dm space map disk: optimise sm_disk_dec_block
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>
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@ -140,26 +140,10 @@ static int sm_disk_inc_block(struct dm_space_map *sm, dm_block_t b)
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static int sm_disk_dec_block(struct dm_space_map *sm, dm_block_t b)
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{
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int r;
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uint32_t old_count;
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enum allocation_event ev;
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struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
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r = sm_ll_dec(&smd->ll, b, &ev);
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if (!r && (ev == SM_FREE)) {
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/*
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* It's only free if it's also free in the last
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* transaction.
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*/
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r = sm_ll_lookup(&smd->old_ll, b, &old_count);
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if (r)
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return r;
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if (!old_count)
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smd->nr_allocated_this_transaction--;
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}
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return r;
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return sm_ll_dec(&smd->ll, b, &ev);
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}
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static int sm_disk_new_block(struct dm_space_map *sm, dm_block_t *b)
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