qemu: block: Implement helpers for dealing with bitmaps during block commit

qemuBlockBitmapsHandleCommitStart prepares for disabling the bitmaps in
the 'base' of the commit job so that the bitmaps are not dirtied by the
commit job. This needs to be done prior to start of the commit job.

qemuBlockBitmapsHandleCommitFinish then calculates the necessary merges
that agregate all the bitmaps between the commited images and write them
into the base bitmap.

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

diff --git a/src/qemu/qemu_block.c b/src/qemu/qemu_block.c
index 9e41578a6e8e87310390aa6661b1f3d8e97f7e9b..cc2edff5e0cdc8a02dcbb4a0eed3eefe693489f1 100644 (file)
--- a/src/qemu/qemu_block.c
+++ b/src/qemu/qemu_block.c
@@ -2990,6 +2990,225 @@ qemuBlockBitmapsHandleBlockcopy(virStorageSourcePtr src,
 }
 
 
+/**
+ * @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: 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);
+
+    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
+ *
+ * Calculates the necessary bitmap merges/additions/enablements to properly
+ * handle commit of images from 'top' into 'base'. The necessary operations
+ * in the form of arguments of the 'transaction' command are filled into
+ * 'actions' if there is anything to do. Otherwise NULL is returned.
+ */
+int
+qemuBlockBitmapsHandleCommitFinish(virStorageSourcePtr topsrc,
+                                   virStorageSourcePtr basesrc,
+                                   virHashTablePtr blockNamedNodeData,
+                                   virJSONValuePtr *actions,
+                                   char **disabledBitmapsBase)
+{
+    g_autoptr(virJSONValue) act = virJSONValueNewArray();
+    virStorageSourcePtr n;
+    qemuBlockNamedNodeDataPtr entry;
+    g_autoptr(virHashTable) commitdata = NULL;
+    struct qemuBlockBitmapsHandleCommitData *bitmapdata;
+    size_t i;
+
+    commitdata = virHashNew(qemuBlockBitmapsHandleCommitDataFree);
+
+    for (n = topsrc; n != basesrc; n = n->backingStore) {
+        if (!(entry = virHashLookup(blockNamedNodeData, n->nodeformat)))
+            continue;
+
+        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(*disabledBitmapsBase, 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;
+}
+
+
 /**
  * qemuBlockReopenFormat:
  * @vm: domain object

diff --git a/src/qemu/qemu_block.h b/src/qemu/qemu_block.h
index e012052352b2193007a0293b71d7be0f6c4c8b86..75b25bfea5b3e924acfaa693ad09e14480f8d63c 100644 (file)
--- a/src/qemu/qemu_block.h
+++ b/src/qemu/qemu_block.h
@@ -232,6 +232,20 @@ 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,
+                                   virHashTablePtr blockNamedNodeData,
+                                   virJSONValuePtr *actions,
+                                   char **disabledBitmapsBase);
+
 int
 qemuBlockReopenReadWrite(virDomainObjPtr vm,
                          virStorageSourcePtr src,