On Tue, Dec 12, 2023 at 8:18 PM Chengming Zhou
<[email protected]> wrote:
>
> The zswap_load() and zswap_writeback_entry() have the same part that
> decompress the data from zswap_entry to page, so refactor out the
> common part as __zswap_load(entry, page).
>
> Signed-off-by: Chengming Zhou <[email protected]>
> Reviewed-by: Nhat Pham <[email protected]>
On a second look, there a few nits here.
First I think it makes more sense to move this refactoring ahead of
reusing destmem. Right now, we add the destmem reuse to zswap_load()
only, then we do the refactor and zswap_writeback_entry() gets it
automatically, so there is a slight change coming to
zswap_writeback_entry() hidden in the refactoring patch.
Let's refactor out __zswap_load() first, then reuse destmem in it.
> ---
> mm/zswap.c | 107 ++++++++++++++++++++++---------------------------------------
> 1 file changed, 38 insertions(+), 69 deletions(-)
>
> diff --git a/mm/zswap.c b/mm/zswap.c
> index fa186945010d..2f095c919a5c 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -1392,6 +1392,41 @@ static int zswap_enabled_param_set(const char *val,
> return ret;
> }
>
> +static void __zswap_load(struct zswap_entry *entry, struct page *page)
> +{
> + struct scatterlist input, output;
> + unsigned int dlen = PAGE_SIZE;
> + struct crypto_acomp_ctx *acomp_ctx;
> + struct zpool *zpool;
> + u8 *src;
> + int ret;
> +
> + acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
> + mutex_lock(acomp_ctx->mutex);
> +
> + zpool = zswap_find_zpool(entry);
> + src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO);
> + if (!zpool_can_sleep_mapped(zpool)) {
> + memcpy(acomp_ctx->dstmem, src, entry->length);
> + src = acomp_ctx->dstmem;
> + zpool_unmap_handle(zpool, entry->handle);
> + }
> +
> + sg_init_one(&input, src, entry->length);
> + sg_init_table(&output, 1);
> + sg_set_page(&output, page, PAGE_SIZE, 0);
> + acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, dlen);
We should pass PAGE_SIZE here directly, BUG_ON(acomp_ctx->req->dlen)
below, and remove the dlen variable.
> + ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait);
We should just BUG_ON() here directly an remove the ret variable.
On 2023/12/14 08:52, Yosry Ahmed wrote:
> On Tue, Dec 12, 2023 at 8:18 PM Chengming Zhou
> <[email protected]> wrote:
>>
>> The zswap_load() and zswap_writeback_entry() have the same part that
>> decompress the data from zswap_entry to page, so refactor out the
>> common part as __zswap_load(entry, page).
>>
>> Signed-off-by: Chengming Zhou <[email protected]>
>> Reviewed-by: Nhat Pham <[email protected]>
>
> On a second look, there a few nits here.
>
> First I think it makes more sense to move this refactoring ahead of
> reusing destmem. Right now, we add the destmem reuse to zswap_load()
> only, then we do the refactor and zswap_writeback_entry() gets it
> automatically, so there is a slight change coming to
> zswap_writeback_entry() hidden in the refactoring patch.
>
> Let's refactor out __zswap_load() first, then reuse destmem in it.
>
Ok, will put it first.
>> ---
>> mm/zswap.c | 107 ++++++++++++++++++++++---------------------------------------
>> 1 file changed, 38 insertions(+), 69 deletions(-)
>>
>> diff --git a/mm/zswap.c b/mm/zswap.c
>> index fa186945010d..2f095c919a5c 100644
>> --- a/mm/zswap.c
>> +++ b/mm/zswap.c
>> @@ -1392,6 +1392,41 @@ static int zswap_enabled_param_set(const char *val,
>> return ret;
>> }
>>
>> +static void __zswap_load(struct zswap_entry *entry, struct page *page)
>> +{
>> + struct scatterlist input, output;
>> + unsigned int dlen = PAGE_SIZE;
>> + struct crypto_acomp_ctx *acomp_ctx;
>> + struct zpool *zpool;
>> + u8 *src;
>> + int ret;
>> +
>> + acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
>> + mutex_lock(acomp_ctx->mutex);
>> +
>> + zpool = zswap_find_zpool(entry);
>> + src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO);
>> + if (!zpool_can_sleep_mapped(zpool)) {
>> + memcpy(acomp_ctx->dstmem, src, entry->length);
>> + src = acomp_ctx->dstmem;
>> + zpool_unmap_handle(zpool, entry->handle);
>> + }
>> +
>> + sg_init_one(&input, src, entry->length);
>> + sg_init_table(&output, 1);
>> + sg_set_page(&output, page, PAGE_SIZE, 0);
>> + acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, dlen);
>
> We should pass PAGE_SIZE here directly, BUG_ON(acomp_ctx->req->dlen)
> below, and remove the dlen variable.
>
>> + ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait);
>
> We should just BUG_ON() here directly an remove the ret variable.
Ok, thanks!
On 2023/12/14 08:52, Yosry Ahmed wrote:
> On Tue, Dec 12, 2023 at 8:18 PM Chengming Zhou
> <[email protected]> wrote:
>>
>> The zswap_load() and zswap_writeback_entry() have the same part that
>> decompress the data from zswap_entry to page, so refactor out the
>> common part as __zswap_load(entry, page).
>>
>> Signed-off-by: Chengming Zhou <[email protected]>
>> Reviewed-by: Nhat Pham <[email protected]>
>
> On a second look, there a few nits here.
>
> First I think it makes more sense to move this refactoring ahead of
> reusing destmem. Right now, we add the destmem reuse to zswap_load()
> only, then we do the refactor and zswap_writeback_entry() gets it
> automatically, so there is a slight change coming to
> zswap_writeback_entry() hidden in the refactoring patch.
>
> Let's refactor out __zswap_load() first, then reuse destmem in it.
I tried but found that putting the __zswap_load() first would introduce
another failure case in zswap_writeback_entry(), since the temporary
memory allocation may fail.
So instead, I also move the dstmem reusing in zswap_writeback_entry() to
the dstmem reusing patch. Then this patch becomes having only refactoring.
Thanks.
On Mon, Dec 18, 2023 at 12:15 AM Chengming Zhou
<[email protected]> wrote:
>
> On 2023/12/14 08:52, Yosry Ahmed wrote:
> > On Tue, Dec 12, 2023 at 8:18 PM Chengming Zhou
> > <[email protected]> wrote:
> >>
> >> The zswap_load() and zswap_writeback_entry() have the same part that
> >> decompress the data from zswap_entry to page, so refactor out the
> >> common part as __zswap_load(entry, page).
> >>
> >> Signed-off-by: Chengming Zhou <[email protected]>
> >> Reviewed-by: Nhat Pham <[email protected]>
> >
> > On a second look, there a few nits here.
> >
> > First I think it makes more sense to move this refactoring ahead of
> > reusing destmem. Right now, we add the destmem reuse to zswap_load()
> > only, then we do the refactor and zswap_writeback_entry() gets it
> > automatically, so there is a slight change coming to
> > zswap_writeback_entry() hidden in the refactoring patch.
> >
> > Let's refactor out __zswap_load() first, then reuse destmem in it.
>
> I tried but found that putting the __zswap_load() first would introduce
> another failure case in zswap_writeback_entry(), since the temporary
> memory allocation may fail.
>
> So instead, I also move the dstmem reusing in zswap_writeback_entry() to
> the dstmem reusing patch. Then this patch becomes having only refactoring.
We could have still refactored __zswap_load() first by making it
return an int initially when split, then void later. Anyway, it's not
a big deal. The new series looks fine.