On Mon, Sep 03, 2007 at 08:59:02AM +0200, Jan Engelhardt wrote: > > On Sep 2 2007 22:20, Josef 'Jeff' Sipek wrote: > >+ > >+While rebuilding Unionfs's objects, we also purge any page mappings and > >+truncate inode pages (see fs/Unionfs/dentry.c:purge_inode_data). This is to > > fs/unionfs/dentry.c > > >+Unionfs maintains the following important invariant regarding mtime's, > >+ctime's, and atime's: the upper inode object's times are the max() of all of > > utimes, ctimes and atimes. > > >+2. Lockdep (a debugging feature) isn't aware of stacking, and so it > >+ incorrectly complains about locking problems. The problem boils down to > >+ this: Lockdep considers all objects of a certain type to be in the same > >+ class, for example, all inodes. Lockdep doesn't like to see a lock held > >+ on two inodes within the same task, and warns that it could lead to a > >+ deadlock. However, stackable file systems do precisely that: they lock > >+ an upper object, and then a lower object, in a strict order to avoid > >+ locking problems; in addition, Unionfs, as a fan-out file system, may > >+ have to lock several lower inodes. We are currently looking into Lockdep > >+ to see how to make it aware of stackable file systems. In the mean time, > > meantime > > >@@ -86,5 +86,12 @@ command: > > > > # mount -t unionfs -o remount,incgen none MOUNTPOINT > > > >+Note that the older way of incrementing the generation number using an > >+ioctl, is no longer supported in Unionfs 2.0. Ioctls in general are not > > 2.1? Thanks. Jeff. -- Penguin : Linux version 2.4.20-46.9.legacysmp on an i386 machine (2778.72 BogoMips). - 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
