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[libvirt] [PATCH v1 4/5] qemu_migration: Send disk sizes to the other side



Up 'til now, users need to precreate non-shared storage on migration
themselves. This is not very friendly requirement and we should do
something about it. In this patch, the migration cookie is extended,
so that <nbd/> section does not only contain NBD port, but info on
disks being migrated. This patch sends a list of pairs of:

    <disk target; disk size>

to the destination. The actual storage allocation is left for next
commit.

Signed-off-by: Michal Privoznik <mprivozn redhat com>
---
 src/qemu/qemu_migration.c | 180 +++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 161 insertions(+), 19 deletions(-)

diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index a1b1458..d4b3acf 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -141,6 +141,10 @@ typedef struct _qemuMigrationCookieNBD qemuMigrationCookieNBD;
 typedef qemuMigrationCookieNBD *qemuMigrationCookieNBDPtr;
 struct _qemuMigrationCookieNBD {
     int port; /* on which port does NBD server listen for incoming data */
+
+    size_t ndisks;  /* Number of items in @target and @alloc arrays */
+    char **target;  /* Disk target */
+    size_t *alloc;  /* And its allocation */
 };
 
 typedef struct _qemuMigrationCookie qemuMigrationCookie;
@@ -206,6 +210,19 @@ qemuMigrationCookieNetworkFree(qemuMigrationCookieNetworkPtr network)
 }
 
 
+static void qemuMigrationCookieNBDFree(qemuMigrationCookieNBDPtr nbd)
+{
+    if (!nbd)
+        return;
+
+    while (nbd->ndisks)
+        VIR_FREE(nbd->target[--nbd->ndisks]);
+    VIR_FREE(nbd->target);
+    VIR_FREE(nbd->alloc);
+    VIR_FREE(nbd);
+}
+
+
 static void qemuMigrationCookieFree(qemuMigrationCookiePtr mig)
 {
     if (!mig)
@@ -213,13 +230,13 @@ static void qemuMigrationCookieFree(qemuMigrationCookiePtr mig)
 
     qemuMigrationCookieGraphicsFree(mig->graphics);
     qemuMigrationCookieNetworkFree(mig->network);
+    qemuMigrationCookieNBDFree(mig->nbd);
 
     VIR_FREE(mig->localHostname);
     VIR_FREE(mig->remoteHostname);
     VIR_FREE(mig->name);
     VIR_FREE(mig->lockState);
     VIR_FREE(mig->lockDriver);
-    VIR_FREE(mig->nbd);
     VIR_FREE(mig->jobInfo);
     VIR_FREE(mig);
 }
@@ -523,18 +540,86 @@ qemuMigrationCookieAddNetwork(qemuMigrationCookiePtr mig,
 }
 
 
+/**
+ * qemuMigrationGetDiskSize:
+ * @disk: disk to query
+ * @alloc: disk size in bytes
+ *
+ * For given disk get its image size.
+ *
+ * Returns: 0 on success,
+ *         -1 on failure,
+ *          1 if disk size doesn't matter
+ */
+static int
+qemuMigrationGetDiskSize(virQEMUDriverPtr driver,
+                         virDomainObjPtr vm,
+                         virDomainDiskDefPtr disk,
+                         size_t *alloc)
+{
+    int ret = -1;
+    virDomainBlockInfo info;
+
+    if (!virStorageSourceIsLocalStorage(disk->src) ||
+        !disk->src->path)
+        return 1;
+
+    if (qemuDomainGetBlockInfoImpl(driver, vm, disk,
+                                   &info, disk->src->path) < 0)
+        goto cleanup;
+
+    *alloc = info.capacity;
+    ret = 0;
+ cleanup:
+    return ret;
+}
+
+
 static int
 qemuMigrationCookieAddNBD(qemuMigrationCookiePtr mig,
-                          virQEMUDriverPtr driver ATTRIBUTE_UNUSED,
+                          virQEMUDriverPtr driver,
                           virDomainObjPtr vm)
 {
     qemuDomainObjPrivatePtr priv = vm->privateData;
+    size_t i;
 
     /* It is not a bug if there already is a NBD data */
     if (!mig->nbd &&
         VIR_ALLOC(mig->nbd) < 0)
         return -1;
 
+    if (vm->def->ndisks &&
+        (VIR_ALLOC_N(mig->nbd->target, vm->def->ndisks) < 0 ||
+         VIR_ALLOC_N(mig->nbd->alloc, vm->def->ndisks) < 0))
+        return -1;
+    mig->nbd->ndisks = 0;
+
+    for (i = 0; i < vm->def->ndisks; i++) {
+        virDomainDiskDefPtr disk = vm->def->disks[i];
+        int rc;
+        size_t alloc;
+
+        /* skip shared, RO and source-less disks */
+        if (disk->src->shared || disk->src->readonly ||
+            !virDomainDiskGetSource(disk))
+            continue;
+
+        if ((rc = qemuMigrationGetDiskSize(driver, vm, disk, &alloc)) < 0) {
+            /* error reported */
+            return -1;
+        } else if (rc > 0) {
+            /* Don't add this disk */
+            continue;
+        }
+
+        if (VIR_STRDUP(mig->nbd->target[mig->nbd->ndisks],
+                       disk->dst) < 0)
+            return -1;
+
+        mig->nbd->alloc[mig->nbd->ndisks] = alloc;
+        mig->nbd->ndisks++;
+    }
+
     mig->nbd->port = priv->nbdPort;
     mig->flags |= QEMU_MIGRATION_COOKIE_NBD;
 
