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@xxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
---
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; \
--
1.9.1
--
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