On Tuesday 18 December 2007 09:54, David Howells wrote: > Nick Piggin <[EMAIL PROTECTED]> wrote: > > This reintroduces the fault vs truncate race window, which must be fixed. > > Hmmm... perhaps.
What do you mean by perhaps? > I remember that cropped up in NFS, but I'm doing things > a bit differently to NFS. Remind me again how that worked please. How what worked? NFS is using invalidate inode pages quite frequently so it ran into the race more often. > > Also, it is adding a fair bit of complexity in an area where we should > > instead be reducing it. I think your filesystem should not be doing > > writeback caching of dirty data in the cases where it is so problematic > > (or at least, disallow mmap and read on the dirty data until it has been > > written back or failed). > > Eh? It's a stateless network filesystem. There's a gap between writing to > a file (perhaps though an mmap) and the pagecache pages being written back > in which someone may change the security on a file and block the writeback. > There's nothing I can do to prevent it, so I have to instead deal with the > consequences should they arise. See the description of patch 25 for > examples. > > So you say I shouldn't do any writeback caching at all? No, you could do writeback caching but disallow read of dirty data. But yeah, a coherent mmap isn't possible then, I guess. > > But otherwise I guess if you really want to discard the dirty data after > > a failed writeback attempt, what's wrong with just > > invalidate_inode_pages2? > > Erm... Because it deadlocks? Why don't you call it after calling end_page_writeback? - To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
