On Mon, 6 November 2006 14:50:58 -0600, Eric Sandeen wrote: > > > > While you're at it, how about making last_ino per-sb instead of > > system-wide? ino collisions after a wrap are just as bad as inos > > beyond 32bit. And this should be a fairly simple method to reduce the > > risk. > > Using a global counter for multiple filesystems should actually -reduce- > the chance of a collision on the same filesystem, since after you wrap the > recycled number may go to a different filesystem. You're missing something. The chance for a collision _per wrap_ is reduced, as you said. But the number of wraps goes up. Overall and for large numbers, the two effects compensate each other. For not-so-large numbers, you can get by without the wrap by having this per-sb. And if you have just one or two wrapping filesystems, at least the others are protected. It's not much, but it is a simple thing to do. > To fix this properly, we'd need some sort of checking that the inode number > isn't currently being used on the filesystem in question before it's > assigned to the new inode. Absolutely. Thinking about it, iget() already has a lot of what is needed - except that it can block and has side effects we don't really want. Sounds more complicated, but I would love to be proven wrong here. :) Jörn -- Joern's library part 7: http://www.usenix.org/publications/library/proceedings/neworl/full_papers/mckusick.a - 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
