Re: [PATCH 1/2] bcache: avoid nr_stripes overflow in bcache_device_init()

On 7/12/20 11:47 AM, Coly Li wrote:

For some block devices which large capacity (e.g. 8TB) but small io_opt size (e.g. 8 sectors), in bcache_device_init() the stripes number calcu- lated by, DIV_ROUND_UP_ULL(sectors, d->stripe_size); might be overflow to the unsigned int bcache_device->nr_stripes.

This patch uses an unsigned long variable to store DIV_ROUND_UP_ULL() and after the value is checked to be available in unsigned int range, sets it to bache_device->nr_stripes. Then the overflow is avoided.

Does that work on 32-bit, where sizeof(unsigned long) == 4?