Messages in this thread |  | | From | Daniel Phillips <> | Subject | Re: The INN/mmap bug | Date | Tue, 19 Sep 2000 00:08:18 +0200 |
| |
Alexander Viro wrote: > > On Mon, 18 Sep 2000, Andreas Dilger wrote: > > > Alexander writes: > > > * uptodate pages should never become non-uptodate. > > > uptodate .. pages ... never have data _older_ than on disk > > > > This may actually be a problem in the future... what about shared access > > block devices like FCAL or a distributed filesystem? It has to be > > possible for pages to become non-uptodate in a sane way. > > So what the heck do you do when something modifies mmaped page when you > get the change of on-disk one? Say it, writer is notified that write had > been completed, sends packet to you and you flip a bit on a page that > happens to be mmaped on the place where write had happened. > > Write-through-pagecache is OK, but write straight to disk bypassing the > cache? Welcome to the fun with aliases...
Yes, I think that's one rule we can write down right now: to update a block on disk you have to go through the buffer. Not going through the buffer is about the same as accessing a semaphore-protected resource without bothering with the semaphore.
-- Daniel - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
|  |