save: support BYPASS_CACHE during qemu save/restore

Wire together the previous patches to support file system cache bypass during API save/restore requests in qemu. * src/qemu/qemu_driver.c (qemuDomainSaveInternal, doCoreDump) (qemudDomainObjStart, qemuDomainSaveImageOpen, qemuDomainObjRestore) (qemuDomainObjStart): Add parameter. (qemuDomainSaveFlags, qemuDomainManagedSave, qemudDomainCoreDump) (processWatchdogEvent, qemudDomainStartWithFlags, qemuAutostartDomain) (qemuDomainRestoreFlags): Update callers.
2024-12-23 14:15:28 +00:00 · 2011-07-11 12:07:50 -06:00 · 2011-07-11 12:07:50 -06:00 · 58e668d2ea
commit 58e668d2ea
parent 519a1c4379
1 changed files with 115 additions and 46 deletions
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@ -117,11 +117,12 @@ static void processWatchdogEvent(void *data, void *opaque);

 static int qemudShutdown(void);

-static int qemudDomainObjStart(virConnectPtr conn,
-                               struct qemud_driver *driver,
-                               virDomainObjPtr vm,
-                               bool start_paused,
-                               bool autodestroy);
+static int qemuDomainObjStart(virConnectPtr conn,
+                              struct qemud_driver *driver,
+                              virDomainObjPtr vm,
+                              bool start_paused,
+                              bool autodestroy,
+                              bool bypass_cache);

 static int qemudDomainGetMaxVcpus(virDomainPtr dom);

@ -149,9 +150,11 @@ qemuAutostartDomain(void *payload, const void *name ATTRIBUTE_UNUSED, void *opaq
                  vm->def->name,
                  err ? err->message : _("unknown error"));
    } else {
+        /* XXX need to wire bypass-cache autostart into qemu.conf */
        if (vm->autostart &&
            !virDomainObjIsActive(vm) &&
-            qemudDomainObjStart(data->conn, data->driver, vm, false, false) < 0) {
+            qemuDomainObjStart(data->conn, data->driver, vm,
+                               false, false, false) < 0) {
            err = virGetLastError();
            VIR_ERROR(_("Failed to autostart VM '%s': %s"),
                      vm->def->name,
@ -2190,7 +2193,7 @@ qemuCompressProgramName(int compress)
 static int
 qemuDomainSaveInternal(struct qemud_driver *driver, virDomainPtr dom,
                       virDomainObjPtr vm, const char *path,
-                       int compressed)
+                       int compressed, bool bypass_cache)
 {
    char *xml = NULL;
    struct qemud_save_header header;
@ -2205,6 +2208,8 @@ qemuDomainSaveInternal(struct qemud_driver *driver, virDomainPtr dom,
    int fd = -1;
    uid_t uid = getuid();
    gid_t gid = getgid();
+    int directFlag = 0;
+    virFileDirectFdPtr directFd = NULL;

    memset(&header, 0, sizeof(header));
    memcpy(header.magic, QEMUD_SAVE_MAGIC, sizeof(header.magic));
@ -2287,15 +2292,23 @@ qemuDomainSaveInternal(struct qemud_driver *driver, virDomainPtr dom,
    /* Obtain the file handle.  */

    /* First try creating the file as root */
+    if (bypass_cache) {
+        directFlag = virFileDirectFdFlag();
+        if (directFlag < 0) {
+            qemuReportError(VIR_ERR_OPERATION_FAILED, "%s",
+                            _("bypass cache unsupported by this system"));
+            goto endjob;
+        }
+    }
    if (!is_reg) {
-        fd = open(path, O_WRONLY | O_TRUNC);
+        fd = open(path, O_WRONLY | O_TRUNC | directFlag);
        if (fd < 0) {
            virReportSystemError(errno, _("unable to open %s"), path);
            goto endjob;
        }
    } else {
-        if ((fd = virFileOpenAs(path, O_CREAT|O_TRUNC|O_WRONLY,
-                                S_IRUSR|S_IWUSR,
+        int oflags = O_CREAT | O_TRUNC | O_WRONLY | directFlag;
+        if ((fd = virFileOpenAs(path, oflags, S_IRUSR | S_IWUSR,
                                uid, gid, 0)) < 0) {
            /* If we failed as root, and the error was permission-denied
               (EACCES or EPERM), assume it's on a network-connected share
@ -2341,7 +2354,7 @@ qemuDomainSaveInternal(struct qemud_driver *driver, virDomainPtr dom,

