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authorAl Viro <viro@zeniv.linux.org.uk>2015-01-31 20:08:47 -0500
committerAl Viro <viro@zeniv.linux.org.uk>2015-02-17 22:21:11 -0500
commit4b8164b91d9fdff4dbac0a742d076bdff7fda21b (patch)
tree694a818c62c0716194e63179670af3035413ef74
parentf5af19d10d151c5a2afae3306578f485c244db25 (diff)
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>
-rw-r--r--include/linux/uio.h2
-rw-r--r--mm/iov_iter.c15
2 files changed, 17 insertions, 0 deletions
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 07a022641996..71880299ed48 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -98,6 +98,8 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
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 827732047da1..9d96e283520c 100644
--- a/mm/iov_iter.c
+++ b/mm/iov_iter.c
@@ -751,3 +751,18 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages)
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);