[libvirt RFCv11 21/33] qemu: migration: implement qemuMigrationSrcToFilesMultiFd for save

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implement a function similar to qemuMigrationSrcToFile
that migrates to multiple files using QEMU multifd, and use it
for VIR_DOMAIN_SAVE_PARALLEL saves.

Signed-off-by: Claudio Fontana <cfontana@xxxxxxx>
---
 src/qemu/qemu_migration.c | 131 +++++++++++++++++++++++++-------------
 src/qemu/qemu_migration.h |   7 ++
 src/qemu/qemu_saveimage.c |   8 ++-
 3 files changed, 98 insertions(+), 48 deletions(-)

diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index f130ccbe26..fa6cddcc59 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -5875,13 +5875,14 @@ qemuMigrationDstFinish(virQEMUDriver *driver,
     return dom;
 }
 
-
 /* Helper function called while vm is active.  */
-int
-qemuMigrationSrcToFile(virQEMUDriver *driver, virDomainObj *vm,
-                       int fd,
-                       virCommand *compressor,
-                       virDomainAsyncJob asyncJob)
+static int
+qemuMigrationSrcToFileAux(virQEMUDriver *driver, virDomainObj *vm,
+                          int fd,
+                          virCommand *compressor,
+                          virDomainAsyncJob asyncJob,
+                          const char *sun_path,
+                          int nchannels)
 {
     qemuDomainObjPrivate *priv = vm->privateData;
     bool bwParam = virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_MIGRATION_PARAM_BANDWIDTH);
@@ -5892,24 +5893,26 @@ qemuMigrationSrcToFile(virQEMUDriver *driver, virDomainObj *vm,
     char *errbuf = NULL;
     virErrorPtr orig_err = NULL;
     g_autoptr(qemuMigrationParams) migParams = NULL;
+    bool needParams = (bwParam || sun_path);
 
+    if (sun_path && !virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_MIGRATE_MULTIFD)) {
+        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                       _("QEMU does not seem to support multifd migration, required for parallel migration to files"));
+        return -1;
+    }
     if (qemuMigrationSetDBusVMState(driver, vm) < 0)
         return -1;
 
     /* Increase migration bandwidth to unlimited since target is a file.
      * Failure to change migration speed is not fatal. */
-    if (bwParam) {
-        if (!(migParams = qemuMigrationParamsNew()))
-            return -1;
+    if (needParams && !((migParams = qemuMigrationParamsNew())))
+        return -1;
 
+    if (bwParam) {
         if (qemuMigrationParamsSetULL(migParams,
                                       QEMU_MIGRATION_PARAM_MAX_BANDWIDTH,
                                       QEMU_DOMAIN_MIG_BANDWIDTH_MAX * 1024 * 1024) < 0)
             return -1;
-
-        if (qemuMigrationParamsApply(driver, vm, asyncJob, migParams) < 0)
-            return -1;
-
         priv->migMaxBandwidth = QEMU_DOMAIN_MIG_BANDWIDTH_MAX;
     } else {
         if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) == 0) {
@@ -5920,6 +5923,17 @@ qemuMigrationSrcToFile(virQEMUDriver *driver, virDomainObj *vm,
         }
     }
 
+    if (sun_path) {
+        qemuMigrationParamsSetCap(migParams, QEMU_MIGRATION_CAP_MULTIFD);
+        if (qemuMigrationParamsSetInt(migParams,
+                                      QEMU_MIGRATION_PARAM_MULTIFD_CHANNELS,
+                                      nchannels) < 0)
+            return -1;
+    }
+
+    if (needParams && qemuMigrationParamsApply(driver, vm, asyncJob, migParams) < 0)
+        return -1;
+
     if (!virDomainObjIsActive(vm)) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                        _("guest unexpectedly quit"));
@@ -5927,45 +5941,53 @@ qemuMigrationSrcToFile(virQEMUDriver *driver, virDomainObj *vm,
         return -1;
     }
 
