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 <[email protected]> Reported-by: Marcin Jabrzyk <[email protected]> --- drivers/block/zram/zcomp.c | 5 +++++ drivers/block/zram/zcomp.h | 1 + drivers/block/zram/zram_drv.c | 3 +++ 3 files changed, 9 insertions(+) diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c index a1a8b8e..965d1af 100644 --- a/drivers/block/zram/zcomp.c +++ b/drivers/block/zram/zcomp.c @@ -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); diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h index c59d1fc..46e2b9f 100644 --- a/drivers/block/zram/zcomp.h +++ b/drivers/block/zram/zcomp.h @@ -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); diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 28f6e46..1cd8ade 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -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; } -- 2.4.1.314.g9532ead -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
