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iov_iter: use bvec iterator to implement iterate_bvec()

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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 <ming.lei@canonical.com>
Tested-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Ming Lei 2016-05-30 21:34:32 +08:00 committed by Jens Axboe
parent 80f162ff06
commit 1bdc76aea1
1 changed files with 15 additions and 30 deletions
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45
lib/iov_iter.c
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@ -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; \