            /* Retry creating the file as driver->user */

-            if ((fd = virFileOpenAs(path, O_CREAT|O_TRUNC|O_WRONLY,
+            if ((fd = virFileOpenAs(path, oflags,
                                    S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP,
                                    driver->user, driver->group,
                                    VIR_FILE_OPEN_AS_UID)) < 0) {
@ -2359,6 +2372,9 @@ qemuDomainSaveInternal(struct qemud_driver *driver, virDomainPtr dom,
        }
    }

+    if (bypass_cache && (directFd = virFileDirectFdNew(&fd, path)) == NULL)
+        goto endjob;
+
    /* Write header to file, followed by XML */
    if (qemuDomainSaveHeader(fd, path, xml, &header) < 0) {
        VIR_FORCE_CLOSE(fd);
@ -2374,6 +2390,8 @@ qemuDomainSaveInternal(struct qemud_driver *driver, virDomainPtr dom,
        virReportSystemError(errno, _("unable to close %s"), path);
        goto endjob;
    }
+    if (virFileDirectFdClose(directFd) < 0)
+        goto endjob;

    ret = 0;

@ -2406,6 +2424,7 @@ endjob:

 cleanup:
    VIR_FORCE_CLOSE(fd);
+    virFileDirectFdFree(directFd);
    VIR_FREE(xml);
    if (ret != 0 && is_reg)
        unlink(path);
@ -2441,7 +2460,7 @@ qemuDomainSaveFlags(virDomainPtr dom, const char *path, const char *dxml,
    int ret = -1;
    virDomainObjPtr vm = NULL;

-    virCheckFlags(0, -1);
+    virCheckFlags(VIR_DOMAIN_SAVE_BYPASS_CACHE, -1);
    if (dxml) {
        qemuReportError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s",
                        _("xml modification unsupported"));
@ -2483,7 +2502,8 @@ qemuDomainSaveFlags(virDomainPtr dom, const char *path, const char *dxml,
        goto cleanup;
    }

-    ret = qemuDomainSaveInternal(driver, dom, vm, path, compressed);
+    ret = qemuDomainSaveInternal(driver, dom, vm, path, compressed,
+                                 (flags & VIR_DOMAIN_SAVE_BYPASS_CACHE) != 0);
    vm = NULL;

 cleanup:
@ -2521,7 +2541,7 @@ qemuDomainManagedSave(virDomainPtr dom, unsigned int flags)
    int ret = -1;
    int compressed;

-    virCheckFlags(0, -1);
+    virCheckFlags(VIR_DOMAIN_SAVE_BYPASS_CACHE, -1);

    qemuDriverLock(driver);
    vm = virDomainFindByUUID(&driver->domains, dom->uuid);
@ -2546,7 +2566,8 @@ qemuDomainManagedSave(virDomainPtr dom, unsigned int flags)
    VIR_INFO("Saving state to %s", name);

    compressed = QEMUD_SAVE_FORMAT_RAW;
-    ret = qemuDomainSaveInternal(driver, dom, vm, name, compressed);
+    ret = qemuDomainSaveInternal(driver, dom, vm, name, compressed,
+                                 (flags & VIR_DOMAIN_SAVE_BYPASS_CACHE) != 0);
    vm = NULL;

 cleanup:
@ -2630,18 +2651,33 @@ static int
 doCoreDump(struct qemud_driver *driver,
           virDomainObjPtr vm,
           const char *path,
-           enum qemud_save_formats compress)
+           enum qemud_save_formats compress,
+           bool bypass_cache)
 {
    int fd = -1;
    int ret = -1;
+    virFileDirectFdPtr directFd = NULL;
+    int directFlag = 0;

