[libvirt] [PATCH 9/8] save: support direct autodump in qemu.conf

[Eric Blake]

When auto-dumping a domain on crash events, let the user configure
whether to have the VIR_DUMP_DIRECT flag effects.

* src/qemu/qemu.conf (auto_dump_direct): Document new variable.
* src/qemu/libvirtd_qemu.aug (vnc_entry): Let augeas parse it.
* src/qemu/qemu_conf.h (qemud_driver): Store new preference.
* src/qemu/qemu_conf.c (qemudLoadDriverConfig): Parse it.
* src/qemu/qemu_driver.c (processWatchdogEvent): Honor it.
---
 src/qemu/libvirtd_qemu.aug |    1 +
 src/qemu/qemu.conf         |    8 ++++++++
 src/qemu/qemu_conf.c       |    6 +++++-
 src/qemu/qemu_conf.h       |    3 ++-
 src/qemu/qemu_driver.c     |    4 ++--
 5 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/qemu/libvirtd_qemu.aug b/src/qemu/libvirtd_qemu.aug
index 66858ae..dea6770 100644
--- a/src/qemu/libvirtd_qemu.aug
+++ b/src/qemu/libvirtd_qemu.aug
@@ -41,6 +41,7 @@ module Libvirtd_qemu =
                  | str_entry "save_image_format"
                  | str_entry "dump_image_format"
                  | str_entry "auto_dump_path"
+                 | bool_entry "auto_dump_direct"
                  | str_entry "hugetlbfs_mount"
                  | bool_entry "relaxed_acs_check"
                  | bool_entry "vnc_allow_host_audio"
diff --git a/src/qemu/qemu.conf b/src/qemu/qemu.conf
index 934f99b..2a0664d 100644
--- a/src/qemu/qemu.conf
+++ b/src/qemu/qemu.conf
@@ -208,6 +208,14 @@
 #
 # auto_dump_path = "/var/lib/libvirt/qemu/dump"

+# When a domain is configured to be auto-dumped, enabling this flag
+# has the same effect as using the VIR_DUMP_DIRECT flag with the
+# virDomainCoreDump API.  That is, the system uses O_DIRECT if possible,
+# which puts less pressure on the file system cache but may cause
+# slower operation.
+#
+# auto_dump_direct = 0
+
 # If provided by the host and a hugetlbfs mount point is configured,
 # a guest may request huge page backing.  When this mount point is
 # unspecified here, determination of a host mount point in /proc/mounts
diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index 3d8aba4..cf6cb6b 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -1,7 +1,7 @@
 /*
  * qemu_conf.c: QEMU configuration management
  *
- * Copyright (C) 2006, 2007, 2008, 2009, 2010 Red Hat, Inc.
+ * Copyright (C) 2006-2011 Red Hat, Inc.
  * Copyright (C) 2006 Daniel P. Berrange
  *
  * This library is free software; you can redistribute it and/or
@@ -378,6 +378,10 @@ int qemudLoadDriverConfig(struct qemud_driver *driver,
         }
     }

+    p = virConfGetValue (conf, "auto_dump_direct");
+    CHECK_TYPE ("auto_dump_direct", VIR_CONF_LONG);
+    if (p) driver->autoDumpDirect = true;
+
     p = virConfGetValue (conf, "hugetlbfs_mount");
     CHECK_TYPE ("hugetlbfs_mount", VIR_CONF_STRING);
     if (p && p->str) {
diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h
index fa4c607..bc025af 100644
--- a/src/qemu/qemu_conf.h
+++ b/src/qemu/qemu_conf.h
@@ -1,7 +1,7 @@
 /*
  * qemu_conf.h: QEMU configuration management
  *
- * Copyright (C) 2006-2007, 2009-2010 Red Hat, Inc.
+ * Copyright (C) 2006-2007, 2009-2011 Red Hat, Inc.
  * Copyright (C) 2006 Daniel P. Berrange
  *
  * This library is free software; you can redistribute it and/or
@@ -119,6 +119,7 @@ struct qemud_driver {
     char *dumpImageFormat;

     char *autoDumpPath;
+    bool autoDumpDirect;

     pciDeviceList *activePciHostdevs;

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index e414e5f..d7cd069 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -2863,9 +2863,9 @@ static void processWatchdogEvent(void *data, void *opaque)
                 goto endjob;
             }

-            /* XXX wire up qemu.conf to support whether to do direct dumps */
             ret = doCoreDump(driver, wdEvent->vm, dumpfile,
-                             getCompressionType(driver), false);
+                             getCompressionType(driver),
+                             driver->autoDumpDirect);
             if (ret < 0)
                 qemuReportError(VIR_ERR_OPERATION_FAILED,
                                 "%s", _("Dump failed"));
-- 
1.7.4.4