Re: [PATCH 1/3] block: implement an unprep function corresponding directly to prep

[James Bottomley <James.Bottomley@HansenPartnership.com>]

On Thu, 2010-07-01 at 19:49 +0900, FUJITA Tomonori wrote:
> From: James Bottomley <James.Bottomley@suse.de>
> 
> Reviewed-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

Well, I forgot this, but otherwise looks fine:

Signed-off-by: James Bottomley <James.Bottomley@suse.de>

> ---
>  block/blk-core.c        |   25 +++++++++++++++++++++++++
>  block/blk-settings.c    |   17 +++++++++++++++++
>  drivers/scsi/scsi_lib.c |    2 +-
>  include/linux/blkdev.h  |    4 ++++
>  4 files changed, 47 insertions(+), 1 deletions(-)
> 
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 3c37894..5ab3ac2 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -608,6 +608,7 @@ blk_init_allocated_queue_node(struct request_queue *q, request_fn_proc *rfn,
>  
>  	q->request_fn		= rfn;
>  	q->prep_rq_fn		= NULL;
> +	q->unprep_rq_fn		= NULL;
>  	q->unplug_fn		= generic_unplug_device;
>  	q->queue_flags		= QUEUE_FLAG_DEFAULT;
>  	q->queue_lock		= lock;
> @@ -2133,6 +2134,26 @@ static bool blk_update_bidi_request(struct request *rq, int error,
>  	return false;
>  }
>  
> +/**
> + * blk_unprep_request - unprepare a request
> + * @req:	the request
> + *
> + * This function makes a request ready for complete resubmission (or
> + * completion).  It happens only after all error handling is complete,
> + * so represents the appropriate moment to deallocate any resources
> + * that were allocated to the request in the prep_rq_fn.  The queue
> + * lock is held when calling this.
> + */
> +void blk_unprep_request(struct request *req)
> +{
> +	struct request_queue *q = req->q;
> +
> +	req->cmd_flags &= ~REQ_DONTPREP;
> +	if (q->unprep_rq_fn)
> +		q->unprep_rq_fn(q, req);
> +}
> +EXPORT_SYMBOL_GPL(blk_unprep_request);
> +
>  /*
>   * queue lock must be held
>   */
> @@ -2148,6 +2169,10 @@ static void blk_finish_request(struct request *req, int error)
>  
>  	blk_delete_timer(req);
>  
> +	if (req->cmd_flags & REQ_DONTPREP)
> +		blk_unprep_request(req);
> +
> +
>  	blk_account_io_done(req);
>  
>  	if (req->end_io)
> diff --git a/block/blk-settings.c b/block/blk-settings.c
> index f5ed5a1..a234f4b 100644
> --- a/block/blk-settings.c
> +++ b/block/blk-settings.c
> @@ -37,6 +37,23 @@ void blk_queue_prep_rq(struct request_queue *q, prep_rq_fn *pfn)
>  EXPORT_SYMBOL(blk_queue_prep_rq);
>  
>  /**
> + * blk_queue_unprep_rq - set an unprepare_request function for queue
> + * @q:		queue
> + * @ufn:	unprepare_request function
> + *
> + * It's possible for a queue to register an unprepare_request callback
> + * which is invoked before the request is finally completed. The goal
> + * of the function is to deallocate any data that was allocated in the
> + * prepare_request callback.
> + *
> + */
> +void blk_queue_unprep_rq(struct request_queue *q, unprep_rq_fn *ufn)
> +{
> +	q->unprep_rq_fn = ufn;
> +}
> +EXPORT_SYMBOL(blk_queue_unprep_rq);
> +
> +/**
>   * blk_queue_merge_bvec - set a merge_bvec function for queue
>   * @q:		queue
>   * @mbfn:	merge_bvec_fn
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index 5f11608..ee83619 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -85,7 +85,7 @@ static void scsi_unprep_request(struct request *req)
>  {
>  	struct scsi_cmnd *cmd = req->special;
>  
> -	req->cmd_flags &= ~REQ_DONTPREP;
> +	blk_unprep_request(req);
>  	req->special = NULL;
>  
>  	scsi_put_command(cmd);
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 204fbe2..6bba04c 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -200,6 +200,7 @@ struct request_pm_state
>  typedef void (request_fn_proc) (struct request_queue *q);
>  typedef int (make_request_fn) (struct request_queue *q, struct bio *bio);
>  typedef int (prep_rq_fn) (struct request_queue *, struct request *);
> +typedef void (unprep_rq_fn) (struct request_queue *, struct request *);
>  typedef void (unplug_fn) (struct request_queue *);
>  
>  struct bio_vec;
> @@ -282,6 +283,7 @@ struct request_queue
>  	request_fn_proc		*request_fn;
>  	make_request_fn		*make_request_fn;
>  	prep_rq_fn		*prep_rq_fn;
> +	unprep_rq_fn		*unprep_rq_fn;
>  	unplug_fn		*unplug_fn;
>  	merge_bvec_fn		*merge_bvec_fn;
>  	prepare_flush_fn	*prepare_flush_fn;
> @@ -841,6 +843,7 @@ extern void blk_complete_request(struct request *);
>  extern void __blk_complete_request(struct request *);
>  extern void blk_abort_request(struct request *);
>  extern void blk_abort_queue(struct request_queue *);
> +extern void blk_unprep_request(struct request *);
>  
>  /*
>   * Access functions for manipulating queue properties
> @@ -885,6 +888,7 @@ extern int blk_queue_dma_drain(struct request_queue *q,
>  extern void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn);
>  extern void blk_queue_segment_boundary(struct request_queue *, unsigned long);
>  extern void blk_queue_prep_rq(struct request_queue *, prep_rq_fn *pfn);
> +extern void blk_queue_unprep_rq(struct request_queue *, unprep_rq_fn *ufn);
>  extern void blk_queue_merge_bvec(struct request_queue *, merge_bvec_fn *);
>  extern void blk_queue_dma_alignment(struct request_queue *, int);
>  extern void blk_queue_update_dma_alignment(struct request_queue *, int);