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lightnvm: pblk: fix race condition on metadata I/O 

In pblk, when a new line is allocated, metadata for the previously
written line is scheduled. This is done through a fixed memory region
that is shared through time and contexts across different lines and
therefore protected by a lock. Unfortunately, this lock is not properly
covering all the metadata used for sharing this memory regions,
resulting in a race condition.

This patch fixes this race condition by protecting this metadata
properly.

Fixes: dd2a434373 ("lightnvm: pblk: sched. metadata on write thread")
Signed-off-by: Javier González <javier@cnexlabs.com>
Signed-off-by: Matias Bjørling <mb@lightnvm.io>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
hifive-unleashed-5.1
Javier González 2018-10-09 13:11:35 +02:00 committed by Jens Axboe
parent 656e33ca3d
commit d8adaa3b86
1 changed files with 7 additions and 7 deletions
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14
drivers/lightnvm/pblk-write.c
View File

@ -417,12 +417,11 @@ int pblk_submit_meta_io(struct pblk *pblk, struct pblk_line *meta_line)
rqd->ppa_list[i] = addr_to_gen_ppa(pblk, paddr, id);
}
spin_lock(&l_mg->close_lock);
emeta->mem += rq_len;
if (emeta->mem >= lm->emeta_len[0]) {
spin_lock(&l_mg->close_lock);
if (emeta->mem >= lm->emeta_len[0])
list_del(&meta_line->list);
spin_unlock(&l_mg->close_lock);
}
spin_unlock(&l_mg->close_lock);
pblk_down_page(pblk, rqd->ppa_list, rqd->nr_ppas);
@ -491,14 +490,15 @@ static struct pblk_line *pblk_should_submit_meta_io(struct pblk *pblk,
struct pblk_line *meta_line;
spin_lock(&l_mg->close_lock);
retry:
if (list_empty(&l_mg->emeta_list)) {
spin_unlock(&l_mg->close_lock);
return NULL;
}
meta_line = list_first_entry(&l_mg->emeta_list, struct pblk_line, list);
if (meta_line->emeta->mem >= lm->emeta_len[0])
goto retry;
if (meta_line->emeta->mem >= lm->emeta_len[0]) {
spin_unlock(&l_mg->close_lock);
return NULL;
}
spin_unlock(&l_mg->close_lock);
if (!pblk_valid_meta_ppa(pblk, meta_line, data_rqd))