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



On Tue, Apr 21, 2015 at 03:47:34PM -0600, Jim Fehlig wrote:
> 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.

For virtlockd it doesn't matter, but with the sanlock driver there is a
tiny difference due to VIR_LOCK_MANAGER_NEW_STARTED being passed to the
virLockManagerNew() method in the Start case.

Regards,
Daniel
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