iov_iter: lift memzero_page() to highmem.h

Patch series "btrfs: Convert kmap/memset/kunmap to memzero_user()".

Lifting memzero_user(), convert it to kmap_local_page() and then use it
in btrfs.

This patch (of 3):

memzero_page() can replace the kmap/memset/kunmap pattern in other
places in the code.  While zero_user() has the same interface it is not
the same call and its use should be limited and some of those calls may
be better converted from zero_user() to memzero_page().[1] But that is
not addressed in this series.

Lift memzero_page() to highmem.

[1] https://lore.kernel.org/lkml/CAHk-=wijdojzo56FzYqE5TOYw2Vws7ik3LEMGj9SPQaJJ+Z73Q@mail.gmail.com/

Link: https://lkml.kernel.org/r/20210309212137.2610186-1-ira.weiny@intel.com
Link: https://lkml.kernel.org/r/20210309212137.2610186-2-ira.weiny@intel.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: David Sterba <dsterba@suse.com>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 44170f3..832b49b 100644 (file)
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -332,4 +332,11 @@ static inline void memcpy_to_page(struct page *page, size_t offset,
        kunmap_local(to);
 }
 
+static inline void memzero_page(struct page *page, size_t offset, size_t len)
+{
+       char *addr = kmap_atomic(page);
+       memset(addr + offset, 0, len);
+       kunmap_atomic(addr);
+}
+
 #endif /* _LINUX_HIGHMEM_H */

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 61228a6..c701b7a 100644 (file)
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -5,6 +5,7 @@
 #include <linux/fault-inject-usercopy.h>
 #include <linux/uio.h>
 #include <linux/pagemap.h>
+#include <linux/highmem.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/splice.h>
@@ -507,13 +508,6 @@ void iov_iter_init(struct iov_iter *i, unsigned int direction,
 }
 EXPORT_SYMBOL(iov_iter_init);
 
-static void memzero_page(struct page *page, size_t offset, size_t len)
-{
-       char *addr = kmap_atomic(page);
-       memset(addr + offset, 0, len);
-       kunmap_atomic(addr);
-}
-
 static inline bool allocated(struct pipe_buffer *buf)
 {
        return buf->ops == &default_pipe_buf_ops;