qemu: Rewrite bitmap handling for block commit

Reuse qemuBlockGetBitmapMergeActions which allows removing the ad-hoc
implementation of bitmap merging for block commit. The new approach is
way simpler and more robust and also allows us to get rid of the
disabling of bitmaps done prior to the start as we actually do want to
update the bitmaps in the base.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

src/qemu/qemu_block.c

@@ -3209,117 +3209,7 @@ qemuBlockBitmapsHandleBlockcopy(virStorageSourcePtr src,
 /**
  * @topsrc: virStorageSource representing 'top' of the job
  * @basesrc: virStorageSource representing 'base' of the job
- * @blockNamedNodeData: hash table containing data about bitmaps
+ * @active: commit job is an active layer block-commit
- * @actions: filled with arguments for a 'transaction' command
- * @disabledBitmapsBase: filled with a list of bitmap names which must be disabled
- *
- * Prepares data for correctly handling bitmaps during the start of a commit
- * job. The bitmaps in the 'base' image must be disabled, so that the writes
- * done by the blockjob don't dirty the enabled bitmaps.
- *
- * @actions and @disabledBitmapsBase are untouched if no bitmaps need
- * to be disabled.
- */
-int
-qemuBlockBitmapsHandleCommitStart(virStorageSourcePtr topsrc,
-                                  virStorageSourcePtr basesrc,
-                                  virHashTablePtr blockNamedNodeData,
-                                  virJSONValuePtr *actions,
-                                  char ***disabledBitmapsBase)
-{
-    g_autoptr(virJSONValue) act = virJSONValueNewArray();
-    VIR_AUTOSTRINGLIST bitmaplist = NULL;
-    size_t curbitmapstr = 0;
-    qemuBlockNamedNodeDataPtr entry;
-    bool disable_bitmaps = false;
-    size_t i;
-
-    if (!(entry = virHashLookup(blockNamedNodeData, basesrc->nodeformat)))
-        return 0;
-
-    bitmaplist = g_new0(char *, entry->nbitmaps + 1);
-
-    for (i = 0; i < entry->nbitmaps; i++) {
-        qemuBlockNamedNodeDataBitmapPtr bitmap = entry->bitmaps[i];
-
-        if (!bitmap->recording || bitmap->inconsistent ||
-            !qemuBlockBitmapChainIsValid(topsrc, bitmap->name, blockNamedNodeData))
-            continue;
-
-        disable_bitmaps = true;
-
-        if (qemuMonitorTransactionBitmapDisable(act, basesrc->nodeformat,
-                                                bitmap->name) < 0)
-            return -1;
-
-        bitmaplist[curbitmapstr++] = g_strdup(bitmap->name);
-    }
-
-    if (disable_bitmaps) {
-        *actions = g_steal_pointer(&act);
-        *disabledBitmapsBase = g_steal_pointer(&bitmaplist);
-    }
-
-    return 0;
-}
-
-
-struct qemuBlockBitmapsHandleCommitData {
-    bool skip;
-    bool create;
-    bool enable;
-    const char *basenode;
-    virJSONValuePtr merge;
-    unsigned long long granularity;
-    bool persistent;
-};
-
-
-static void
-qemuBlockBitmapsHandleCommitDataFree(void *opaque)
-{
-    struct qemuBlockBitmapsHandleCommitData *data = opaque;
-
-    virJSONValueFree(data->merge);
-    g_free(data);
-}
-
-
-static int
-qemuBlockBitmapsHandleCommitFinishIterate(void *payload,
-                                          const void *entryname,
-                                          void *opaque)
-{
-    struct qemuBlockBitmapsHandleCommitData *data = payload;
-    const char *bitmapname = entryname;
-    virJSONValuePtr actions = opaque;
-
-    if (data->skip)
-        return 0;
-
-    if (data->create) {
-        if (qemuMonitorTransactionBitmapAdd(actions, data->basenode, bitmapname,
-                                            data->persistent, !data->enable,
-                                            data->granularity) < 0)
-            return -1;
-    } else {
-        if (data->enable &&
-            qemuMonitorTransactionBitmapEnable(actions, data->basenode, bitmapname) < 0)
-            return -1;
-    }
-
-    if (data->merge &&
-        qemuMonitorTransactionBitmapMerge(actions, data->basenode, bitmapname,
-                                          &data->merge) < 0)
-        return -1;
-
-    return 0;
-}
-
-
-/**
- * @topsrc: virStorageSource representing 'top' of the job
- * @basesrc: virStorageSource representing 'base' of the job
  * @blockNamedNodeData: hash table containing data about bitmaps
  * @actions: filled with arguments for a 'transaction' command
  * @disabledBitmapsBase: bitmap names which were disabled
@@ -3332,95 +3222,20 @@ qemuBlockBitmapsHandleCommitFinishIterate(void *payload,
 int
 qemuBlockBitmapsHandleCommitFinish(virStorageSourcePtr topsrc,
                                    virStorageSourcePtr basesrc,
+                                   bool active,
                                    virHashTablePtr blockNamedNodeData,
-                                   virJSONValuePtr *actions,
+                                   virJSONValuePtr *actions)
-                                   char **disabledBitmapsBase)
 {
-    g_autoptr(virJSONValue) act = virJSONValueNewArray();
+    virStorageSourcePtr writebitmapsrc = NULL;
-    virStorageSourcePtr n;
-    qemuBlockNamedNodeDataPtr entry;
-    g_autoptr(virHashTable) commitdata = NULL;
-    struct qemuBlockBitmapsHandleCommitData *bitmapdata;
-    size_t i;
 
