On Wed, Jan 10, 2018 at 02:47:41PM -0800, Yu Zhao wrote:
> We waste sizeof(swp_entry_t) for zswap header when using zsmalloc
> as zpool driver because zsmalloc doesn't support eviction.
>
> Add zpool_evictable() to detect if zpool is potentially evictable,
> and use it in zswap to avoid waste memory for zswap header.
>
> Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx>
> ---
> include/linux/zpool.h | 2 ++
> mm/zpool.c | 26 ++++++++++++++++++++++++--
> mm/zsmalloc.c | 7 -------
> mm/zswap.c | 20 ++++++++++----------
> 4 files changed, 36 insertions(+), 19 deletions(-)
>
> diff --git a/include/linux/zpool.h b/include/linux/zpool.h
> index 004ba807df96..7238865e75b0 100644
> --- a/include/linux/zpool.h
> +++ b/include/linux/zpool.h
> @@ -108,4 +108,6 @@ void zpool_register_driver(struct zpool_driver *driver);
>
> int zpool_unregister_driver(struct zpool_driver *driver);
>
> +bool zpool_evictable(struct zpool *pool);
> +
> #endif
> diff --git a/mm/zpool.c b/mm/zpool.c
> index fd3ff719c32c..ec63ef32d73d 100644
> --- a/mm/zpool.c
> +++ b/mm/zpool.c
> @@ -21,6 +21,7 @@ struct zpool {
> struct zpool_driver *driver;
> void *pool;
> const struct zpool_ops *ops;
> + bool evictable;
>
> struct list_head list;
> };
> @@ -142,7 +143,7 @@ EXPORT_SYMBOL(zpool_has_pool);
> *
> * This creates a new zpool of the specified type. The gfp flags will be
> * used when allocating memory, if the implementation supports it. If the
> - * ops param is NULL, then the created zpool will not be shrinkable.
> + * ops param is NULL, then the created zpool will not be evictable.
> *
> * Implementations must guarantee this to be thread-safe.
> *
> @@ -180,6 +181,8 @@ struct zpool *zpool_create_pool(const char *type, const char *name, gfp_t gfp,
> zpool->driver = driver;
> zpool->pool = driver->create(name, gfp, ops, zpool);
> zpool->ops = ops;
> + zpool->evictable = zpool->driver->shrink &&
> + zpool->ops && zpool->ops->evict;
The zpool->" prefix is a result out copy & paste. Fixed in the next
version. Sorry for the spam.
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