On Wed 25-03-09 02:35:01, Nick Piggin wrote: > On Tuesday 24 March 2009 21:32:04 Andrew Morton wrote: > > On Tue, 24 Mar 2009 18:44:21 +1100 Nick Piggin <nickpiggin@xxxxxxxxxxxx> > wrote: > > > On Friday 20 March 2009 03:46:39 Jan Kara wrote: > > > > On Fri 20-03-09 02:48:21, Nick Piggin wrote: > > > > > Holding mapping->private_lock over the __set_page_dirty should > > > > > fix it, although I guess you'd want to release it before calling > > > > > __mark_inode_dirty so as not to put inode_lock under there. I > > > > > have a patch for this if it sounds reasonable. > > > > > > > > Yes, that seems to be a bug - the function actually looked suspitious > > > > to me yesterday but I somehow convinced myself that it's fine. Probably > > > > because fsx-linux is single-threaded. > > > > > > After a whole lot of chasing my own tail in the VM and buffer layers, > > > I think it is a problem in ext2 (and I haven't been able to reproduce > > > with ext3 yet, which might lend weight to that, although as we have > > > seen, it is very timing dependent). > > > > > > That would be slightly unfortunate because we still have Jan's ext3 > > > problem, and also another reported problem of corruption on ext3 (on > > > brd driver). > > > > > > Anyway, when I have reproduced the problem with the test case, the > > > "lost" writes are all reported to be holes. Unfortunately, that doesn't > > > point straight to the filesystem, because ext2 allocates blocks in this > > > case at writeout time, so if dirty bits are getting lost, then it would > > > be normal to see holes. > > > > > > I then put in a whole lot of extra infrastructure to track metadata about > > > each struct page (when it was last written out, when it last had the > > > number of writable ptes reach 0, when the dirty bits were last cleared > > > etc). And none of the normal asertions were triggering: eg. when any page > > > is removed from pagecache (except truncates), it has always had all its > > > buffers written out *after* all ptes were made readonly or unmapped. Lots > > > of other tests and crap like that. > > > > > > So I tried what I should have done to start with and did an e2fsck after > > > seeing corruption. Yes, it comes up with errors. > > > > Do you recall what the errors were? > > OK, after running several tests in parallel and having 3 of them > blow up, I unmounted the fs (so error-case files are still intact). Nick, what tests do you use? Because on the first reading the ext2 code looks correct so I'll probably have to reproduce the corruption... Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
