[libvirt] [PATCH 2/2] network: bridge_driver: don't lose transient networks on daemon restart
Peter Krempa
pkrempa at redhat.com
Thu Apr 18 12:10:38 UTC 2013
On 04/17/13 18:07, Laine Stump wrote:
> On 04/17/2013 04:40 AM, Peter Krempa wrote:
>> Until now tranisent networks weren't really useful as libvirtd wasn't
>> able to remember them across restarts. This patch adds support for
>> loading status files of transient networks (that already were generated)
>> so that the status isn't lost.
>>
>> This patch chops up virNetworkObjUpdateParseFile and turns it into
>> virNetworkLoadState and a few friends that will help us to load status
>> XMLs and refactors the functions that are loading the configs to use
>> them.
>> ---
>> src/conf/network_conf.c | 220 +++++++++++++++++++++++++++++---------------
>> src/conf/network_conf.h | 10 +-
>> src/libvirt_private.syms | 2 +-
>> src/network/bridge_driver.c | 51 ++++++----
>> 4 files changed, 184 insertions(+), 99 deletions(-)
>>
>> diff --git a/src/conf/network_conf.c b/src/conf/network_conf.c
>> index 75584a0..009e90c 100644
>> --- a/src/conf/network_conf.c
>> +++ b/src/conf/network_conf.c
>> @@ -1967,81 +1967,6 @@ cleanup:
>> return def;
>> }
>>
>> -int
>> -virNetworkObjUpdateParseFile(const char *filename,
>> - virNetworkObjPtr net)
>> -{
>> - int ret = -1;
>> - xmlDocPtr xml = NULL;
>> - xmlNodePtr node = NULL;
>> - virNetworkDefPtr tmp = NULL;
>> - xmlXPathContextPtr ctxt = NULL;
>> -
>> - xml = virXMLParse(filename, NULL, _("(network status)"));
>> - if (!xml)
>> - return -1;
>> -
>> - ctxt = xmlXPathNewContext(xml);
>> - if (ctxt == NULL) {
>> - virReportOOMError();
>> - goto cleanup;
>> - }
>> -
>> - node = xmlDocGetRootElement(xml);
>> - if (xmlStrEqual(node->name, BAD_CAST "networkstatus")) {
>> - /* Newer network status file. Contains useful
>> - * info which are not to be found in bare config XML */
>> - char *class_id = NULL;
>> - char *floor_sum = NULL;
>> -
>> - ctxt->node = node;
>> - class_id = virXPathString("string(./class_id[1]/@bitmap)", ctxt);
>> - if (class_id) {
>> - virBitmapFree(net->class_id);
>> - if (virBitmapParse(class_id, 0,
>> - &net->class_id, CLASS_ID_BITMAP_SIZE) < 0) {
>> - virReportError(VIR_ERR_INTERNAL_ERROR,
>> - _("Malformed 'class_id' attribute: %s"),
>> - class_id);
>> - VIR_FREE(class_id);
>> - goto cleanup;
>> - }
>> - }
>> - VIR_FREE(class_id);
>> -
>> - floor_sum = virXPathString("string(./floor[1]/@sum)", ctxt);
>> - if (floor_sum &&
>> - virStrToLong_ull(floor_sum, NULL, 10, &net->floor_sum) < 0) {
>> - virReportError(VIR_ERR_INTERNAL_ERROR,
>> - _("Malformed 'floor_sum' attribute: %s"),
>> - floor_sum);
>> - VIR_FREE(floor_sum);
>> - }
>> - VIR_FREE(floor_sum);
>> - }
>> -
>> - node = virXPathNode("//network", ctxt);
>> - if (!node) {
>> - virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
>> - _("Could not find any 'network' element"));
>> - goto cleanup;
>> - }
>> -
>> - ctxt->node = node;
>> - tmp = virNetworkDefParseXML(ctxt);
>> -
>> - if (tmp) {
>> - net->newDef = net->def;
>> - net->def = tmp;
>> - }
>> -
>> - ret = 0;
>> -
>> -cleanup:
>> - xmlFreeDoc(xml);
>> - xmlXPathFreeContext(ctxt);
>> - return ret;
>> -}
>>
>> static int
>> virNetworkDNSDefFormat(virBufferPtr buf,
>> @@ -2554,6 +2479,117 @@ cleanup:
>> return ret;
>> }
>>
>> +virNetworkObjPtr
>> +virNetworkLoadState(virNetworkObjListPtr nets,
>> + const char *configDir,
>
> Maybe call it "stateDir" just to avoid confusion?
