On Sun, Oct 28, 2018 at 04:49:47PM +0100, Christoph Hellwig wrote:
On Sun, Oct 28, 2018 at 08:51:31AM +0800, Ming Lei wrote:
On Fri, Oct 26, 2018 at 09:44:15AM +0200, Christoph Hellwig wrote:
if (req_sects > UINT_MAX >> 9)
req_sects = UINT_MAX >> 9;
req_sects = (UINT_MAX >> 9) & ~bs_mask;Given that we have this same thing duplicated in write zeroes what about a documented helper?
IMO, using UINT_MAX & bs_mask is better because it is self-explanatory in the context.
I don't think it is in any way. I understand it because I know the code, but there is nothing that documents why we do that.
Then how about introducing this helper?
/* + * The max sectors one bio can handle is 'UINT_MAX >> 9' becasue + * bvec_iter.bi_size is defined as 'unsigned int', also it has to aligned + * to with logical block size which is minimum accepted unit by hardware. + */ +static inline unsigned int blk_max_allowed_max_secotrs(struct request_queue *q) +{ + return round_down(UINT_MAX, queue_logical_block_size(q)) >> 9; +} + +/*
Thanks, Ming