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>

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index 8883eea..71ebee0 100644 (file)
--- 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;
 }
 
 /*