    /* Create an empty file with appropriate ownership.  */
-    if ((fd = open(path, O_CREAT|O_TRUNC|O_WRONLY, S_IRUSR|S_IWUSR)) < 0) {
+    if (bypass_cache) {
+        directFlag = virFileDirectFdFlag();
+        if (directFlag < 0) {
+            qemuReportError(VIR_ERR_OPERATION_FAILED, "%s",
+                            _("bypass cache unsupported by this system"));
+            goto cleanup;
+        }
+    }
+    if ((fd = open(path, O_CREAT | O_TRUNC | O_WRONLY | directFlag,
+                   S_IRUSR | S_IWUSR)) < 0) {
        qemuReportError(VIR_ERR_OPERATION_FAILED,
                        _("failed to create '%s'"), path);
        goto cleanup;
    }

+    if (bypass_cache && (directFd = virFileDirectFdNew(&fd, path)) == NULL)
+        goto cleanup;
+
    if (qemuMigrationToFile(driver, vm, fd, 0, path,
                            qemuCompressProgramName(compress), true, false) < 0)
        goto cleanup;
@ -2652,11 +2688,14 @@ doCoreDump(struct qemud_driver *driver,
                             path);
        goto cleanup;
    }
+    if (virFileDirectFdClose(directFd) < 0)
+        goto cleanup;

    ret = 0;

 cleanup:
    VIR_FORCE_CLOSE(fd);
+    virFileDirectFdClose(directFd);
    if (ret != 0)
        unlink(path);
    return ret;
@ -2700,7 +2739,7 @@ static int qemudDomainCoreDump(virDomainPtr dom,
    int ret = -1;
    virDomainEventPtr event = NULL;

-    virCheckFlags(VIR_DUMP_LIVE | VIR_DUMP_CRASH, -1);
+    virCheckFlags(VIR_DUMP_LIVE | VIR_DUMP_CRASH | VIR_DUMP_BYPASS_CACHE, -1);

    qemuDriverLock(driver);
    vm = virDomainFindByUUID(&driver->domains, dom->uuid);
@ -2741,7 +2780,8 @@ static int qemudDomainCoreDump(virDomainPtr dom,
        }
    }

-    ret = doCoreDump(driver, vm, path, getCompressionType(driver));
+    ret = doCoreDump(driver, vm, path, getCompressionType(driver),
+                     (flags & VIR_DUMP_BYPASS_CACHE) != 0);
    if (ret < 0)
        goto endjob;

@ -2912,10 +2952,9 @@ static void processWatchdogEvent(void *data, void *opaque)
                goto endjob;
            }

-            ret = doCoreDump(driver,
-                             wdEvent->vm,
-                             dumpfile,
-                             getCompressionType(driver));
+            /* XXX wire up qemu.conf to support bypass-cache dumps */
+            ret = doCoreDump(driver, wdEvent->vm, dumpfile,
+                             getCompressionType(driver), false);
            if (ret < 0)
                qemuReportError(VIR_ERR_OPERATION_FAILED,
                                "%s", _("Dump failed"));
@ -3652,18 +3691,29 @@ cleanup:
    return ret;
 }

-static int ATTRIBUTE_NONNULL(3) ATTRIBUTE_NONNULL(4)
+static int ATTRIBUTE_NONNULL(3) ATTRIBUTE_NONNULL(4) ATTRIBUTE_NONNULL(6)
 qemuDomainSaveImageOpen(struct qemud_driver *driver,
                        const char *path,
                        virDomainDefPtr *ret_def,
-                        struct qemud_save_header *ret_header)
+                        struct qemud_save_header *ret_header,
+                        bool bypass_cache, virFileDirectFdPtr *directFd)
 {
    int fd;
    struct qemud_save_header header;
    char *xml = NULL;
    virDomainDefPtr def = NULL;
+    int directFlag = 0;

