From c8ef4373f815e030c3dd505b00bd9fffebe333f3 Mon Sep 17 00:00:00 2001

Message-Id: <c8ef4373f815e030c3dd505b00bd9fffebe333f3@dist-git>

From: Michal Privoznik <mprivozn@redhat.com>

Date: Fri, 28 Nov 2014 15:15:06 +0100

Subject: [PATCH] qemu: Don't track quiesced state of FSs

https://bugzilla.redhat.com/show_bug.cgi?id=1160084

As of b6d4dad11b (1.2.5) we are trying to keep the status of FSFreeze

in the guest. Even though I've tried to fixed couple of corner cases

(6ea54769ba18), it occurred to me just recently, that the approach is

broken by design. Firstly, there are many other ways to talk to

qemu-ga (even through libvirt) that filesystems can be thawed (e.g.

qemu-agent-command) without libvirt noticing. Moreover, there are

plenty of ways to thaw filesystems without even qemu-ga noticing (yes,

qemu-ga keeps internal track of FSFreeze status). So, instead of

keeping the track ourselves, or asking qemu-ga for stale state, it's

the best to let qemu-ga deal with that (and possibly let guest kernel

propagate an error).

Moreover, there's one bug with the following approach, if fsfreeze

command failed, we've executed fsthaw subsequently. So issuing

domfsfreeze in virsh gave the following result:

virsh # domfsfreeze gentoo

Froze 1 filesystem(s)

virsh # domfsfreeze gentoo

error: Unable to freeze filesystems

error: internal error: unable to execute QEMU agent command 'guest-fsfreeze-freeze': The command guest-fsfreeze-freeze has been disabled for this instance

virsh # domfsfreeze gentoo

Froze 1 filesystem(s)

virsh # domfsfreeze gentoo

error: Unable to freeze filesystems

error: internal error: unable to execute QEMU agent command 'guest-fsfreeze-freeze': The command guest-fsfreeze-freeze has been disabled for this instance

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

(cherry picked from commit 6085d917d5c5839b7ed351e99fadbbb56f5178fe)

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>

---

 src/qemu/qemu_domain.c  |  5 -----

 src/qemu/qemu_domain.h  |  2 --

 src/qemu/qemu_driver.c  | 44 ++------------------------------------------

 src/qemu/qemu_process.c |  5 -----

 4 files changed, 2 insertions(+), 54 deletions(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c

index d248d5b..01fa3ac 100644

--- a/src/qemu/qemu_domain.c

+++ b/src/qemu/qemu_domain.c

@@ -564,9 +564,6 @@ qemuDomainObjPrivateXMLFormat(virBufferPtr buf, void *data)

         virBufferAddLit(buf, "</devices>\n");

     }

-    if (priv->quiesced)

-        virBufferAddLit(buf, "<quiesced/>\n");

-

     return 0;

 }

@@ -751,8 +748,6 @@ qemuDomainObjPrivateXMLParse(xmlXPathContextPtr ctxt, void *data)

     }

     VIR_FREE(nodes);

-    priv->quiesced = virXPathBoolean("boolean(./quiesced)", ctxt) == 1;

-

     return 0;

  error:

diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h

index e4ea4ce..ebb282a 100644

--- a/src/qemu/qemu_domain.h

+++ b/src/qemu/qemu_domain.h

@@ -187,8 +187,6 @@ struct _qemuDomainObjPrivate {

     char **qemuDevices; /* NULL-terminated list of devices aliases known to QEMU */

     bool hookRun;  /* true if there was a hook run over this domain */

-

-    bool quiesced; /* true if filesystems are quiesced */

 };

 typedef enum {

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c

index e096cee..a9a7d30 100644

--- a/src/qemu/qemu_driver.c

+++ b/src/qemu/qemu_driver.c

@@ -12627,34 +12627,17 @@ qemuDomainPrepareDiskChainElement(virQEMUDriverPtr driver,

  * is sent but failed, and number of frozen filesystems on success. If -2 is

  * returned, FSThaw should be called revert the quiesced status. */

 static int

-qemuDomainSnapshotFSFreeze(virQEMUDriverPtr driver,

+qemuDomainSnapshotFSFreeze(virQEMUDriverPtr driver ATTRIBUTE_UNUSED,

                            virDomainObjPtr vm,

                            const char **mountpoints,

                            unsigned int nmountpoints)

