sync_file_range(SYNC_FILE_RANGE_WRITE) blocks?

[Pavel Machek <pavel@suse.cz>]

Hi!

sync_file_range(SYNC_FILE_RANGE_WRITE) blocks ... which makes problem
for s2disk: there we want to start writeout as early as possible
(system is going to shut down after write, and we need the data on
disk).

Unfortuantely, sync_file_range(SYNC_FILE_RANGE_WRITE) blocks, which
does not work for us. Is there non-blocking variant? "Start writeout
on this fd, but don't block me"?

For now I'm doing:

static inline int start_writeout(int fd)
{
#ifdef SYS_sync_file_range
        if (fork())
                return 0;
        else {
                syscall(SYS_sync_file_range, fd,
                        (loff_t)0, (loff_t)0, SYNC_FILE_RANGE_WRITE);
                exit(0);
        }
#else
        errno = ENOSYS;
        return -1;
#endif
}

...but I'd prefer something more elegant...
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html