-    commitdata = virHashNew(qemuBlockBitmapsHandleCommitDataFree);
+    if (active)
+        writebitmapsrc = basesrc;
 
-    for (n = topsrc; n != basesrc; n = n->backingStore) {
+    if (qemuBlockGetBitmapMergeActions(topsrc, basesrc, basesrc, NULL, NULL,
-        if (!(entry = virHashLookup(blockNamedNodeData, n->nodeformat)))
+                                       writebitmapsrc, actions,
-            continue;
+                                       blockNamedNodeData) < 0)
-
-        for (i = 0; i < entry->nbitmaps; i++) {
-            qemuBlockNamedNodeDataBitmapPtr bitmap = entry->bitmaps[i];
-
-            if (!(bitmapdata = virHashLookup(commitdata, bitmap->name))) {
-                bitmapdata = g_new0(struct qemuBlockBitmapsHandleCommitData, 1);
-
-                /* we must mirror the state of the topmost bitmap and merge
-                 * everything else */
-                bitmapdata->create = true;
-                bitmapdata->enable = bitmap->recording;
-                bitmapdata->basenode = basesrc->nodeformat;
-                bitmapdata->merge = virJSONValueNewArray();
-                bitmapdata->granularity = bitmap->granularity;
-                bitmapdata->persistent = bitmap->persistent;
-
-                if (virHashAddEntry(commitdata, bitmap->name, bitmapdata) < 0) {
-                    qemuBlockBitmapsHandleCommitDataFree(bitmapdata);
-                    return -1;
-                }
-            }
-
-            if (bitmap->inconsistent ||
-                !qemuBlockBitmapChainIsValid(topsrc, bitmap->name, blockNamedNodeData))
-                bitmapdata->skip = true;
-
-            if (qemuMonitorTransactionBitmapMergeSourceAddBitmap(bitmapdata->merge,
-                                                                 n->nodeformat,
-                                                                 bitmap->name) < 0)
-                return -1;
-        }
-    }
-
-    if ((entry = virHashLookup(blockNamedNodeData, basesrc->nodeformat))) {
-        /* note that all bitmaps in 'base' were disabled when commit was started */
-        for (i = 0; i < entry->nbitmaps; i++) {
-            qemuBlockNamedNodeDataBitmapPtr bitmap = entry->bitmaps[i];
-
-            if ((bitmapdata = virHashLookup(commitdata, bitmap->name))) {
-                bitmapdata->create = false;
-            } else {
-                if (disabledBitmapsBase) {
-                    char **disabledbitmaps;
-
-                    for (disabledbitmaps = disabledBitmapsBase; *disabledbitmaps; disabledbitmaps++) {
-                        if (STREQ(*disabledbitmaps, bitmap->name)) {
-                            bitmapdata = g_new0(struct qemuBlockBitmapsHandleCommitData, 1);
-
-                            bitmapdata->create = false;
-                            bitmapdata->enable = true;
-                            bitmapdata->basenode = basesrc->nodeformat;
-                            bitmapdata->granularity = bitmap->granularity;
-                            bitmapdata->persistent = bitmap->persistent;
-
-                            if (virHashAddEntry(commitdata, bitmap->name, bitmapdata) < 0) {
-                                qemuBlockBitmapsHandleCommitDataFree(bitmapdata);
-                                return -1;
-                            }
-
-                            break;
-                        }
-                    }
-                }
-            }
-        }
-    }
-
-    if (virHashForEach(commitdata, qemuBlockBitmapsHandleCommitFinishIterate, act) < 0)
         return -1;
 