@@ -763,7 +848,18 @@ qemuMigrationCookieXMLFormat(virQEMUDriverPtr driver,
         virBufferAddLit(buf, "<nbd");
         if (mig->nbd->port)
             virBufferAsprintf(buf, " port='%d'", mig->nbd->port);
-        virBufferAddLit(buf, "/>\n");
+        if (mig->nbd->ndisks) {
+            virBufferAddLit(buf, ">\n");
+            virBufferAdjustIndent(buf, 2);
+            for (i = 0; i < mig->nbd->ndisks; i++)
+                virBufferAsprintf(buf, "<disk target='%s' alloc='%zu'/>\n",
+                                  mig->nbd->target[i],
+                                  mig->nbd->alloc[i]);
+            virBufferAdjustIndent(buf, -2);
+            virBufferAddLit(buf, "</nbd>\n");
+        } else {
+            virBufferAddLit(buf, "/>\n");
+        }
     }
 
     if (mig->flags & QEMU_MIGRATION_COOKIE_STATS && mig->jobInfo)
@@ -891,6 +987,65 @@ qemuMigrationCookieNetworkXMLParse(xmlXPathContextPtr ctxt)
 }
 
 
+static qemuMigrationCookieNBDPtr
+qemuMigrationCookieNBDXMLParse(xmlXPathContextPtr ctxt)
+{
+    qemuMigrationCookieNBDPtr ret = NULL;
+    char *port = NULL, *alloc = NULL;
+    size_t i;
+    int n;
+    xmlNodePtr *disks = NULL;
+    xmlNodePtr save_ctxt = ctxt->node;
+
+    if (VIR_ALLOC(ret) < 0)
+        goto error;
+
+    port = virXPathString("string(./nbd/@port)", ctxt);
+    if (port && virStrToLong_i(port, NULL, 10, &ret->port) < 0) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Malformed nbd port '%s'"),
+                       port);
+        goto error;
+    }
+
+    /* Now check if source sent a list of disks to prealloc. We might be
+     * talking to an older server, so it's not an error if the list is
+     * missing. */
+    if ((n = virXPathNodeSet("./nbd/disk", ctxt, &disks)) > 0) {
+        if (VIR_ALLOC_N(ret->target, n) < 0 ||
+            VIR_ALLOC_N(ret->alloc, n) < 0)
+            goto error;
+        ret->ndisks = n;
+
+        for (i = 0; i < n; i++) {
+            ctxt->node = disks[i];
+            VIR_FREE(alloc);
+
+            ret->target[i] = virXPathString("string(./@target)", ctxt);
+            alloc = virXPathString("string(./@alloc)", ctxt);
+            if (virStrToLong_ull(alloc, NULL, 10, (unsigned long long *)
+                                 &ret->alloc[i]) < 0) {
+                virReportError(VIR_ERR_INTERNAL_ERROR,
+                               _("Malformed disk allocation: '%s'"),
+                               alloc);
+                goto error;
+            }
+        }
+    }
+
+ cleanup:
+    VIR_FREE(port);
+    VIR_FREE(alloc);
+    VIR_FREE(disks);
+    ctxt->node = save_ctxt;
+    return ret;
+ error:
+    qemuMigrationCookieNBDFree(ret);
+    ret = NULL;
+    goto cleanup;
+}
+
+
 static qemuDomainJobInfoPtr
 qemuMigrationCookieStatisticsXMLParse(xmlXPathContextPtr ctxt)
 {
@@ -1123,22 +1278,9 @@ qemuMigrationCookieXMLParse(qemuMigrationCookiePtr mig,
         goto error;
 
     if (flags & QEMU_MIGRATION_COOKIE_NBD &&
-        virXPathBoolean("boolean(./nbd)", ctxt)) {
-        char *port;
-
-        if (VIR_ALLOC(mig->nbd) < 0)
-            goto error;
-
-        port = virXPathString("string(./nbd/@port)", ctxt);
-        if (port && virStrToLong_i(port, NULL, 10, &mig->nbd->port) < 0) {
-            virReportError(VIR_ERR_INTERNAL_ERROR,
-                           _("Malformed nbd port '%s'"),
-                           port);
-            VIR_FREE(port);
-            goto error;
-        }
-        VIR_FREE(port);
-    }
+        virXPathBoolean("boolean(./nbd)", ctxt) &&
+        (!(mig->nbd = qemuMigrationCookieNBDXMLParse(ctxt))))
+        goto error;
 
     if (flags & QEMU_MIGRATION_COOKIE_STATS &&
         virXPathBoolean("boolean(./statistics)", ctxt) &&
-- 
2.0.4


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