On Wed 2015-07-15 14:54:56, NeilBrown wrote:
> On Tue, 14 Jul 2015 15:13:00 +0200 Pavel Machek <[email protected]> wrote:
>
> > Hi!
> >
> > > BTW When you "swap" to a file the mtime doesn't get updated. No one
> > > seems to
> > > complain about that. I guess it is a rather narrow use-case though.
> >
> > Actually yes, I'd like to complain.
> >
> > It was not swap, it was mount -o loop, but I guess that's the same
> > case. Then rsync refused to work on that file... and being on slow ARM
> > system it took me a while to figure out WTF is going on.
> >
> > So yes, we have problems with mtime, and yes, they matter.
> > Pavel
>
> Odd...
> I assume you mean
> mount -o loop /some/file /mountpoint
>
> and then when you write to the filesystem on /mountpoint the mtime
> of /some/file doesn't get updated?
> I think it should.
> drivers/block/loop.c uses vfs_iter_write() to write to a file.
> That calls f_op->write_iter which will typically call
> generic_file_write_iter() which will call file_update_time() to update
> the time stamps.
Yes, that. I'm pretty sure I seen it, but it was probably on 2.6.X
kernel... Does it make sense to try to reproduce it on the old kernel?
> What filesystem was /some/file on?
Very probably VFAT.
> I just did some testing on ext4 and it seems to do the right thing
> mtime gets updated.
Yes, I tried here, and it seems to be ok.
Thanks,
Pavel
--
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(cesky, pictures)
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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