That sounds better.
>
>> + const char *name)
>> +{
>> + char *configFile = NULL;
>> + virNetworkDefPtr def = NULL;
>> + virNetworkObjPtr net = NULL;
>> + xmlDocPtr xml = NULL;
>> + xmlNodePtr node = NULL;
>> + xmlXPathContextPtr ctxt = NULL;
>> + virBitmapPtr class_id_map = NULL;
>> + unsigned long long floor_sum_val = 0;
>> +
>> +
>> + if ((configFile = virNetworkConfigFile(configDir, name)) == NULL)
>> + goto error;
>> +
>> + if (!(xml = virXMLParseCtxt(configFile, NULL, _("(network status)"), &ctxt)))
>> + goto error;
>> +
>> + if (!(node = virXPathNode("//network", ctxt))) {
>> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
>> + _("Could not find any 'network' element in status file"));
>> + goto error;
>> + }
>
>
> Won't that fail when reading an old-style network status file that has
> <network> at the toplevel rather than inside <networkstatus>? Or is
> "//xyz" some special XPath notation that means "find this node anywhere
> in the hierarchy"?
>
Yes, //xyz means: "select node matching xyz no matter where they are
from the current node", the current in this case is either
<networkstatus> in case of the new file, or only <network> (and thus
selectable) in case of the old file.
>
>
>> +
>> + /* parse the definition first */
>> + ctxt->node = node;
>> + if (!(def = virNetworkDefParseXML(ctxt)))
>> + goto error;
>> +
>> + if (!STREQ(name, def->name)) {
>> + virReportError(VIR_ERR_INTERNAL_ERROR,
>> + _("Network config filename '%s'"
>> + " does not match network name '%s'"),
>> + configFile, def->name);
>> + goto error;
>> + }
>> +
>> + if (def->forward.type == VIR_NETWORK_FORWARD_NONE ||
>> + def->forward.type == VIR_NETWORK_FORWARD_NAT ||
>> + def->forward.type == VIR_NETWORK_FORWARD_ROUTE) {
>> + /* state configs should always have the bridge stored in the file */
>> + if (!def->bridge || strstr(def->bridge, "%d")) {
>> + virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
>> + _("network status XML does not contain valid bridge "
>> + "name"));
>> + goto error;
>> + }
>> + }
>
>
> Is there a reason this extra validation was needed here? We don't use
> def->bridge anywhere else in this function, and I would assume that the
> other functions using def after return will be properly validating what
> they use.
I'm not really sure if this is needed here. I ported it here from the
persistent config loader function where it validates and fills the
bridge name. Here it should always be filled but I wanted to be sure
that it doesn't break anything when a user would mess with the status files.
If you think it's useless, I'll be happy deleting it :)
>
>
>> +
>> + /* now parse possible status data */
>> + node = xmlDocGetRootElement(xml);
>> + if (xmlStrEqual(node->name, BAD_CAST "networkstatus")) {
>> + /* Newer network status file. Contains useful
>> + * info which are not to be found in bare config XML */
>> + char *class_id = NULL;
>> + char *floor_sum = NULL;
>> +
>> + ctxt->node = node;
>> + if ((class_id = virXPathString("string(./class_id[1]/@bitmap)", ctxt))) {
>> + if (virBitmapParse(class_id, 0, &class_id_map,
>> + CLASS_ID_BITMAP_SIZE) < 0) {
>> + virReportError(VIR_ERR_INTERNAL_ERROR,
>> + _("Malformed 'class_id' attribute: %s"),
>> + class_id);
>> + VIR_FREE(class_id);
>> + goto error;
>> + }
>> + }
>> + VIR_FREE(class_id);
>> +
>> + floor_sum = virXPathString("string(./floor[1]/@sum)", ctxt);
>> + if (floor_sum &&
>> + virStrToLong_ull(floor_sum, NULL, 10, &floor_sum_val) < 0) {
>> + virReportError(VIR_ERR_INTERNAL_ERROR,
>> + _("Malformed 'floor_sum' attribute: %s"),
>> + floor_sum);
>> + VIR_FREE(floor_sum);
>> + }
>> + VIR_FREE(floor_sum);
>> + }
>> +
>> + /* create the object */
>> + if (!(net = virNetworkAssignDef(nets, def, true)))
>> + goto error;
>> + /* no goto error below this comment */
>
> You should make that comment less ambiguous, i.e. "do not put any "goto
> error" anywhere below this comment"
>
>> +
>> + /* assign status data stored in the network object */
>> + if (class_id_map) {
>> + virBitmapFree(net->class_id);
>
>
> Rather than calling virBitmapFree here, I think it would be better to
> call it after cleanup: (and remove it from error:), just to make it
> easier for someone to verify that it will always be properly freed.
