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new helper: dup_iter()

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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>
This commit is contained in:
Al Viro
2015-01-31 20:08:47 -05:00
parent f5af19d10d
commit 4b8164b91d
2 changed files with 17 additions and 0 deletions
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2
include/linux/uio.h
View File

@@ -98,6 +98,8 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
size_t maxsize, size_t *start); size_t maxsize, size_t *start);
int iov_iter_npages(const struct iov_iter *i, int maxpages); 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) static inline size_t iov_iter_count(struct iov_iter *i)
{ {
return i->count; return i->count;

15
mm/iov_iter.c
View File

@@ -751,3 +751,18 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages)
return npages; return npages;
} }
EXPORT_SYMBOL(iov_iter_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);