Re: [PATCH/RESEND v3 1/5] z3fold: make pages_nr atomic

From: Dan Streetman
Date: Wed Feb 01 2017 - 10:05:03 EST


On Tue, Jan 31, 2017 at 3:39 PM, Vitaly Wool <vitalywool@xxxxxxxxx> wrote:
> This patch converts pages_nr per-pool counter to atomic64_t.
>
> Signed-off-by: Vitaly Wool <vitalywool@xxxxxxxxx>

Reviewed-by: Dan Streetman <ddstreet@xxxxxxxx>

> ---
> mm/z3fold.c | 20 +++++++++-----------
> 1 file changed, 9 insertions(+), 11 deletions(-)
>
> diff --git a/mm/z3fold.c b/mm/z3fold.c
> index 207e5dd..2273789 100644
> --- a/mm/z3fold.c
> +++ b/mm/z3fold.c
> @@ -80,7 +80,7 @@ struct z3fold_pool {
> struct list_head unbuddied[NCHUNKS];
> struct list_head buddied;
> struct list_head lru;
> - u64 pages_nr;
> + atomic64_t pages_nr;
> const struct z3fold_ops *ops;
> struct zpool *zpool;
> const struct zpool_ops *zpool_ops;
> @@ -238,7 +238,7 @@ static struct z3fold_pool *z3fold_create_pool(gfp_t gfp,
> INIT_LIST_HEAD(&pool->unbuddied[i]);
> INIT_LIST_HEAD(&pool->buddied);
> INIT_LIST_HEAD(&pool->lru);
> - pool->pages_nr = 0;
> + atomic64_set(&pool->pages_nr, 0);
> pool->ops = ops;
> return pool;
> }
> @@ -350,7 +350,7 @@ static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
> if (!page)
> return -ENOMEM;
> spin_lock(&pool->lock);
> - pool->pages_nr++;
> + atomic64_inc(&pool->pages_nr);
> zhdr = init_z3fold_page(page);
>
> if (bud == HEADLESS) {
> @@ -443,10 +443,9 @@ static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
> return;
> }
>
> - if (bud != HEADLESS) {
> - /* Remove from existing buddy list */
> + /* Remove from existing buddy list */
> + if (bud != HEADLESS)
> list_del(&zhdr->buddy);
> - }
>
> if (bud == HEADLESS ||
> (zhdr->first_chunks == 0 && zhdr->middle_chunks == 0 &&
> @@ -455,7 +454,7 @@ static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
> list_del(&page->lru);
> clear_bit(PAGE_HEADLESS, &page->private);
> free_z3fold_page(zhdr);
> - pool->pages_nr--;
> + atomic64_dec(&pool->pages_nr);
> } else {
> z3fold_compact_page(zhdr);
> /* Add to the unbuddied list */
> @@ -573,7 +572,7 @@ static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries)
> */
> clear_bit(PAGE_HEADLESS, &page->private);
> free_z3fold_page(zhdr);
> - pool->pages_nr--;
> + atomic64_dec(&pool->pages_nr);
> spin_unlock(&pool->lock);
> return 0;
> } else if (!test_bit(PAGE_HEADLESS, &page->private)) {
> @@ -676,12 +675,11 @@ static void z3fold_unmap(struct z3fold_pool *pool, unsigned long handle)
> * z3fold_get_pool_size() - gets the z3fold pool size in pages
> * @pool: pool whose size is being queried
> *
> - * Returns: size in pages of the given pool. The pool lock need not be
> - * taken to access pages_nr.
> + * Returns: size in pages of the given pool.
> */
> static u64 z3fold_get_pool_size(struct z3fold_pool *pool)
> {
> - return pool->pages_nr;
> + return atomic64_read(&pool->pages_nr);
> }
>
> /*****************
> --
> 2.4.2