You probably misread that. The virBitmapFree call frees the old
definition (note the "net->" )here and assigns a new one that was parsed
from the status config.
>
>
>> + net->class_id = class_id_map;
>> + }
>> +
>> + if (floor_sum_val > 0)
>> + net->floor_sum = floor_sum_val;
>> +
>> +
>> +cleanup:
>> + VIR_FREE(configFile);
>> + xmlFreeDoc(xml);
>> + xmlXPathFreeContext(ctxt);
>> + return net;
>> +
>> +error:
>> + virBitmapFree(class_id_map);
... whereas here the status config definition is freed in case it wasn't
used.
>> + virNetworkDefFree(def);
>> + goto cleanup;
>> +}
>> +
>> virNetworkObjPtr virNetworkLoadConfig(virNetworkObjListPtr nets,
>> const char *configDir,
>> const char *autostartDir,
>> @@ -2612,6 +2648,40 @@ error:
>> return NULL;
>> }
>>
>> +
>> +int
>> +virNetworkLoadAllState(virNetworkObjListPtr nets,
>> + const char *configDir)
I'll rename this variable too.
>> +{
>> + DIR *dir;
>> + struct dirent *entry;
>> +
>> + if (!(dir = opendir(configDir))) {
>> + if (errno == ENOENT)
>> + return 0;
>> +
>> + virReportSystemError(errno, _("Failed to open dir '%s'"), configDir);
>> + return -1;
>> + }
>> +
>> + while ((entry = readdir(dir))) {
>> + virNetworkObjPtr net;
>> +
>> + if (entry->d_name[0] == '.')
>> + continue;
>> +
>> + if (!virFileStripSuffix(entry->d_name, ".xml"))
>> + continue;
>> +
>> + if ((net = virNetworkLoadState(nets, configDir, entry->d_name)))
>> + virNetworkObjUnlock(net);
>> + }
>> +
>> + closedir(dir);
>> + return 0;
>> +}
>> +
>> +
>> int virNetworkLoadAllConfigs(virNetworkObjListPtr nets,
>> const char *configDir,
>> const char *autostartDir)
>> diff --git a/src/conf/network_conf.h b/src/conf/network_conf.h
>> index 1a86e3d..7d4c40b 100644
>> --- a/src/conf/network_conf.h
>> +++ b/src/conf/network_conf.h
>> @@ -280,9 +280,6 @@ virNetworkDefPtr virNetworkDefParseString(const char *xmlStr);
>> virNetworkDefPtr virNetworkDefParseFile(const char *filename);
>> virNetworkDefPtr virNetworkDefParseNode(xmlDocPtr xml,
>> xmlNodePtr root);
>> -int virNetworkObjUpdateParseFile(const char *filename,
>> - virNetworkObjPtr net);
>> -
>> char *virNetworkDefFormat(const virNetworkDefPtr def, unsigned int flags);
>>
>> static inline const char *
>> @@ -318,10 +315,17 @@ virNetworkObjPtr virNetworkLoadConfig(virNetworkObjListPtr nets,
>> const char *autostartDir,
>> const char *file);
>>
>> +virNetworkObjPtr virNetworkLoadState(virNetworkObjListPtr nets,
>> + const char *configDir,
>> + const char *name);
>> +
>> int virNetworkLoadAllConfigs(virNetworkObjListPtr nets,
>> const char *configDir,
>> const char *autostartDir);
>>
>> +int virNetworkLoadAllState(virNetworkObjListPtr nets,
>> + const char *configDir);
>> +
>> int virNetworkDeleteConfig(const char *configDir,
>> const char *autostartDir,
>> virNetworkObjPtr net);
>> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
>> index 30fdcd7..f778e9c 100644
>> --- a/src/libvirt_private.syms
>> +++ b/src/libvirt_private.syms
>> @@ -454,6 +454,7 @@ virNetworkIpDefNetmask;
>> virNetworkIpDefPrefix;
>> virNetworkList;
>> virNetworkLoadAllConfigs;
>> +virNetworkLoadAllState;
>> virNetworkObjAssignDef;
>> virNetworkObjFree;
>> virNetworkObjGetPersistentDef;
