alpha: add conditional fdatasync support

While most arches have had the fdatasync syscall for a long time, the
alpha port didn't add it until the 2.6.22 release.

This is heavily based on Aurelien Jarno's initial work.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

ports/ChangeLog.alpha

@@ -1,3 +1,11 @@
+2012-08-27  Mike Frysinger  <vapier@gentoo.org>
+
+	[BZ #5400]
+	* sysdeps/unix/sysv/linux/alpha/Makefile (CFLAGS-fdatasync.c): Define.
+	* sysdeps/unix/sysv/linux/alpha/fdatasync.c: New file
+	* sysdeps/unix/sysv/linux/alpha/kernel-features.h
+	(__ASSUME_FDATASYNC): Define.
+
 2012-08-16  Carlos O'Donell  <carlos_odonell@mentor.com>
 
 	* sysdeps/alpha/ldsodefs.h (ARCH_PLTENTER_MEMBERS)

ports/sysdeps/unix/sysv/linux/alpha/Makefile

@@ -20,6 +20,7 @@ sysdep_routines += osf_select osf_gettimeofday osf_settimeofday \
 # Support old ipc control
 sysdep_routines += oldmsgctl oldsemctl oldshmctl
 
+CFLAGS-fdatasync.c = -fexceptions
 CFLAGS-ioperm.c = -Wa,-mev6
 endif
 

ports/sysdeps/unix/sysv/linux/alpha/fdatasync.c

@@ -0,0 +1,65 @@
+/* fdatasync -- synchronize at least the data part of a file with
+   the underlying media. Linux version.
+
+   Copyright (C) 2007-2012 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <unistd.h>
+
+#include <sysdep-cancel.h>
+#include <sys/syscall.h>
+#include <bp-checks.h>
+
+#include <kernel-features.h>
+
+static int
+do_fdatasync (int fd)
+{
+#ifdef __ASSUME_FDATASYNC
+  return INLINE_SYSCALL (fdatasync, 1, fd);
+#elif defined __NR_fdatasync
+  static int __have_no_fdatasync;
+
+  if (!__builtin_expect (__have_no_fdatasync, 0))
+    {
+      int result = INLINE_SYSCALL (fdatasync, 1, fd);
+      if (__builtin_expect (result, 0) != -1 || errno != ENOSYS)
+	return result;
+
+      __have_no_fdatasync = 1;
+    }
+#endif
+  return INLINE_SYSCALL (fsync, 1, fd);
+}
+
+int
+__fdatasync (int fd)
+{
+  if (SINGLE_THREAD_P)
+    return do_fdatasync (fd);
+
+  int oldtype = LIBC_CANCEL_ASYNC ();
+
+  int result = do_fdatasync (fd);
+
+  LIBC_CANCEL_RESET (oldtype);
+
+  return result;
+}
+
+weak_alias (__fdatasync, fdatasync)

ports/sysdeps/unix/sysv/linux/alpha/kernel-features.h

@@ -82,4 +82,9 @@
 #undef __ASSUME_STATFS64
 #define __ASSUME_STATFS64 0
 
+/* Support for fsyncdata was added for alpha after 2.6.21.  */
+#if __LINUX_KERNEL_VERSION >= 0x020616
+# define __ASSUME_FDATASYNC	1
+#endif
+
 #endif /* _KERNEL_FEATURES_H */