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ide-atapi,tape,floppy: allow ->pc_callback() to change rq->data_len

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Impact: allow residual count implementation in ->pc_callback()

rq->data_len has two duties - carrying the number of input bytes on
issue and carrying residual count back to the issuer on completion.
ide-atapi completion callback ->pc_callback() is the right place to do
this but currently ide-atapi depends on rq->data_len carrying the
original request size after calling ->pc_callback() to complete the pc
request.

This patch makes ide_pc_intr(), ide_tape_issue_pc() and
ide_floppy_issue_pc() cache length to complete before calling
->pc_callback() so that it can modify rq->data_len as necessary.

Note: As using rq->data_len for two purposes can make cases like this
      incorrect in subtle ways, future changes will introduce separate
      field for residual count.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Tejun Heo 2009-04-19 08:46:02 +09:00 • committed by Jens Axboe
parent 08f370f0a2
commit eb6a61bb95
3 changed files with 18 additions and 8 deletions
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16
drivers/ide/ide-atapi.c
View file

@ -409,6 +409,16 @@ static ide_startstop_t ide_pc_intr(ide_drive_t *drive)
if ((pc->flags & PC_FLAG_WAIT_FOR_DSC) && (stat & ATA_DSC) == 0)
dsc = 1;
/*
* ->pc_callback() might change rq->data_len for
* residual count, cache total length.
*/
if (!blk_special_request(rq) &&
(drive->media == ide_tape && !rq->bio))
done = ide_rq_bytes(rq); /* FIXME */
else
done = blk_rq_bytes(rq);
/* Command finished - Call the callback function */
uptodate = drive->pc_callback(drive, dsc);
@ -417,7 +427,6 @@ static ide_startstop_t ide_pc_intr(ide_drive_t *drive)
if (blk_special_request(rq)) {
rq->errors = 0;
done = blk_rq_bytes(rq);
error = 0;
} else {
@ -426,11 +435,6 @@ static ide_startstop_t ide_pc_intr(ide_drive_t *drive)
rq->errors = -EIO;
}
if (drive->media == ide_tape && !rq->bio)
done = ide_rq_bytes(rq); /* FIXME */
else
done = blk_rq_bytes(rq);
error = uptodate ? 0 : -EIO;
}