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SubjectRe: [PATCH 11/14] scsi: unwind blk_end_request_all and blk_end_request_err calls
On 06/25/2014 06:51 PM, Christoph Hellwig wrote:
> Replace the calls to the various blk_end_request variants with opencode
> equivalents. Blk-mq is using a model that gives the driver control
> between the bio updates and the actual completion, and making the old
> code follow that same model allows us to keep the code more similar for
> both pathes.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> drivers/scsi/scsi_lib.c | 61 ++++++++++++++++++++++++++++++++---------------
> 1 file changed, 42 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index a64b9d3..58534fd 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -625,6 +625,37 @@ static void scsi_release_bidi_buffers(struct scsi_cmnd *cmd)
> cmd->request->next_rq->special = NULL;
> }
>
> +static bool scsi_end_request(struct request *req, int error,
> + unsigned int bytes, unsigned int bidi_bytes)
> +{
> + struct scsi_cmnd *cmd = req->special;
> + struct scsi_device *sdev = cmd->device;
> + struct request_queue *q = sdev->request_queue;
> + unsigned long flags;
> +
> +
> + if (blk_update_request(req, error, bytes))
> + return true;
> +
> + /* Bidi request must be completed as a whole */
> + if (unlikely(bidi_bytes) &&
> + blk_update_request(req->next_rq, error, bidi_bytes))
> + return true;
> +
> + if (blk_queue_add_random(q))
> + add_disk_randomness(req->rq_disk);
> +
> + spin_lock_irqsave(q->queue_lock, flags);
> + blk_finish_request(req, error);
> + spin_unlock_irqrestore(q->queue_lock, flags);
> +
> + if (bidi_bytes)
> + scsi_release_bidi_buffers(cmd);
> + scsi_release_buffers(cmd);
> + scsi_next_command(cmd);
> + return false;
> +}
> +
> /**
> * __scsi_error_from_host_byte - translate SCSI error code into errno
> * @cmd: SCSI command (unused)
> @@ -697,7 +728,7 @@ static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
> * be put back on the queue and retried using the same
> * command as before, possibly after a delay.
> *
> - * c) We can call blk_end_request() with -EIO to fail
> + * c) We can call scsi_end_request() with -EIO to fail
> * the remainder of the request.
> */
> void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
> @@ -749,13 +780,9 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
> * both sides at once.
> */
> req->next_rq->resid_len = scsi_in(cmd)->resid;
> -
> - scsi_release_buffers(cmd);
> - scsi_release_bidi_buffers(cmd);
> -
> - blk_end_request_all(req, 0);
> -
> - scsi_next_command(cmd);
> + if (scsi_end_request(req, 0, blk_rq_bytes(req),
> + blk_rq_bytes(req->next_rq)))
> + BUG();
> return;
> }
> }
> @@ -794,15 +821,16 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
> /*
> * If we finished all bytes in the request we are done now.
> */
> - if (!blk_end_request(req, error, good_bytes))
> - goto next_command;
> + if (!scsi_end_request(req, error, good_bytes, 0))
> + return;
>
> /*
> * Kill remainder if no retrys.
> */
> if (error && scsi_noretry_cmd(cmd)) {
> - blk_end_request_all(req, error);
> - goto next_command;
> + if (scsi_end_request(req, error, blk_rq_bytes(req), 0))
> + BUG();
> + return;
> }
>
> /*
> @@ -947,8 +975,8 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
> scsi_print_sense("", cmd);
> scsi_print_command(cmd);
> }
> - if (!blk_end_request_err(req, error))
> - goto next_command;
> + if (!scsi_end_request(req, error, blk_rq_err_bytes(req), 0))
> + return;
> /*FALLTHRU*/
> case ACTION_REPREP:
> requeue:
> @@ -967,11 +995,6 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
> __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0);
> break;
> }
> - return;
> -
> -next_command:
> - scsi_release_buffers(cmd);
> - scsi_next_command(cmd);
> }
>
> static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
>
YES.

That code really was a mess.

Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@suse.de +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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