[PATCH v6 4/8] iov_iter: use bvec iterator to implement iterate_bvec()
From: Ming Lei <hidden>
Date: 2016-05-30 13:36:37
Also in:
lkml
Subsystem:
library code, the rest, userspace copyin/copyout (uiovec) · Maintainers:
Andrew Morton, Linus Torvalds, Alexander Viro
bvec has one native/mature iterator for long time, so not necessary to use the reinvented wheel for iterating bvecs in lib/iov_iter.c. Two ITER_BVEC test cases are run: - xfstest(-g auto) on loop dio/aio, no regression found - swap file works well under extreme stress(stress-ng --all 64 -t 800 -v), and lots of OOMs are triggerd, and the whole system still survives Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <redacted> --- lib/iov_iter.c | 45 +++++++++++++++------------------------------ 1 file changed, 15 insertions(+), 30 deletions(-)
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 0cd5227..d67c828 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c@@ -56,37 +56,24 @@ n = wanted; \ } -#define iterate_bvec(i, n, __v, __p, skip, STEP) { \ - size_t wanted = n; \ - __p = i->bvec; \ - __v.bv_len = min_t(size_t, n, __p->bv_len - skip); \ - if (likely(__v.bv_len)) { \ - __v.bv_page = __p->bv_page; \ - __v.bv_offset = __p->bv_offset + skip; \ - (void)(STEP); \ - skip += __v.bv_len; \ - n -= __v.bv_len; \ - } \ - while (unlikely(n)) { \ - __p++; \ - __v.bv_len = min_t(size_t, n, __p->bv_len); \ - if (unlikely(!__v.bv_len)) \ +#define iterate_bvec(i, n, __v, __bi, skip, STEP) { \ + struct bvec_iter __start; \ + __start.bi_size = n; \ + __start.bi_bvec_done = skip; \ + __start.bi_idx = 0; \ + for_each_bvec(__v, i->bvec, __bi, __start) { \ + if (!__v.bv_len) \ continue; \ - __v.bv_page = __p->bv_page; \ - __v.bv_offset = __p->bv_offset; \ (void)(STEP); \ - skip = __v.bv_len; \ - n -= __v.bv_len; \ } \ - n = wanted; \ } #define iterate_all_kinds(i, n, v, I, B, K) { \ size_t skip = i->iov_offset; \ if (unlikely(i->type & ITER_BVEC)) { \ - const struct bio_vec *bvec; \ struct bio_vec v; \ - iterate_bvec(i, n, v, bvec, skip, (B)) \ + struct bvec_iter __bi; \ + iterate_bvec(i, n, v, __bi, skip, (B)) \ } else if (unlikely(i->type & ITER_KVEC)) { \ const struct kvec *kvec; \ struct kvec v; \
@@ -104,15 +91,13 @@ if (i->count) { \ size_t skip = i->iov_offset; \ if (unlikely(i->type & ITER_BVEC)) { \ - const struct bio_vec *bvec; \ + const struct bio_vec *bvec = i->bvec; \ struct bio_vec v; \ - iterate_bvec(i, n, v, bvec, skip, (B)) \ - if (skip == bvec->bv_len) { \ - bvec++; \ - skip = 0; \ - } \ - i->nr_segs -= bvec - i->bvec; \ - i->bvec = bvec; \ + struct bvec_iter __bi; \ + iterate_bvec(i, n, v, __bi, skip, (B)) \ + i->bvec = __bvec_iter_bvec(i->bvec, __bi); \ + i->nr_segs -= i->bvec - bvec; \ + skip = __bi.bi_bvec_done; \ } else if (unlikely(i->type & ITER_KVEC)) { \ const struct kvec *kvec; \ struct kvec v; \
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1.9.1