 {

     qemuDomainObjPrivatePtr priv = vm->privateData;

-    virQEMUDriverConfigPtr cfg;

     int frozen;

-    if (priv->quiesced) {

-        virReportError(VIR_ERR_OPERATION_INVALID, "%s",

-                       _("domain is already quiesced"));

-        return -1;

-    }

-

     if (!qemuDomainAgentAvailable(priv, true))

         return -1;

-    priv->quiesced = true;

-

-    cfg = virQEMUDriverGetConfig(driver);

-    if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm) < 0) {

-        priv->quiesced = false;

-        virObjectUnref(cfg);

-        return -1;

-    }

-    virObjectUnref(cfg);

-

     qemuDomainObjEnterAgent(vm);

     frozen = qemuAgentFSFreeze(priv->agent, mountpoints, nmountpoints);

     qemuDomainObjExitAgent(vm);

@@ -12664,24 +12647,17 @@ qemuDomainSnapshotFSFreeze(virQEMUDriverPtr driver,

 /* Return -1 on error, otherwise number of thawed filesystems. */

 static int

-qemuDomainSnapshotFSThaw(virQEMUDriverPtr driver,

+qemuDomainSnapshotFSThaw(virQEMUDriverPtr driver ATTRIBUTE_UNUSED,

                          virDomainObjPtr vm,

                          bool report)

 {

     qemuDomainObjPrivatePtr priv = vm->privateData;

-    virQEMUDriverConfigPtr cfg;

     int thawed;

     virErrorPtr err = NULL;

     if (!qemuDomainAgentAvailable(priv, report))

         return -1;

-    if (!priv->quiesced && report) {

-        virReportError(VIR_ERR_OPERATION_INVALID, "%s",

-                       _("domain is not quiesced"));

-        return -1;

-    }

-

     qemuDomainObjEnterAgent(vm);

     if (!report)

         err = virSaveLastError();

@@ -12692,18 +12668,6 @@ qemuDomainSnapshotFSThaw(virQEMUDriverPtr driver,

     virFreeError(err);

-    if (!report || thawed >= 0) {

-        priv->quiesced = false;

-

-        cfg = virQEMUDriverGetConfig(driver);

-        if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm) < 0) {

-            /* Revert the statuses when we failed to save them. */

-            priv->quiesced = true;

-            thawed = -1;

-        }

-        virObjectUnref(cfg);

-    }

-

     return thawed;

 }

@@ -17562,10 +17526,6 @@ qemuDomainFSFreeze(virDomainPtr dom,

     }

     ret = qemuDomainSnapshotFSFreeze(driver, vm, mountpoints, nmountpoints);

-    if (ret == -2) {

-        qemuDomainSnapshotFSThaw(driver, vm, false);

-        ret = -1;

-    }

  endjob:

     if (!qemuDomainObjEndJob(driver, vm))

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c

index f384b33..1125f4c 100644

--- a/src/qemu/qemu_process.c

+++ b/src/qemu/qemu_process.c

@@ -537,10 +537,6 @@ qemuProcessHandleReset(qemuMonitorPtr mon ATTRIBUTE_UNUSED,

     priv = vm->privateData;

     if (priv->agent)

         qemuAgentNotifyEvent(priv->agent, QEMU_AGENT_EVENT_RESET);

-    /* Clear some domain runtime information. For instance,

-     * fsfreeze won't survive domain reset. This, however,

-     * required the domain status file to be rewritten onto disk. */

-    priv->quiesced = false;

     if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm) < 0)

         VIR_WARN("Failed to save status on vm %s", vm->def->name);

@@ -4972,7 +4968,6 @@ void qemuProcessStop(virQEMUDriverPtr driver,

     virPortAllocatorRelease(driver->migrationPorts, priv->nbdPort);

     priv->nbdPort = 0;

-    priv->quiesced = false;

     if (priv->agent) {

         qemuAgentClose(priv->agent);

-- 

2.1.3