[PATCH -next] io_uring: Add missing include <linux/highmem.h>

[YueHaibing]

Fix build error:

fs/io_uring.c:1628:21: error: implicit declaration of function 'kmap' [-Werror=implicit-function-declaration]
fs/io_uring.c:1643:4: error: implicit declaration of function 'kunmap' [-Werror=implicit-function-declaration]

Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Fixes: 311ae9e159d8 ("io_uring: fix dead-hung for non-iter fixed rw")
Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
---
 fs/io_uring.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 2c2e8c2..745eb00 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -69,6 +69,7 @@
 #include <linux/nospec.h>
 #include <linux/sizes.h>
 #include <linux/hugetlb.h>
+#include <linux/highmem.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/io_uring.h>
-- 
2.7.4