[PATCH] [4.8-rc7, regression] fault_in_multipages_readable() throws set-but-unused error

From: Dave Chinner
Date: Sun Sep 25 2016 - 19:58:11 EST

From: Dave Chinner <dchinner@xxxxxxxxxx>

When building XFS with -Werror, it now fails with:

./include/linux/pagemap.h: In function Âfault_in_multipages_readableÂ:
./include/linux/pagemap.h:602:16: error: variable Âc set but not used [-Werror=unused-but-set-variable]
volatile char c;

This is a regression caused by commit e23d415 ("fix
fault_in_multipages_...() on architectures with no-op access_ok()").
Fix it by re-adding the "(void)c" trick taht was previously used to
make the compiler think the variable is used.

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
include/linux/pagemap.h | 1 +
1 file changed, 1 insertion(+)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 7e3d537..01e8443 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -620,6 +620,7 @@ static inline int fault_in_multipages_readable(const char __user *uaddr,
return __get_user(c, end);

+ (void)c;
return 0;