On Thu, 17 Nov 2016, Douglas Anderson wrote:
> diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
> index b3ba142e59a4..885ba5482d9f 100644
> --- a/drivers/md/dm-bufio.c
> +++ b/drivers/md/dm-bufio.c
> @@ -89,6 +89,7 @@ struct dm_bufio_client {
>
> struct list_head lru[LIST_SIZE];
> unsigned long n_buffers[LIST_SIZE];
> + unsigned long n_all_buffers;
>
> struct block_device *bdev;
> unsigned block_size;
> @@ -485,6 +486,7 @@ static void __link_buffer(struct dm_buffer *b, sector_t block, int dirty)
> struct dm_bufio_client *c = b->c;
>
> c->n_buffers[dirty]++;
> + c->n_all_buffers++;
> b->block = block;
> b->list_mode = dirty;
> list_add(&b->lru_list, &c->lru[dirty]);
> @@ -502,6 +504,7 @@ static void __unlink_buffer(struct dm_buffer *b)
> BUG_ON(!c->n_buffers[b->list_mode]);
>
> c->n_buffers[b->list_mode]--;
> + c->n_all_buffers--;
> __remove(b->c, b);
> list_del(&b->lru_list);
> }
> @@ -515,6 +518,7 @@ static void __relink_lru(struct dm_buffer *b, int dirty)
>
> BUG_ON(!c->n_buffers[b->list_mode]);
>
> + /* NOTE: don't update n_all_buffers: -1 + 1 = 0 */
> c->n_buffers[b->list_mode]--;
> c->n_buffers[dirty]++;
> b->list_mode = dirty;
> @@ -1588,17 +1592,10 @@ static unsigned long
> dm_bufio_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
> {
> struct dm_bufio_client *c;
> - unsigned long count;
>
> c = container_of(shrink, struct dm_bufio_client, shrinker);
> - if (sc->gfp_mask & __GFP_FS)
> - dm_bufio_lock(c);
> - else if (!dm_bufio_trylock(c))
> - return 0;
>
> - count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];
> - dm_bufio_unlock(c);
> - return count;
> + return c->n_all_buffers;
> }
>
> /*
Would be better to just avoid taking the mutex at all and returning
c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY] with a comment that
the estimate might be wrong, but the actual count may vary between
->count_objects() and ->scan_objects() anyway, so we don't actually care?
--
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