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dm space map disk: optimise sm_disk_dec_block

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Don't waste time spotting blocks that have been allocated and then freed
in the same transaction.

The extra lookup is expensive, and I don't think it really gives us much.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Joe Thornber 2013-08-09 14:19:32 +01:00 committed by Mike Snitzer
parent 41d35d25e9
commit 40c57f475f
1 changed files with 1 additions and 17 deletions
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18
drivers/md/persistent-data/dm-space-map-disk.c
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@ -140,26 +140,10 @@ static int sm_disk_inc_block(struct dm_space_map *sm, dm_block_t b)
static int sm_disk_dec_block(struct dm_space_map *sm, dm_block_t b)
{
int r;
uint32_t old_count;
enum allocation_event ev;
struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
r = sm_ll_dec(&smd->ll, b, &ev);
if (!r && (ev == SM_FREE)) {
/*
* It's only free if it's also free in the last
* transaction.
*/
r = sm_ll_lookup(&smd->old_ll, b, &old_count);
if (r)
return r;
if (!old_count)
smd->nr_allocated_this_transaction--;
}
return r;
return sm_ll_dec(&smd->ll, b, &ev);
}
static int sm_disk_new_block(struct dm_space_map *sm, dm_block_t *b)