There is no way to get a string with all the crypto comp algorithms
supported by the crypto comp engine, so we need to maintain our own
backends list. At the same time we additionally need to use
crypto_has_comp() to make sure that the user has requested a compression
algorithm that is recognized by the crypto comp engine. Relying on
/proc/crypto is not an options here, because it does not show
not-yet-inserted compression modules.
Example:
modprobe zram
cat /proc/crypto | grep -i lz4
modprobe lz4
cat /proc/crypto | grep -i lz4
name : lz4
driver : lz4-generic
module : lz4
So the user can't tell exactly if the lz4 is really supported from
/proc/crypto output, unless someone or something has loaded it.
This patch also adds crypto_has_comp() to zcomp_available_show(). We
store all the compression algorithms names in zcomp's `backends' array,
regardless the CONFIG_CRYPTO_FOO configuration, but show only those that
are also supported by crypto engine. This helps user to know the exact
list of compression algorithms that can be used.
Example:
module lz4 is not loaded yet, but is supported by the crypto
engine. /proc/crypto has no information on this module, while
zram's `comp_algorithm' lists it:
cat /proc/crypto | grep -i lz4
cat /sys/block/zram0/comp_algorithm
[lzo] lz4 deflate lz4hc 842
We still use the `backends' array to determine if the requested
compression backend is known to crypto api. This array, however, may not
contain some entries, therefore as the last step we call crypto_has_comp()
function which attempts to insmod the requested compression algorithm to
determine if crypto api supports it. The advantage of this method is that
now we permit the usage of out-of-tree crypto compression modules
(implementing S/W or H/W compression).
[sergey.senozhatsky@gmail.com: zram-use-crypto-api-to-check-alg-availability-v3]
Link: http://lkml.kernel.org/r/20160604024902.11778-4-sergey.senozhatsky@gmail.com
Link: http://lkml.kernel.org/r/20160531122017.2878-5-sergey.senozhatsky@gmail.com
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
#select lzo compression algorithm
echo lzo > /sys/block/zram0/comp_algorithm
+ For the time being, the `comp_algorithm' content does not necessarily
+ show every compression algorithm supported by the kernel. We keep this
+ list primarily to simplify device configuration and one can configure
+ a new device with a compression algorithm that is not listed in
+ `comp_algorithm'. The thing is that, internally, ZRAM uses Crypto API
+ and, if some of the algorithms were built as modules, it's impossible
+ to list all of them using, for instance, /proc/crypto or any other
+ method. This, however, has an advantage of permitting the usage of
+ custom crypto compression modules (implementing S/W or H/W
+ compression).
+
4) Set Disksize
Set disk size by writing the value to sysfs node 'disksize'.
The value can be either in bytes or you can use mem suffixes.
NULL
};
-static const char *find_backend(const char *compress)
-{
- int i = 0;
- while (backends[i]) {
- if (sysfs_streq(compress, backends[i]))
- break;
- i++;
- }
- return backends[i];
-}
-
static void zcomp_strm_free(struct zcomp_strm *zstrm)
{
if (!IS_ERR_OR_NULL(zstrm->tfm))
return zstrm;
}
+bool zcomp_available_algorithm(const char *comp)
+{
+ int i = 0;
+
+ while (backends[i]) {
+ if (sysfs_streq(comp, backends[i]))
+ return true;
+ i++;
+ }
+
+ /*
+ * Crypto does not ignore a trailing new line symbol,
+ * so make sure you don't supply a string containing
+ * one.
+ * This also means that we permit zcomp initialisation
+ * with any compressing algorithm known to crypto api.
+ */
+ return crypto_has_comp(comp, 0, 0) == 1;
+}
+
/* show available compressors */
ssize_t zcomp_available_show(const char *comp, char *buf)
{
+ bool known_algorithm = false;
ssize_t sz = 0;
int i = 0;
- while (backends[i]) {
- if (!strcmp(comp, backends[i]))
+ for (; backends[i]; i++) {
+ if (!strcmp(comp, backends[i])) {
+ known_algorithm = true;
sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
"[%s] ", backends[i]);
- else
+ } else {
sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
"%s ", backends[i]);
- i++;
+ }
}
+
+ /*
+ * Out-of-tree module known to crypto api or a missing
+ * entry in `backends'.
+ */
+ if (!known_algorithm && crypto_has_comp(comp, 0, 0) == 1)
+ sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
+ "[%s] ", comp);
+
sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n");
return sz;
}
-bool zcomp_available_algorithm(const char *comp)
-{
- return find_backend(comp) != NULL;
-}
-
struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
{
return *get_cpu_ptr(comp->stream);
struct zcomp *zcomp_create(const char *compress)
{
struct zcomp *comp;
- const char *backend;
int error;
- backend = find_backend(compress);
- if (!backend)
+ if (!zcomp_available_algorithm(compress))
return ERR_PTR(-EINVAL);
comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
if (!comp)
return ERR_PTR(-ENOMEM);
- comp->name = backend;
+ comp->name = compress;
error = zcomp_init(comp);
if (error) {
kfree(comp);
struct device_attribute *attr, const char *buf, size_t len)
{
struct zram *zram = dev_to_zram(dev);
+ char compressor[CRYPTO_MAX_ALG_NAME];
size_t sz;
- if (!zcomp_available_algorithm(buf))
+ strlcpy(compressor, buf, sizeof(compressor));
+ /* ignore trailing newline */
+ sz = strlen(compressor);
+ if (sz > 0 && compressor[sz - 1] == '\n')
+ compressor[sz - 1] = 0x00;
+
+ if (!zcomp_available_algorithm(compressor))
return -EINVAL;
down_write(&zram->init_lock);
pr_info("Can't change algorithm for initialized device\n");
return -EBUSY;
}
- strlcpy(zram->compressor, buf, sizeof(zram->compressor));
-
- /* ignore trailing newline */
- sz = strlen(zram->compressor);
- if (sz > 0 && zram->compressor[sz - 1] == '\n')
- zram->compressor[sz - 1] = 0x00;
+ strlcpy(zram->compressor, compressor, sizeof(compressor));
up_write(&zram->init_lock);
return len;
}
#ifndef _ZRAM_DRV_H_
#define _ZRAM_DRV_H_
-#include <linux/spinlock.h>
+#include <linux/rwsem.h>
#include <linux/zsmalloc.h>
+#include <linux/crypto.h>
#include "zcomp.h"
* we can store in a disk.
*/
u64 disksize; /* bytes */
- char compressor[10];
+ char compressor[CRYPTO_MAX_ALG_NAME];
/*
* zram is claimed so open request will be failed
*/
projects / cascardo / linux.git / commitdiff