On 12/16/14 09:04, Eric Blake wrote:
A coming patch will make it optionally possible to list backing chain block stats; in this mode of operation, block.counts is no longer the number of <disks> in the domain, but the number of blocks in the array being reported. We still want block.count listed first, but rather than iterate the tree twice (once to count, and once to list stats), it's easier to just touch things up after the fact.
* src/qemu/qemu_driver.c (qemuDomainGetStatsBlock): Compute count after the fact.
Signed-off-by: Eric Blake <eblake@redhat.com> --- src/qemu/qemu_driver.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index ef73502..1127312 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -18542,13 +18542,14 @@ qemuDomainGetStatsBlock(virQEMUDriverPtr driver, int *maxparams, unsigned int privflags) { - size_t i; + size_t i = 0; int ret = -1; int rc; virHashTablePtr stats = NULL; qemuDomainObjPrivatePtr priv = dom->privateData; bool abbreviated = false; virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver); + int count_index = -1;
if (!HAVE_JOB(privflags) || !virDomainObjIsActive(dom)) { abbreviated = true; /* it's ok, just go ahead silently */ @@ -18565,9 +18566,13 @@ qemuDomainGetStatsBlock(virQEMUDriverPtr driver, } }
- QEMU_ADD_COUNT_PARAM(record, maxparams, "block", dom->def->ndisks); + /* When listing backing chains, it's easier to fix up the count + * after the iteration than it is to iterate twice; but we still + * want count listed first. */ + count_index = record->nparams;
The index is remembered prior ..
+ QEMU_ADD_COUNT_PARAM(record, maxparams, "block", 0);
to adding the element into the array. As the macro may jump to cleanup precisely at this moment, if adding of the element failed you'd ...
- for (i = 0; i < dom->def->ndisks; i++) { + for (; i < dom->def->ndisks; i++) { qemuBlockStats *entry; virDomainDiskDefPtr disk = dom->def->disks[i];
@@ -18627,6 +18632,8 @@ qemuDomainGetStatsBlock(virQEMUDriverPtr driver, ret = 0;
cleanup: + if (count_index >= 0) + record->params[count_index].value.ui = i;
Touch a non-existent field here. if (ret == 0 && count_index >= 0) ...
virHashFree(stats); virObjectUnref(cfg); return ret;
ACK with the tweak above. Peter