>> @@ -465,7 +466,6 @@ virNetworkObjSetDefTransient;
>> virNetworkObjUnlock;
>> virNetworkObjUnsetDefTransient;
>> virNetworkObjUpdate;
>> -virNetworkObjUpdateParseFile;
>> virNetworkRemoveInactive;
>> virNetworkSaveConfig;
>> virNetworkSaveStatus;
>> diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c
>> index bca6bd9..56af108 100644
>> --- a/src/network/bridge_driver.c
>> +++ b/src/network/bridge_driver.c
>> @@ -181,6 +181,7 @@ networkRemoveInactive(struct network_driver *driver,
>> char *radvdconfigfile = NULL;
>> char *configfile = NULL;
>> char *radvdpidbase = NULL;
>> + char *statusfile = NULL;
>> dnsmasqContext *dctx = NULL;
>> virNetworkDefPtr def = virNetworkObjGetPersistentDef(net);
>>
>> @@ -202,6 +203,9 @@ networkRemoveInactive(struct network_driver *driver,
>> if (!(configfile = networkDnsmasqConfigFileName(def->name)))
>> goto no_memory;
>>
>> + if (!(statusfile = virNetworkConfigFile(NETWORK_STATE_DIR, def->name)))
>> + goto no_memory;
>> +
>> /* dnsmasq */
>> dnsmasqDelete(dctx);
>> unlink(leasefile);
>> @@ -211,6 +215,9 @@ networkRemoveInactive(struct network_driver *driver,
>> unlink(radvdconfigfile);
>> virPidFileDelete(NETWORK_PID_DIR, radvdpidbase);
>>
>> + /* remove status file */
>> + unlink(statusfile);
>> +
>> /* remove the network definition */
>> virNetworkRemoveInactive(&driver->networks, net);
>>
>> @@ -221,6 +228,7 @@ cleanup:
>> VIR_FREE(configfile);
>> VIR_FREE(radvdconfigfile);
>> VIR_FREE(radvdpidbase);
>> + VIR_FREE(statusfile);
>> dnsmasqContextFree(dctx);
>> return ret;
>>
>> @@ -254,33 +262,15 @@ networkBridgeDummyNicName(const char *brname)
>> }
>>
>> static void
>> -networkFindActiveConfigs(struct network_driver *driver) {
>> +networkFindActiveConfigs(struct network_driver *driver)
>> +{
>> unsigned int i;
>>
>> for (i = 0 ; i < driver->networks.count ; i++) {
>> virNetworkObjPtr obj = driver->networks.objs[i];
>> - char *config;
>>
>> virNetworkObjLock(obj);
>>
>> - if ((config = virNetworkConfigFile(NETWORK_STATE_DIR,
>> - obj->def->name)) == NULL) {
>> - virNetworkObjUnlock(obj);
>> - continue;
>> - }
>> -
>> - if (access(config, R_OK) < 0) {
>> - VIR_FREE(config);
>> - virNetworkObjUnlock(obj);
>> - continue;
>> - }
>> -
>> - /* Try and load the live config */
>> - if (virNetworkObjUpdateParseFile(config, obj) < 0)
>> - VIR_WARN("Unable to update config of '%s' network",
>> - obj->def->name);
>> - VIR_FREE(config);
>> -
>> /* If bridge exists, then mark it active */
>> if (obj->def->bridge &&
>> virNetDevExists(obj->def->bridge) == 1) {
>
>
> This simple check for the bridge device's existence isn't adequate for
> network types that have no bridge, or for network types that have a
> bridge that isn't managed by libvirt (i.e. forward
> mode='bridge|hostdev'). In those cases libvirt makes no external changes
> to the system that could be used to detect if the network is active or
> not - the only useful indicator is the presence of the state file. (In
> general I think that should be true for networks where libvirt
> creates/manages the bridge too; if the state file exists but the bridge
> doesn't, that just means that the network needs to be reconstructed, not
> that it should be marked inactive).
