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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: Borislav Petkov <petkovbb@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
This commit is contained in:
Borislav Petkov 2008-04-27 15:38:25 +02:00 committed by Bartlomiej Zolnierkiewicz
parent ddfe7a7763
commit 5e69bd959d
1 changed files with 5 additions and 91 deletions
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96
drivers/ide/ide-tape.c
View File

@ -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);
@ -2311,37 +2249,13 @@ 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)
if (test_bit(IDETAPE_FLAG_PIPELINE_ERR, &tape->flags))
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);
return idetape_queue_rw_tail(drive, REQ_IDETAPE_READ, blocks,
tape->merge_stage->bh);
}
static void idetape_pad_zeros(ide_drive_t *drive, int bcount)