Re: [libvirt] [PATCH v2] blockjob: use stable disk string in job event

When the block job event was first added, it was for block pull, where the active layer of the disk remains the same name. It was also in a day where we only cared about local files, and so we always had a canonical absolute file name. But two things have changed since then: we now have network disks, where determining a single absolute string does not really make sense; and we have two-phase jobs (copy and active commit) where the name of the active layer changes between the first event (ready, on the old name) and second (complete, on the pivoted name). Adam Litke reported that having an unstable string between events makes life harder for clients. Furthermore, all of our API that operate on a particular disk of a domain accept multiple strings: not only the absolute name of the active layer, but also the destination device name (such as 'vda'). As this latter name is stable, even for network sources, it serves as a better string to supply in block job events. But backwards-compatibility demands that we should not change the name handed to users unless they explicitly request it. Therefore, this patch adds a new event, BLOCK_JOB_2 (alas, I couldn't think of any nicer name), and has to double up on emitting both old-style and new-style events according to what clients have registered for (see also how IOError and IOErrorReason emits double events, but there the difference was a larger struct rather than changed meaning of one of the struct members). Unfortunately, adding a new event isn't something that can easily be broken into pieces, so the commit is rather large. * include/libvirt/libvirt.h.in (virDomainEventID): Add a new id for VIR_DOMAIN_EVENT_ID_BLOCK_JOB_2. (virConnectDomainEventBlockJobCallback): Document new semantics. * src/conf/domain_event.c (_virDomainEventBlockJob): Rename field, to ensure we catch all clients. (virDomainEventBlockJobNew): Add parameter. (virDomainEventBlockJobDispose, virDomainEventBlockJobNew) (virDomainEventBlockJobNewFromObj) (virDomainEventBlockJobNewFromDom) (virDomainEventDispatchDefaultFunc): Adjust clients. (virDomainEventBlockJob2NewFromObj) (virDomainEventBlockJob2NewFromDom): New functions. * src/conf/domain_event.h: Add new prototypes. * src/libvirt_private.syms (domain_event.h): Export new functions. * src/qemu/qemu_driver.c (qemuDomainBlockJobImpl): Generate two different events. * src/qemu/qemu_process.c (qemuProcessHandleBlockJob): Likewise. * src/remote/remote_protocol.x (remote_domain_event_block_job_msg): Adjust client. (remote_domain_event_block_job_2_msg): New struct. (REMOTE_PROC_DOMAIN_EVENT_BLOCK_JOB_2): New RPC. * src/remote/remote_driver.c (remoteDomainBuildEventBlockJobHelper): Adjust client. (remoteDomainBuildEventBlockJob2): New handler. (remoteEvents): Register new event. * daemon/remote.c (remoteRelayDomainEventBlockJob): Adjust client. (remoteRelayDomainEventBlockJob2): New handler. (domainEventCallbacks): Register new event. * tools/virsh-domain.c (vshEventCallbacks): Likewise. (vshEventBlockJobPrint): Adjust client. * src/remote_protocol-structs: Regenerate. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- v1: https://www.redhat.com/archives/libvir-list/2014-June/msg00675.html Diff from v1: add a new event type, and keep clients of the old event unchanged in what they get in their callback. daemon/remote.c | 47 +++++++++++++++++++++++++++++++++++---- include/libvirt/libvirt.h.in | 18 ++++++++++++--- src/conf/domain_event.c | 52 +++++++++++++++++++++++++++++++++----------- src/conf/domain_event.h | 15 +++++++++++-- src/libvirt_private.syms | 2 ++ src/qemu/qemu_driver.c | 8 ++++++- src/qemu/qemu_process.c | 7 ++++++ src/remote/remote_driver.c | 33 +++++++++++++++++++++++++++- src/remote/remote_protocol.x | 18 +++++++++++++-- src/remote_protocol-structs | 10 ++++++++- tools/virsh-domain.c | 7 ++++-- 11 files changed, 188 insertions(+), 29 deletions(-) diff --git a/daemon/remote.c b/daemon/remote.c index 34c96c9..56cf84f 100644 --- a/daemon/remote.c +++ b/daemon/remote.c @@ -558,7 +558,7 @@ remoteRelayDomainEventGraphics(virConnectPtr conn, static int remoteRelayDomainEventBlockJob(virConnectPtr conn, virDomainPtr dom, - const char *path, + const char *disk, int type, int status, void *opaque)

@@ -571,11 +571,11 @@ remoteRelayDomainEventBlockJob(virConnectPtr conn, return -1; VIR_DEBUG("Relaying domain block job event %s %d %s %i, %i, callback %d", - dom->name, dom->id, path, type, status, callback->callbackID); + dom->name, dom->id, disk, type, status, callback->callbackID); /* build return data */ memset(&data, 0, sizeof(data)); - if (VIR_STRDUP(data.path, path) < 0) + if (VIR_STRDUP(data.disk, disk) < 0) goto error; data.type = type; data.status = status;

@@ -596,7 +596,7 @@ remoteRelayDomainEventBlockJob(virConnectPtr conn, return 0; error: - VIR_FREE(data.path); + VIR_FREE(data.disk); return -1; }

diff --git a/include/libvirt/libvirt.h.in b/include/libvirt/libvirt.h.in index dc88c40..c36fec3 100644 --- a/include/libvirt/libvirt.h.in +++ b/include/libvirt/libvirt.h.in @@ -4852,13 +4852,24 @@ typedef enum { * virConnectDomainEventBlockJobCallback: * @conn: connection object * @dom: domain on which the event occurred - * @disk: fully-qualified filename of the affected disk + * @disk: name associated with the affected disk

