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Subject[PATCH 26/28] blk_end_request: changing ide-cd (take 3)
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This patch converts ide-cd (cdrom_newpc_intr()) to use blk_end_request().

ide-cd (cdrom_newpc_intr()) has some tricky behaviors below which
need to use blk_end_request_callback().
Needs to:
1. call post_transform_command() to modify request contents
2. wait completing request until DRQ_STAT is cleared
after end_that_request_first() and before end_that_request_last().

As for the second one, ide-cd will wait for the interrupt from device.
So blk_end_request_callback() has to return without completing request
even if no leftover in the request.
ide-cd uses a dummy callback function, which just returns value '1',
to tell blk_end_request_callback() about that.

Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
---
drivers/ide/ide-cd.c | 78 +++++++++++++++++++++++++++++++++++++++------------
1 files changed, 61 insertions(+), 17 deletions(-)

Index: 2.6.24-rc3-mm2/drivers/ide/ide-cd.c
===================================================================
--- 2.6.24-rc3-mm2.orig/drivers/ide/ide-cd.c
+++ 2.6.24-rc3-mm2/drivers/ide/ide-cd.c
@@ -1669,6 +1669,37 @@ static void post_transform_command(struc
}
}

+/*
+ * Called from blk_end_request_callback() after the data of the request
+ * is completed and before the request is completed.
+ */
+static int cdrom_newpc_intr_dma_cb(struct request *rq)
+{
+ ide_drive_t *drive = rq->q->queuedata;
+ spinlock_t *ide_lock = rq->q->queue_lock;
+ unsigned long flags = 0UL;
+
+ rq->data_len = 0;
+ post_transform_command(rq);
+
+ spin_lock_irqsave(ide_lock, flags);
+ HWGROUP(drive)->rq = NULL;
+ spin_unlock_irqrestore(ide_lock, flags);
+
+ return 0;
+}
+
+/*
+ * Called from blk_end_request_callback() after the data of the request
+ * is completed and before the request is completed.
+ * By returning value '1', blk_end_request_callback() returns immediately
+ * without completing the request.
+ */
+static int cdrom_newpc_intr_dummy_cb(struct request *rq)
+{
+ return 1;
+}
+
typedef void (xfer_func_t)(ide_drive_t *, void *, u32);

/*
@@ -1707,9 +1738,16 @@ static ide_startstop_t cdrom_newpc_intr(
return ide_error(drive, "dma error", stat);
}

- end_that_request_chunk(rq, 1, rq->data_len);
- rq->data_len = 0;
- goto end_request;
+ /*
+ * post_transform_command() needs to be called after
+ * the data of the request is completed, since it may
+ * modify the data area of the request.
+ * So use the callback special feature of blk_end_request().
+ */
+ if (blk_end_request_callback(rq, 1, rq->data_len,
+ cdrom_newpc_intr_dma_cb))
+ BUG();
+ return ide_stopped;
}

/*
@@ -1727,8 +1765,18 @@ static ide_startstop_t cdrom_newpc_intr(
/*
* If DRQ is clear, the command has completed.
*/
- if ((stat & DRQ_STAT) == 0)
- goto end_request;
+ if ((stat & DRQ_STAT) == 0) {
+ if (!rq->data_len)
+ post_transform_command(rq);
+
+ spin_lock_irqsave(&ide_lock, flags);
+ if (__blk_end_request(rq, 1, 0))
+ BUG();
+ HWGROUP(drive)->rq = NULL;
+ spin_unlock_irqrestore(&ide_lock, flags);
+
+ return ide_stopped;
+ }

/*
* check which way to transfer data
@@ -1781,7 +1829,14 @@ static ide_startstop_t cdrom_newpc_intr(
rq->data_len -= blen;

if (rq->bio)
- end_that_request_chunk(rq, 1, blen);
+ /*
+ * The request can't be completed until DRQ is cleared.
+ * So complete the data, but don't complete the request
+ * using the dummy function for the callback feature
+ * of blk_end_request().
+ */
+ blk_end_request_callback(rq, 1, blen,
+ cdrom_newpc_intr_dummy_cb);
else
rq->data += blen;
}
@@ -1802,17 +1857,6 @@ static ide_startstop_t cdrom_newpc_intr(

ide_set_handler(drive, cdrom_newpc_intr, rq->timeout, NULL);
return ide_started;
-
-end_request:
- if (!rq->data_len)
- post_transform_command(rq);
-
- spin_lock_irqsave(&ide_lock, flags);
- blkdev_dequeue_request(rq);
- end_that_request_last(rq, 1);
- HWGROUP(drive)->rq = NULL;
- spin_unlock_irqrestore(&ide_lock, flags);
- return ide_stopped;
}

static ide_startstop_t cdrom_write_intr(ide_drive_t *drive)
-
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