[dm-devel] [PATCH] dm thin: fix list_add corruption in process_discard
Mikulas Patocka
mpatocka at redhat.com
Sat Apr 21 16:12:07 UTC 2012
On Fri, 20 Apr 2012, Mike Snitzer wrote:
> Use pool->lock to protect pool's prepared_discards list.
>
> Signed-off-by: Mike Snitzer <snitzer at redhat.com>
> ---
> drivers/md/dm-thin.c | 5 +++++
> 1 files changed, 5 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
> index 7218882..7297eb7 100644
> --- a/drivers/md/dm-thin.c
> +++ b/drivers/md/dm-thin.c
> @@ -1181,6 +1181,7 @@ static void no_space(struct cell *cell)
> static void process_discard(struct thin_c *tc, struct bio *bio)
> {
> int r;
> + unsigned long flags;
> struct pool *pool = tc->pool;
> struct cell *cell, *cell2;
> struct cell_key key, key2;
> @@ -1222,7 +1223,9 @@ static void process_discard(struct thin_c *tc, struct bio *bio)
> m->bio = bio;
>
> if (!ds_add_work(&pool->all_io_ds, &m->list)) {
> + spin_lock_irqsave(&pool->lock, flags);
> list_add(&m->list, &pool->prepared_discards);
> + spin_unlock_irqrestore(&pool->lock, flags);
> wake_worker(pool);
> }
> } else {
> @@ -2630,8 +2633,10 @@ static int thin_endio(struct dm_target *ti,
> if (h->all_io_entry) {
> INIT_LIST_HEAD(&work);
> ds_dec(h->all_io_entry, &work);
> + spin_lock_irqsave(&pool->lock, flags);
> list_for_each_entry_safe(m, tmp, &work, list)
> list_add(&m->list, &pool->prepared_discards);
BTW. you can use list_splice to join two lists, you don't have to walk one
list and insert entries to the other list one-by-one.
Mikulas
> + spin_unlock_irqrestore(&pool->lock, flags);
> }
>
> mempool_free(h, pool->endio_hook_pool);
> --
> 1.7.4.4
>
> --
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