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Commit 97c566ce authored by Borislav Petkov's avatar Borislav Petkov Committed by Bartlomiej Zolnierkiewicz
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ide-tape: remove pipeline-specific code from idetape_add_chrdev_write_request 



Refrain from adding more write requests to the pipeline and queue them
directly on the device's request queue instead.

[bart: re-do for minimal behavior changes]

Signed-off-by: default avatarBorislav Petkov <petkovbb@gmail.com>
Signed-off-by: default avatarBartlomiej Zolnierkiewicz <bzolnier@gmail.com>
parent f64eee7b

drivers/ide/ide-tape.c

+2 −53
Original line number Diff line number Diff line
@@ -2202,28 +2202,16 @@ static void idetape_wait_first_stage(ide_drive_t *drive) 
	spin_unlock_irqrestore(&tape->lock, flags);

}



/*

 * Try to add a character device originated write request to our pipeline. In

 * case we don't succeed, we revert to non-pipelined operation mode for this

 * request. In order to accomplish that, we

 *

 * 1. Try to allocate a new pipeline stage.

 * 2. If we can't, wait for more and more requests to be serviced and try again

 * each time.

 * 3. If we still can't allocate a stage, fallback to non-pipelined operation

 * mode for this request.

 */

/* Queue up a character device originated write request. */

static int idetape_add_chrdev_write_request(ide_drive_t *drive, int blocks)

{

	idetape_tape_t *tape = drive->driver_data;

	idetape_stage_t *new_stage;

	unsigned long flags;

	struct request *rq;



	debug_log(DBG_CHRDEV, "Enter %s\n", __func__);



	/* Attempt to allocate a new stage. Beware possible race conditions. */

	while ((new_stage = idetape_kmalloc_stage(tape)) == NULL) {

	while (1) {

		spin_lock_irqsave(&tape->lock, flags);

		if (test_bit(IDETAPE_FLAG_PIPELINE_ACTIVE, &tape->flags)) {

			idetape_wait_for_request(drive, tape->active_data_rq);
@@ -2234,49 +2222,10 @@ static int idetape_add_chrdev_write_request(ide_drive_t *drive, int blocks) 
			if (test_bit(IDETAPE_FLAG_PIPELINE_ACTIVE,

					&tape->flags))

				continue;

			/*

			 * The machine is short on memory. Fallback to non-

			 * pipelined operation mode for this request.

			 */

			return idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE,

						blocks, tape->merge_stage->bh);

		}

	}

	rq = &new_stage->rq;

	idetape_init_rq(rq, REQ_IDETAPE_WRITE);

	/* Doesn't actually matter - We always assume sequential access */

	rq->sector = tape->first_frame;

	rq->current_nr_sectors = blocks;

	rq->nr_sectors = blocks;



	idetape_switch_buffers(tape, new_stage);

	idetape_add_stage_tail(drive, new_stage);

	tape->pipeline_head++;

	idetape_calculate_speeds(drive);



	/*

	 * Estimate whether the tape has stopped writing by checking if our

	 * write pipeline is currently empty. If we are not writing anymore,

	 * wait for the pipeline to be almost completely full (90%) before

	 * starting to service requests, so that we will be able to keep up with

	 * the higher speeds of the tape.

	 */

	if (!test_bit(IDETAPE_FLAG_PIPELINE_ACTIVE, &tape->flags)) {

		if (tape->nr_stages >= tape->max_stages * 9 / 10 ||

			tape->nr_stages >= tape->max_stages -

			tape->uncontrolled_pipeline_head_speed * 3 * 1024 /

			tape->blk_size) {

			tape->measure_insert_time = 1;

			tape->insert_time = jiffies;

			tape->insert_size = 0;

			tape->insert_speed = 0;

			idetape_plug_pipeline(drive);

		}

	}

	if (test_and_clear_bit(IDETAPE_FLAG_PIPELINE_ERR, &tape->flags))

		/* Return a deferred error */

		return -EIO;

	return blocks;

}



/*