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Date: Wed, 2 Nov 2022 13:13:06 -0700
From: Minchan Kim <minchan@...nel.org>
To: Sergey Senozhatsky <senozhatsky@...omium.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Nitin Gupta <ngupta@...are.org>, linux-kernel@...r.kernel.org,
linux-mm@...ck.org
Subject: Re: [PATCHv4 1/9] zram: Preparation for multi-zcomp support
On Tue, Oct 18, 2022 at 01:55:25PM +0900, Sergey Senozhatsky wrote:
> The patch turns compression streams and compressor algorithm
> name struct zram members into arrays, so that we can have
> multiple compression streams support (in the next patches).
>
> The patch uses a rather explicit API for compressor selection:
>
> - Get primary (default) compression stream
> zcomp_stream_get(zram->comps[ZRAM_PRIMARY_ZCOMP])
> - Get secondary compression stream
> zcomp_stream_get(zram->comps[ZRAM_SECONDARY_ZCOMP])
>
> We use similar API for compression streams put().
>
> At this point we always have just one compression stream,
> since CONFIG_ZRAM_MULTI_COMP is not yet defined.
>
> Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>
> ---
> drivers/block/zram/zcomp.c | 6 +--
> drivers/block/zram/zcomp.h | 2 +-
> drivers/block/zram/zram_drv.c | 87 ++++++++++++++++++++++++-----------
> drivers/block/zram/zram_drv.h | 14 +++++-
> 4 files changed, 77 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
> index 0916de952e09..55af4efd7983 100644
> --- a/drivers/block/zram/zcomp.c
> +++ b/drivers/block/zram/zcomp.c
> @@ -206,7 +206,7 @@ void zcomp_destroy(struct zcomp *comp)
> * case of allocation error, or any other error potentially
> * returned by zcomp_init().
> */
> -struct zcomp *zcomp_create(const char *compress)
> +struct zcomp *zcomp_create(const char *alg)
> {
> struct zcomp *comp;
> int error;
> @@ -216,14 +216,14 @@ struct zcomp *zcomp_create(const char *compress)
> * is not loaded yet. We must do it here, otherwise we are about to
> * call /sbin/modprobe under CPU hot-plug lock.
> */
> - if (!zcomp_available_algorithm(compress))
> + if (!zcomp_available_algorithm(alg))
> return ERR_PTR(-EINVAL);
>
> comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
> if (!comp)
> return ERR_PTR(-ENOMEM);
>
> - comp->name = compress;
> + comp->name = alg;
> error = zcomp_init(comp);
> if (error) {
> kfree(comp);
> diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h
> index 40f6420f4b2e..cdefdef93da8 100644
> --- a/drivers/block/zram/zcomp.h
> +++ b/drivers/block/zram/zcomp.h
> @@ -27,7 +27,7 @@ int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node);
> ssize_t zcomp_available_show(const char *comp, char *buf);
> bool zcomp_available_algorithm(const char *comp);
>
> -struct zcomp *zcomp_create(const char *comp);
> +struct zcomp *zcomp_create(const char *alg);
> void zcomp_destroy(struct zcomp *comp);
>
> struct zcomp_strm *zcomp_stream_get(struct zcomp *comp);
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 966aab902d19..770ea3489eb6 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -1007,36 +1007,53 @@ static ssize_t comp_algorithm_show(struct device *dev,
> struct zram *zram = dev_to_zram(dev);
>
> down_read(&zram->init_lock);
> - sz = zcomp_available_show(zram->compressor, buf);
> + sz = zcomp_available_show(zram->comp_algs[ZRAM_PRIMARY_ZCOMP], buf);
> up_read(&zram->init_lock);
>
> return sz;
> }
>
> +static void comp_algorithm_set(struct zram *zram, u32 idx, const char *alg)
> +{
> + /* Do not kfree() algs that we didn't allocate, IOW the default ones */
> + if (zram->comp_algs[idx] != default_compressor)
> + kfree(zram->comp_algs[idx]);
> + zram->comp_algs[idx] = alg;
> +}
> +
> static ssize_t comp_algorithm_store(struct device *dev,
> struct device_attribute *attr, const char *buf, size_t len)
> {
> struct zram *zram = dev_to_zram(dev);
> - char compressor[ARRAY_SIZE(zram->compressor)];
> + char *compressor;
