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Date: Thu, 15 Oct 2015 10:07:33 +0900
From: Joonsoo Kim <iamjoonsoo.kim@....com>
To: Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Minchan Kim <minchan@...nel.org>,
Nitin Gupta <ngupta@...are.org>,
Herbert Xu <herbert@...dor.apana.org.au>,
"David S. Miller" <davem@...emloft.net>,
Stephan Mueller <smueller@...onox.de>,
linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org
Subject: Re: [PATCH v4 7/8] zram: use crypto contextless compression API to
(de)compress
On Thu, Oct 15, 2015 at 09:38:41AM +0900, Sergey Senozhatsky wrote:
> Hi,
>
> On (10/14/15 16:38), Joonsoo Kim wrote:
> [..]
> > Creates virtual block devices called /dev/zramX (X = 0, 1, ...).
> > @@ -18,9 +17,8 @@ config ZRAM
> > config ZRAM_LZ4_COMPRESS
> > bool "Enable LZ4 algorithm support"
> > depends on ZRAM
> > - select LZ4_COMPRESS
> > - select LZ4_DECOMPRESS
> > + select CRYPTO_LZ4
> > default n
> > help
> > This option enables LZ4 compression algorithm support. Compression
> > - algorithm can be changed using `comp_algorithm' device attribute.
> > \ No newline at end of file
> > + algorithm can be changed using `comp_algorithm' device attribute.
> > diff --git a/drivers/block/zram/Makefile b/drivers/block/zram/Makefile
> > index be0763f..9e2b79e 100644
> > --- a/drivers/block/zram/Makefile
> > +++ b/drivers/block/zram/Makefile
> > @@ -1,5 +1,3 @@
> > -zram-y := zcomp_lzo.o zcomp.o zram_drv.o
> > -
> > -zram-$(CONFIG_ZRAM_LZ4_COMPRESS) += zcomp_lz4.o
> > +zram-y := zcomp.o zram_drv.o
>
> + git rm zcomp_lzo.* zcomp_lz4.* :)
Will do. :)
>
>
> > obj-$(CONFIG_ZRAM) += zram.o
> > diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
> > index e3016da..9be83db 100644
> > --- a/drivers/block/zram/zcomp.c
> > +++ b/drivers/block/zram/zcomp.c
> > @@ -15,10 +15,6 @@
> > #include <linux/sched.h>
> >
> > #include "zcomp.h"
> > -#include "zcomp_lzo.h"
> > -#ifdef CONFIG_ZRAM_LZ4_COMPRESS
> > -#include "zcomp_lz4.h"
> > -#endif
> >
> > /*
> > * single zcomp_strm backend
> > @@ -43,19 +39,20 @@ struct zcomp_strm_multi {
> > wait_queue_head_t strm_wait;
> > };
> >
> > -static struct zcomp_backend *backends[] = {
> > - &zcomp_lzo,
> > +static const char * const backends[] = {
> > + "lzo",
> > #ifdef CONFIG_ZRAM_LZ4_COMPRESS
>
> a nitpick -- this CONFIG option does not exist at this point.
Will fix.
>
> > - &zcomp_lz4,
> > + "lz4",
> > #endif
> > NULL
> > };
> >
> > -static struct zcomp_backend *find_backend(const char *compress)
> > +static const char *find_backend(const char *compress)
> > {
> > int i = 0;
> > while (backends[i]) {
> > - if (sysfs_streq(compress, backends[i]->name))
> > + if (sysfs_streq(compress, backends[i]) &&
> > + crypto_has_comp(backends[i], 0, 0))
>
> again (the same as in my previous email). I'd rather prefer to have
> FOO backends in ` const char * const backends[]' array only when the
> corresponding CONFIG_CRYPTO_FOO option has been selected. otherwise you
> have to find an intersection of two independent sets. sort of unreasonable
> to me.
Okay.
