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qcow2: Update discard_single_l2() to support L2 slices 

discard_single_l2() limits the number of clusters to be discarded
to the amount that fits inside an L2 table. Since we'll be loading
L2 slices instead of full tables we need to update that limit. The
function is renamed to discard_in_l2_slice() for clarity.

Apart from that, this function doesn't need any additional changes, so
this patch simply updates the variable name from l2_table to l2_slice.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-id: 1cb44a5b68be5334cb01b97a3db3a3c5a43396e5.1517840877.git.berto@igalia.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Alberto Garcia 2018-02-05 16:33:24 +02:00 committed by Max Reitz
parent 6d99a34447
commit 21ab3add9c
1 changed files with 16 additions and 16 deletions
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32
block/qcow2-cluster.c
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@ -1631,32 +1631,32 @@ int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset)
/*
* This discards as many clusters of nb_clusters as possible at once (i.e.
* all clusters in the same L2 table) and returns the number of discarded
* all clusters in the same L2 slice) and returns the number of discarded
* clusters.
*/
static int discard_single_l2(BlockDriverState *bs, uint64_t offset,
uint64_t nb_clusters, enum qcow2_discard_type type,
bool full_discard)
static int discard_in_l2_slice(BlockDriverState *bs, uint64_t offset,
uint64_t nb_clusters,
enum qcow2_discard_type type, bool full_discard)
{
BDRVQcow2State *s = bs->opaque;
uint64_t *l2_table;
uint64_t *l2_slice;
int l2_index;
int ret;
int i;
ret = get_cluster_table(bs, offset, &l2_table, &l2_index);
ret = get_cluster_table(bs, offset, &l2_slice, &l2_index);
if (ret < 0) {
return ret;
}
/* Limit nb_clusters to one L2 table */
nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
/* Limit nb_clusters to one L2 slice */
nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index);
assert(nb_clusters <= INT_MAX);
for (i = 0; i < nb_clusters; i++) {
uint64_t old_l2_entry;
old_l2_entry = be64_to_cpu(l2_table[l2_index + i]);
old_l2_entry = be64_to_cpu(l2_slice[l2_index + i]);
/*
* If full_discard is false, make sure that a discarded area reads back
@ -1694,18 +1694,18 @@ static int discard_single_l2(BlockDriverState *bs, uint64_t offset,
}
/* First remove L2 entries */
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
if (!full_discard && s->qcow_version >= 3) {
l2_table[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);
l2_slice[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);
} else {
l2_table[l2_index + i] = cpu_to_be64(0);
l2_slice[l2_index + i] = cpu_to_be64(0);
}
/* Then decrease the refcount */
qcow2_free_any_clusters(bs, old_l2_entry, 1, type);
}
qcow2_cache_put(s->l2_table_cache, (void **) &l2_table);
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
return nb_clusters;
}
@ -1729,10 +1729,10 @@ int qcow2_cluster_discard(BlockDriverState *bs, uint64_t offset,
s->cache_discards = true;
/* Each L2 table is handled by its own loop iteration */
/* Each L2 slice is handled by its own loop iteration */
while (nb_clusters > 0) {
cleared = discard_single_l2(bs, offset, nb_clusters, type,
full_discard);
cleared = discard_in_l2_slice(bs, offset, nb_clusters, type,
full_discard);
if (cleared < 0) {
ret = cleared;
goto fail;