diff options
| -rw-r--r-- | mm/iov_iter.c | 104 |
1 files changed, 28 insertions, 76 deletions
diff --git a/mm/iov_iter.c b/mm/iov_iter.c index 798fcb4294e7..e91bf0accc47 100644 --- a/mm/iov_iter.c +++ b/mm/iov_iter.c @@ -70,6 +70,33 @@ } \ } +#define iterate_and_advance(i, n, v, I, B) { \ + 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 { \ + 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; \ + } \ + i->count -= n; \ + i->iov_offset = skip; \ +} + static size_t copy_to_iter_iovec(void *from, size_t bytes, struct iov_iter *i) { size_t skip, copy, left, wanted; @@ -366,42 +393,6 @@ static size_t zero_iovec(size_t bytes, struct iov_iter *i) return wanted - bytes; } -static void advance_iovec(struct iov_iter *i, size_t bytes) -{ - BUG_ON(i->count < bytes); - - if (likely(i->nr_segs == 1)) { - i->iov_offset += bytes; - i->count -= bytes; - } else { - const struct iovec *iov = i->iov; - size_t base = i->iov_offset; - unsigned long nr_segs = i->nr_segs; - - /* - * The !iov->iov_len check ensures we skip over unlikely - * zero-length segments (without overruning the iovec). - */ - while (bytes || unlikely(i->count && !iov->iov_len)) { - int copy; - - copy = min(bytes, iov->iov_len - base); - BUG_ON(!i->count || i->count < copy); - i->count -= copy; - bytes -= copy; - base += copy; - if (iov->iov_len == base) { - iov++; - nr_segs--; - base = 0; - } - } - i->iov = iov; - i->iov_offset = base; - i->nr_segs = nr_segs; - } -} - /* * Fault in the first iovec of the given iov_iter, to a maximum length * of bytes. Returns 0 on success, or non-zero if the memory could not be @@ -685,42 +676,6 @@ static size_t zero_bvec(size_t bytes, struct iov_iter *i) return wanted - bytes; } -static void advance_bvec(struct iov_iter *i, size_t bytes) -{ - BUG_ON(i->count < bytes); - - if (likely(i->nr_segs == 1)) { - i->iov_offset += bytes; - i->count -= bytes; - } else { - const struct bio_vec *bvec = i->bvec; - size_t base = i->iov_offset; - unsigned long nr_segs = i->nr_segs; - - /* - * The !iov->iov_len check ensures we skip over unlikely - * zero-length segments (without overruning the iovec). - */ - while (bytes || unlikely(i->count && !bvec->bv_len)) { - int copy; - - copy = min(bytes, bvec->bv_len - base); - BUG_ON(!i->count || i->count < copy); - i->count -= copy; - bytes -= copy; - base += copy; - if (bvec->bv_len == base) { - bvec++; - nr_segs--; - base = 0; - } - } - i->bvec = bvec; - i->iov_offset = base; - i->nr_segs = nr_segs; - } -} - static ssize_t get_pages_bvec(struct iov_iter *i, struct page **pages, size_t maxsize, unsigned maxpages, size_t *start) @@ -849,10 +804,7 @@ EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); void iov_iter_advance(struct iov_iter *i, size_t size) { - if (i->type & ITER_BVEC) - advance_bvec(i, size); - else - advance_iovec(i, size); + iterate_and_advance(i, size, v, 0, 0) } EXPORT_SYMBOL(iov_iter_advance); |