- 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)) \
- if (skip == bvec->bv_len) { \
- bvec++; \
- skip = 0; \
- } \
- i->nr_segs -= bvec - i->bvec; \
- i->bvec = bvec; \
- } else if (unlikely(i->type & ITER_KVEC)) { \
- const struct kvec *kvec; \
- struct kvec v; \
- iterate_kvec(i, n, v, kvec, skip, (K)) \
- if (skip == kvec->iov_len) { \
- kvec++; \
- skip = 0; \
- } \
- i->nr_segs -= kvec - i->kvec; \
- i->kvec = kvec; \
- } else { \
- const struct iovec *iov; \
- struct iovec v; \
- iterate_iovec(i, n, v, iov, skip, (I)) \
- if (skip == iov->iov_len) { \
- iov++; \
- skip = 0; \
+ if (unlikely(i->count < n)) \
+ n = i->count; \
+ if (i->count) { \
+ 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)) \
+ if (skip == bvec->bv_len) { \
+ bvec++; \
+ skip = 0; \
+ } \
+ i->nr_segs -= bvec - i->bvec; \
+ i->bvec = bvec; \
+ } else if (unlikely(i->type & ITER_KVEC)) { \
+ const struct kvec *kvec; \
+ struct kvec v; \
+ iterate_kvec(i, n, v, kvec, skip, (K)) \
+ if (skip == kvec->iov_len) { \
+ kvec++; \
+ skip = 0; \
+ } \
+ i->nr_segs -= kvec - i->kvec; \
+ i->kvec = kvec; \
+ } else { \
+ const struct iovec *iov; \
+ struct iovec v; \
+ iterate_iovec(i, n, v, iov, skip, (I)) \
+ if (skip == iov->iov_len) { \
+ iov++; \
+ skip = 0; \
+ } \
+ i->nr_segs -= iov - i->iov; \
+ i->iov = iov; \