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qcow2: Round QCowL2Meta.offset down to cluster boundary

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The offset within the cluster is already present as n_start and this is
what the code uses. QCowL2Meta.offset is only needed at a cluster
granularity.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2012-12-07 18:08:42 +01:00
parent a7f3d65b65
commit 1d3afd649b
2 changed files with 24 additions and 2 deletions
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4
block/qcow2-cluster.c
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@ -631,7 +631,7 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
old_cluster = g_malloc(m->nb_clusters * sizeof(uint64_t));
/* copy content of unmodified sectors */
start_sect = (m->offset & ~(s->cluster_size - 1)) >> 9;
start_sect = m->offset >> 9;
if (m->n_start) {
cow = true;
qemu_co_mutex_unlock(&s->lock);
@ -966,7 +966,7 @@ again:
.cluster_offset = keep_clusters == 0 ?
alloc_cluster_offset : cluster_offset,
.alloc_offset = alloc_cluster_offset,
.offset = alloc_offset,
.offset = alloc_offset & ~(s->cluster_size - 1),
.n_start = keep_clusters == 0 ? n_start : 0,
.nb_clusters = nb_clusters,
.nb_available = MIN(requested_sectors, avail_sectors),

22
block/qcow2.h
View File

@ -199,12 +199,34 @@ struct QCowAIOCB;
/* XXX This could be private for qcow2-cluster.c */
typedef struct QCowL2Meta
{
/** Guest offset of the first newly allocated cluster */
uint64_t offset;
/** Host offset of the first cluster of the request */
uint64_t cluster_offset;
/** Host offset of the first newly allocated cluster */
uint64_t alloc_offset;
/**
* Number of sectors between the start of the first allocated cluster and
* the area that the guest actually writes to.
*/
int n_start;
/**
* Number of sectors from the start of the first allocated cluster to
* the end of the (possibly shortened) request
*/
int nb_available;
/** Number of newly allocated clusters */
int nb_clusters;
/**
* Requests that overlap with this allocation and wait to be restarted
* when the allocating request has completed.
*/
CoQueue dependent_requests;
QLIST_ENTRY(QCowL2Meta) next_in_flight;