2008/1/10, Jakob Oestergaard <[EMAIL PROTECTED]>: > On Thu, Jan 10, 2008 at 03:03:03AM +0300, Anton Salikhmetov wrote: > ... > > > I guess a third possible time (if we want to minimize the number of > > > updates) would be when natural syncing of the file data to disk, by > > > other things in the VM, would be about to clear the I_DIRTY_PAGES > > > flag on the inode. That way we do not need to remember any special > > > "we already flushed all dirty data, but we have not updated the mtime > > > and ctime yet" state. > > > > > > Does this sound reasonable? > > > > No, it doesn't. The msync() system call called with the MS_ASYNC flag > > should (the POSIX standard requires that) update the st_ctime and > > st_mtime stamps in the same manner as for the MS_SYNC flag. However, > > the current implementation of msync() doesn't call the do_fsync() > > function for the MS_ASYNC case. The msync() function may be called > > with the MS_ASYNC flag before "natural syncing". > > If the update was done as Rik suggested, with the addition that msync() > triggered an explicit sync of the inode data, then everything would be ok, > right?
Indeed, if msync() is called with MS_SYNC an explicit sync is triggered, and Rik's suggestion would work. However, the POSIX standard requires a call to msync() with MS_ASYNC to update the st_ctime and st_mtime stamps too. No explicit sync of the inode data is triggered in the current implementation of msync(). Hence Rik's suggestion would fail to satisfy POSIX in the latter case. > > -- > > / jakob > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
