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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
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+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;
}

/*