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Commit d93435c3 authored by Sergey Senozhatsky's avatar Sergey Senozhatsky Committed by Linus Torvalds
Browse files

zram: check comp algorithm availability earlier 



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: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reported-by: default avatarMarcin Jabrzyk <m.jabrzyk@samsung.com>
Acked-by: default avatarMinchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4bbacd51

drivers/block/zram/zcomp.c

+5 −0
Original line number Original line Diff line number Diff line
@@ -286,6 +286,11 @@ ssize_t zcomp_available_show(const char *comp, char *buf) 
	return sz;

	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)

bool zcomp_set_max_streams(struct zcomp *comp, int num_strm)

{

{

	return comp->set_max_streams(comp, num_strm);

	return comp->set_max_streams(comp, num_strm);

drivers/block/zram/zcomp.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -51,6 +51,7 @@ struct zcomp { 
};

};





ssize_t zcomp_available_show(const char *comp, char *buf);

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);

struct zcomp *zcomp_create(const char *comp, int max_strm);

void zcomp_destroy(struct zcomp *comp);

void zcomp_destroy(struct zcomp *comp);

drivers/block/zram/zram_drv.c

+3 −0
Original line number Original line Diff line number Diff line
@@ -378,6 +378,9 @@ static ssize_t comp_algorithm_store(struct device *dev, 
	if (sz > 0 && zram->compressor[sz - 1] == '\n')

	if (sz > 0 && zram->compressor[sz - 1] == '\n')

		zram->compressor[sz - 1] = 0x00;

		zram->compressor[sz - 1] = 0x00;





	if (!zcomp_available_algorithm(zram->compressor))

		len = -EINVAL;



	up_write(&zram->init_lock);

	up_write(&zram->init_lock);

	return len;

	return len;

}

}