-    if (virJSONValueArraySize(act) > 0)
-        *actions = g_steal_pointer(&act);
-
     return 0;
 }
 

src/qemu/qemu_block.h

@@ -243,19 +243,12 @@ qemuBlockBitmapsHandleBlockcopy(virStorageSourcePtr src,
                                 bool shallow,
                                 virJSONValuePtr *actions);
 
-int
-qemuBlockBitmapsHandleCommitStart(virStorageSourcePtr topsrc,
-                                  virStorageSourcePtr basesrc,
-                                  virHashTablePtr blockNamedNodeData,
-                                  virJSONValuePtr *actions,
-                                  char ***disabledBitmapsBase);
-
 int
 qemuBlockBitmapsHandleCommitFinish(virStorageSourcePtr topsrc,
                                    virStorageSourcePtr basesrc,
+                                   bool active,
                                    virHashTablePtr blockNamedNodeData,
-                                   virJSONValuePtr *actions,
+                                   virJSONValuePtr *actions);
-                                   char **disabledBitmapsBase);
 
 int
 qemuBlockReopenReadWrite(virDomainObjPtr vm,

src/qemu/qemu_blockjob.c

@@ -1069,6 +1069,7 @@ qemuBlockJobProcessEventCompletedCommitBitmaps(virDomainObjPtr vm,
     qemuDomainObjPrivatePtr priv = vm->privateData;
     g_autoptr(virHashTable) blockNamedNodeData = NULL;
     g_autoptr(virJSONValue) actions = NULL;
+    bool active = job->type == QEMU_BLOCKJOB_TYPE_ACTIVE_COMMIT;
 
     if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKDEV_REOPEN))
         return 0;
@@ -1078,16 +1079,18 @@ qemuBlockJobProcessEventCompletedCommitBitmaps(virDomainObjPtr vm,
 
     if (qemuBlockBitmapsHandleCommitFinish(job->data.commit.top,
                                            job->data.commit.base,
+                                           active,
                                            blockNamedNodeData,
-                                           &actions,
+                                           &actions) < 0)
-                                           job->data.commit.disabledBitmapsBase) < 0)
         return 0;
 
     if (!actions)
         return 0;
 
-    if (qemuBlockReopenReadWrite(vm, job->data.commit.base, asyncJob) < 0)
+    if (!active) {
-        return -1;
+        if (qemuBlockReopenReadWrite(vm, job->data.commit.base, asyncJob) < 0)
+            return -1;
+    }
 
     if (qemuDomainObjEnterMonitorAsync(priv->driver, vm, asyncJob) < 0)
         return -1;
@@ -1097,8 +1100,10 @@ qemuBlockJobProcessEventCompletedCommitBitmaps(virDomainObjPtr vm,
     if (qemuDomainObjExitMonitor(priv->driver, vm) < 0)
         return -1;
 
-    if (qemuBlockReopenReadOnly(vm, job->data.commit.base, asyncJob) < 0)
+    if (!active) {
-        return -1;
+        if (qemuBlockReopenReadOnly(vm, job->data.commit.base, asyncJob) < 0)
+            return -1;
+    }
 
     return 0;
 }
@@ -1268,6 +1273,9 @@ qemuBlockJobProcessEventCompletedActiveCommit(virQEMUDriverPtr driver,
     job->disk->src = job->data.commit.base;
     job->disk->src->readonly = job->data.commit.top->readonly;
 
