From: NeilBrown Date: Sun, 18 Jun 2017 04:38:59 +0000 (+1000) Subject: block: don't check for BIO_MAX_PAGES in blk_bio_segment_split() X-Git-Tag: v4.13-rc1~70^2~43 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=58c94cc19e0800e8c0d0d708e37eeb4dee564ba9;p=karo-tx-linux.git block: don't check for BIO_MAX_PAGES in blk_bio_segment_split() blk_bio_segment_split() makes sure bios have no more than BIO_MAX_PAGES entries in the bi_io_vec. This was done because bio_clone_bioset() (when given a mempool bioset) could not handle larger io_vecs. No driver uses bio_clone_bioset() any more, they all use bio_clone_fast() if anything, and bio_clone_fast() doesn't clone the bi_io_vec. The main user of of bio_clone_bioset() at this level is bounce.c, and bouncing now happens before blk_bio_segment_split(), so that is not of concern. So remove the big helpful comment and the code. Reviewed-by: Christoph Hellwig Signed-off-by: NeilBrown Signed-off-by: Jens Axboe --- diff --git a/block/blk-merge.c b/block/blk-merge.c index e7862e9dcc39..cea544ec5d96 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -108,24 +108,8 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, bool do_split = true; struct bio *new = NULL; const unsigned max_sectors = get_max_io_size(q, bio); - unsigned bvecs = 0; bio_for_each_segment(bv, bio, iter) { - /* - * With arbitrary bio size, the incoming bio may be very - * big. We have to split the bio into small bios so that - * each holds at most BIO_MAX_PAGES bvecs because - * bio_clone_bioset() can fail to allocate big bvecs. - * - * Those drivers which will need to use bio_clone_bioset() - * should tell us in some way. For now, impose the - * BIO_MAX_PAGES limit on all queues. - * - * TODO: handle users of bio_clone_bioset() differently. - */ - if (bvecs++ >= BIO_MAX_PAGES) - goto split; - /* * If the queue doesn't support SG gaps and adding this * offset would create a gap, disallow it.