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() 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@xxxxxxxxxx>
Cc: Jens Axboe <jens.axboe@xxxxxxxxxx>
---
drivers/ide/ide-atapi.c | 19 +++++++++++--------
1 files changed, 11 insertions(+), 8 deletions(-)
diff --git a/drivers/ide/ide-atapi.c b/drivers/ide/ide-atapi.c
index bc7dfcf..2b456c4 100644
--- a/drivers/ide/ide-atapi.c
+++ b/drivers/ide/ide-atapi.c
@@ -328,6 +328,7 @@ static ide_startstop_t ide_pc_intr(ide_drive_t *drive)
/* No more interrupts */
if ((stat & ATA_DRQ) == 0) {
+ unsigned int done;
int uptodate;
debug_log("Packet command completed, %d bytes transferred\n",
@@ -367,6 +368,15 @@ 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 (drive->media == ide_tape)
+ done = ide_rq_bytes(rq); /* FIXME */
+ else
+ done = blk_rq_bytes(rq);
+
/* Command finished - Call the callback function */
uptodate = drive->pc_callback(drive, dsc);
@@ -375,20 +385,13 @@ static ide_startstop_t ide_pc_intr(ide_drive_t *drive)
if (blk_special_request(rq)) {
rq->errors = 0;
- ide_complete_rq(drive, 0, blk_rq_bytes(rq));
+ ide_complete_rq(drive, 0, done);
} else {
- unsigned int done;
-
if (blk_fs_request(rq) == 0 && uptodate <= 0) {
if (rq->errors == 0)
rq->errors = -EIO;
}
- if (drive->media == ide_tape)
- done = ide_rq_bytes(rq); /* FIXME */
- else
- done = blk_rq_bytes(rq);
-
ide_complete_rq(drive, uptodate ? 0 : -EIO, done);
}
--
1.6.0.2
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