>
> > break;
> > i++;
> > }
> > @@ -65,7 +62,7 @@ static struct zcomp_backend *find_backend(const char *compress)
> > static void zcomp_strm_free(struct zcomp *comp, struct zcomp_strm *zstrm)
> > {
> > if (zstrm->private)
> > - comp->backend->destroy(zstrm->private);
> > + crypto_ccomp_free_context(comp->tfm, zstrm->private);
> > free_pages((unsigned long)zstrm->buffer, 1);
> > kfree(zstrm);
> > }
> > @@ -80,7 +77,13 @@ static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp)
> > if (!zstrm)
> > return NULL;
> >
> > - zstrm->private = comp->backend->create();
> > + zstrm->private = crypto_ccomp_alloc_context(comp->tfm);
> > + if (IS_ERR(zstrm->private)) {
> > + zstrm->private = NULL;
> > + zcomp_strm_free(comp, zstrm);
> > + return NULL;
> > + }
> > +
> > /*
> > * allocate 2 pages. 1 for compressed data, plus 1 extra for the
> > * case when compressed size is larger than the original one
> > @@ -274,12 +277,12 @@ ssize_t zcomp_available_show(const char *comp, char *buf)
> > int i = 0;
> >
> > while (backends[i]) {
> > - if (!strcmp(comp, backends[i]->name))
> > + if (!strcmp(comp, backends[i]))
> > sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
> > - "[%s] ", backends[i]->name);
> > + "[%s] ", backends[i]);
> > else
> > sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
> > - "%s ", backends[i]->name);
> > + "%s ", backends[i]);
> > i++;
> > }
> > sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n");
> > @@ -320,7 +323,10 @@ void zcomp_compress_end(struct zcomp *comp, struct zcomp_strm *zstrm)
> > /* May return NULL, may sleep */
> > struct zcomp_strm *zcomp_decompress_begin(struct zcomp *comp)
> > {
> > - return NULL;
> > + if (crypto_ccomp_decomp_noctx(comp->tfm))
> > + return NULL;
> > +
> > + return zcomp_strm_find(comp);
> > }
> >
> > void zcomp_decompress_end(struct zcomp *comp, struct zcomp_strm *zstrm)
> > @@ -330,22 +336,29 @@ void zcomp_decompress_end(struct zcomp *comp, struct zcomp_strm *zstrm)
> > }
> >
> > int zcomp_compress(struct zcomp *comp, struct zcomp_strm *zstrm,
> > - const unsigned char *src, size_t *dst_len)
> > + const unsigned char *src, unsigned int *dst_len)
> > {
> > - return comp->backend->compress(src, zstrm->buffer, dst_len,
> > - zstrm->private);
> > + *dst_len = PAGE_SIZE << 1;
> > +
> > + return crypto_ccomp_compress(comp->tfm, src, PAGE_SIZE,
> > + zstrm->buffer, dst_len, zstrm->private);
> > }
> >
> > int zcomp_decompress(struct zcomp *comp, struct zcomp_strm *zstrm,
> > const unsigned char *src,
> > - size_t src_len, unsigned char *dst)
> > + unsigned int src_len, unsigned char *dst)
> > {
> > - return comp->backend->decompress(src, src_len, dst);
> > + unsigned int size = PAGE_SIZE;
> > + void *private = zstrm ? zstrm->private : NULL;
> > +
> > + return crypto_ccomp_decompress(comp->tfm, src, src_len,
> > + dst, &size, private);
> > }
> >
> > void zcomp_destroy(struct zcomp *comp)
> > {
> > comp->destroy(comp);
> > + crypto_free_ccomp(comp->tfm);
> > kfree(comp);
> > }
> >
> > @@ -360,7 +373,7 @@ void zcomp_destroy(struct zcomp *comp)
> > struct zcomp *zcomp_create(const char *compress, int max_strm)
> > {
> > struct zcomp *comp;
> > - struct zcomp_backend *backend;
> > + const char *backend;
> > int error;
> >
> > backend = find_backend(compress);
> > @@ -371,12 +384,18 @@ struct zcomp *zcomp_create(const char *compress, int max_strm)
> > if (!comp)
> > return ERR_PTR(-ENOMEM);
> >
> > - comp->backend = backend;
> > + comp->tfm = crypto_alloc_ccomp(backend, 0, 0);
> > + if (IS_ERR(comp->tfm)) {
> > + kfree(comp);
> > + return ERR_CAST(comp->tfm);
> > + }
> > +
> > if (max_strm > 1)
> > error = zcomp_strm_multi_create(comp, max_strm);
> > else
> > error = zcomp_strm_single_create(comp);
> > if (error) {
> > + crypto_free_ccomp(comp->tfm);
> > kfree(comp);
>
> hm... zcomp_destroy(comp) ?
It's not possible to use zcomp_destroy() here. It tries to access
field of comp->stream which could be NULL.
Thanks.
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