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Re: [libvirt] [PATCH 3/3] libxl: provide integration with lock manager



Daniel P. Berrange wrote:
> On Fri, Apr 17, 2015 at 03:36:22PM -0600, Jim Fehlig wrote:
>   
>> Provide integration with libvirt's lock manager in the libxl driver.
>>
>> Signed-off-by: Jim Fehlig <jfehlig suse com>
>> ---
>>  src/Makefile.am                      | 12 +++++++++
>>  src/libxl/libvirtd_libxl.aug         |  2 ++
>>  src/libxl/libxl.conf                 | 10 ++++++++
>>  src/libxl/libxl_conf.c               | 14 +++++++++++
>>  src/libxl/libxl_conf.h               |  6 +++++
>>  src/libxl/libxl_domain.c             | 47 ++++++++++++++++++++++++++++++++++--
>>  src/libxl/libxl_domain.h             |  1 +
>>  src/libxl/libxl_driver.c             | 25 +++++++++++++++++++
>>  src/libxl/libxl_migration.c          |  6 +++++
>>  src/libxl/test_libvirtd_libxl.aug.in |  1 +
>>  10 files changed, 122 insertions(+), 2 deletions(-)
>>
>> diff --git a/src/Makefile.am b/src/Makefile.am
>> index 9a5f16c..1438174 100644
>> --- a/src/Makefile.am
>> +++ b/src/Makefile.am
>> @@ -2246,6 +2246,12 @@ BUILT_SOURCES += locking/qemu-lockd.conf
>>  DISTCLEANFILES += locking/qemu-lockd.conf
>>  endif WITH_QEMU
>>  
>> +if WITH_LIBXL
>> +nodist_conf_DATA += locking/libxl-lockd.conf
>> +BUILT_SOURCES += locking/libxl-lockd.conf
>> +DISTCLEANFILES += locking/libxl-lockd.conf
>> +endif WITH_LIBXL
>> +
>>  locking/%-lockd.conf: $(srcdir)/locking/lockd.conf
>>  	$(AM_V_GEN)$(MKDIR_P) locking ; \
>>  	cp $< $@
>> @@ -2431,6 +2437,12 @@ nodist_conf_DATA += locking/qemu-sanlock.conf
>>  BUILT_SOURCES += locking/qemu-sanlock.conf
>>  DISTCLEANFILES += locking/qemu-sanlock.conf
>>  endif WITH_QEMU
>> +
>> +if WITH_LIBXL
>> +nodist_conf_DATA += locking/libxl-sanlock.conf
>> +BUILT_SOURCES += locking/libxl-sanlock.conf
>> +DISTCLEANFILES += locking/libxl-sanlock.conf
>> +endif WITH_LIBXL
>>  else ! WITH_SANLOCK
>>  EXTRA_DIST += $(LOCK_DRIVER_SANLOCK_SOURCES)
>>  endif ! WITH_SANLOCK
>> diff --git a/src/libxl/libvirtd_libxl.aug b/src/libxl/libvirtd_libxl.aug
>> index f225954..d5aa150 100644
>> --- a/src/libxl/libvirtd_libxl.aug
>> +++ b/src/libxl/libvirtd_libxl.aug
>> @@ -25,9 +25,11 @@ module Libvirtd_libxl =
>>  
>>     (* Config entry grouped by function - same order as example config *)
>>     let autoballoon_entry = bool_entry "autoballoon"
>> +   let lock_entry = str_entry "lock_manager"
>>  
>>     (* Each entry in the config is one of the following ... *)
>>     let entry = autoballoon_entry
>> +             | lock_entry
>>  
>>     let comment = [ label "#comment" . del /#[ \t]*/ "# " .  store /([^ \t\n][^\n]*)?/ . del /\n/ "\n" ]
>>     let empty = [ label "#empty" . eol ]
>> diff --git a/src/libxl/libxl.conf b/src/libxl/libxl.conf
>> index c104d40..ba3de7a 100644
>> --- a/src/libxl/libxl.conf
>> +++ b/src/libxl/libxl.conf
>> @@ -10,3 +10,13 @@
>>  # autoballoon setting.
>>  #
>>  #autoballoon = 1
>> +
>> +
>> +# In order to prevent accidentally starting two domains that
>> +# share one writable disk, libvirt offers two approaches for
>> +# locking files: sanlock and virtlockd.  sanlock is an external
>> +# project which libvirt integrates with via the libvirt-lock-sanlock
>> +# package.  virtlockd is a libvirt implementation that is enabled with
>> +# "lockd".  Accepted values are "sanlock" and "lockd".
>> +#
>> +#lock_manager = "lockd"
>> diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c
>> index 6ea2889..503e8a4 100644
>> --- a/src/libxl/libxl_conf.c
>> +++ b/src/libxl/libxl_conf.c
>> @@ -102,6 +102,7 @@ libxlDriverConfigDispose(void *obj)
>>      VIR_FREE(cfg->libDir);
>>      VIR_FREE(cfg->saveDir);
>>      VIR_FREE(cfg->autoDumpDir);
>> +    VIR_FREE(cfg->lockManagerName);
>>  }
>>  
>>  
>> @@ -1495,6 +1496,7 @@ int libxlDriverConfigLoadFile(libxlDriverConfigPtr cfg,
>>                                const char *filename)
>>  {
>>      virConfPtr conf = NULL;
>> +    virConfValuePtr p;
>>      int ret = -1;
>>  
