->info.alias) < 0)
goto cleanup;
/* XXX Here, we know we are about to alter disk->src->backingStore if
* successful, so we nuke the existing chain so that future commands will
* recompute it. Better would be storing the chain ourselves rather than
* reprobing, but this requires modifying domain_conf and our XML to fully
* track the chain across libvirtd restarts. */
virStorageSourceBackingStoreClear(disk->src);
if (virStorageFileInit(snap->src) < 0)
goto cleanup;
if (qemuGetDriveSourceString(snap->src, NULL, &source) < 0)
goto cleanup;
if (VIR_STRDUP(newsource, snap->src->path) < 0)
if (!(newDiskSrc = virStorageSourceCopy(snap->src, false)))
goto cleanup;
if (persistDisk &&
VIR_STRDUP(persistSource, snap->src->path) < 0)
if (virStorageSourceInitChainElement(newDiskSrc, disk->src, false) < 0)
goto cleanup;
if (persistDisk) {
if (!(persistDiskSrc = virStorageSourceCopy(snap->src, false)))
goto cleanup;
if (virStorageSourceInitChainElement(persistDiskSrc, persistDisk->src,
false) < 0)
goto cleanup;
}
switch ((virStorageType)snap->src->type) {
case VIR_STORAGE_TYPE_BLOCK:
case VIR_STORAGE_TYPE_FILE:
@ -12902,15 +12900,6 @@ qemuDomainSnapshotCreateSingleDiskActive(virQEMUDriverPtr driver,
case VIR_STORAGE_TYPE_NETWORK:
switch (snap->src->protocol) {
case VIR_STORAGE_NET_PROTOCOL_GLUSTER:
if (!(newhosts = virStorageNetHostDefCopy(snap->src->nhosts,
snap->src->hosts)))
goto cleanup;
if (persistDisk &&
!(persistHosts = virStorageNetHostDefCopy(snap->src->nhosts,
snap->src->hosts)))
goto cleanup;
break;
default:
@ -12961,45 +12950,24 @@ qemuDomainSnapshotCreateSingleDiskActive(virQEMUDriverPtr driver,
/* Update vm in place to match changes. */
need_unlink = false;
VIR_FREE(disk->src->path);
virStorageNetHostDefFree(disk->src->nhosts, disk->src->hosts);
disk->src->path = newsource;
disk->src->format = format;
disk->src->type = snap->src->type;
disk->src->protocol = snap->src->protocol;
disk->src->nhosts = snap->src->nhosts;
disk->src->hosts = newhosts;
newsource = NULL;
newhosts = NULL;
newDiskSrc->backingStore = disk->src;
disk->src = newDiskSrc;
newDiskSrc = NULL;
if (persistDisk) {
VIR_FREE(persistDisk->src->path);
virStorageNetHostDefFree(persistDisk->src->nhosts,
persistDisk->src->hosts);
persistDisk->src->path = persistSource;
persistDisk->src->format = format;
persistDisk->src->type = snap->src->type;
persistDisk->src->protocol = snap->src->protocol;
persistDisk->src->nhosts = snap->src->nhosts;
persistDisk->src->hosts = persistHosts;
persistSource = NULL;
persistHosts = NULL;
persistDiskSrc->backingStore = persistDisk->src;
persistDisk->src = persistDiskSrc;
persistDiskSrc = NULL;
}
cleanup:
if (need_unlink && virStorageFileUnlink(snap->src))
VIR_WARN("unable to unlink just-created %s", source);
virStorageFileDeinit(snap->src);
virStorageSourceFree(newDiskSrc);
virStorageSourceFree(persistDiskSrc);
VIR_FREE(device);
VIR_FREE(source);
VIR_FREE(newsource);
VIR_FREE(persistSource);
virStorageNetHostDefFree(snap->src->nhosts, newhosts);
virStorageNetHostDefFree(snap->src->nhosts, persistHosts);
return ret;
}
@ -13009,21 +12977,15 @@ qemuDomainSnapshotCreateSingleDiskActive(virQEMUDriverPtr driver,
static void
qemuDomainSnapshotUndoSingleDiskActive(virQEMUDriverPtr driver,
virDomainObjPtr vm,
virDomainDiskDefPtr origdisk,
virDomainDiskDefPtr disk,
virDomainDiskDefPtr persistDisk,
bool need_unlink)
{
char *source = NULL;
char *persistSource = NULL;
virStorageSourcePtr tmp;
struct stat st;
ignore_value(virStorageFileInit(disk->src));
if (VIR_STRDUP(source, origdisk->src->path) < 0 ||
(persistDisk && VIR_STRDUP(persistSource, source) < 0))
goto cleanup;
qemuDomainPrepareDiskChainElement(driver, vm, disk, disk->src,
VIR_DISK_CHAIN_NO_ACCESS);
if (need_unlink &&
@ -13031,35 +12993,20 @@ qemuDomainSnapshotUndoSingleDiskActive(virQEMUDriverPtr driver,
virStorageFileUnlink(disk->src) < 0)
VIR_WARN("Unable to remove just-created %s", disk->src->path);
/* Update vm in place to match changes. */
VIR_FREE(disk->src->path);
disk->src->path = source;
source = NULL;
disk->src->format = origdisk->src->format;
disk->src->type = origdisk->src->type;
disk->src->protocol = origdisk->src->protocol;
virStorageNetHostDefFree(disk->src->nhosts, disk->src->hosts);
disk->src->nhosts = origdisk->src->nhosts;
disk->src->hosts = virStorageNetHostDefCopy(origdisk->src->nhosts,
origdisk->src->hosts);
if (persistDisk) {
VIR_FREE(persistDisk->src->path);
persistDisk->src->path = persistSource;
persistSource = NULL;
persistDisk->src->format = origdisk->src->format;
persistDisk->src->type = origdisk->src->type;
persistDisk->src->protocol = origdisk->src->protocol;
virStorageNetHostDefFree(persistDisk->src->nhosts,
persistDisk->src->hosts);
persistDisk->src->nhosts = origdisk->src->nhosts;
persistDisk->src->hosts = virStorageNetHostDefCopy(origdisk->src->nhosts,
origdisk->src->hosts);
}
cleanup:
virStorageFileDeinit(disk->src);
VIR_FREE(source);
VIR_FREE(persistSource);
/* Update vm in place to match changes. */
tmp = disk->src;
disk->src = tmp->backingStore;
tmp->backingStore = NULL;
virStorageSourceFree(tmp);
if (persistDisk) {
tmp = persistDisk->src;
persistDisk->src = tmp->backingStore;
tmp->backingStore = NULL;
virStorageSourceFree(tmp);
}
}
/* The domain is expected to be locked and active. */
@ -13163,7 +13110,6 @@ qemuDomainSnapshotCreateDiskActive(virQEMUDriverPtr driver,
}
qemuDomainSnapshotUndoSingleDiskActive(driver, vm,
snap->def->dom->disks[i],
vm->def->disks[i],
persistDisk,
need_unlink);