Re: [PATCH] update ctime and mtime for mmaped write

From: Miklos Szeredi
Date: Wed Feb 21 2007 - 13:51:59 EST

> > > > This flag is checked in msync() and __fput(), and if set, the file
> > > > times are updated and the flag is cleared
> > >
> > > Why not also check inside vfs_getattr?
> >
> > This is the minimum, that the standard asks for.
> >
> > Note, your porposal would touch the times in vfs_getattr(), which
> > means, that the modification times would depend on the time of the
> > last stat() call, which is not really right, though it would still be
> > conforming.
> >
> > It is much saner, if the modification time is always the time of the
> > last write() or msync().
> I disagree. The above doesn't allow a program like 'make' to discover
> whether or not the file has changed by simply calling stat(). Instead,
> you're forcing a call to msync()+stat().

Yes, but that's the only portable way _anyway_.

And it probably doesn't matter, programs using mmap to write to a file
_will_ call msync, or at least close the file, when they're done.

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