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Storage: Introduce shadow vol for refresh while the main vol builds.

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Libvirt periodically refreshes all volumes in a storage pool, including
the volumes being cloned.
While cloning a storage volume from parent, we drop pool locks. Subsequent
volume refresh sometimes changes allocation for an ongoing copy, and leads
to corrupt images.
Fix: Introduce a shadow volume that isolates the volume object under refresh
from the base which has a copy ongoing.

Signed-off-by: Prerna Saxena <prerna@linux.vnet.ibm.com>
Signed-off-by: Ján Tomko <jtomko@redhat.com>
This commit is contained in:
Prerna Saxena 2015-06-26 17:05:11 +05:30 committed by Ján Tomko
parent ea1c7b652b
commit 7e7dee4389
1 changed files with 14 additions and 6 deletions
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20
src/storage/storage_driver.c
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@ -1898,9 +1898,8 @@ storageVolCreateXMLFrom(virStoragePoolPtr obj,
{
virStoragePoolObjPtr pool, origpool = NULL;
virStorageBackendPtr backend;
virStorageVolDefPtr origvol = NULL, newvol = NULL;
virStorageVolDefPtr origvol = NULL, newvol = NULL, shadowvol = NULL;
virStorageVolPtr ret = NULL, volobj = NULL;
unsigned long long allocation;
int buildret;
virCheckFlags(VIR_STORAGE_VOL_CREATE_PREALLOC_METADATA |
@ -2010,6 +2009,15 @@ storageVolCreateXMLFrom(virStoragePoolPtr obj,
if (backend->createVol(obj->conn, pool, newvol) < 0)
goto cleanup;
/* Make a shallow copy of the 'defined' volume definition, since the
* original allocation value will change as the user polls 'info',
* but we only need the initial requested values
*/
if (VIR_ALLOC(shadowvol) < 0)
goto cleanup;
memcpy(shadowvol, newvol, sizeof(*newvol));
pool->volumes.objs[pool->volumes.count++] = newvol;
volobj = virGetStorageVol(obj->conn, pool->def->name, newvol->name,
newvol->key, NULL, NULL);
@ -2029,7 +2037,7 @@ storageVolCreateXMLFrom(virStoragePoolPtr obj,
virStoragePoolObjUnlock(origpool);
}
buildret = backend->buildVolFrom(obj->conn, pool, newvol, origvol, flags);
buildret = backend->buildVolFrom(obj->conn, pool, shadowvol, origvol, flags);
storageDriverLock();
virStoragePoolObjLock(pool);
@ -2039,7 +2047,6 @@ storageVolCreateXMLFrom(virStoragePoolPtr obj,
origvol->in_use--;
newvol->building = false;
allocation = newvol->target.allocation;
pool->asyncjobs--;
if (origpool) {
@ -2059,8 +2066,8 @@ storageVolCreateXMLFrom(virStoragePoolPtr obj,
* it updates the pool values
*/
if (pool->def->type != VIR_STORAGE_POOL_DISK) {
pool->def->allocation += allocation;
pool->def->available -= allocation;
pool->def->allocation += shadowvol->target.allocation;
pool->def->available -= shadowvol->target.allocation;
}
VIR_INFO("Creating volume '%s' in storage pool '%s'",
@ -2071,6 +2078,7 @@ storageVolCreateXMLFrom(virStoragePoolPtr obj,
cleanup:
virObjectUnref(volobj);
virStorageVolDefFree(newvol);
VIR_FREE(shadowvol);
if (pool)
virStoragePoolObjUnlock(pool);
if (origpool)