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[libvirt] [PATCH v2 1/2] support compressed crashdump of guests



Thank you for advices for v1. This version adss dump_image_format config
for qemu.conf. 1/2 adds dump_image_format, 2/2 adds the check for availability of
compression program for save_image_format and dump_image_format.
==
Add dump_image_format[] to qemu.conf and support compressed dump
at virsh dump. coredump compression is important for saving disk space
in an environment where multiple guest run.
(In general, "disk space for dump" is specially allocated and will be
 a dead space in the system. It's used only at emergency. So, it's better
 to have both of save_image_format and dump_image_format. "save" is done
 in scheduled manner with enough calculated disk space for it.)

This code reuses some of save_image_format[] and supports the same format
with virsh save.

---
 src/qemu/qemu.conf     |    4 ++++
 src/qemu/qemu_conf.c   |   11 +++++++++++
 src/qemu/qemu_conf.h   |    1 +
 src/qemu/qemu_driver.c |   30 +++++++++++++++++++++++++-----
 4 files changed, 41 insertions(+), 5 deletions(-)

Index: libvirt-0.8.4/src/qemu/qemu_conf.c
===================================================================
--- libvirt-0.8.4.orig/src/qemu/qemu_conf.c
+++ libvirt-0.8.4/src/qemu/qemu_conf.c
@@ -324,6 +324,17 @@ int qemudLoadDriverConfig(struct qemud_d
         }
     }
 
+    p = virConfGetValue (conf, "dump_image_format");
+    CHECK_TYPE ("dump_image_format", VIR_CONF_STRING);
+    if (p && p->str) {
+	VIR_FREE(driver->dumpImageFormat);
+	if (!(driver->dumpImageFormat = strdup(p->str))) {
+		virReportOOMError();
+		virConfFree(conf);
+		return -1;
+	}
+    }
+
      p = virConfGetValue (conf, "hugetlbfs_mount");
      CHECK_TYPE ("hugetlbfs_mount", VIR_CONF_STRING);
      if (p && p->str) {
Index: libvirt-0.8.4/src/qemu/qemu_conf.h
===================================================================
--- libvirt-0.8.4.orig/src/qemu/qemu_conf.h
+++ libvirt-0.8.4/src/qemu/qemu_conf.h
@@ -159,6 +159,7 @@ struct qemud_driver {
     virSecurityDriverPtr securitySecondaryDriver;
 
     char *saveImageFormat;
+    char *dumpImageFormat;
 
     pciDeviceList *activePciHostdevs;
 
Index: libvirt-0.8.4/src/qemu/qemu.conf
===================================================================
--- libvirt-0.8.4.orig/src/qemu/qemu.conf
+++ libvirt-0.8.4/src/qemu/qemu.conf
@@ -144,7 +144,11 @@
 # saving a domain in order to save disk space; the list above is in descending
 # order by performance and ascending order by compression ratio.
 #
+# save_image_format is used when you use 'virsh save' at scheduled saving.
+# dump_image_format is used when you use 'virsh dump' at emergency crashdump.
+#
 # save_image_format = "raw"
+# dump_image_format = "raw"
 
 # If provided by the host and a hugetlbfs mount point is configured,
 # a guest may request huge page backing.  When this mount point is
Index: libvirt-0.8.4/src/qemu/qemu_driver.c
===================================================================
--- libvirt-0.8.4.orig/src/qemu/qemu_driver.c
+++ libvirt-0.8.4/src/qemu/qemu_driver.c
@@ -5716,11 +5716,15 @@ static int qemudDomainCoreDump(virDomain
     int resume = 0, paused = 0;
     int ret = -1, fd = -1;
     virDomainEventPtr event = NULL;
-    const char *args[] = {
-        "cat",
-        NULL,
-    };
+    int compress;
     qemuDomainObjPrivatePtr priv;
+    /*
+     * We reuse "save" flag for "dump" here. Then, we can support the same
+     * format in "save" and "dump".
+     */
+    compress = QEMUD_SAVE_FORMAT_RAW;
+    if (driver->dumpImageFormat)
+	compress = qemudSaveCompressionTypeFromString(driver->dumpImageFormat);
 
     qemuDriverLock(driver);
     vm = virDomainFindByUUID(&driver->domains, dom->uuid);
@@ -5787,9 +5791,25 @@ static int qemudDomainCoreDump(virDomain
     }
 
     qemuDomainObjEnterMonitorWithDriver(driver, vm);
-    ret = qemuMonitorMigrateToFile(priv->mon,
+    if (compress == QEMUD_SAVE_FORMAT_RAW) {
+	const char *args[] = {
+		"cat",
+		NULL,
+	};
+	ret = qemuMonitorMigrateToFile(priv->mon,
                                    QEMU_MONITOR_MIGRATE_BACKGROUND,
                                    args, path, 0);
+    } else {
+	const char *prog = qemudSaveCompressionTypeToString(compress);
+	const char *args[] = {
+		prog,
+		"-c",
+		NULL,
+	};
+	ret = qemuMonitorMigrateToFile(priv->mon,
+				QEMU_MONITOR_MIGRATE_BACKGROUND,
+				args, path, 0);
+    }
     qemuDomainObjExitMonitorWithDriver(driver, vm);
     if (ret < 0)
         goto endjob;


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