Re: [PATCH] Fix ext2 error reporting on fsync

[Andrew Morton <akpm@osdl.org>]

Andrew Morton <akpm@osdl.org> wrote:
>
>  Another approach would be to allocate a new buffer_head which "belongs" to
>  the address_space.  So instead of doing:
> 
>  		bh<->bh<->address_space<->bh<->bh
> 
>  we do:
> 
>                       address_space
>                             ^
>                             |
>                             v
>  		bh<->bh<->bh'<->bh<->bh
> 
>  and set a magic bit in bh' which says "this is not a real bh; your
>  address_space is at *b_private".

And if we do that, we can actually shrink the address_space by 2*sizeof(long):

- private_list can become `struct buffer_head *metadata_buffers'

- and if we're going to abandon the address_space.private* genericity, we
  can remove address_space.assoc_mapping and use a new
  address_space->metadata_buffers->b_bdev->metadata_lock.