Eric Blake 4bffafb2eb getstats: add new flag for block backing chain ... This patch introduces access to allocation information about a backing chain of a live domain. While querying storage volumes for read-only disks could provide some of the details, we do NOT want to read() a file while qemu is writing it. Also, there is one case where we have to rely on qemu: when doing a block commit into a backing file, where that file is stored in qcow2 format on a host block device, we want to know the current highest write offset into that image, in order to know if the disk must be resized larger. qemu-img does not (currently) show this information, and none of the earlier block APIs were extensible enough to expose it. But virDomainListGetStats is perfect for the job! We don't need a new group of statistics, as the existing block group is sufficient. On the other hand, as existing libvirt releases already report 1:1 mapping of block.count to <disk> devices, changing the array size could confuse older clients; and even with newer clients, the time and memory taken to report additional statistics is not always necessary (backing files are generally read-only except for block-commit, so while read statistics may change, sizing statistics will not). So the choice here is to add a new flag that only newer callers will pass, when they are prepared for the additional information. This patch introduces the new API, but it will take more patches to get it implemented for qemu. * include/libvirt/libvirt-domain.h (VIR_CONNECT_GET_ALL_DOMAINS_STATS_BACKING): New flag. * src/libvirt-domain.c (virConnectGetAllDomainStats): Document it, and add a new field when it is in use. * tools/virsh-domain-monitor.c (cmdDomstats): Use new flag. * tools/virsh.pod (domstats): Document it. Signed-off-by: Eric Blake <eblake@redhat.com>		2014-12-17 01:41:38 -07:00
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libvirt	getstats: add new flag for block backing chain	2014-12-17 01:41:38 -07:00
Makefile.am	maint: use LGPL correctly	2013-05-20 14:03:48 -06:00