4 files changed, 19 insertions, 3 deletions

diff --git a/arch/mips/include/asm/fcntl.h b/arch/mips/include/asm/fcntl.h
index 2a52333a062d..7c6681aa2ab8 100644
--- a/arch/mips/include/asm/fcntl.h
+++ b/arch/mips/include/asm/fcntl.h
@@ -10,7 +10,7 @@
 
 
 #define O_APPEND        0x0008
-#define O_SYNC          0x0010
+#define O_DSYNC         0x0010  /* used to be O_SYNC, see below */
 #define O_NONBLOCK      0x0080
 #define O_CREAT         0x0100  /* not fcntl */
 #define O_TRUNC         0x0200  /* not fcntl */
@@ -18,6 +18,21 @@
 #define O_NOCTTY        0x0800  /* not fcntl */
 #define FASYNC          0x1000  /* fcntl, for BSD compatibility */
 #define O_LARGEFILE     0x2000  /* allow large file opens */
+/*
+ * Before Linux 2.6.32 only O_DSYNC semantics were implemented, but using
+ * the O_SYNC flag.  We continue to use the existing numerical value
+ * for O_DSYNC semantics now, but using the correct symbolic name for it.
+ * This new value is used to request true Posix O_SYNC semantics.  It is
+ * defined in this strange way to make sure applications compiled against
+ * new headers get at least O_DSYNC semantics on older kernels.
+ *
+ * This has the nice side-effect that we can simply test for O_DSYNC
+ * wherever we do not care if O_DSYNC or O_SYNC is used.
+ *
+ * Note: __O_SYNC must never be used directly.
+ */
+#define __O_SYNC        0x4000
+#define O_SYNC          (__O_SYNC|O_DSYNC)
 #define O_DIRECT        0x8000  /* direct disk access hint */
 
 #define F_GETLK         14
diff --git a/arch/mips/kernel/kspd.c b/arch/mips/kernel/kspd.c
index ad4e017ed2f3..80e2ba694bab 100644
--- a/arch/mips/kernel/kspd.c
+++ b/arch/mips/kernel/kspd.c
@@ -82,6 +82,7 @@ static int sp_stopping;
 #define MTSP_O_SHLOCK           0x0010
 #define MTSP_O_EXLOCK           0x0020
 #define MTSP_O_ASYNC            0x0040
+/* XXX: check which of these is actually O_SYNC vs O_DSYNC */
 #define MTSP_O_FSYNC            O_SYNC
 #define MTSP_O_NOFOLLOW         0x0100
 #define MTSP_O_SYNC             0x0080
diff --git a/arch/mips/loongson/common/mem.c b/arch/mips/loongson/common/mem.c
index 7c92f79b6480..e94ef158f980 100644
--- a/arch/mips/loongson/common/mem.c
+++ b/arch/mips/loongson/common/mem.c
@@ -26,7 +26,7 @@ void __init prom_init_memory(void)
 /* override of arch/mips/mm/cache.c: __uncached_access */
 int __uncached_access(struct file *file, unsigned long addr)
 {
-        if (file->f_flags & O_SYNC)
+        if (file->f_flags & O_DSYNC)
                 return 1;
 
         return addr >= __pa(high_memory) ||
diff --git a/arch/mips/mm/cache.c b/arch/mips/mm/cache.c
index 694d51f523d1..102b2dfa542a 100644
--- a/arch/mips/mm/cache.c
+++ b/arch/mips/mm/cache.c
@@ -194,7 +194,7 @@ void __devinit cpu_cache_init(void)
 
 int __weak __uncached_access(struct file *file, unsigned long addr)
 {
-        if (file->f_flags & O_SYNC)
+        if (file->f_flags & O_DSYNC)
                 return 1;
 
         return addr >= __pa(high_memory);