[dm-devel] [PATCH] dm-bufio

[Mikulas Patocka]

On Mon, 17 Oct 2011, Joe Thornber wrote:

> On Mon, Oct 17, 2011 at 10:05:26AM -0400, Mikulas Patocka wrote:
> > 
> > 
> > On Mon, 17 Oct 2011, Joe Thornber wrote:
> > 
> > > On Fri, Oct 14, 2011 at 03:14:34PM -0400, Mikulas Patocka wrote:
> > > @@ -493,8 +500,10 @@ static void use_inline_bio(struct dm_buf
> > >  static void submit_io(struct dm_buffer *b, int rw, sector_t block,
> > >                       bio_end_io_t *end_io)
> > >  {
> > > -       if (b->c->block_size <= DM_BUFIO_INLINE_VECS * PAGE_SIZE &&
> > > -           b->data_mode != DATA_MODE_VMALLOC)
> > > +       if (rw == WRITE && b->c->write_callback)
> > > +               b->c->write_callback(b);
> > >         if (likely(b->c->block_size <= DM_BUFIO_INLINE_VECS * PAGE_SIZE) &&
> > >             likely(b->data_mode != DATA_MODE_VMALLOC))
> > >                 use_inline_bio(b, rw, block, end_io);
> > >         else
> > >                 use_dmio(b, rw, block, end_io);
> > > @@ -550,8 +559,6 @@ static void __write_dirty_buffer(struct
> > >         clear_bit(B_DIRTY, &b->state);
> > >         wait_on_bit_lock(&b->state, B_WRITING,
> > >                          do_io_schedule, TASK_UNINTERRUPTIBLE);
> > > -       if (b->c->write_callback)
> > > -               b->c->write_callback(b);
> > >         submit_io(b, WRITE, b->block, write_endio);
> > >  }
> > > 
> > > 
> > > This doesn't seem an improvement.  Except ... it changes the behaviour
> > > of dm_bufio_release_move().  So was there a preexisting bug in
> > > dm_bufio_release_move() that you're trying to fix with this patch?
> > 
> > The actual reason was to do this callback in dm_bufio_release_move() too 
> > --- just for consistency. (the user of dm_bufio_release_move() doesn't use 
> > write_callback anyway).
> 
> thinp uses dm_bufio_release_move() and write_callback.  So yes, this
> is a bug fix.  I thought so and merged.

BTW. it still uses the old block number in "prepare_for_write" callback. 
Do you use this block number somewhere? Should we link the buffer to the 
new block before the call and the link it back?

Mikulas

> - Joe
>