Introduce fixed sys_sync_file_range2() syscall, implement on PowerPC and ARM

Not all the world is an i386.  Many architectures need 64-bit arguments to be
aligned in suitable pairs of registers, and the original
sys_sync_file_range(int, loff_t, loff_t, int) was therefore wasting an
argument register for padding after the first integer.  Since we don't
normally have more than 6 arguments for system calls, that left no room for
the final argument on some architectures.

Fix this by introducing sys_sync_file_range2(int, int, loff_t, loff_t) which
all fits nicely.  In fact, ARM already had that, but called it
sys_arm_sync_file_range.  Move it to fs/sync.c and rename it, then implement
the needed compatibility routine.  And stop the missing syscall check from
bitching about the absence of sys_sync_file_range() if we've implemented
sys_sync_file_range2() instead.

Tested on PPC32 and with 32-bit and 64-bit userspace on PPC64.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Acked-by: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index b02070eac422..83d0ec11235e 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -598,6 +598,8 @@ asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags);
 
 asmlinkage long sys_sync_file_range(int fd, loff_t offset, loff_t nbytes,
                                         unsigned int flags);
+asmlinkage long sys_sync_file_range2(int fd, unsigned int flags,
+                                     loff_t offset, loff_t nbytes);
 asmlinkage long sys_get_robust_list(int pid,
                                     struct robust_list_head __user * __user *head_ptr,
                                     size_t __user *len_ptr);