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zram: check comp algorithm availability earlier

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Improvement idea by Marcin Jabrzyk.

comp_algorithm_store() silently accepts any supplied algorithm name,
because zram performs algorithm availability check later, during the
device configuration phase in disksize_store() and emits the following
error:

  "zram: Cannot initialise %s compressing backend"

this error line is somewhat generic and, besides, can indicate a failed
attempt to allocate compression backend's working buffers.

add algorithm availability check to comp_algorithm_store():

  echo lzz > /sys/block/zram0/comp_algorithm
  -bash: echo: write error: Invalid argument

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reported-by: Marcin Jabrzyk <m.jabrzyk@samsung.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Sergey Senozhatsky 2015-06-25 15:00:32 -07:00 committed by Linus Torvalds
parent 4bbacd51a6
commit d93435c3fb
3 changed files with 9 additions and 0 deletions
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5
drivers/block/zram/zcomp.c
View File

@ -286,6 +286,11 @@ ssize_t zcomp_available_show(const char *comp, char *buf)
return sz;
}
bool zcomp_available_algorithm(const char *comp)
{
return find_backend(comp) != NULL;
}
bool zcomp_set_max_streams(struct zcomp *comp, int num_strm)
{
return comp->set_max_streams(comp, num_strm);

1
drivers/block/zram/zcomp.h
View File

@ -51,6 +51,7 @@ struct zcomp {
};
ssize_t zcomp_available_show(const char *comp, char *buf);
bool zcomp_available_algorithm(const char *comp);
struct zcomp *zcomp_create(const char *comp, int max_strm);
void zcomp_destroy(struct zcomp *comp);

3
drivers/block/zram/zram_drv.c
View File

@ -378,6 +378,9 @@ static ssize_t comp_algorithm_store(struct device *dev,
if (sz > 0 && zram->compressor[sz - 1] == '\n')
zram->compressor[sz - 1] = 0x00;
if (!zcomp_available_algorithm(zram->compressor))
len = -EINVAL;
up_write(&zram->init_lock);
return len;
}