fs/compat: convert to COMPAT_SYSCALL_DEFINE with changing parameter types

Some fs compat system calls have unsigned long parameters instead of
compat_ulong_t.
In order to allow the COMPAT_SYSCALL_DEFINE macro generate code that
performs proper zero and sign extension convert all 64 bit parameters
their corresponding 32 bit counterparts.

compat_sys_io_getevents() is a bit different: the non-compat version
has signed parameters for the "min_nr" and "nr" parameters while the
compat version has unsigned parameters.
So change this as well. For all practical purposes this shouldn't make
any difference (doesn't fix a real bug).
Also introduce a generic compat_aio_context_t type which can be used
everywhere.
The access_ok() check within compat_sys_io_getevents() got also removed
since the non-compat sys_io_getevents() should be able to handle
everything anyway.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

fs/compat_ioctl.c

@@ -1538,9 +1538,10 @@ static int compat_ioctl_check_table(unsigned int xcmd)
 	return ioctl_pointer[i] == xcmd;
 }
 
-asmlinkage long compat_sys_ioctl(unsigned int fd, unsigned int cmd,
-				unsigned long arg)
+COMPAT_SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd,
+		       compat_ulong_t, arg32)
 {
+	unsigned long arg = arg32;
 	struct fd f = fdget(fd);
 	int error = -EBADF;
 	if (!f.file)