ext4: use memcpy_to_page() in pagecache_write()

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Link: https://lore.kernel.org/r/20210207190425.38107-7-chaitanya.kulkarni@wdc.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/verity.c

@@ -77,17 +77,14 @@ static int pagecache_write(struct inode *inode, const void *buf, size_t count,
 				 PAGE_SIZE - offset_in_page(pos));
 		struct page *page;
 		void *fsdata;
-		void *addr;
 		int res;
 
 		res = pagecache_write_begin(NULL, inode->i_mapping, pos, n, 0,
 					    &page, &fsdata);
 		if (res)
 			return res;
 
-		addr = kmap_atomic(page);
-		memcpy(addr + offset_in_page(pos), buf, n);
-		kunmap_atomic(addr);
+		memcpy_to_page(page, offset_in_page(pos), buf, n);
 
 		res = pagecache_write_end(NULL, inode->i_mapping, pos, n, n,
 					  page, fsdata);