Re: [libvirt] [PATCHv2 6/6] Widening API change - accept empty path for virDomainBlockStats

And provide domain summary stat in that case, for lxc backend. Use case is a container inheriting all devices from the host, e.g. when doing application containerization. --- Notes on v2: - adapted virDomainBlockStats docs - adapted virsh domblkstat docs - made virsh actually accept empty disk argument - pedaling back a bit on the API change - accepting a NULL ptr for the disk arg would need changing the remote protocol, so better just take the empty string. Makes this less invasive even. src/libvirt.c | 8 ++++++-- src/lxc/lxc_driver.c | 10 ++++++++++ tools/virsh-domain-monitor.c | 11 ++++++++--- tools/virsh.pod | 5 +++-- 4 files changed, 27 insertions(+), 7 deletions(-) diff --git a/src/libvirt.c b/src/libvirt.c index 87a4d46..ead0813 100644 --- a/src/libvirt.c +++ b/src/libvirt.c @@ -7781,7 +7781,9 @@ error: * an unambiguous source name of the block device (the <source * file='...'/> sub-element, such as "/path/to/image"). Valid names * can be found by calling virDomainGetXMLDesc() and inspecting - * elements within //domain/devices/disk. + * elements within //domain/devices/disk. Some drivers might also + * accept the empty string for the @disk parameter, and then yield + * summary stats for the entire domain. * * Domains may have more than one block device. To get stats for * each you should make multiple calls to this function. @@ -7847,7 +7849,9 @@ error: * an unambiguous source name of the block device (the <source * file='...'/> sub-element, such as "/path/to/image"). Valid names * can be found by calling virDomainGetXMLDesc() and inspecting - * elements within //domain/devices/disk. + * elements within //domain/devices/disk. Some drivers might also + * accept the empty string for the @disk parameter, and then yield + * summary stats for the entire domain. * * Domains may have more than one block device. To get stats for * each you should make multiple calls to this function. diff --git a/src/lxc/lxc_driver.c b/src/lxc/lxc_driver.c index bf6fd5c..31f1625 100644 --- a/src/lxc/lxc_driver.c +++ b/src/lxc/lxc_driver.c @@ -2046,6 +2046,16 @@ lxcDomainBlockStats(virDomainPtr dom, goto cleanup; } + if (!*path) { + /* empty path - return entire domain blkstats instead */ + ret = virCgroupGetBlkioIoServiced(priv->cgroup, + &stats->rd_bytes, + &stats->wr_bytes, + &stats->rd_req, + &stats->wr_req); + goto cleanup; + } + if ((idx = virDomainDiskIndexByName(vm->def, path, false)) < 0) { virReportError(VIR_ERR_INVALID_ARG, _("invalid path: %s"), path); diff --git a/tools/virsh-domain-monitor.c b/tools/virsh-domain-monitor.c index b29b82a..6be253f 100644 --- a/tools/virsh-domain-monitor.c +++ b/tools/virsh-domain-monitor.c @@ -880,7 +880,7 @@ static const vshCmdOptDef opts_domblkstat[] = { }, {.name = "device", .type = VSH_OT_DATA, - .flags = VSH_OFLAG_REQ, + .flags = VSH_OFLAG_EMPTY_OK, .help = N_("block device") }, {.name = "human", @@ -946,8 +946,13 @@ cmdDomblkstat(vshControl *ctl, const vshCmd *cmd) if (!(dom = vshCommandOptDomain(ctl, cmd, &name))) return false; - if (vshCommandOptStringReq(ctl, cmd, "device", &device) < 0) - goto cleanup; + /* device argument is optional now. if it's missing, supply empty + string to denote 'all devices'. A NULL device arg would violate + API contract. + */ + rc = vshCommandOptStringReq(ctl, cmd, "device", &device); /* and ignore rc */ + if (!device) + device = ""; rc = virDomainBlockStatsFlags(dom, device, NULL, &nparams, 0); diff --git a/tools/virsh.pod b/tools/virsh.pod index 3534b54..c3ca016 100644 --- a/tools/virsh.pod +++ b/tools/virsh.pod @@ -616,12 +616,13 @@ If I<--graceful> is specified, don't resort to extreme measures (e.g. SIGKILL) when the guest doesn't stop after a reasonable timeout; return an error instead. -=item B<domblkstat> I<domain> I<block-device> [I<--human>] +=item B<domblkstat> I<domain> [I<block-device>] [I<--human>] Get device block stats for a running domain. A I<block-device> corresponds to a unique target name (<target dev='name'/>) or source file (<source file='name'/>) for one of the disk devices attached to I<domain> (see -also B<domblklist> for listing these names). +also B<domblklist> for listing these names). On a lxc domain, omitting the +I<block-device> yields device block stats summarily for the entire domain. Use I<--human> for a more human readable output.