From a1c6dd1700b461d84c6db3d62468c60f4e3b0a55 Mon Sep 17 00:00:00 2001

Message-Id: <a1c6dd1700b461d84c6db3d62468c60f4e3b0a55@dist-git>

From: Peter Krempa <pkrempa@redhat.com>

Date: Tue, 20 Jun 2017 14:45:38 +0200

Subject: [PATCH] qemu: snapshot: Load data necessary for relative block commit

 to work

Commit 7456c4f5f introduced a regression by not reloading the backing

chain of a disk after snapshot. The regression was caused as

src->relPath was not set and thus the block commit code could not

determine the relative path.

This patch adds code that will load the backing store string if

VIR_DOMAIN_SNAPSHOT_CREATE_REUSE_EXT and store it in the correct place

when a snapshot is successfully completed.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1461303

(cherry picked from commit e20853e1d32ff517e6feec3146066ec433fc39e6)

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>

Reviewed-by: Pavel Hrdina <phrdina@redhat.com>

---

 src/qemu/qemu_driver.c | 19 +++++++++++++++++--

 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c

index c7c5e28ca3..a2fb41b91a 100644

--- a/src/qemu/qemu_driver.c

+++ b/src/qemu/qemu_driver.c

@@ -14094,6 +14094,7 @@ struct _qemuDomainSnapshotDiskData {

     bool created; /* @src was created by the snapshot code */

     bool prepared; /* @src was prepared using qemuDomainDiskChainElementPrepare */

     virDomainDiskDefPtr disk;

+    char *relPath; /* relative path component to fill into original disk */

     virStorageSourcePtr persistsrc;

     virDomainDiskDefPtr persistdisk;

@@ -14127,6 +14128,7 @@ qemuDomainSnapshotDiskDataFree(qemuDomainSnapshotDiskDataPtr data,

             virStorageSourceFree(data[i].src);

         }

         virStorageSourceFree(data[i].persistsrc);

+        VIR_FREE(data[i].relPath);

     }

     VIR_FREE(data);

@@ -14142,11 +14144,13 @@ qemuDomainSnapshotDiskDataFree(qemuDomainSnapshotDiskDataPtr data,

 static qemuDomainSnapshotDiskDataPtr

 qemuDomainSnapshotDiskDataCollect(virQEMUDriverPtr driver,

                                   virDomainObjPtr vm,

-                                  virDomainSnapshotObjPtr snap)

+                                  virDomainSnapshotObjPtr snap,

+                                  bool reuse)

 {

     size_t i;

     qemuDomainSnapshotDiskDataPtr ret;

     qemuDomainSnapshotDiskDataPtr dd;

+    char *backingStoreStr;

     if (VIR_ALLOC_N(ret, snap->def->ndisks) < 0)

         return NULL;

@@ -14170,6 +14174,16 @@ qemuDomainSnapshotDiskDataCollect(virQEMUDriverPtr driver,

         dd->initialized = true;

+        /* relative backing store paths need to be updated so that relative

+         * block commit still works */

+        if (reuse &&

+            (backingStoreStr = virStorageFileGetBackingStoreStr(dd->src))) {

+            if (virStorageIsRelative(backingStoreStr))

+                VIR_STEAL_PTR(dd->relPath, backingStoreStr);

+            else

+                VIR_FREE(backingStoreStr);

+        }

+

         /* Note that it's unsafe to assume that the disks in the persistent

          * definition match up with the disks in the live definition just by

          * checking that the target name is the same. We've done that

@@ -14213,6 +14227,7 @@ qemuDomainSnapshotUpdateDiskSources(qemuDomainSnapshotDiskDataPtr dd,

     if (dd->initialized)

         virStorageFileDeinit(dd->src);

+    VIR_STEAL_PTR(dd->disk->src->relPath, dd->relPath);

     VIR_STEAL_PTR(dd->src->backingStore, dd->disk->src);

     VIR_STEAL_PTR(dd->disk->src, dd->src);

@@ -14326,7 +14341,7 @@ qemuDomainSnapshotCreateDiskActive(virQEMUDriverPtr driver,

     /* prepare a list of objects to use in the vm definition so that we don't

      * have to roll back later */

-    if (!(diskdata = qemuDomainSnapshotDiskDataCollect(driver, vm, snap)))

+    if (!(diskdata = qemuDomainSnapshotDiskDataCollect(driver, vm, snap, reuse)))

         goto cleanup;

     cfg = virQEMUDriverGetConfig(driver);

-- 

2.13.1