+    if (qemuBlockJobProcessEventCompletedCommitBitmaps(vm, job, asyncJob) < 0)
+        return;
+
     qemuBlockJobEventProcessConcludedRemoveChain(driver, vm, asyncJob, job->data.commit.top);
 
     if (job->data.commit.deleteCommittedImages)
@@ -1339,6 +1347,7 @@ qemuBlockJobProcessEventFailedActiveCommit(virQEMUDriverPtr driver,
                                            virDomainObjPtr vm,
                                            qemuBlockJobDataPtr job)
 {
+    g_autoptr(virJSONValue) actions = virJSONValueNewArray();
     virDomainDiskDefPtr disk = job->disk;
 
     VIR_DEBUG("active commit job '%s' on VM '%s' failed", job->name, vm->def->name);
@@ -1346,6 +1355,10 @@ qemuBlockJobProcessEventFailedActiveCommit(virQEMUDriverPtr driver,
     if (!disk)
         return;
 
+    ignore_value(qemuMonitorTransactionBitmapRemove(actions, disk->mirror->nodeformat,
+                                                    "libvirt-tmp-activewrite"));
+
+
     /* Ideally, we would make the backing chain read only again (yes, SELinux
      * can do that using different labels). But that is not implemented yet and
      * not leaking security driver metadata is more important. */

src/qemu/qemu_driver.c

@@ -17379,9 +17379,9 @@ qemuDomainBlockPivot(virQEMUDriverPtr driver,
 
     case QEMU_BLOCKJOB_TYPE_COPY:
         if (blockdev && !job->jobflagsmissing) {
-            g_autoptr(virHashTable) blockNamedNodeData = NULL;
             bool shallow = job->jobflags & VIR_DOMAIN_BLOCK_COPY_SHALLOW;
             bool reuse = job->jobflags & VIR_DOMAIN_BLOCK_COPY_REUSE_EXT;
+            g_autoptr(virHashTable) blockNamedNodeData = NULL;
 
             if (!(blockNamedNodeData = qemuBlockGetNamedNodeData(vm, QEMU_ASYNC_JOB_NONE)))
                 return -1;
@@ -17419,16 +17419,15 @@ qemuDomainBlockPivot(virQEMUDriverPtr driver,
          * the bitmaps if it wasn't present thus must skip this */
         if (blockdev &&
             virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKDEV_REOPEN)) {
-            g_autoptr(virHashTable) blockNamedNodeData = NULL;
 
-            if (!(blockNamedNodeData = qemuBlockGetNamedNodeData(vm, QEMU_ASYNC_JOB_NONE)))
+            actions = virJSONValueNewArray();
-                return -1;
 
-            if (qemuBlockBitmapsHandleCommitFinish(job->data.commit.top,
+            if (qemuMonitorTransactionBitmapAdd(actions,
-                                                   job->data.commit.base,
+                                                job->data.commit.base->nodeformat,
-                                                   blockNamedNodeData,
+                                                "libvirt-tmp-activewrite",
-                                                   &actions,
+                                                false,
-                                                   job->data.commit.disabledBitmapsBase) < 0)
+                                                false,
+                                                0) < 0)
                 return -1;
         }
 
@@ -18549,7 +18548,6 @@ qemuDomainBlockCommit(virDomainPtr dom,
     const char *nodebase = NULL;
     bool persistjob = false;
     bool blockdev = false;
-    g_autoptr(virJSONValue) bitmapDisableActions = NULL;
     VIR_AUTOSTRINGLIST bitmapDisableList = NULL;
 
     virCheckFlags(VIR_DOMAIN_BLOCK_COMMIT_SHALLOW |
@@ -18714,27 +18712,6 @@ qemuDomainBlockCommit(virDomainPtr dom,
             goto endjob;
     }
 
