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: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

1 files changed, 2 insertions, 53 deletions

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index 8883eea4658f..71ebee001882 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -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;
 }
 
 /*