[libvirt] [PATCH] support compressed crashdump of guests

[KAMEZAWA Hiroyuki]

Now, virsh dump doesn't support compresses dump.
This patch adds GZIP and LZOP option to virsh dump and support
it at qemu coredump. (AFAIK, LZOP is available on RHEL6.)

When I did 4G guest dump,
(Raw)	3844669750 
(Gzip)	1029846577
(LZOP)	1416263880 (faster than gzip in general)

This will be a help for a host where crash-dump is used
and several guests works on it.

help message is modified as this.
  NAME
    dump - dump the core of a domain to a file for analysis

  SYNOPSIS
    dump [--live] [--crash] [--gzip] [--lzop] <domain> <file>

  DESCRIPTION
    Core dump a domain.

  OPTIONS
    --live           perform a live core dump if supported
    --crash          crash the domain after core dump
    --gzip           gzip dump(only one compression allowed
    --lzop           lzop dump(only one compression allowed
    [--domain] <string>  domain name, id or uuid
    [--file] <string>  where to dump the core

Tested on Fedora-13+x86-64.

Note: for better compression, we may have to skip pages filled by
zero or freed pages. But it seems it's qemu's works.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>
---
 include/libvirt/libvirt.h.in |    2 ++
 src/qemu/qemu_driver.c       |   23 +++++++++++++++++++----
 tools/virsh.c                |   10 +++++++++-
 3 files changed, 30 insertions(+), 5 deletions(-)

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
@@ -5710,7 +5710,7 @@ cleanup:
 
 static int qemudDomainCoreDump(virDomainPtr dom,
                                const char *path,
-                               int flags ATTRIBUTE_UNUSED) {
+                               int flags) {
     struct qemud_driver *driver = dom->conn->privateData;
     virDomainObjPtr vm;
     int resume = 0, paused = 0;
@@ -5720,6 +5720,14 @@ static int qemudDomainCoreDump(virDomain
         "cat",
         NULL,
     };
+    const char *zargs[] = {
+	"gzip",
+	NULL,
+    };
+    const char *lzargs[] = {
+	"lzop",
+	NULL,
+    };
     qemuDomainObjPrivatePtr priv;
 
     qemuDriverLock(driver);
@@ -5787,9 +5795,16 @@ static int qemudDomainCoreDump(virDomain
     }
 
     qemuDomainObjEnterMonitorWithDriver(driver, vm);
-    ret = qemuMonitorMigrateToFile(priv->mon,
-                                   QEMU_MONITOR_MIGRATE_BACKGROUND,
-                                   args, path, 0);
+    if (flags & VIR_DUMP_GZIP)
+	ret = qemuMonitorMigrateToFile(priv->mon,
+		QEMU_MONITOR_MIGRATE_BACKGROUND, zargs, path, 0);
+    else if (flags & VIR_DUMP_LZOP)
+	ret = qemuMonitorMigrateToFile(priv->mon,
+		QEMU_MONITOR_MIGRATE_BACKGROUND, lzargs, path, 0);
+    else
+	ret = qemuMonitorMigrateToFile(priv->mon,
+		QEMU_MONITOR_MIGRATE_BACKGROUND, args, path, 0);
+
     qemuDomainObjExitMonitorWithDriver(driver, vm);
     if (ret < 0)
         goto endjob;
Index: libvirt-0.8.4/tools/virsh.c
===================================================================
--- libvirt-0.8.4.orig/tools/virsh.c
+++ libvirt-0.8.4/tools/virsh.c
@@ -1751,6 +1751,8 @@ static const vshCmdInfo info_dump[] = {
 static const vshCmdOptDef opts_dump[] = {
     {"live", VSH_OT_BOOL, 0, N_("perform a live core dump if supported")},
     {"crash", VSH_OT_BOOL, 0, N_("crash the domain after core dump")},
+    {"gzip", VSH_OT_BOOL, 0, N_("gzip dump(only one compression allowed")},
+    {"lzop", VSH_OT_BOOL, 0, N_("lzop dump(only one compression allowed")},
     {"domain", VSH_OT_DATA, VSH_OFLAG_REQ, N_("domain name, id or uuid")},
     {"file", VSH_OT_DATA, VSH_OFLAG_REQ, N_("where to dump the core")},
     {NULL, 0, 0, NULL}
@@ -1778,7 +1780,13 @@ cmdDump(vshControl *ctl, const vshCmd *c
         flags |= VIR_DUMP_LIVE;
     if (vshCommandOptBool (cmd, "crash"))
         flags |= VIR_DUMP_CRASH;
-
+    if (vshCommandOptBool (cmd, "gzip"))
+	flags |= VIR_DUMP_GZIP;
+    if (vshCommandOptBool (cmd, "lzop"))
+        flags |= VIR_DUMP_LZOP;
+    if ((flags & (VIR_DUMP_GZIP | VIR_DUMP_LZOP))
+	 == (VIR_DUMP_GZIP | VIR_DUMP_LZOP))
+	return FALSE;
     if (virDomainCoreDump(dom, to, flags) == 0) {
         vshPrint(ctl, _("Domain %s dumped to %s\n"), name, to);
     } else {
Index: libvirt-0.8.4/include/libvirt/libvirt.h.in
===================================================================
--- libvirt-0.8.4.orig/include/libvirt/libvirt.h.in
+++ libvirt-0.8.4/include/libvirt/libvirt.h.in
@@ -402,6 +402,8 @@ typedef virDomainMemoryStatStruct *virDo
 typedef enum {
     VIR_DUMP_CRASH   = (1 << 0), /* crash after dump */
     VIR_DUMP_LIVE    = (1 << 1), /* live dump */
+    VIR_DUMP_GZIP    = (1 << 2), /* gzip dump file */
+    VIR_DUMP_LZOP    = (1 << 3), /* lzop dump file */
 } virDomainCoreDumpFlags;
 
 /* Domain migration flags. */