-    if ((fd = virFileOpenAs(path, O_RDONLY, 0, getuid(), getgid(), 0)) < 0) {
+    if (bypass_cache) {
+        directFlag = virFileDirectFdFlag();
+        if (directFlag < 0) {
+            qemuReportError(VIR_ERR_OPERATION_FAILED, "%s",
+                            _("bypass cache unsupported by this system"));
+            goto error;
+        }
+    }
+    if ((fd = virFileOpenAs(path, O_RDONLY | directFlag, 0,
+                            getuid(), getgid(), 0)) < 0) {
        if ((fd != -EACCES && fd != -EPERM) ||
            driver->user == getuid()) {
            qemuReportError(VIR_ERR_OPERATION_FAILED,
@ -3673,7 +3723,7 @@ qemuDomainSaveImageOpen(struct qemud_driver *driver,

        /* Opening as root failed, but qemu runs as a different user
         * that might have better luck. */
-        if ((fd = virFileOpenAs(path, O_RDONLY, 0,
+        if ((fd = virFileOpenAs(path, O_RDONLY | directFlag, 0,
                                driver->user, driver->group,
                                VIR_FILE_OPEN_AS_UID)) < 0) {
            qemuReportError(VIR_ERR_OPERATION_FAILED,
@ -3681,6 +3731,8 @@ qemuDomainSaveImageOpen(struct qemud_driver *driver,
            goto error;
        }
    }
+    if (bypass_cache && (*directFd = virFileDirectFdNew(&fd, path)) == NULL)
+        goto error;

    if (saferead(fd, &header, sizeof(header)) != sizeof(header)) {
        qemuReportError(VIR_ERR_OPERATION_FAILED,
@ -3859,8 +3911,9 @@ qemuDomainRestoreFlags(virConnectPtr conn,
    int fd = -1;
    int ret = -1;
    struct qemud_save_header header;
+    virFileDirectFdPtr directFd = NULL;

-    virCheckFlags(0, -1);
+    virCheckFlags(VIR_DOMAIN_SAVE_BYPASS_CACHE, -1);
    if (dxml) {
        qemuReportError(VIR_ERR_ARGUMENT_UNSUPPORTED, "%s",
                        _("xml modification unsupported"));
@ -3869,7 +3922,9 @@ qemuDomainRestoreFlags(virConnectPtr conn,

    qemuDriverLock(driver);

-    fd = qemuDomainSaveImageOpen(driver, path, &def, &header);
+    fd = qemuDomainSaveImageOpen(driver, path, &def, &header,
+                                 (flags & VIR_DOMAIN_SAVE_BYPASS_CACHE) != 0,
+                                 &directFd);
    if (fd < 0)
        goto cleanup;

@ -3888,6 +3943,8 @@ qemuDomainRestoreFlags(virConnectPtr conn,
        goto cleanup;

    ret = qemuDomainSaveImageStartVM(conn, driver, vm, &fd, &header, path);
+    if (virFileDirectFdClose(directFd) < 0)
+        VIR_WARN("Failed to close %s", path);

    if (qemuDomainObjEndJob(driver, vm) == 0)
        vm = NULL;
@ -3899,6 +3956,7 @@ qemuDomainRestoreFlags(virConnectPtr conn,
 cleanup:
    virDomainDefFree(def);
    VIR_FORCE_CLOSE(fd);
+    virFileDirectFdFree(directFd);
    if (vm)
        virDomainObjUnlock(vm);
    qemuDriverUnlock(driver);
@ -3916,14 +3974,17 @@ static int
 qemuDomainObjRestore(virConnectPtr conn,
                     struct qemud_driver *driver,
                     virDomainObjPtr vm,
-                     const char *path)
+                     const char *path,
+                     bool bypass_cache)
 {
    virDomainDefPtr def = NULL;
    int fd = -1;
    int ret = -1;
    struct qemud_save_header header;
+    virFileDirectFdPtr directFd = NULL;

-    fd = qemuDomainSaveImageOpen(driver, path, &def, &header);
+    fd = qemuDomainSaveImageOpen(driver, path, &def, &header,
+                                 bypass_cache, &directFd);
    if (fd < 0)
        goto cleanup;

@ -3945,10 +4006,13 @@ qemuDomainObjRestore(virConnectPtr conn,
    def = NULL;

    ret = qemuDomainSaveImageStartVM(conn, driver, vm, &fd, &header, path);
+    if (virFileDirectFdClose(directFd) < 0)
+        VIR_WARN("Failed to close %s", path);

 cleanup:
    virDomainDefFree(def);
    VIR_FORCE_CLOSE(fd);
+    virFileDirectFdFree(directFd);
    return ret;
 }

