[PATCH v2 2/3] use a nocache copy for bvecs and kvecs in copy_from_iter_nocache()

[Brian Boylston]

Update copy_from_iter_nocache() to use memcpy_nocache()
for bvecs and kvecs.

Cc: Ross Zwisler <ross.zwis...@linux.intel.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: <x...@kernel.org>
Cc: Al Viro <v...@zeniv.linux.org.uk>
Cc: Dan Williams <dan.j.willi...@intel.com>
Signed-off-by: Brian Boylston <brian.boyls...@hpe.com>
Reviewed-by: Toshi Kani <toshi.k...@hpe.com>
Reported-by: Oliver Moreno <oliver.mor...@hpe.com>
---
 lib/iov_iter.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 7e3138c..71e4531 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -342,6 +342,13 @@ static void memcpy_from_page(char *to, struct page *page, 
size_t offset, size_t
        kunmap_atomic(from);
 }
 
+static void memcpy_from_page_nocache(char *to, struct page *page, size_t 
offset, size_t len)
+{
+       char *from = kmap_atomic(page);
+       memcpy_nocache(to, from + offset, len);
+       kunmap_atomic(from);
+}
+
 static void memcpy_to_page(struct page *page, size_t offset, const char *from, 
size_t len)
 {
        char *to = kmap_atomic(page);
@@ -392,9 +399,10 @@ size_t copy_from_iter_nocache(void *addr, size_t bytes, 
struct iov_iter *i)
        iterate_and_advance(i, bytes, v,
                __copy_from_user_nocache((to += v.iov_len) - v.iov_len,
                                         v.iov_base, v.iov_len),
-               memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page,
-                                v.bv_offset, v.bv_len),
-               memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len)
+               memcpy_from_page_nocache((to += v.bv_len) - v.bv_len,
+                                        v.bv_page, v.bv_offset, v.bv_len),
+               memcpy_nocache((to += v.iov_len) - v.iov_len,
+                              v.iov_base, v.iov_len)
        )
 
        return bytes;
-- 
2.8.3