Re: [libvirt] [PATCH 09/10] qemu: Add -blockdev support for external snapshots

[Ján Tomko]

On Fri, Aug 16, 2019 at 03:54:43PM +0200, Peter Krempa wrote:

Use the code for creating or attaching new storage source in the
snapshot code and switch to 'blockdev-snapshot' for creating the
snapshot itself.

Signed-off-by: Peter Krempa 
---
src/qemu/qemu_driver.c | 104 ++---
1 file changed, 88 insertions(+), 16 deletions(-)



Reviewed-by: Ján Tomko 

Jano


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[libvirt] [PATCH 09/10] qemu: Add -blockdev support for external snapshots

[Peter Krempa]

Use the code for creating or attaching new storage source in the
snapshot code and switch to 'blockdev-snapshot' for creating the
snapshot itself.

Signed-off-by: Peter Krempa 
---
 src/qemu/qemu_driver.c | 104 ++---
 1 file changed, 88 insertions(+), 16 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 6e10b691e9..c22f74adaa 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -15270,6 +15270,8 @@ struct _qemuDomainSnapshotDiskData {
 bool prepared; /* @src was prepared using 
qemuDomainStorageSourceAccessAllow */
 virDomainDiskDefPtr disk;
 char *relPath; /* relative path component to fill into original disk */
+qemuBlockStorageSourceChainDataPtr crdata;
+bool blockdevadded;

 virStorageSourcePtr persistsrc;
 virDomainDiskDefPtr persistdisk;
@@ -15283,7 +15285,8 @@ static void
 qemuDomainSnapshotDiskDataCleanup(qemuDomainSnapshotDiskDataPtr data,
   size_t ndata,
   virQEMUDriverPtr driver,
-  virDomainObjPtr vm)
+  virDomainObjPtr vm,
+  qemuDomainAsyncJob asyncJob)
 {
 size_t i;

@@ -15294,6 +15297,15 @@ 
qemuDomainSnapshotDiskDataCleanup(qemuDomainSnapshotDiskDataPtr data,
 /* on success of the snapshot the 'src' and 'persistsrc' properties 
will
  * be set to NULL by qemuDomainSnapshotUpdateDiskSources */
 if (data[i].src) {
+if (data[i].blockdevadded) {
+if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) == 0) 
{
+
+
qemuBlockStorageSourceAttachRollback(qemuDomainGetMonitor(vm),
+ 
data[i].crdata->srcdata[0]);
+ignore_value(qemuDomainObjExitMonitor(driver, vm));
+}
+}
+
 if (data[i].created &&
 virStorageFileUnlink(data[i].src) < 0) {
 VIR_WARN("Unable to remove just-created %s",
@@ -15312,6 +15324,7 @@ 
qemuDomainSnapshotDiskDataCleanup(qemuDomainSnapshotDiskDataPtr data,
 VIR_FREE(data[i].relPath);
 }

+qemuBlockStorageSourceChainDataFree(data[i].crdata);
 VIR_FREE(data);
 }

@@ -15319,15 +15332,20 @@ 
qemuDomainSnapshotDiskDataCleanup(qemuDomainSnapshotDiskDataPtr data,
 static int
 qemuDomainSnapshotDiskDataCollectOne(virQEMUDriverPtr driver,
  virDomainObjPtr vm,
+ virQEMUDriverConfigPtr cfg,
  virDomainDiskDefPtr disk,
  virDomainSnapshotDiskDefPtr snapdisk,
  qemuDomainSnapshotDiskDataPtr dd,
- bool reuse)
+ bool reuse,
+ bool blockdev,
+ qemuDomainAsyncJob asyncJob)
 {
+qemuDomainObjPrivatePtr priv = vm->privateData;
 char *backingStoreStr;
 virDomainDiskDefPtr persistdisk;
 bool supportsCreate;
 bool supportsBacking;
+int rc;

 dd->disk = disk;

@@ -15393,6 +15411,44 @@ qemuDomainSnapshotDiskDataCollectOne(virQEMUDriverPtr 
driver,

 dd->prepared = true;

+if (blockdev) {
+/* create a terminator for the snapsot disks so that qemu does not try
+ * to open them at first */
+virObjectUnref(dd->src->backingStore);
+if (!(dd->src->backingStore = virStorageSourceNew()))
+return -1;
+
+if (qemuDomainPrepareStorageSourceBlockdev(dd->disk, dd->src,
+   priv, cfg) < 0)
+return -1;
+
+if (!(dd->crdata = 
qemuBuildStorageSourceChainAttachPrepareBlockdevTop(dd->src,
+   
priv->qemuCaps)))
+return -1;
+
+if (reuse) {
+if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) < 0)
+return -1;
+
+rc = qemuBlockStorageSourceAttachApply(qemuDomainGetMonitor(vm),
+   dd->crdata->srcdata[0]);
+
+if (qemuDomainObjExitMonitor(driver, vm) < 0 || rc < 0)
+return -1;
+} else {
+if (qemuBlockStorageSourceCreateDetectSize(vm, dd->src, 
dd->disk->src,
+   asyncJob) < 0)
+return -1;
+
+if (qemuBlockStorageSourceCreate(vm, dd->src, dd->disk->src,
+ NULL, dd->crdata->srcdata[0],
+ asyncJob) < 0)
+return -1;
+}
+
+dd->blockdevadded = true;
+}
+
 return 0;
 }

@@ -15407,7 +15463,10 @@ static int