@ -4197,11 +4261,13 @@ static int qemudNumDefinedDomains(virConnectPtr conn) {
 }


-static int qemudDomainObjStart(virConnectPtr conn,
-                               struct qemud_driver *driver,
-                               virDomainObjPtr vm,
-                               bool start_paused,
-                               bool autodestroy)
+static int
+qemuDomainObjStart(virConnectPtr conn,
+                   struct qemud_driver *driver,
+                   virDomainObjPtr vm,
+                   bool start_paused,
+                   bool autodestroy,
+                   bool bypass_cache)
 {
    int ret = -1;
    char *managed_save;
@ -4216,7 +4282,8 @@ static int qemudDomainObjStart(virConnectPtr conn,
        goto cleanup;

    if (virFileExists(managed_save)) {
-        ret = qemuDomainObjRestore(conn, driver, vm, managed_save);
+        ret = qemuDomainObjRestore(conn, driver, vm, managed_save,
+                                   bypass_cache);

        if ((ret == 0) && (unlink(managed_save) < 0))
            VIR_WARN("Failed to remove the managed state %s", managed_save);
@ -4242,14 +4309,15 @@ cleanup:
 }

 static int
-qemudDomainStartWithFlags(virDomainPtr dom, unsigned int flags)
+qemuDomainStartWithFlags(virDomainPtr dom, unsigned int flags)
 {
    struct qemud_driver *driver = dom->conn->privateData;
    virDomainObjPtr vm;
    int ret = -1;

    virCheckFlags(VIR_DOMAIN_START_PAUSED |
-                  VIR_DOMAIN_START_AUTODESTROY, -1);
+                  VIR_DOMAIN_START_AUTODESTROY |
+                  VIR_DOMAIN_START_BYPASS_CACHE, -1);

    qemuDriverLock(driver);
    vm = virDomainFindByUUID(&driver->domains, dom->uuid);
@ -4271,9 +4339,10 @@ qemudDomainStartWithFlags(virDomainPtr dom, unsigned int flags)
        goto endjob;
    }

-    if (qemudDomainObjStart(dom->conn, driver, vm,
-                            (flags & VIR_DOMAIN_START_PAUSED) != 0,
-                            (flags & VIR_DOMAIN_START_AUTODESTROY) != 0) < 0)
+    if (qemuDomainObjStart(dom->conn, driver, vm,
+                           (flags & VIR_DOMAIN_START_PAUSED) != 0,
+                           (flags & VIR_DOMAIN_START_AUTODESTROY) != 0,
+                           (flags & VIR_DOMAIN_START_BYPASS_CACHE) != 0) < 0)
        goto endjob;

    ret = 0;
@ -4290,9 +4359,9 @@ cleanup:
 }

 static int
-qemudDomainStart(virDomainPtr dom)
+qemuDomainStart(virDomainPtr dom)
 {
-    return qemudDomainStartWithFlags(dom, 0);
+    return qemuDomainStartWithFlags(dom, 0);
 }

 static int
@ -8993,8 +9062,8 @@ static virDriver qemuDriver = {
    .domainXMLToNative = qemuDomainXMLToNative, /* 0.6.4 */
    .listDefinedDomains = qemudListDefinedDomains, /* 0.2.0 */
    .numOfDefinedDomains = qemudNumDefinedDomains, /* 0.2.0 */
-    .domainCreate = qemudDomainStart, /* 0.2.0 */
-    .domainCreateWithFlags = qemudDomainStartWithFlags, /* 0.8.2 */
+    .domainCreate = qemuDomainStart, /* 0.2.0 */
+    .domainCreateWithFlags = qemuDomainStartWithFlags, /* 0.8.2 */
    .domainDefineXML = qemudDomainDefine, /* 0.2.0 */
    .domainUndefine = qemudDomainUndefine, /* 0.2.0 */
    .domainUndefineFlags = qemuDomainUndefineFlags, /* 0.9.4 */