2 files changed, 91 insertions, 0 deletions

diff --git a/include/linux/uio.h b/include/linux/uio.h
index 6e16945ec832..28ed2d904deb 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -124,6 +124,8 @@ static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
 {
         i->count = count;
 }
+size_t csum_and_copy_to_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
+size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
 
 int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
 int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len);
diff --git a/mm/iov_iter.c b/mm/iov_iter.c
index 1618e378277e..1d2cdeb57c58 100644
--- a/mm/iov_iter.c
+++ b/mm/iov_iter.c
@@ -3,6 +3,7 @@
 #include <linux/pagemap.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
+#include <net/checksum.h>
 
 #define iterate_iovec(i, n, __v, __p, skip, STEP) {     \
         size_t left;                                    \
@@ -586,6 +587,94 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
 }
 EXPORT_SYMBOL(iov_iter_get_pages_alloc);
 
+size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum,
+                               struct iov_iter *i)
+{
+        char *to = addr;
+        __wsum sum, next;
+        size_t off = 0;
+        if (unlikely(bytes > i->count))
+                bytes = i->count;
+
+        if (unlikely(!bytes))
+                return 0;
+
+        sum = *csum;
+        iterate_and_advance(i, bytes, v, ({
+                int err = 0;
+                next = csum_and_copy_from_user(v.iov_base, 
+                                               (to += v.iov_len) - v.iov_len,
+                                               v.iov_len, 0, &err);
+                if (!err) {
+                        sum = csum_block_add(sum, next, off);
+                        off += v.iov_len;
+                }
+                err ? v.iov_len : 0;
+        }), ({
+                char *p = kmap_atomic(v.bv_page);
+                next = csum_partial_copy_nocheck(p + v.bv_offset,
+                                                 (to += v.bv_len) - v.bv_len,
+                                                 v.bv_len, 0);
+                kunmap_atomic(p);
+                sum = csum_block_add(sum, next, off);
+                off += v.bv_len;
+        }),({
+                next = csum_partial_copy_nocheck(v.iov_base,
+                                                 (to += v.iov_len) - v.iov_len,
+                                                 v.iov_len, 0);
+                sum = csum_block_add(sum, next, off);
+                off += v.iov_len;
+        })
+        )
+        *csum = sum;
+        return bytes;
+}
+EXPORT_SYMBOL(csum_and_copy_from_iter);
+
+size_t csum_and_copy_to_iter(void *addr, size_t bytes, __wsum *csum,
+                             struct iov_iter *i)
+{
+        char *from = addr;
+        __wsum sum, next;
+        size_t off = 0;
+        if (unlikely(bytes > i->count))
+                bytes = i->count;
+
+        if (unlikely(!bytes))
+                return 0;
+
+        sum = *csum;
+        iterate_and_advance(i, bytes, v, ({
+                int err = 0;
+                next = csum_and_copy_to_user((from += v.iov_len) - v.iov_len,
+                                             v.iov_base, 
+                                             v.iov_len, 0, &err);
+                if (!err) {
+                        sum = csum_block_add(sum, next, off);
+                        off += v.iov_len;
+                }
+                err ? v.iov_len : 0;
+        }), ({
+                char *p = kmap_atomic(v.bv_page);
+                next = csum_partial_copy_nocheck((from += v.bv_len) - v.bv_len,
+                                                 p + v.bv_offset,
+                                                 v.bv_len, 0);
+                kunmap_atomic(p);
+                sum = csum_block_add(sum, next, off);
+                off += v.bv_len;
+        }),({
+                next = csum_partial_copy_nocheck((from += v.iov_len) - v.iov_len,
+                                                 v.iov_base,
+                                                 v.iov_len, 0);
+                sum = csum_block_add(sum, next, off);
+                off += v.iov_len;
+        })
+        )
+        *csum = sum;
+        return bytes;
+}
+EXPORT_SYMBOL(csum_and_copy_to_iter);
+
 int iov_iter_npages(const struct iov_iter *i, int maxpages)
 {
         size_t size = i->count;