iov_iter.c: iterate_and_advance
same as iterate_all_kinds, but iterator is moved to the position past the last byte we'd handled. iov_iter_advance() converted to it Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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parent
04a311655b
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7ce2a91e51
104
mm/iov_iter.c
104
mm/iov_iter.c
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@ -70,6 +70,33 @@
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} \
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}
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#define iterate_and_advance(i, n, v, I, B) { \
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size_t skip = i->iov_offset; \
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if (unlikely(i->type & ITER_BVEC)) { \
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const struct bio_vec *bvec; \
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struct bio_vec v; \
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iterate_bvec(i, n, v, bvec, skip, (B)) \
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if (skip == bvec->bv_len) { \
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bvec++; \
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skip = 0; \
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} \
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i->nr_segs -= bvec - i->bvec; \
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i->bvec = bvec; \
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} else { \
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const struct iovec *iov; \
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struct iovec v; \
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iterate_iovec(i, n, v, iov, skip, (I)) \
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if (skip == iov->iov_len) { \
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iov++; \
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skip = 0; \
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} \
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i->nr_segs -= iov - i->iov; \
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i->iov = iov; \
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} \
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i->count -= n; \
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i->iov_offset = skip; \
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}
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static size_t copy_to_iter_iovec(void *from, size_t bytes, struct iov_iter *i)
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{
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size_t skip, copy, left, wanted;
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@ -366,42 +393,6 @@ static size_t zero_iovec(size_t bytes, struct iov_iter *i)
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return wanted - bytes;
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}
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static void advance_iovec(struct iov_iter *i, size_t bytes)
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{
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BUG_ON(i->count < bytes);
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if (likely(i->nr_segs == 1)) {
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i->iov_offset += bytes;
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i->count -= bytes;
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} else {
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const struct iovec *iov = i->iov;
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size_t base = i->iov_offset;
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unsigned long nr_segs = i->nr_segs;
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/*
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* The !iov->iov_len check ensures we skip over unlikely
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* zero-length segments (without overruning the iovec).
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*/
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while (bytes || unlikely(i->count && !iov->iov_len)) {
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int copy;
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copy = min(bytes, iov->iov_len - base);
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BUG_ON(!i->count || i->count < copy);
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i->count -= copy;
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bytes -= copy;
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base += copy;
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if (iov->iov_len == base) {
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iov++;
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nr_segs--;
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base = 0;
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}
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}
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i->iov = iov;
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i->iov_offset = base;
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i->nr_segs = nr_segs;
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}
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}
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/*
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* Fault in the first iovec of the given iov_iter, to a maximum length
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* of bytes. Returns 0 on success, or non-zero if the memory could not be
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@ -685,42 +676,6 @@ static size_t zero_bvec(size_t bytes, struct iov_iter *i)
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return wanted - bytes;
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}
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static void advance_bvec(struct iov_iter *i, size_t bytes)
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{
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BUG_ON(i->count < bytes);
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if (likely(i->nr_segs == 1)) {
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i->iov_offset += bytes;
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i->count -= bytes;
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} else {
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const struct bio_vec *bvec = i->bvec;
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size_t base = i->iov_offset;
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unsigned long nr_segs = i->nr_segs;
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/*
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* The !iov->iov_len check ensures we skip over unlikely
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* zero-length segments (without overruning the iovec).
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*/
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while (bytes || unlikely(i->count && !bvec->bv_len)) {
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int copy;
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copy = min(bytes, bvec->bv_len - base);
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BUG_ON(!i->count || i->count < copy);
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i->count -= copy;
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bytes -= copy;
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base += copy;
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if (bvec->bv_len == base) {
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bvec++;
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nr_segs--;
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base = 0;
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}
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}
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i->bvec = bvec;
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i->iov_offset = base;
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i->nr_segs = nr_segs;
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}
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}
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static ssize_t get_pages_bvec(struct iov_iter *i,
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struct page **pages, size_t maxsize, unsigned maxpages,
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size_t *start)
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@ -849,10 +804,7 @@ EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
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void iov_iter_advance(struct iov_iter *i, size_t size)
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{
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if (i->type & ITER_BVEC)
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advance_bvec(i, size);
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else
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advance_iovec(i, size);
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iterate_and_advance(i, size, v, 0, 0)
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}
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EXPORT_SYMBOL(iov_iter_advance);
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