On Thu, Aug 27, 2009 at 10:24:28AM -0700, Ulrich Drepper wrote: > The problem with O_* extensions is that the syscall doesn't fail if the > flag is not handled. This is a problem in the open implementation which > can only be fixed with a new syscall. > > Why cannot just go on and say we interpret O_SYNC like O_SYNC and > O_SYNC|O_DSYNC like O_DSYNC. The POSIX spec explicitly requires that > the latter handled like O_SYNC. > > We could handle it by allocating two bits, only one is handled in the > kernel. If the O_DSYNC definition for userlevel would be different from > the kernel definition then the kernel could interpret O_SYNC|O_DSYNC > like O_DSYNC. The libc would then have to translate the userlevel > O_DSYNC into the kernel O_DSYNC. If the libc is too old for the kernel > and the application, the userlevel flag would be passed to the kernel > and nothing bad happens. What about hte following variant: - given that our current O_SYNC really is and always has been actuall Posix O_DSYNC keep the numerical value and rename it to O_DSYNC in the headers. - Add a new O_SYNC definition: #define O_SYNC (O_DSYNC|O_REALLY_SYNC) and do full O_SYNC handling in new kernels if O_REALLY_SYNC is present. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
