Don't leak mount flags into kernel

[zfs.git] / lib / libspl / include / sys / mount.h

diff --git a/lib/libspl/include/sys/mount.h b/lib/libspl/include/sys/mount.h
index 9eb893f..7b1e06b 100644 (file)
--- a/lib/libspl/include/sys/mount.h
+++ b/lib/libspl/include/sys/mount.h
@@ -51,11 +51,33 @@
 #define MS_DIRSYNC             S_WRITE
 #endif
 
-#define        MS_USERS        0x40000000
-#define        MS_OWNER        0x10000000
-#define        MS_GROUP        0x08000000
-#define        MS_COMMENT      0x02000000
-#define        MS_FORCE        MNT_FORCE
-#define        MS_DETACH       MNT_DETACH
+#define        MS_USERS        (MS_NOEXEC|MS_NOSUID|MS_NODEV)
+#define        MS_OWNER        (MS_NOSUID|MS_NODEV)
+#define        MS_GROUP        (MS_NOSUID|MS_NODEV)
+#define        MS_COMMENT      0
+
+/*
+ * Older glibc <sys/mount.h> headers did not define all the available
+ * umount2(2) flags.  Both MNT_FORCE and MNT_DETACH are supported in the
+ * kernel back to 2.4.11 so we define them correctly if they are missing.
+ */
+#ifdef MNT_FORCE
+# define MS_FORCE      MNT_FORCE
+#else
+# define MS_FORCE      0x00000001
+#endif /* MNT_FORCE */
+
+#ifdef MNT_DETACH
+# define MS_DETACH     MNT_DETACH
+#else
+# define MS_DETACH     0x00000002
+#endif /* MNT_DETACH */
+
+/*
+ * Overlay mount is default in Linux, but for solaris/zfs
+ * compatibility, MS_OVERLAY is defined to explicitly have the user
+ * provide a flag (-O) to mount over a non empty directory.
+ */
+#define MS_OVERLAY      0x00000004
 
 #endif /* _LIBSPL_SYS_MOUNT_H */