>>      /* Check the file is readable before opening it, otherwise
>> @@ -1512,6 +1514,18 @@ int libxlDriverConfigLoadFile(libxlDriverConfigPtr cfg,
>>      if (libxlGetAutoballoonConf(cfg, conf) < 0)
>>          goto cleanup;
>>  
>> +    if ((p = virConfGetValue(conf, "lock_manager"))) {
>> +        if (p->type != VIR_CONF_STRING) {
>> +            virReportError(VIR_ERR_INTERNAL_ERROR,
>> +                           "%s",
>> +                           _("Unexpected type for 'lock_manager' setting"));
>> +            goto cleanup;
>> +        }
>> +
>> +        if (VIR_STRDUP(cfg->lockManagerName, p->str) < 0)
>> +            goto cleanup;
>> +    }
>> +
>>      ret = 0;
>>  
>>   cleanup:
>> diff --git a/src/libxl/libxl_conf.h b/src/libxl/libxl_conf.h
>> index 5ba1a71..0a1c0db 100644
>> --- a/src/libxl/libxl_conf.h
>> +++ b/src/libxl/libxl_conf.h
>> @@ -38,6 +38,7 @@
>>  # include "virobject.h"
>>  # include "virchrdev.h"
>>  # include "virhostdev.h"
>> +# include "locking/lock_manager.h"
>>  
>>  # define LIBXL_DRIVER_NAME "xenlight"
>>  # define LIBXL_VNC_PORT_MIN  5900
>> @@ -98,6 +99,8 @@ struct _libxlDriverConfig {
>>       * memory for new domains from domain0. */
>>      bool autoballoon;
>>  
>> +    char *lockManagerName;
>> +
>>      /* Once created, caps are immutable */
>>      virCapsPtr caps;
>>  
>> @@ -144,6 +147,9 @@ struct _libxlDriverPrivate {
>>  
>>      /* Immutable pointer, lockless APIs*/
>>      virSysinfoDefPtr hostsysinfo;
>> +
>> +    /* Immutable pointer. lockless access */
>> +    virLockManagerPluginPtr lockManager;
>>  };
>>  
>>  # define LIBXL_SAVE_MAGIC "libvirt-xml\n \0 \r"
>> diff --git a/src/libxl/libxl_domain.c b/src/libxl/libxl_domain.c
>> index 77d46d0..70247f5 100644
>> --- a/src/libxl/libxl_domain.c
>> +++ b/src/libxl/libxl_domain.c
>> @@ -34,6 +34,7 @@
>>  #include "virlog.h"
>>  #include "virstring.h"
>>  #include "virtime.h"
>> +#include "locking/domain_lock.h"
>>  
>>  #define VIR_FROM_THIS VIR_FROM_LIBXL
>>  
>> @@ -217,12 +218,36 @@ libxlDomainObjPrivateFree(void *data)
>>  {
>>      libxlDomainObjPrivatePtr priv = data;
>>  
>> +    VIR_FREE(priv->lockState);
>>      virObjectUnref(priv);
>>  }
>>  
>> +static int
>> +libxlDomainObjPrivateXMLParse(xmlXPathContextPtr ctxt, void *data)
>> +{
>> +    libxlDomainObjPrivatePtr priv = data;
>> +
>> +    priv->lockState = virXPathString("string(./lockstate)", ctxt);
>> +
>> +    return 0;
>> +}
>> +
>> +static int
>> +libxlDomainObjPrivateXMLFormat(virBufferPtr buf, void *data)
>> +{
>> +    libxlDomainObjPrivatePtr priv = data;
>> +
>> +    if (priv->lockState)
>> +        virBufferAsprintf(buf, "<lockstate>%s</lockstate>\n", priv->lockState);
>> +
>> +    return 0;
>> +}
>> +
>>  virDomainXMLPrivateDataCallbacks libxlDomainXMLPrivateDataCallbacks = {
>>      .alloc = libxlDomainObjPrivateAlloc,
>>      .free = libxlDomainObjPrivateFree,
>> +    .parse = libxlDomainObjPrivateXMLParse,
>> +    .format = libxlDomainObjPrivateXMLFormat,
>>  };
>>  
>>  
>> @@ -668,6 +693,11 @@ libxlDomainCleanup(libxlDriverPrivatePtr driver,
>>      virHostdevReAttachDomainDevices(hostdev_mgr, LIBXL_DRIVER_NAME,
>>                                      vm->def, VIR_HOSTDEV_SP_PCI, NULL);
>>  
>> +    VIR_FREE(priv->lockState);
>> +    if (virDomainLockProcessPause(driver->lockManager, vm, &priv->lockState) < 0)
>> +        VIR_WARN("Unable to release lease on %s", vm->def->name);
>> +    VIR_DEBUG("Preserving lock state '%s'", NULLSTR(priv->lockState));
>>     
>
> I see a few calls to ProcessPause, but I'm not seeing any to ProcessResume,
> so I think you might have missed a few places needing hooks.
>   

Currently I'm not using ProcessResume and instead calling ProcessStart
with paused param set to false.  ProcessStart is called in
libxlDomainStart, which is called by all paths that start a domain, e.g.
start, create, restore, migrate, etc.  I was under the impression that
ProcessResume is not needed if ProcessStart is called with paused=false.

Regards,
Jim


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