Well, as that piece of code was pre-existing I didn't dare to touch it.
If we are going to remove this kind of check, we need to make sure that
transient configs (status files) are deleted at reboot of the machine so
that we don't re-create networks on host reboot. Or do we want to do that?.
Also, without this check, the removal code of inactive transient
networks isn't really needed.
>
>
>> @@ -307,6 +297,21 @@ networkFindActiveConfigs(struct network_driver *driver) {
>> cleanup:
>> virNetworkObjUnlock(obj);
>> }
>> +
>> +redo:
>> + /* remove inactive transient domains */
>> + for (i = 0 ; i < driver->networks.count ; i++) {
>> + virNetworkObjPtr obj = driver->networks.objs[i];
>> +
>> + virNetworkObjLock(obj);
>> +
>> + if (!obj->persistent && !obj->active) {
>> + networkRemoveInactive(driver, obj);
>
> I think you have a deadlock here, don't you? networkRemoveInactive()
> calls virNetworkRemoveInactive(), which will scan through this same
> array, locking each network object before seeing if it's the one we want
> to delete. But you've already locked it.
Fortunately, this doesn't deadlock. virNetworkRemoveInactive unlocks the
passed network object before entering the list and scanning through it.
>
> Since we already hold the network driver lock, and we're operating at a
> single-threaded place for the network driver anyway, I think the
> virNetworkObjLock() here is unnecessary.
Yes, at this point it is not necessary for concurrency but it's
necessary for virNetworkRemoveInactive anyways.
>
>
>> + goto redo;
>
>
> It seems a bit drastic to redo all the way from the beginning of the
> list. Since this function already assumes enough knowledge about the
> list of network objects to know that it's an array, and it knows which
> position in the array contains the object we're deleting, we might as
> well go all the way and let this code "know" that when an object is
> removed, the remainder of the list is moved up by one; then all we need
> to do is go to the top of the loop without doing i++.
>
> So, you could just write this as a while loop instead of a for loop, put
> the "i++;" at the bottom of the loop, and do a "continue;" instead of
> "goto redo;"
Yeah, I can do that. I wanted to make it implementation agnostic, but as
the array removal implementation is known, I can abuse that knowledge
and save re-iterating (although that shouldn't really be a problem).
>
>
>> + }
>> +
>> + virNetworkObjUnlock(obj);
>> + }
>> }
>>
>>
>> @@ -416,6 +421,10 @@ networkStartup(bool privileged,
>> /* if this fails now, it will be retried later with dnsmasqCapsRefresh() */
>> driverState->dnsmasqCaps = dnsmasqCapsNewFromBinary(DNSMASQ);
>>
>> + if (virNetworkLoadAllState(&driverState->networks,
>> + NETWORK_STATE_DIR) < 0)
>> + goto error;
>> +
>> if (virNetworkLoadAllConfigs(&driverState->networks,
>> driverState->networkConfigDir,
>> driverState->networkAutostartDir) < 0)
>> @@ -480,6 +489,8 @@ networkReload(void) {
>> return 0;
>>
>> networkDriverLock(driverState);
>> + virNetworkLoadAllState(&driverState->networks,
>> + NETWORK_STATE_DIR);
>> virNetworkLoadAllConfigs(&driverState->networks,
>> driverState->networkConfigDir,
>> driverState->networkAutostartDir);
>
>
> Otherwise looks good, and will be a nice thing to get fixed.
>
>
> --
> libvir-list mailing list
> libvir-list at redhat.com
> https://www.redhat.com/mailman/listinfo/libvir-list
>
Peter
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