Re: [PATCH] Fix ext2 error reporting on fsync

[Chris Mason <mason@suse.com>]

On Thursday 12 January 2006 15:47, Andrew Morton wrote:
> Jan Kara <jack@suse.cz> wrote:
> > > Jan Kara <jack@suse.cz> wrote:
> > >
> > > hm, yes, try_to_free_buffers() against a blockdev page is a problem. 
> > > But I think it's fixable.
> > >
> > > In the second loop of drop_buffers(), if we find a bh which had a write
> > > error we need to set AS_EIO on the address_space which is interested in
> > > this buffer.
> > >
> > > That address_space is pinned by a) the fact that it has buffers at
> > > ->private_list and b) we hold the blockdev mapping's private_lock.
> > >
> > > The only problem is actually _finding_ the address_space which is
> > > interested in this buffer_head.  Looks like we'd need a backpointer in
> > > the buffer_head.
> >
> >   Yes, the pointer seems to be inevitable in this solution. If you think
> > the improvement is worth adding 4 bytes to each buffer_head, then I can
> > write the patch.
>
> hm.  It only affects what are now rarely-used filesystems like ext2, minix,
> etc.  Not sure about reiser3.  But it is a strict correctness issue.  I
> suppose we should do it.  It'd be nice to find a way to avoid increasing
> the bh size..
>

I know my patch is pretty nasty, but is it really worth adding complexity to 
the base code for this corner case?

> It'll be a hard patch to test.

I'll dig up $partner.  They had a nasty test suite for that kind of thing.

-chris