[libvirt] [PATCH v2 4/4] qemu_hotplug: try harder to eject media

[Pavel Hrdina]

Some guests lock the tray and QEMU eject command will simply fail to
eject the media.  But the guest OS can handle this attempt to eject the
media and can unlock the tray and open it. In this case, we should try
again to actually eject the media.

If the first attempt fails to detect a tray_open we will fail with
error, from monitor.  If we receive that event, we know, that the guest
properly reacted to the eject request, unlocked the tray and opened it.
In this case, we need to run the command again to actually eject the
media from the device.  The reason to call it again is, that QEMU don't
wait for the guest to react and report an error, that the tray is
locked.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1147471

Signed-off-by: Pavel Hrdina <phrdina at redhat.com>
---
 src/qemu/qemu_hotplug.c | 73 +++++++++++++++++++++++--------------------------
 src/qemu/qemu_process.c |  2 ++
 2 files changed, 36 insertions(+), 39 deletions(-)

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index 0628964..17595b7 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -59,7 +59,7 @@
 
 VIR_LOG_INIT("qemu.qemu_hotplug");
 
-#define CHANGE_MEDIA_RETRIES 10
+#define CHANGE_MEDIA_TIMEOUT 5000
 
 /* Wait up to 5 seconds for device removal to finish. */
 unsigned long long qemuDomainRemoveDeviceWaitTime = 1000ull * 5;
@@ -166,12 +166,13 @@ qemuDomainChangeEjectableMedia(virQEMUDriverPtr driver,
                                virStorageSourcePtr newsrc,
                                bool force)
 {
-    int ret = -1;
+    int ret = -1, rc;
     char *driveAlias = NULL;
     qemuDomainObjPrivatePtr priv = vm->privateData;
-    int retries = CHANGE_MEDIA_RETRIES;
     const char *format = NULL;
     char *sourcestr = NULL;
+    bool ejectRetry = false;
+    unsigned long long now;
 
     if (!disk->info.alias) {
         virReportError(VIR_ERR_INTERNAL_ERROR,
@@ -193,36 +194,31 @@ qemuDomainChangeEjectableMedia(virQEMUDriverPtr driver,
     if (!(driveAlias = qemuDeviceDriveHostAlias(disk, priv->qemuCaps)))
         goto error;
 
-    qemuDomainObjEnterMonitor(driver, vm);
-    ret = qemuMonitorEjectMedia(priv->mon, driveAlias, force);
-    if (qemuDomainObjExitMonitor(driver, vm) < 0) {
-        ret = -1;
-        goto cleanup;
-    }
-
-    if (ret < 0)
-        goto error;
+    do {
+        qemuDomainObjEnterMonitor(driver, vm);
+        rc = qemuMonitorEjectMedia(priv->mon, driveAlias, force);
+        if (qemuDomainObjExitMonitor(driver, vm) < 0)
+            goto cleanup;
 
-    virObjectRef(vm);
-    /* we don't want to report errors from media tray_open polling */
-    while (retries) {
-        if (disk->tray_status == VIR_DOMAIN_DISK_TRAY_OPEN)
-            break;
+        if (rc == -2) {
+            /* we've already tried, error out */
+            if (ejectRetry)
+                goto error;
+            VIR_DEBUG("tray is locked, wait for the guest to unlock "
+                      "the tray and try to eject it again");
+            ejectRetry = true;
+        } else if (rc < 0) {
+            goto error;
+        }
 
-        retries--;
-        virObjectUnlock(vm);
-        VIR_DEBUG("Waiting 500ms for tray to open. Retries left %d", retries);
-        usleep(500 * 1000); /* sleep 500ms */
-        virObjectLock(vm);
-    }
-    virObjectUnref(vm);
+        if (virTimeMillisNow(&now) < 0)
+            goto error;
 
-    if (retries <= 0) {
-        virReportError(VIR_ERR_OPERATION_FAILED, "%s",
-                       _("Unable to eject media"));
-        ret = -1;
-        goto error;
-    }
+        while (disk->tray_status != VIR_DOMAIN_DISK_TRAY_OPEN) {
+            if (virDomainObjWaitUntil(vm, now + CHANGE_MEDIA_TIMEOUT) != 0)
+                goto error;
+        }
+    } while (ejectRetry && rc != 0);
 
     if (!virStorageSourceIsEmpty(newsrc)) {
         if (qemuGetDriveSourceString(newsrc, conn, &sourcestr) < 0)
@@ -237,19 +233,17 @@ qemuDomainChangeEjectableMedia(virQEMUDriverPtr driver,
             }
         }
         qemuDomainObjEnterMonitor(driver, vm);
-        ret = qemuMonitorChangeMedia(priv->mon,
-                                     driveAlias,
-                                     sourcestr,
-                                     format);
-        if (qemuDomainObjExitMonitor(driver, vm) < 0) {
-            ret = -1;
+        rc = qemuMonitorChangeMedia(priv->mon,
+                                    driveAlias,
+                                    sourcestr,
+                                    format);
+        if (qemuDomainObjExitMonitor(driver, vm) < 0)
             goto cleanup;
-        }
     }
 
-    virDomainAuditDisk(vm, disk->src, newsrc, "update", ret >= 0);
+    virDomainAuditDisk(vm, disk->src, newsrc, "update", rc >= 0);
 
-    if (ret < 0)
+    if (rc < 0)
         goto error;
 
     /* remove the old source from shared device list */
@@ -259,6 +253,7 @@ qemuDomainChangeEjectableMedia(virQEMUDriverPtr driver,
     virStorageSourceFree(disk->src);
     disk->src = newsrc;
     newsrc = NULL;
+    ret = 0;
 
  cleanup:
     VIR_FREE(driveAlias);
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index a688feb..648ba00 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -1152,6 +1152,8 @@ qemuProcessHandleTrayChange(qemuMonitorPtr mon ATTRIBUTE_UNUSED,
             VIR_WARN("Unable to save status on vm %s after tray moved event",
                      vm->def->name);
         }
+
+        virDomainObjBroadcast(vm);
     }
 
     virObjectUnlock(vm);
-- 
2.4.4