-    if (compressor && virPipe(pipeFD) < 0)
+    if (!sun_path && compressor && virPipe(pipeFD) < 0)
         return -1;
 
-    /* All right! We can use fd migration, which means that qemu
-     * doesn't have to open() the file, so while we still have to
-     * grant SELinux access, we can do it on fd and avoid cleanup
-     * later, as well as skip futzing with cgroup.  */
-    if (qemuSecuritySetImageFDLabel(driver->securityManager, vm->def,
-                                    compressor ? pipeFD[1] : fd) < 0)
-        goto cleanup;
-
     if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) < 0)
         goto cleanup;
 
-    if (!compressor) {
-        rc = qemuMonitorMigrateToFd(priv->mon,
-                                    QEMU_MONITOR_MIGRATE_BACKGROUND,
-                                    fd);
+    if (sun_path) {
+        rc = qemuMonitorMigrateToSocket(priv->mon,
+                                        QEMU_MONITOR_MIGRATE_BACKGROUND,
+                                        sun_path);
     } else {
-        virCommandSetInputFD(compressor, pipeFD[0]);
-        virCommandSetOutputFD(compressor, &fd);
-        virCommandSetErrorBuffer(compressor, &errbuf);
-        virCommandDoAsyncIO(compressor);
-        if (virSetCloseExec(pipeFD[1]) < 0) {
-            virReportSystemError(errno, "%s",
-                                 _("Unable to set cloexec flag"));
-            qemuDomainObjExitMonitor(vm);
-            goto cleanup;
-        }
-        if (virCommandRunAsync(compressor, NULL) < 0) {
-            qemuDomainObjExitMonitor(vm);
+        /*
+         * All right! We can use fd migration, which means that qemu
+         * doesn't have to open() the file, so while we still have to
+         * grant SELinux access, we can do it on fd and avoid cleanup
+         * later, as well as skip futzing with cgroup.
+         */
+        if (qemuSecuritySetImageFDLabel(driver->securityManager, vm->def,
+                                        compressor ? pipeFD[1] : fd) < 0)
             goto cleanup;
+
+        if (!compressor) {
+            rc = qemuMonitorMigrateToFd(priv->mon,
+                                        QEMU_MONITOR_MIGRATE_BACKGROUND,
+                                        fd);
+        } else {
+            virCommandSetInputFD(compressor, pipeFD[0]);
+            virCommandSetOutputFD(compressor, &fd);
+            virCommandSetErrorBuffer(compressor, &errbuf);
+            virCommandDoAsyncIO(compressor);
+            if (virSetCloseExec(pipeFD[1]) < 0) {
+                virReportSystemError(errno, "%s",
+                                     _("Unable to set cloexec flag"));
+                qemuDomainObjExitMonitor(vm);
+                goto cleanup;
+            }
+            if (virCommandRunAsync(compressor, NULL) < 0) {
+                qemuDomainObjExitMonitor(vm);
+                goto cleanup;
+            }
+            rc = qemuMonitorMigrateToFd(priv->mon,
+                                        QEMU_MONITOR_MIGRATE_BACKGROUND,
+                                        pipeFD[1]);
+            if (VIR_CLOSE(pipeFD[0]) < 0 ||
+                VIR_CLOSE(pipeFD[1]) < 0)
+                VIR_WARN("failed to close intermediate pipe");
         }
-        rc = qemuMonitorMigrateToFd(priv->mon,
-                                    QEMU_MONITOR_MIGRATE_BACKGROUND,
-                                    pipeFD[1]);
-        if (VIR_CLOSE(pipeFD[0]) < 0 ||
-            VIR_CLOSE(pipeFD[1]) < 0)
-            VIR_WARN("failed to close intermediate pipe");
     }
     qemuDomainObjExitMonitor(vm);
     if (rc < 0)
@@ -5986,7 +6008,7 @@ qemuMigrationSrcToFile(virQEMUDriver *driver, virDomainObj *vm,
         goto cleanup;
     }
 
