Re: [PATCH -v5 2/2] Updating ctime and mtime at syncing

[Rogier Wolff]

On Thu, Jan 17, 2008 at 04:16:47PM +0300, Anton Salikhmetov wrote:
> 2008/1/17, Miklos Szeredi <miklos@xxxxxxxxxx>:
> > > > 4. Recording the time was the file data changed
> > > >
> > > > Finally, I noticed yet another issue with the previous version of my patch.
> > > > Specifically, the time stamps were set to the current time of the moment
> > > > when syncing but not the write reference was being done. This led to the
> > > > following adverse effect on my development system:
> > > >
> > > > 1) a text file A was updated by process B;
> > > > 2) process B exits without calling any of the *sync() functions;
> > > > 3) vi editor opens the file A;
> > > > 4) file data synced, file times updated;
> > > > 5) vi is confused by "thinking" that the file was changed after 3).
> >
> > Updating the time in remove_vma() would fix this, no?
> 
> We need to save modification time. Otherwise, updating time stamps
> will be confusing the vi editor.

If process B exits before vi opens the file, the timestamp should at
the latest be the time that process B exits. There is no excuse for
setting the timestamp later than the time that B exits.

If process B no longer modifies the file, but still keeps it mapped
until after vi starts, then the system can't help the
situation. Wether or not B acesses those pages is unknown to the
system. So you get what you deserve.

	Roger. 

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