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Commit 5e69bd95 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_read_request() 



In order to do away with queueing read requests on the pipeline, several things
have to be done:

1. Do not allocate additional pipeline stages in idetape_init_read() until
(tape->nr_stages < max_stages) and do only read operation preparations. As a
collateral result, idetape_add_stage_tail() becomes unused so remove it.

2. Queue the read request's buffer directly thru idetape_queue_rw_tail().

3. Remove now unused idetape_kmalloc_stage() and idetape_switch_buffers().

[bart: simplify the original patch]

Signed-off-by: default avatarBorislav Petkov <petkovbb@gmail.com>
Signed-off-by: default avatarBartlomiej Zolnierkiewicz <bzolnier@gmail.com>
parent ddfe7a77

drivers/ide/ide-tape.c

+5 −91
Original line number Diff line number Diff line
@@ -1586,15 +1586,6 @@ abort: 
	return NULL;

}



static idetape_stage_t *idetape_kmalloc_stage(idetape_tape_t *tape)

{

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



	if (tape->nr_stages >= tape->max_stages)

		return NULL;

	return __idetape_kmalloc_stage(tape, 0, 0);

}



static int idetape_copy_stage_from_user(idetape_tape_t *tape,

		idetape_stage_t *stage, const char __user *buf, int n)

{
@@ -1672,39 +1663,6 @@ static void idetape_init_merge_stage(idetape_tape_t *tape) 
	}

}



static void idetape_switch_buffers(idetape_tape_t *tape, idetape_stage_t *stage)

{

	struct idetape_bh *tmp;



	tmp = stage->bh;

	stage->bh = tape->merge_stage->bh;

	tape->merge_stage->bh = tmp;

	idetape_init_merge_stage(tape);

}



/* Add a new stage at the end of the pipeline. */

static void idetape_add_stage_tail(ide_drive_t *drive, idetape_stage_t *stage)

{

	idetape_tape_t *tape = drive->driver_data;

	unsigned long flags;



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



	spin_lock_irqsave(&tape->lock, flags);

	stage->next = NULL;

	if (tape->last_stage != NULL)

		tape->last_stage->next = stage;

	else

		tape->first_stage = stage;

		tape->next_stage  = stage;

	tape->last_stage = stage;

	if (tape->next_stage == NULL)

		tape->next_stage = tape->last_stage;

	tape->nr_stages++;

	tape->nr_pending_stages++;

	spin_unlock_irqrestore(&tape->lock, flags);

}



/* Install a completion in a pending request and sleep until it is serviced. The

 * caller should ensure that the request will not be serviced before we install

 * the completion (usually by disabling interrupts).
@@ -2228,10 +2186,7 @@ static void idetape_empty_write_pipeline(ide_drive_t *drive) 
static int idetape_init_read(ide_drive_t *drive, int max_stages)

{

	idetape_tape_t *tape = drive->driver_data;

	idetape_stage_t *new_stage;

	struct request rq;

	int bytes_read;

	u16 blocks = *(u16 *)&tape->caps[12];



	/* Initialize read operation */

	if (tape->chrdev_dir != IDETAPE_DIR_READ) {
@@ -2267,21 +2222,7 @@ static int idetape_init_read(ide_drive_t *drive, int max_stages) 
			}

		}

	}

	idetape_init_rq(&rq, REQ_IDETAPE_READ);

	rq.sector = tape->first_frame;

	rq.nr_sectors = blocks;

	rq.current_nr_sectors = blocks;

	if (!test_bit(IDETAPE_FLAG_PIPELINE_ERR, &tape->flags) &&

	    tape->nr_stages < max_stages) {

		new_stage = idetape_kmalloc_stage(tape);

		while (new_stage != NULL) {

			new_stage->rq = rq;

			idetape_add_stage_tail(drive, new_stage);

			if (tape->nr_stages >= max_stages)

				break;

			new_stage = idetape_kmalloc_stage(tape);

		}

	}



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

		if (tape->nr_pending_stages >= 3 * max_stages / 4) {

			tape->measure_insert_time = 1;
@@ -2301,9 +2242,6 @@ static int idetape_init_read(ide_drive_t *drive, int max_stages) 
static int idetape_add_chrdev_read_request(ide_drive_t *drive, int blocks)

{

	idetape_tape_t *tape = drive->driver_data;

	unsigned long flags;

	struct request *rq_ptr;

	int bytes_read;



	debug_log(DBG_PROCS, "Enter %s, %d blocks\n", __func__, blocks);
@@ -2311,38 +2249,14 @@ static int idetape_add_chrdev_read_request(ide_drive_t *drive, int blocks) 
	if (test_bit(IDETAPE_FLAG_FILEMARK, &tape->flags))

		return 0;



	/* Wait for the next block to reach the head of the pipeline. */

	idetape_init_read(drive, tape->max_stages);

	if (tape->first_stage == NULL) {



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

		return 0;



	return idetape_queue_rw_tail(drive, REQ_IDETAPE_READ, blocks,

				     tape->merge_stage->bh);

}

	idetape_wait_first_stage(drive);

	rq_ptr = &tape->first_stage->rq;

	bytes_read = tape->blk_size * (rq_ptr->nr_sectors -

					rq_ptr->current_nr_sectors);

	rq_ptr->nr_sectors = 0;

	rq_ptr->current_nr_sectors = 0;



	if (rq_ptr->errors == IDETAPE_ERROR_EOD)

		return 0;

	else {

		idetape_switch_buffers(tape, tape->first_stage);

		if (rq_ptr->errors == IDETAPE_ERROR_FILEMARK)

			set_bit(IDETAPE_FLAG_FILEMARK, &tape->flags);

		spin_lock_irqsave(&tape->lock, flags);

		idetape_remove_stage_head(drive);

		spin_unlock_irqrestore(&tape->lock, flags);

	}

	if (bytes_read > blocks * tape->blk_size) {

		printk(KERN_ERR "ide-tape: bug: trying to return more bytes"

				" than requested\n");

		bytes_read = blocks * tape->blk_size;

	}

	return (bytes_read);

}



static void idetape_pad_zeros(ide_drive_t *drive, int bcount)

{