new helper: dup_iter()
Copy iter and kmemdup the underlying array for the copy. Returns
a pointer to result of kmemdup() to be kfree()'d later.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 07a0226..7188029 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -98,6 +98,8 @@
size_t maxsize, size_t *start);
int iov_iter_npages(const struct iov_iter *i, int maxpages);
+const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
+
static inline size_t iov_iter_count(struct iov_iter *i)
{
return i->count;
diff --git a/mm/iov_iter.c b/mm/iov_iter.c
index 8277320..9d96e283 100644
--- a/mm/iov_iter.c
+++ b/mm/iov_iter.c
@@ -751,3 +751,18 @@
return npages;
}
EXPORT_SYMBOL(iov_iter_npages);
+
+const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
+{
+ *new = *old;
+ if (new->type & ITER_BVEC)
+ return new->bvec = kmemdup(new->bvec,
+ new->nr_segs * sizeof(struct bio_vec),
+ flags);
+ else
+ /* iovec and kvec have identical layout */
+ return new->iov = kmemdup(new->iov,
+ new->nr_segs * sizeof(struct iovec),
+ flags);
+}
+EXPORT_SYMBOL(dup_iter);
