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qcow2: simplify qcow2_cache_put() and qcow2_cache_entry_mark_dirty()

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Since all tables are now stored together, it is possible to obtain
the position of a particular table directly from its address, so the
operation becomes O(1).

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Alberto Garcia 2015-05-11 15:54:54 +03:00 committed by Kevin Wolf
parent 72e80b8901
commit baf07d60f5
1 changed files with 15 additions and 17 deletions
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32
block/qcow2-cache.c
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@ -49,6 +49,16 @@ static inline void *qcow2_cache_get_table_addr(BlockDriverState *bs,
return (uint8_t *) c->table_array + (size_t) table * s->cluster_size;
}
static inline int qcow2_cache_get_table_idx(BlockDriverState *bs,
Qcow2Cache *c, void *table)
{
BDRVQcowState *s = bs->opaque;
ptrdiff_t table_offset = (uint8_t *) table - (uint8_t *) c->table_array;
int idx = table_offset / s->cluster_size;
assert(idx >= 0 && idx < c->size && table_offset % s->cluster_size == 0);
return idx;
}
Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables)
{
BDRVQcowState *s = bs->opaque;
@ -337,16 +347,12 @@ int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
int qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table)
{
int i;
int i = qcow2_cache_get_table_idx(bs, c, *table);
for (i = 0; i < c->size; i++) {
if (qcow2_cache_get_table_addr(bs, c, i) == *table) {
goto found;
}
if (c->entries[i].offset == 0) {
return -ENOENT;
}
return -ENOENT;
found:
c->entries[i].ref--;
*table = NULL;
@ -357,15 +363,7 @@ found:
void qcow2_cache_entry_mark_dirty(BlockDriverState *bs, Qcow2Cache *c,
void *table)
{
int i;
for (i = 0; i < c->size; i++) {
if (qcow2_cache_get_table_addr(bs, c, i) == table) {
goto found;
}
}
abort();
found:
int i = qcow2_cache_get_table_idx(bs, c, table);
assert(c->entries[i].offset != 0);
c->entries[i].dirty = true;
}