Re: [PATCH 11/18] swim: dequeue in-flight request

[Sergei Shtylyov]

Hello.

Tejun Heo wrote:

> swim processes requests one-by-one synchronously and can easily be
> converted to dequeuing model.  Convert it.
>
> [ Impact: dequeue in-flight request ]
>
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Laurent Vivier <Laurent@xxxxxxxxxxxx>
> ---
>  drivers/block/swim.c |   47 +++++++++++++++++++++++------------------------
>  1 files changed, 23 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/block/swim.c b/drivers/block/swim.c
> index fc6a1c3..dedd489 100644
> --- a/drivers/block/swim.c
> +++ b/drivers/block/swim.c
> @@ -514,7 +514,7 @@ static int floppy_read_sectors(struct floppy_state *fs,
>  			ret = swim_read_sector(fs, side, track, sector,
>  						buffer);
>  			if (try-- == 0)
> -				return -1;
> +				return -EIO;
>  		} while (ret != 512);
>  
>  		buffer += ret;
> @@ -528,38 +528,37 @@ static void redo_fd_request(struct request_queue *q)
>  	struct request *req;
>  	struct floppy_state *fs;
>  
> -	while ((req = elv_next_request(q))) {
> +	req = elv_next_request(q);
> +	if (req)
> +		blkdev_dequeue_request(req);
> +
> +	while (req) {
> +		int err = -EIO;
>  
>  		fs = req->rq_disk->private_data;
> -		if (blk_rq_pos(req) >= fs->total_secs) {
> -			__blk_end_request_cur(req, -EIO);
> -			continue;
> -		}
> -		if (!fs->disk_in) {
> -			__blk_end_request_cur(req, -EIO);
> -			continue;
> -		}
> -		if (rq_data_dir(req) == WRITE) {
> -			if (fs->write_protected) {
> -				__blk_end_request_cur(req, -EIO);
> -				continue;
> -			}
> -		}
> +		if (blk_rq_pos(req) >= fs->total_secs)
> +			goto done;
> +		if (!fs->disk_in)
> +			goto done;
> +		if (rq_data_dir(req) == WRITE && fs->write_protected)
> +			goto done;
> +
>  		switch (rq_data_dir(req)) {
>  		case WRITE:
>  			/* NOT IMPLEMENTED */
> -			__blk_end_request_cur(req, -EIO);
>  			break;
>  		case READ:
> -			if (floppy_read_sectors(fs, blk_rq_pos(req),
> -						blk_rq_cur_sectors(req),
> -						req->buffer)) {
> -				__blk_end_request_cur(req, -EIO);
> -				continue;
> -			}
> -			__blk_end_request_cur(req, 0);
> +			err = floppy_read_sectors(fs, blk_rq_pos(req),
> +						  blk_rq_cur_sectors(req),
> +						  req->buffer);
>  			break;
>  		}
> +	done:
> +		if (!__blk_end_request_cur(req, err)) {
> +			req = elv_next_request(q);
> +			if (req)
> +				blkdev_dequeue_request(req);
> +		}
>  	}
>  }

  And without duplication:

@@ -528,38 +528,37 @@
static void redo_fd_request(struct request_queue *q)
{
- 	struct request *req;
	struct floppy_state *fs;

-	while ((req = elv_next_request(q))) {
+	while (1) {
+	 	struct request *req = elv_next_request(q);
+		int err;
+ 
+		if (req == NULL)
+			break;
+		blkdev_dequeue_request(req);

+again:
+		err = -EIO;
		fs = req->rq_disk->private_data;
-		if (blk_rq_pos(req) >= fs->total_secs) {
-			__blk_end_request_cur(req, -EIO);
-			continue;
-		}
-		if (!fs->disk_in) {
-			__blk_end_request_cur(req, -EIO);
-			continue;
-		}
-		if (rq_data_dir(req) == WRITE) {
-			if (fs->write_protected) {
-				__blk_end_request_cur(req, -EIO);
-				continue;
-			}
-		}
+		if (blk_rq_pos(req) >= fs->total_secs)
+			goto done;
+		if (!fs->disk_in)
+			goto done;
+		if (rq_data_dir(req) == WRITE && fs->write_protected)
+			goto done;
+
		switch (rq_data_dir(req)) {
		case WRITE:
			/* NOT IMPLEMENTED */
-			__blk_end_request_cur(req, -EIO);
			break;
		case READ:
-			if (floppy_read_sectors(fs, blk_rq_pos(req),
-						blk_rq_cur_sectors(req),
-						req->buffer)) {
-				__blk_end_request_cur(req, -EIO);
-				continue;
-			}
-			__blk_end_request_cur(req, 0);
+			err = floppy_read_sectors(fs, blk_rq_pos(req),
+						  blk_rq_cur_sectors(req),
+						  req->buffer);
			break;
		}
+	done:
+		if (__blk_end_request_cur(req, err))
+			goto again;
	}
}


MBR, Sergei


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