Re: [PATCH] block: allow for_each_bvec to support zero len bvec
From: Matthew Wilcox <willy@infradead.org>
Date: 2020-08-10 03:33:14
Also in:
linux-block
On Mon, Aug 10, 2020 at 11:19:15AM +0800, Ming Lei wrote:
quoted hunk ↗ jump to hunk
+++ b/include/linux/bvec.h@@ -117,11 +117,18 @@ static inline bool bvec_iter_advance(const struct bio_vec *bv, return true; } +static inline void bvec_iter_skip_zero_bvec(struct bvec_iter *iter) +{ + iter->bi_bvec_done = 0; + iter->bi_idx++; +} + #define for_each_bvec(bvl, bio_vec, iter, start) \ for (iter = (start); \ (iter).bi_size && \ ((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \ - bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len)) + (bvl).bv_len ? bvec_iter_advance((bio_vec), &(iter), \ + (bvl).bv_len) : bvec_iter_skip_zero_bvec(&(iter)))
What if you have two zero-length bvecs in a row? Won't this just skip the first one? It would seem better to me to put the bv_len test in bvec_iter_advance() instead of making the macro more complicated.