* @type: type of block job (virDomainBlockJobType) * @status: status of the operation (virConnectDomainEventBlockJobStatus) * @opaque: application specified data * - * The callback signature to use when registering for an event of type - * VIR_DOMAIN_EVENT_ID_BLOCK_JOB with virConnectDomainEventRegisterAny() + * The string returned for @disk can be used in any of the libvirt API + * that operate on a particular disk of the domain, and depends on what + * event type was registered with virConnectDomainEventRegisterAny(). + * If the callback was registered using the older type of + * VIR_DOMAIN_EVENT_ID_BLOCK_JOB, then @disk contains the absolute file + * name of the host resource for the active layer of the disk; however, + * this name is unstable (pivoting via block copy or active block commit + * will change which file is active, giving a different name for the two + * events associated with the same job) and cannot be relied on if the + * active layer is associated with a network resource. If the callback + * was registered using the newer type of VIR_DOMAIN_EVENT_ID_BLOCK_JOB_2, + * then @disk will contain the device target shorthand (the <target + * dev='...'/> sub-element, such as "vda"). */ typedef void (*virConnectDomainEventBlockJobCallback)(virConnectPtr conn, virDomainPtr dom,

diff --git a/src/conf/domain_event.c b/src/conf/domain_event.c index b565732..43794d3 100644 --- a/src/conf/domain_event.c +++ b/src/conf/domain_event.c @@ -128,7 +128,7 @@ typedef virDomainEventIOError *virDomainEventIOErrorPtr; struct _virDomainEventBlockJob { virDomainEvent parent; - char *path; + char *disk;

int type; int status; };

@@ -775,10 +775,11 @@ virDomainEventGraphicsNewFromObj(virDomainObjPtr obj, } static virObjectEventPtr -virDomainEventBlockJobNew(int id, +virDomainEventBlockJobNew(int event, + int id, const char *name, unsigned char *uuid, - const char *path, + const char *disk,

int type, int status) {

@@ -804,22 +805,46 @@ virDomainEventBlockJobNew(int id, virObjectEventPtr virDomainEventBlockJobNewFromObj(virDomainObjPtr obj, - const char *path, + const char *disk,

int type, int status) { - return virDomainEventBlockJobNew(obj->def->id, obj->def->name, - obj->def->uuid, path, type, status); + return virDomainEventBlockJobNew(VIR_DOMAIN_EVENT_ID_BLOCK_JOB, + obj->def->id, obj->def->name, + obj->def->uuid, disk, type, status); } virObjectEventPtr virDomainEventBlockJobNewFromDom(virDomainPtr dom, - const char *path, + const char *disk,

int type, int status) { - return virDomainEventBlockJobNew(dom->id, dom->name, dom->uuid, - path, type, status); + return virDomainEventBlockJobNew(VIR_DOMAIN_EVENT_ID_BLOCK_JOB, + dom->id, dom->name, dom->uuid, + disk, type, status); +} + +virObjectEventPtr +virDomainEventBlockJob2NewFromObj(virDomainObjPtr obj, + const char *disk, + int type, + int status) +{ + return virDomainEventBlockJobNew(VIR_DOMAIN_EVENT_ID_BLOCK_JOB_2, + obj->def->id, obj->def->name, + obj->def->uuid, disk, type, status); +} + +virObjectEventPtr +virDomainEventBlockJob2NewFromDom(virDomainPtr dom, + const char *disk, + int type, + int status) +{ + return virDomainEventBlockJobNew(VIR_DOMAIN_EVENT_ID_BLOCK_JOB_2, + dom->id, dom->name, dom->uuid, + disk, type, status); } virObjectEventPtr

diff --git a/src/conf/domain_event.h b/src/conf/domain_event.h index 9c41090..c7b8761 100644 --- a/src/conf/domain_event.h +++ b/src/conf/domain_event.h @@ -117,16 +117,27 @@ virDomainEventControlErrorNewFromObj(virDomainObjPtr obj); virObjectEventPtr virDomainEventBlockJobNewFromObj(virDomainObjPtr obj, - const char *path, + const char *disk, int type, int status); virObjectEventPtr virDomainEventBlockJobNewFromDom(virDomainPtr dom, - const char *path, + const char *disk, int type, int status);

virObjectEventPtr +virDomainEventBlockJob2NewFromObj(virDomainObjPtr obj, + const char *disk, + int type, + int status); +virObjectEventPtr +virDomainEventBlockJob2NewFromDom(virDomainPtr dom, + const char *disk, + int type, + int status); + +virObjectEventPtr virDomainEventDiskChangeNewFromObj(virDomainObjPtr obj, const char *oldSrcPath, const char *newSrcPath,

diff --git a/src/remote/remote_protocol.x b/src/remote/remote_protocol.x index ab9b83d..95a1437 100644 --- a/src/remote/remote_protocol.x +++ b/src/remote/remote_protocol.x @@ -2352,7 +2352,7 @@ struct remote_domain_event_callback_graphics_msg { struct remote_domain_event_block_job_msg { remote_nonnull_domain dom; - remote_nonnull_string path; + remote_nonnull_string disk;

int type; int status; };

diff --git a/src/remote_protocol-structs b/src/remote_protocol-structs index 5b22049..3abc076 100644 --- a/src/remote_protocol-structs +++ b/src/remote_protocol-structs @@ -1797,7 +1797,7 @@ struct remote_domain_event_callback_graphics_msg { }; struct remote_domain_event_block_job_msg { remote_nonnull_domain dom; - remote_nonnull_string path; + remote_nonnull_string disk;

int type; int status; };