> size_t sz;
>
> - strscpy(compressor, buf, sizeof(compressor));
> + sz = strlen(buf);
> + if (sz >= CRYPTO_MAX_ALG_NAME)
> + return -E2BIG;
> +
> + compressor = kstrdup(buf, GFP_KERNEL);
> + if (!compressor)
> + return -ENOMEM;
> +
> /* ignore trailing newline */
> - sz = strlen(compressor);
> if (sz > 0 && compressor[sz - 1] == '\n')
> compressor[sz - 1] = 0x00;
>
> - if (!zcomp_available_algorithm(compressor))
> + if (!zcomp_available_algorithm(compressor)) {
> + kfree(compressor);
> return -EINVAL;
> + }
>
> down_write(&zram->init_lock);
> if (init_done(zram)) {
> up_write(&zram->init_lock);
> + kfree(compressor);
> pr_info("Can't change algorithm for initialized device\n");
> return -EBUSY;
> }
>
> - strcpy(zram->compressor, compressor);
> + comp_algorithm_set(zram, ZRAM_PRIMARY_ZCOMP, compressor);
> up_write(&zram->init_lock);
> return len;
> }
> @@ -1284,7 +1301,7 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
> size = zram_get_obj_size(zram, index);
>
> if (size != PAGE_SIZE)
> - zstrm = zcomp_stream_get(zram->comp);
> + zstrm = zcomp_stream_get(zram->comps[ZRAM_PRIMARY_ZCOMP]);
>
> src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
> if (size == PAGE_SIZE) {
> @@ -1296,7 +1313,7 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
> dst = kmap_atomic(page);
> ret = zcomp_decompress(zstrm, src, size, dst);
> kunmap_atomic(dst);
> - zcomp_stream_put(zram->comp);
> + zcomp_stream_put(zram->comps[ZRAM_PRIMARY_ZCOMP]);
> }
> zs_unmap_object(zram->mem_pool, handle);
> zram_slot_unlock(zram, index);
> @@ -1363,13 +1380,13 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
> kunmap_atomic(mem);
>
> compress_again:
> - zstrm = zcomp_stream_get(zram->comp);
> + zstrm = zcomp_stream_get(zram->comps[ZRAM_PRIMARY_ZCOMP]);
> src = kmap_atomic(page);
> ret = zcomp_compress(zstrm, src, &comp_len);
> kunmap_atomic(src);
>
> if (unlikely(ret)) {
> - zcomp_stream_put(zram->comp);
> + zcomp_stream_put(zram->comps[ZRAM_PRIMARY_ZCOMP]);
> pr_err("Compression failed! err=%d\n", ret);
> zs_free(zram->mem_pool, handle);
> return ret;
> @@ -1397,7 +1414,7 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
> __GFP_HIGHMEM |
> __GFP_MOVABLE);
> if (IS_ERR((void *)handle)) {
> - zcomp_stream_put(zram->comp);
> + zcomp_stream_put(zram->comps[ZRAM_PRIMARY_ZCOMP]);
> atomic64_inc(&zram->stats.writestall);
> handle = zs_malloc(zram->mem_pool, comp_len,
> GFP_NOIO | __GFP_HIGHMEM |
> @@ -1414,14 +1431,14 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
> * zstrm buffer back. It is necessary that the dereferencing
> * of the zstrm variable below occurs correctly.
> */
> - zstrm = zcomp_stream_get(zram->comp);
> + zstrm = zcomp_stream_get(zram->comps[ZRAM_PRIMARY_ZCOMP]);
> }
>
> alloced_pages = zs_get_total_pages(zram->mem_pool);
> update_used_max(zram, alloced_pages);
>
> if (zram->limit_pages && alloced_pages > zram->limit_pages) {
> - zcomp_stream_put(zram->comp);
> + zcomp_stream_put(zram->comps[ZRAM_PRIMARY_ZCOMP]);
> zs_free(zram->mem_pool, handle);
> return -ENOMEM;
> }
> @@ -1435,7 +1452,7 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
> if (comp_len == PAGE_SIZE)
> kunmap_atomic(src);
>
> - zcomp_stream_put(zram->comp);
> + zcomp_stream_put(zram->comps[ZRAM_PRIMARY_ZCOMP]);
> zs_unmap_object(zram->mem_pool, handle);
> atomic64_add(comp_len, &zram->stats.compr_data_size);
> out:
> @@ -1710,6 +1727,20 @@ static int zram_rw_page(struct block_device *bdev, sector_t sector,
> return ret;
> }
>
> +static void zram_destroy_comps(struct zram *zram)
> +{
> + u32 idx;
> +
> + for (idx = 0; idx < ZRAM_MAX_ZCOMPS; idx++) {
> + struct zcomp *comp = zram->comps[idx];
> +
> + zram->comps[idx] = NULL;
> + if (IS_ERR_OR_NULL(comp))
nit:
Why don't you use just NULL check? I don't see any error setting
for zram->comps(Maybe later patch? Will keep check)?
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