ide-tape: use standard data transfer mechanism
Impact: use standard way to transfer data
ide-tape uses rq in an interesting way. For r/w requests, rq->special
is used to carry a private buffer management structure idetape_bh and
rq->nr_sectors and current_nr_sectors are initialized to the number of
idetape blocks which isn't necessary 512 bytes. Also,
rq->current_nr_sectors is used to report back the residual count in
units of idetape blocks.
This peculiarity taxes both block layer and ide. ide-atapi has
different paths and hooks to accomodate it and what a rq means becomes
quite confusing and making changes at the block layer becomes quite
difficult and error-prone.
This patch makes ide-tape use bio instead. With the previous patch,
ide-tape currently is using single contiguos buffer so replacing it
isn't difficult. Data buffer is mapped into bio using
blk_rq_map_kern() in idetape_queue_rw_tail(). idetape_io_buffers()
and idetape_update_buffers() are dropped and pc->bh is set to null to
tell ide-atapi to use standard data transfer mechanism and idetape_bh
byte counts are updated by the issuer on completion using the residual
count.
This change also nicely removes the FIXME in ide_pc_intr() where
ide-tape rqs need to be completed using ide_rq_bytes() instead of
blk_rq_bytes() (although this didn't really matter as the request
didn't have bio).
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
index b2afbc7..b373ac8 100644
--- a/drivers/ide/ide-tape.c
+++ b/drivers/ide/ide-tape.c
@@ -292,65 +292,6 @@
return tape;
}
-static int idetape_input_buffers(ide_drive_t *drive, struct ide_atapi_pc *pc,
- unsigned int bcount)
-{
- struct idetape_bh *bh = pc->bh;
- int count;
-
- if (bcount && bh) {
- count = min(
- (unsigned int)(bh->b_size - atomic_read(&bh->b_count)),
- bcount);
- drive->hwif->tp_ops->input_data(drive, NULL, bh->b_data +
- atomic_read(&bh->b_count), count);
- bcount -= count;
- atomic_add(count, &bh->b_count);
- if (atomic_read(&bh->b_count) == bh->b_size)
- pc->bh = NULL;
- }
-
- return bcount;
-}
-
-static int idetape_output_buffers(ide_drive_t *drive, struct ide_atapi_pc *pc,
- unsigned int bcount)
-{
- struct idetape_bh *bh = pc->bh;
- int count;
-
- if (bcount && bh) {
- count = min((unsigned int)pc->b_count, (unsigned int)bcount);
- drive->hwif->tp_ops->output_data(drive, NULL, pc->b_data, count);
- bcount -= count;
- pc->b_data += count;
- pc->b_count -= count;
- if (!pc->b_count)
- pc->bh = NULL;
- }
-
- return bcount;
-}
-
-static void idetape_update_buffers(ide_drive_t *drive, struct ide_atapi_pc *pc)
-{
- struct idetape_bh *bh = pc->bh;
- unsigned int bcount = pc->xferred;
-
- if (pc->flags & PC_FLAG_WRITING)
- return;
- if (bcount) {
- if (bh == NULL || bcount > bh->b_size) {
- printk(KERN_ERR "ide-tape: bh == NULL in %s\n",
- __func__);
- return;
- }
- atomic_set(&bh->b_count, bcount);
- if (atomic_read(&bh->b_count) == bh->b_size)
- pc->bh = NULL;
- }
-}
-
/*
* called on each failed packet command retry to analyze the request sense. We
* currently do not utilize this information.
@@ -368,12 +309,10 @@
pc->c[0], tape->sense_key, tape->asc, tape->ascq);
/* Correct pc->xferred by asking the tape. */
- if (pc->flags & PC_FLAG_DMA_ERROR) {
+ if (pc->flags & PC_FLAG_DMA_ERROR)
pc->xferred = pc->req_xfer -
tape->blk_size *
get_unaligned_be32(&sense[3]);
- idetape_update_buffers(drive, pc);
- }
/*
* If error was the result of a zero-length read or write command,
@@ -458,7 +397,7 @@
}
tape->first_frame += blocks;
- rq->current_nr_sectors -= blocks;
+ rq->data_len -= blocks * tape->blk_size;
if (pc->error) {
uptodate = 0;
@@ -520,19 +459,6 @@
idetape_postpone_request(drive);
}
-static int ide_tape_io_buffers(ide_drive_t *drive, struct ide_atapi_pc *pc,
- unsigned int bcount, int write)
-{
- unsigned int bleft;
-
- if (write)
- bleft = idetape_output_buffers(drive, pc, bcount);
- else
- bleft = idetape_input_buffers(drive, pc, bcount);
-
- return bcount - bleft;
-}
-
/*
* Packet Command Interface
*
@@ -683,7 +609,7 @@
ide_init_pc(pc);
put_unaligned(cpu_to_be32(length), (unsigned int *) &pc->c[1]);
pc->c[1] = 1;
- pc->bh = bh;
+ pc->bh = NULL;
pc->buf = NULL;
pc->buf_size = length * tape->blk_size;
pc->req_xfer = pc->buf_size;
@@ -1063,10 +989,12 @@
struct idetape_bh *bh)
{
idetape_tape_t *tape = drive->driver_data;
+ size_t size = blocks * tape->blk_size;
struct request *rq;
- int ret, errors;
+ int ret;
debug_log(DBG_SENSE, "%s: cmd=%d\n", __func__, cmd);
+ BUG_ON(cmd != REQ_IDETAPE_READ && cmd != REQ_IDETAPE_WRITE);
rq = blk_get_request(drive->queue, READ, __GFP_WAIT);
rq->cmd_type = REQ_TYPE_SPECIAL;
@@ -1074,21 +1002,29 @@
rq->rq_disk = tape->disk;
rq->special = (void *)bh;
rq->sector = tape->first_frame;
- rq->nr_sectors = blocks;
- rq->current_nr_sectors = blocks;
+
+ if (size) {
+ ret = blk_rq_map_kern(drive->queue, rq, bh->b_data, size,
+ __GFP_WAIT);
+ if (ret)
+ goto out_put;
+ }
+
blk_execute_rq(drive->queue, tape->disk, rq, 0);
- errors = rq->errors;
- ret = tape->blk_size * (blocks - rq->current_nr_sectors);
- blk_put_request(rq);
+ /* calculate the number of transferred bytes and update bh */
+ size -= rq->data_len;
+ if (cmd == REQ_IDETAPE_READ)
+ atomic_add(size, &bh->b_count);
- if ((cmd & (REQ_IDETAPE_READ | REQ_IDETAPE_WRITE)) == 0)
- return 0;
+ ret = size;
+ if (rq->errors == IDE_DRV_ERROR_GENERAL)
+ ret = -EIO;
if (tape->merge_bh)
idetape_init_merge_buffer(tape);
- if (errors == IDE_DRV_ERROR_GENERAL)
- return -EIO;
+out_put:
+ blk_put_request(rq);
return ret;
}
@@ -2034,8 +1970,6 @@
u16 *ctl = (u16 *)&tape->caps[12];
drive->pc_callback = ide_tape_callback;
- drive->pc_update_buffers = idetape_update_buffers;
- drive->pc_io_buffers = ide_tape_io_buffers;
drive->dev_flags |= IDE_DFLAG_DSC_OVERLAP;