[libvirt] [RFC PATCH 5/5] qemu: snapshot: Improve approach to deal with snapshot metadata
Peter Krempa
pkrempa at redhat.com
Thu Jun 12 15:02:19 UTC 2014
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.
---
src/qemu/qemu_driver.c | 108 +++++++++----------------------------------------
1 file changed, 19 insertions(+), 89 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index e147d28..92abdc9 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -12842,14 +12842,10 @@ qemuDomainSnapshotCreateSingleDiskActive(virQEMUDriverPtr driver,
enum qemuDomainAsyncJob asyncJob)
{
qemuDomainObjPrivatePtr priv = vm->privateData;
+ virStorageSourcePtr tmp;
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;
@@ -12863,26 +12859,12 @@ 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. */
- virStorageSourceClearBackingStore(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)
- goto cleanup;
-
- if (persistDisk &&
- VIR_STRDUP(persistSource, snap->src->path) < 0)
- goto cleanup;
-
switch ((virStorageType)snap->src->type) {
case VIR_STORAGE_TYPE_BLOCK:
reuse = true;
@@ -12910,15 +12892,6 @@ 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:
@@ -12969,33 +12942,18 @@ 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;
+ if (!(tmp = virStorageSourceCopy(snap->src, false)))
+ goto cleanup;
- newsource = NULL;
- newhosts = NULL;
+ tmp->backingStore = disk->src;
+ disk->src = tmp;
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;
+ if (!(tmp = virStorageSourceCopy(snap->src, false)))
+ goto cleanup;
- persistSource = NULL;
- persistHosts = NULL;
+ tmp->backingStore = persistDisk->src;
+ persistDisk->src = tmp;
}
cleanup:
@@ -13004,10 +12962,6 @@ qemuDomainSnapshotCreateSingleDiskActive(virQEMUDriverPtr driver,
virStorageFileDeinit(snap->src);
VIR_FREE(device);
VIR_FREE(source);
- VIR_FREE(newsource);
- VIR_FREE(persistSource);
- virStorageNetHostDefFree(snap->src->nhosts, newhosts);
- virStorageNetHostDefFree(snap->src->nhosts, persistHosts);
return ret;
}
@@ -13017,21 +12971,15 @@ 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 &&
@@ -13039,35 +12987,18 @@ qemuDomainSnapshotUndoSingleDiskActive(virQEMUDriverPtr driver,
virStorageFileUnlink(disk->src) < 0)
VIR_WARN("Unable to remove just-created %s", disk->src->path);
+ virStorageFileDeinit(disk->src);
+
/* 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);
+ tmp = disk->src->backingStore;
+ virStorageSourceFree(disk->src);
+ disk->src = tmp;
+
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);
+ tmp = persistDisk->src->backingStore;
+ virStorageSourceFree(persistDisk->src);
+ persistDisk->src = tmp;
}
-
- cleanup:
- virStorageFileDeinit(disk->src);
- VIR_FREE(source);
- VIR_FREE(persistSource);
}
/* The domain is expected to be locked and active. */
@@ -13170,7 +13101,6 @@ qemuDomainSnapshotCreateDiskActive(virQEMUDriverPtr driver,
}
qemuDomainSnapshotUndoSingleDiskActive(driver, vm,
- snap->def->dom->disks[i],
vm->def->disks[i],
persistDisk,
need_unlink);
--
1.9.3
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