-    if (compressor && virCommandWait(compressor, NULL) < 0)
+    if (!sun_path && compressor && virCommandWait(compressor, NULL) < 0)
         goto cleanup;
 
     qemuDomainEventEmitJobCompleted(driver, vm);
@@ -6025,6 +6047,25 @@ qemuMigrationSrcToFile(virQEMUDriver *driver, virDomainObj *vm,
     return ret;
 }
 
+int
+qemuMigrationSrcToFile(virQEMUDriver *driver, virDomainObj *vm,
+                       int fd,
+                       virCommand *compressor,
+                       virDomainAsyncJob asyncJob)
+{
+    return qemuMigrationSrcToFileAux(driver, vm, fd, compressor,
+                                     asyncJob, NULL, -1);
+}
+
+int
+qemuMigrationSrcToFilesMultiFd(virQEMUDriver *driver, virDomainObj *vm,
+                               virDomainAsyncJob asyncJob,
+                               const char *sun_path,
+                               int nchannels)
+{
+    return qemuMigrationSrcToFileAux(driver, vm, -1, NULL,
+                                     asyncJob, sun_path, nchannels);
+}
 
 int
 qemuMigrationSrcCancel(virQEMUDriver *driver,
diff --git a/src/qemu/qemu_migration.h b/src/qemu/qemu_migration.h
index a8afa66119..ddc8e65489 100644
--- a/src/qemu/qemu_migration.h
+++ b/src/qemu/qemu_migration.h
@@ -213,6 +213,13 @@ qemuMigrationSrcToFile(virQEMUDriver *driver,
                        virDomainAsyncJob asyncJob)
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) G_GNUC_WARN_UNUSED_RESULT;
 
+int
+qemuMigrationSrcToFilesMultiFd(virQEMUDriver *driver, virDomainObj *vm,
+                               virDomainAsyncJob asyncJob,
+                               const char *sun_path,
+                               int nchannels)
+    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) G_GNUC_WARN_UNUSED_RESULT;
+
 int
 qemuMigrationSrcCancel(virQEMUDriver *driver,
                        virDomainObj *vm);
diff --git a/src/qemu/qemu_saveimage.c b/src/qemu/qemu_saveimage.c
index 7d8527596a..8abb919459 100644
--- a/src/qemu/qemu_saveimage.c
+++ b/src/qemu/qemu_saveimage.c
@@ -578,8 +578,11 @@ qemuSaveImageCreate(virQEMUDriver *driver,
         oflags |= O_DIRECT;
     }
 
-    if (virQEMUSaveFdInit(&saveFd, path, oflags, cfg, false) < 0)
+    if (virQEMUSaveFdInit(&saveFd, path, oflags, cfg, flags & VIR_DOMAIN_SAVE_PARALLEL) < 0)
         goto cleanup;
+    if (nconn > 0) {
+        data->header.multifd_channels = nconn;
+    }
     if (qemuSecuritySetImageFDLabel(driver->securityManager, vm->def, saveFd.fd) < 0)
         goto cleanup;
     if (virQEMUSaveDataWrite(data, saveFd.fd, saveFd.path) < 0)
@@ -610,8 +613,7 @@ qemuSaveImageCreate(virQEMUDriver *driver,
             goto cleanup;
         if (chown(sun_path, cfg->user, cfg->group) < 0)
             goto cleanup;
-        /* still using single fd migration for now */
-        if (qemuMigrationSrcToFile(driver, vm, saveFd.fd, compressor, asyncJob) < 0)
+        if (qemuMigrationSrcToFilesMultiFd(driver, vm, asyncJob, sun_path, nconn) < 0)
             goto cleanup;
     } else {
         /* Perform non-parallel migration to file */
-- 
2.26.2





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