vfs: Implement proper O_SYNC semantics

[deliverable/linux.git] / arch / alpha / include / asm / fcntl.h

diff --git a/arch/alpha/include/asm/fcntl.h b/arch/alpha/include/asm/fcntl.h
index 25da0017ec87fb2dd675257d7d16a68cc5f89aff..21b1117a0c61344af1acc94c36dc2f6e475d67a0 100644 (file)
--- a/arch/alpha/include/asm/fcntl.h
+++ b/arch/alpha/include/asm/fcntl.h
@@ -1,8 +1,6 @@
 #ifndef _ALPHA_FCNTL_H
 #define _ALPHA_FCNTL_H
 
-/* open/fcntl - O_SYNC is only implemented on blocks devices and on files
-   located on an ext2 file system */
 #define O_CREAT                 01000  /* not fcntl */
 #define O_TRUNC                 02000  /* not fcntl */
 #define O_EXCL          04000  /* not fcntl */
@@ -10,13 +8,28 @@
 
 #define O_NONBLOCK      00004
 #define O_APPEND        00010
-#define O_SYNC         040000
+#define O_DSYNC                040000  /* used to be O_SYNC, see below */
 #define O_DIRECTORY    0100000 /* must be a directory */
 #define O_NOFOLLOW     0200000 /* don't follow links */
 #define O_LARGEFILE    0400000 /* will be set by the kernel on every open */
 #define O_DIRECT       02000000 /* direct disk access - should check with OSF/1 */
 #define O_NOATIME      04000000
 #define O_CLOEXEC      010000000 /* set close_on_exec */
+/*
+ * 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       020000000
+#define O_SYNC         (__O_SYNC|O_DSYNC)
 
 #define F_GETLK                7
 #define F_SETLK                8