ITER_KVEC = 2,
ITER_BVEC = 4,
ITER_PIPE = 8,
+ ITER_DISCARD = 16,
};
struct iov_iter {
return iov_iter_type(i) == ITER_PIPE;
}
+static inline bool iov_iter_is_discard(const struct iov_iter *i)
+{
+ return iov_iter_type(i) == ITER_DISCARD;
+}
+
static inline unsigned char iov_iter_rw(const struct iov_iter *i)
{
return i->type & (READ | WRITE);
unsigned long nr_segs, size_t count);
void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
size_t count);
+void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
size_t maxsize, unsigned maxpages, size_t *start);
ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
const struct kvec *kvec; \
struct kvec v; \
iterate_kvec(i, n, v, kvec, skip, (K)) \
+ } else if (unlikely(i->type & ITER_DISCARD)) { \
} else { \
const struct iovec *iov; \
struct iovec v; \
} \
i->nr_segs -= kvec - i->kvec; \
i->kvec = kvec; \
+ } else if (unlikely(i->type & ITER_DISCARD)) { \
+ skip += n; \
} else { \
const struct iovec *iov; \
struct iovec v; \
size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
kunmap_atomic(kaddr);
return wanted;
- } else if (likely(!iov_iter_is_pipe(i)))
+ } else if (unlikely(iov_iter_is_discard(i)))
+ return bytes;
+ else if (likely(!iov_iter_is_pipe(i)))
return copy_page_to_iter_iovec(page, offset, bytes, i);
else
return copy_page_to_iter_pipe(page, offset, bytes, i);
{
if (unlikely(!page_copy_sane(page, offset, bytes)))
return 0;
- if (unlikely(iov_iter_is_pipe(i))) {
+ if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
WARN_ON(1);
return 0;
}
kunmap_atomic(kaddr);
return 0;
}
- if (unlikely(iov_iter_is_pipe(i))) {
+ if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
kunmap_atomic(kaddr);
WARN_ON(1);
return 0;
pipe_advance(i, size);
return;
}
+ if (unlikely(iov_iter_is_discard(i))) {
+ i->count -= size;
+ return;
+ }
iterate_and_advance(i, size, v, 0, 0, 0)
}
EXPORT_SYMBOL(iov_iter_advance);
pipe_truncate(i);
return;
}
+ if (unlikely(iov_iter_is_discard(i)))
+ return;
if (unroll <= i->iov_offset) {
i->iov_offset -= unroll;
return;
return i->count; // it is a silly place, anyway
if (i->nr_segs == 1)
return i->count;
+ if (unlikely(iov_iter_is_discard(i)))
+ return i->count;
else if (iov_iter_is_bvec(i))
return min(i->count, i->bvec->bv_len - i->iov_offset);
else
}
EXPORT_SYMBOL(iov_iter_pipe);
+/**
+ * iov_iter_discard - Initialise an I/O iterator that discards data
+ * @i: The iterator to initialise.
+ * @direction: The direction of the transfer.
+ * @count: The size of the I/O buffer in bytes.
+ *
+ * Set up an I/O iterator that just discards everything that's written to it.
+ * It's only available as a READ iterator.
+ */
+void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count)
+{
+ BUG_ON(direction != READ);
+ i->type = ITER_DISCARD | READ;
+ i->count = count;
+ i->iov_offset = 0;
+}
+EXPORT_SYMBOL(iov_iter_discard);
+
unsigned long iov_iter_alignment(const struct iov_iter *i)
{
unsigned long res = 0;
unsigned long res = 0;
size_t size = i->count;
- if (unlikely(iov_iter_is_pipe(i))) {
+ if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
WARN_ON(1);
return ~0U;
}
if (unlikely(iov_iter_is_pipe(i)))
return pipe_get_pages(i, pages, maxsize, maxpages, start);
+ if (unlikely(iov_iter_is_discard(i)))
+ return -EFAULT;
+
iterate_all_kinds(i, maxsize, v, ({
unsigned long addr = (unsigned long)v.iov_base;
size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
if (unlikely(iov_iter_is_pipe(i)))
return pipe_get_pages_alloc(i, pages, maxsize, start);
+ if (unlikely(iov_iter_is_discard(i)))
+ return -EFAULT;
+
iterate_all_kinds(i, maxsize, v, ({
unsigned long addr = (unsigned long)v.iov_base;
size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
__wsum sum, next;
size_t off = 0;
sum = *csum;
- if (unlikely(iov_iter_is_pipe(i))) {
+ if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
WARN_ON(1);
return 0;
}
__wsum sum, next;
size_t off = 0;
sum = *csum;
- if (unlikely(iov_iter_is_pipe(i))) {
+ if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
WARN_ON(1);
return false;
}
__wsum sum, next;
size_t off = 0;
sum = *csum;
- if (unlikely(iov_iter_is_pipe(i))) {
+ if (unlikely(iov_iter_is_pipe(i) || iov_iter_is_discard(i))) {
WARN_ON(1); /* for now */
return 0;
}
if (!size)
return 0;
+ if (unlikely(iov_iter_is_discard(i)))
+ return 0;
if (unlikely(iov_iter_is_pipe(i))) {
struct pipe_inode_info *pipe = i->pipe;
WARN_ON(1);
return NULL;
}
+ if (unlikely(iov_iter_is_discard(new)))
+ return NULL;
if (iov_iter_is_bvec(new))
return new->bvec = kmemdup(new->bvec,
new->nr_segs * sizeof(struct bio_vec),