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qcow2: Allocate l2meta only for cluster allocations

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Even for writes to already allocated clusters, an l2meta is allocated,
though it stays effectively unused. After this patch, only allocating
requests still have one. Each l2meta now describes an in-flight request
that writes to clusters that are not yet hooked up in the L2 table.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2012-12-07 18:08:46 +01:00
parent 060bee8943
commit f50f88b9fe
3 changed files with 31 additions and 31 deletions
Download patch file Download diff file Expand all files Collapse all files

23
block/qcow2-cluster.c
View file

@ -652,9 +652,7 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
uint64_t cluster_offset = m->alloc_offset;
trace_qcow2_cluster_link_l2(qemu_coroutine_self(), m->nb_clusters);
if (m->nb_clusters == 0)
return 0;
assert(m->nb_clusters > 0);
old_cluster = g_malloc(m->nb_clusters * sizeof(uint64_t));
@ -856,7 +854,7 @@ static int do_alloc_cluster_offset(BlockDriverState *bs, uint64_t guest_offset,
* Return 0 on success and -errno in error cases
*/
int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta *m)
int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta **m)
{
BDRVQcowState *s = bs->opaque;
int l2_index, ret, sectors;
@ -928,11 +926,6 @@ again:
}
/* If there is something left to allocate, do that now */
*m = (QCowL2Meta) {
.nb_clusters = 0,
};
qemu_co_queue_init(&m->dependent_requests);
if (nb_clusters > 0) {
uint64_t alloc_offset;
uint64_t alloc_cluster_offset;
@ -980,7 +973,9 @@ again:
cluster_offset = alloc_cluster_offset;
}
*m = (QCowL2Meta) {
*m = g_malloc0(sizeof(**m));
**m = (QCowL2Meta) {
.alloc_offset = alloc_cluster_offset,
.offset = alloc_offset & ~(s->cluster_size - 1),
.nb_clusters = nb_clusters,
@ -995,8 +990,8 @@ again:
.nb_sectors = avail_sectors - nb_sectors,
},
};
qemu_co_queue_init(&m->dependent_requests);
QLIST_INSERT_HEAD(&s->cluster_allocs, m, next_in_flight);
qemu_co_queue_init(&(*m)->dependent_requests);
QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
}
}
@ -1013,8 +1008,8 @@ again:
return 0;
fail:
if (m->nb_clusters > 0) {
QLIST_REMOVE(m, next_in_flight);
if (*m && (*m)->nb_clusters > 0) {
QLIST_REMOVE(*m, next_in_flight);
}
return ret;
}