[PATCH] xfs_io: Avoid using __kernel_rwf_t for older kernels

[Florian Fainelli <florian.fainelli@broadcom.com>]

__kernel_rwf_t was defined with upstream Linux commit
ddef7ed2b5cbafae692d1d580bb5a07808926a9c ("annotate RWF_... flags")
which has been included in Linux v4.14 and newer. When building xfsprogs
against older kernel headers, this type is not defined, leading to the
following build error:

pwrite.c: In function 'pwrite_f':
../include/xfs/linux.h:236:22: error: '__kernel_rwf_t' undeclared (first use in this function); did you mean '__kernel_off_t'?
 #define RWF_ATOMIC ((__kernel_rwf_t)0x00000040)
                      ^~~~~~~~~~~~~~
pwrite.c:329:22: note: in expansion of macro 'RWF_ATOMIC'
    pwritev2_flags |= RWF_ATOMIC;

Fixes: ee6c5941352a ("xfs_io: add RWF_ATOMIC support to pwrite")
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 include/linux.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux.h b/include/linux.h
index e9eb7bfb26a1..68b43393aad7 100644
--- a/include/linux.h
+++ b/include/linux.h
@@ -233,7 +233,7 @@ struct fsxattr {
 
 /* Atomic Write */
 #ifndef RWF_ATOMIC
-#define RWF_ATOMIC	((__kernel_rwf_t)0x00000040)
+#define RWF_ATOMIC	(0x00000040)
 #endif
 
 /*
-- 
2.34.1