On Wed, Dec 27, 2023 at 10:18 PM Barry Song <21cnbao@xxxxxxxxx> wrote:
>
> This is the case the "compressed" data is larger than the original data,
> it is better to return -ENOSPC which can help zswap record a poor compr
> rather than an invalid request. Then we get more friendly counting for
> reject_compress_poor in debugfs.
>
> bool zswap_store(struct folio *folio)
> {
> ...
> ret = zpool_malloc(zpool, dlen, gfp, &handle);
> if (ret == -ENOSPC) {
> zswap_reject_compress_poor++;
> goto put_dstmem;
> }
> if (ret) {
> zswap_reject_alloc_fail++;
> goto put_dstmem;
> }
> ...
> }
>
> Also, zbud_alloc() and z3fold_alloc() are returning ENOSPC in the same
> case, eg
> static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
> unsigned long *handle)
> {
> ...
> if (!size || (gfp & __GFP_HIGHMEM))
> return -EINVAL;
>
> if (size > PAGE_SIZE)
> return -ENOSPC;
> ...
> }
>
> Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
> ---
> mm/zsmalloc.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index b1c0dad7f4cf..c937635e0ad1 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -1364,9 +1364,12 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp)
> int newfg;
> struct zspage *zspage;
>
> - if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE))
> + if (unlikely(!size))
> return (unsigned long)ERR_PTR(-EINVAL);
>
> + if (unlikely(size > ZS_MAX_ALLOC_SIZE))
> + return (unsigned long)ERR_PTR(-ENOSPC);
> +
> handle = cache_alloc_handle(pool, gfp);
> if (!handle)
> return (unsigned long)ERR_PTR(-ENOMEM);
> --
> 2.34.1
>
LGTM.
Reviewed-by: Nhat Pham <nphamcs@xxxxxxxxx>
