dm cache: avoid preallocation if no work in writeback_some_dirty_blocks()

Refactor writeback_some_dirty_blocks() to avoid prealloc_data_structs()
if the policy doesn't have any dirty blocks ready for writeback.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Mike Snitzer 2015-07-16 21:26:10 -04:00
parent 386cb7cdee
commit e782eff591

View File

@ -2061,7 +2061,6 @@ static void process_deferred_writethrough_bios(struct cache *cache)
static void writeback_some_dirty_blocks(struct cache *cache)
{
int r = 0;
dm_oblock_t oblock;
dm_cblock_t cblock;
struct prealloc structs;
@ -2071,15 +2070,11 @@ static void writeback_some_dirty_blocks(struct cache *cache)
memset(&structs, 0, sizeof(structs));
while (spare_migration_bandwidth(cache)) {
if (prealloc_data_structs(cache, &structs))
break;
if (policy_writeback_work(cache->policy, &oblock, &cblock, busy))
break; /* no work to do */
r = policy_writeback_work(cache->policy, &oblock, &cblock, busy);
if (r)
break;
r = get_cell(cache, oblock, &structs, &old_ocell);
if (r) {
if (prealloc_data_structs(cache, &structs) ||
get_cell(cache, oblock, &structs, &old_ocell)) {
policy_set_dirty(cache->policy, oblock);
break;
}