Re: [PATCH 19/19] BLOCK: Make it possible to disable the blocklayer [try #6]

[Trond Myklebust]

On Wed, 2006-08-30 at 12:44 -0700, Andrew Morton wrote:
> I think I'll just slam all this in at the first opportunity.  Stuff will
> break, but it will be easy to fix.
> 
> If you try to upissue this patchset I shall be seeking an IP-routable hand
> grenade.
> 
> On Tue, 29 Aug 2006 19:06:34 +0100
> David Howells <dhowells@xxxxxxxxxx> wrote:
> 
> > +static inline long blk_congestion_wait(int rw, long timeout)
> > +{
> > +	return timeout;
> > +}
> 
> This function is misnamed and is implemented in the wrong place.  It's not
> really a block thing at all.  If/when/soon NFS starts to implement it and
> call it, things will need to be renamed and reshuffled.

Already done in the NFS git tree. See attached patch.


> --- Begin Message ---
> Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
> ---
>
>  block/ll_rw_blk.c         |   12 ++++++++++++
>  fs/nfs/write.c            |    1 +
>  include/linux/blkdev.h    |    1 +
>  include/linux/writeback.h |    1 +
>  mm/page-writeback.c       |    9 +++++++++
>  5 files changed, 24 insertions(+), 0 deletions(-)
>
> diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
> index ddd9253..dcbd6ff 100644
> --- a/block/ll_rw_blk.c
> +++ b/block/ll_rw_blk.c
> @@ -2734,6 +2734,18 @@ long blk_congestion_wait(int rw, long ti
>  
>  EXPORT_SYMBOL(blk_congestion_wait);
>  
> +/**
> + * blk_congestion_end - wake up sleepers on a congestion queue
> + * @rw: READ or WRITE
> + */
> +void blk_congestion_end(int rw)
> +{
> +	wait_queue_head_t *wqh = &congestion_wqh[rw];
> +
> +	if (waitqueue_active(wqh))
> +		wake_up(wqh);
> +}
> +
>  /*
>   * Has to be called with the request spinlock acquired
>   */
> diff --git a/fs/nfs/write.c b/fs/nfs/write.c
> index 7bc500b..1f7a6d4 100644
> --- a/fs/nfs/write.c
> +++ b/fs/nfs/write.c
> @@ -403,6 +403,7 @@ int nfs_writepages(struct address_space 
>  out:
>  	clear_bit(BDI_write_congested, &bdi->state);
>  	wake_up_all(&nfs_write_congestion);
> +	writeback_congestion_end();
>  	return err;
>  }
>  
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index aafe827..96c9040 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -746,6 +746,7 @@ extern void blk_queue_free_tags(request_
>  extern int blk_queue_resize_tags(request_queue_t *, int);
>  extern void blk_queue_invalidate_tags(request_queue_t *);
>  extern long blk_congestion_wait(int rw, long timeout);
> +extern void blk_congestion_end(int rw);
>  
>  extern void blk_rq_bio_prep(request_queue_t *, struct request *, struct bio *);
>  extern int blkdev_issue_flush(struct block_device *, sector_t *);
> diff --git a/include/linux/writeback.h b/include/linux/writeback.h
> index 9e38b56..0422036 100644
> --- a/include/linux/writeback.h
> +++ b/include/linux/writeback.h
> @@ -85,6 +85,7 @@ int wakeup_pdflush(long nr_pages);
>  void laptop_io_completion(void);
>  void laptop_sync_completion(void);
>  void throttle_vm_writeout(void);
> +void writeback_congestion_end(void);
>  
>  /* These are exported to sysctl. */
>  extern int dirty_background_ratio;
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index e630188..77a0bc4 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -803,6 +803,15 @@ int test_set_page_writeback(struct page 
>  EXPORT_SYMBOL(test_set_page_writeback);
>  
>  /*
> + * Wakes up tasks that are being throttled due to writeback congestion
> + */
> +void writeback_congestion_end(void)
> +{
> +	blk_congestion_end(WRITE);
> +}
> +EXPORT_SYMBOL(writeback_congestion_end);
> +
> +/*
>   * Return true if any of the pages in the mapping are marged with the
>   * passed tag.
>   */
>
> --- End Message ---