Re: [dm-devel] [PATCH] dm-bufio

[Mikulas Patocka <mpatocka redhat com>]

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).

Mikulas