> In message <20070110161215.GB12654@xxxxxxxxxxxxxxxxxxxxxxxx>, Jan Kara writes: > > > In message <20070109122644.GB1260@xxxxxxxxxxxxxxxxxxxxxxxx>, Jan Kara writes: > [...] > > > Jan, all of it is duable: we can downgrade the f/s to readonly, grab various > > > locks, search through various lists looking for open fd's and such, then > > > decide if to allow the mount or not. And hopefully all of that can be done > > > in a non-racy manner. But it feels just rather hacky and ugly to me. If > > > this community will endorse such a solution, we'll be happy to develop it. > > > But right now my impression is that if we posted such patches today, some > > > people will have to wipe the vomit off of their monitors... :-) > > I see :). To me it just sounds as if you want to do remount-read-only > > for source filesystems, which is operation we support perfectly fine, > > and after that create union mount. But I agree you cannot do quite that > > since you need to have write access later from your union mount. So > > maybe it's not so easy as I thought. > > On the other hand, there was some effort to support read-only bind-mounts of > > read-write filesystems (there were even some patches floating around but > > I don't think they got merged) and that should be even closer to what > > you'd need... > > I didn't know about those patches, but yes, they do sound useful. I'm > curious who needed such functionality before and why. If someone can point > me to those patches, we can look into using them for Unionfs. Thanks. Dave Hansen writes them. One of recent submissions starts for example at http://openvz.org/pipermail/devel/2006-December/002543.html. Honza -- Jan Kara <jack@xxxxxxx> SuSE CR Labs - 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
