[libvirt] [PATCH 3/3] qemuMigrationPrecreateDisk: Preserve sparse files
John Ferlan
jferlan at redhat.com
Thu Apr 9 10:53:31 UTC 2015
On 04/02/2015 12:48 PM, Michal Privoznik wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=817700
>
> When pre-creating a disk on the destination, a volume XML is
> constructed. The XML is then passed to virStorageVolCreateXML() which
> does the work. But, since there's no <allocation/> in the XML, the
> disk are fully allocated. This possibly breaks sparse allocation user
> has on the migration source.
>
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---
> src/qemu/qemu_migration.c | 31 ++++++++++++++++++++++++++-----
> 1 file changed, 26 insertions(+), 5 deletions(-)
>
> diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
> index 3adb949..a2f68ed 100644
> --- a/src/qemu/qemu_migration.c
> +++ b/src/qemu/qemu_migration.c
> @@ -144,6 +144,7 @@ typedef qemuMigrationCookieNBDDisk *qemuMigrationCookieNBDDiskPtr;
> struct _qemuMigrationCookieNBDDisk {
> char *target; /* Disk target */
> unsigned long long capacity; /* And its capacity */
> + unsigned long long allocation; /* And its allocation */
> };
>
> typedef struct _qemuMigrationCookieNBD qemuMigrationCookieNBD;
> @@ -591,6 +592,7 @@ qemuMigrationCookieAddNBD(qemuMigrationCookiePtr mig,
> disk->dst) < 0)
> goto cleanup;
> mig->nbd->disks[mig->nbd->ndisks].capacity = entry->capacity;
> + mig->nbd->disks[mig->nbd->ndisks].allocation = entry->wr_highest_offset;
> mig->nbd->ndisks++;
> }
>
> @@ -831,8 +833,9 @@ qemuMigrationCookieXMLFormat(virQEMUDriverPtr driver,
> for (i = 0; i < mig->nbd->ndisks; i++) {
> virBufferEscapeString(buf, "<disk target='%s'",
> mig->nbd->disks[i].target);
> - virBufferAsprintf(buf, " capacity='%llu'/>\n",
> - mig->nbd->disks[i].capacity);
> + virBufferAsprintf(buf, " capacity='%llu' allocation='%llu'/>\n",
> + mig->nbd->disks[i].capacity,
> + mig->nbd->disks[i].allocation);
Here you're printing it here regardless of value (-1, 0?)...
> }
> virBufferAdjustIndent(buf, -2);
> virBufferAddLit(buf, "</nbd>\n");
> @@ -970,7 +973,7 @@ static qemuMigrationCookieNBDPtr
> qemuMigrationCookieNBDXMLParse(xmlXPathContextPtr ctxt)
> {
> qemuMigrationCookieNBDPtr ret = NULL;
> - char *port = NULL, *capacity = NULL;
> + char *port = NULL, *capacity = NULL, *allocation = NULL;
> size_t i;
> int n;
> xmlNodePtr *disks = NULL;
> @@ -998,6 +1001,7 @@ qemuMigrationCookieNBDXMLParse(xmlXPathContextPtr ctxt)
> for (i = 0; i < n; i++) {
> ctxt->node = disks[i];
> VIR_FREE(capacity);
> + VIR_FREE(allocation);
>
> if (!(ret->disks[i].target = virXPathString("string(./@target)", ctxt))) {
> virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> @@ -1014,12 +1018,26 @@ qemuMigrationCookieNBDXMLParse(xmlXPathContextPtr ctxt)
> NULLSTR(capacity));
> goto error;
> }
> +
> + allocation = virXPathString("string(./@allocation)", ctxt);
> + if (allocation) {
> + if (virStrToLong_ull(allocation, NULL, 10,
> + &ret->disks[i].allocation) < 0) {
> + virReportError(VIR_ERR_INTERNAL_ERROR,
> + _("Malformed disk allocation: '%s'"),
> + allocation);
> + goto error;
> + }
> + } else {
> + ret->disks[i].allocation = -1;
This would seem to be dangerous - while we don't have a disk that takes
up that much space, why not just leave it at zero for a "marker" of
sorts? Or set it to capacity like virStorageVolDefParseXML would if
allocation wasn't in the XML
> + }
> }
> }
>
> cleanup:
> VIR_FREE(port);
> VIR_FREE(capacity);
> + VIR_FREE(allocation);
> VIR_FREE(disks);
> ctxt->node = save_ctxt;
> return ret;
> @@ -1539,6 +1557,8 @@ qemuMigrationPrecreateDisk(virConnectPtr conn,
> virBufferAdjustIndent(&buf, 2);
> virBufferEscapeString(&buf, "<name>%s</name>\n", volName);
> virBufferAsprintf(&buf, "<capacity>%llu</capacity>\n", nbd->capacity);
> + if (nbd->allocation != -1)
> + virBufferAsprintf(&buf, "<allocation>%llu</allocation>\n", nbd->allocation);
Here of course you compare to -1 and don't print...
While it's perhaps not good to assume allocation == capacity, it's
perhaps no worse than today which would essentially allocate up to
capacity, right? Mixing ULL and -1 just seems dangerous
John
> virBufferAddLit(&buf, "<target>\n");
> virBufferAdjustIndent(&buf, 2);
> virBufferAsprintf(&buf, "<format type='%s'/>\n", format);
> @@ -1583,8 +1603,9 @@ qemuMigrationPrecreateStorage(virConnectPtr conn,
> int indx;
> const char *diskSrcPath;
>
> - VIR_DEBUG("Looking up disk target '%s' (capacity=%llu)",
> - nbd->disks[i].target, nbd->disks[i].capacity);
> + VIR_DEBUG("Looking up disk target '%s' (capacity=%llu allocation=%llu)",
> + nbd->disks[i].target, nbd->disks[i].capacity,
> + nbd->disks[i].allocation);
>
> if ((indx = virDomainDiskIndexByName(vm->def,
> nbd->disks[i].target, false)) < 0) {
>
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