-    if (blockdev &&
-        virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_BLOCKDEV_REOPEN)) {
-        g_autoptr(virHashTable) blockNamedNodeData = NULL;
-        if (!(blockNamedNodeData = qemuBlockGetNamedNodeData(vm, QEMU_ASYNC_JOB_NONE)))
-            goto endjob;
-
-        if (qemuBlockBitmapsHandleCommitStart(topSource, baseSource,
-                                              blockNamedNodeData,
-                                              &bitmapDisableActions,
-                                              &bitmapDisableList) < 0)
-            goto endjob;
-
-        /* if we don't have terminator on 'base' we can't reopen it */
-        if (bitmapDisableActions && !baseSource->backingStore) {
-            virReportError(VIR_ERR_OPERATION_UNSUPPORTED,
-                           _("can't handle bitmaps on unterminated backing image '%s'"),
-                           base);
-            goto endjob;
-        }
-    }
-
     if (!(job = qemuBlockJobDiskNewCommit(vm, disk, top_parent, topSource,
                                           baseSource, &bitmapDisableList,
                                           flags & VIR_DOMAIN_BLOCK_COMMIT_DELETE,
@@ -18759,23 +18736,6 @@ qemuDomainBlockCommit(virDomainPtr dom,
             !(backingPath = qemuBlockGetBackingStoreString(baseSource, false)))
             goto endjob;
 
-        if (bitmapDisableActions) {
-            int rc;
-
-            if (qemuBlockReopenReadWrite(vm, baseSource, QEMU_ASYNC_JOB_NONE) < 0)
-                goto endjob;
-
-            qemuDomainObjEnterMonitor(driver, vm);
-            rc = qemuMonitorTransaction(priv->mon, &bitmapDisableActions);
-            if (qemuDomainObjExitMonitor(driver, vm) < 0)
-                goto endjob;
-
-            if (qemuBlockReopenReadOnly(vm, baseSource, QEMU_ASYNC_JOB_NONE) < 0)
-                goto endjob;
-
-            if (rc < 0)
-                goto endjob;
-        }
     } else {
         device = job->name;
     }

tests/qemublocktest.c

@@ -928,12 +928,11 @@ testQemuBlockBitmapBlockcommit(const void *opaque)
 
     g_autofree char *actual = NULL;
     g_autofree char *expectpath = NULL;
-    g_autoptr(virJSONValue) actionsDisable = NULL;
     g_autoptr(virJSONValue) actionsMerge = NULL;
     g_autoptr(virJSONValue) nodedatajson = NULL;
     g_autoptr(virHashTable) nodedata = NULL;
     g_auto(virBuffer) buf = VIR_BUFFER_INITIALIZER;
-    VIR_AUTOSTRINGLIST bitmapsDisable = NULL;
+    bool active = data->top == data->chain;
 
     expectpath = g_strdup_printf("%s/%s%s", abs_srcdir,
                                  blockcommitPrefix, data->name);
@@ -947,20 +946,10 @@ testQemuBlockBitmapBlockcommit(const void *opaque)
         return -1;
     }
 
-    if (qemuBlockBitmapsHandleCommitStart(data->top, data->base, nodedata,
-                                          &actionsDisable, &bitmapsDisable) < 0)
-        return -1;
-
-    virBufferAddLit(&buf, "pre job bitmap disable:\n");
-
-    if (actionsDisable &&
-        virJSONValueToBuffer(actionsDisable, &buf, true) < 0)
-        return -1;
-
     virBufferAddLit(&buf, "merge bitmpas:\n");
 
-    if (qemuBlockBitmapsHandleCommitFinish(data->top, data->base, nodedata,
+    if (qemuBlockBitmapsHandleCommitFinish(data->top, data->base, active, nodedata,
-                                           &actionsMerge, bitmapsDisable) < 0)
+                                           &actionsMerge) < 0)
         return -1;
 
     if (actionsMerge &&
@@ -1357,6 +1346,7 @@ mymain(void)
 #define TEST_BITMAP_BLOCKCOMMIT(testname, topimg, baseimg, ndf) \
     do {\
         blockbitmapblockcommitdata.name = testname; \
+        blockbitmapblockcommitdata.chain = bitmapSourceChain; \
         blockbitmapblockcommitdata.top = testQemuBitmapGetFakeChainEntry(bitmapSourceChain, topimg); \
         blockbitmapblockcommitdata.base = testQemuBitmapGetFakeChainEntry(bitmapSourceChain, baseimg); \
         blockbitmapblockcommitdata.nodedatafile = ndf; \

tests/qemublocktestdata/bitmapblockcommit/empty

@@ -1,2 +1 @@
-pre job bitmap disable:
 merge bitmpas: