[PATCH RESEND] libata: implement drain buffers

[PATCH RESEND] libata: implement drain buffers

[James Bottomley]

From: James Bottomley <James.Bottomley@HansenPartnership.com>
Date: Thu, 10 Jan 2008 11:42:50 -0600
Subject: libata: implement drain buffers

This just updates the libata slave configure routine to take advantage
of the block layer drain buffers.

I suspect I should also be checking for AHCI as well as ATA_DEV_ATAPI,
but I couldn't see how to do that easily.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
---
 drivers/ata/libata-scsi.c |   26 ++++++++++++++++++++++----
 1 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 8ffff44..a28351c 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -826,8 +826,8 @@ static void ata_scsi_sdev_config(struct scsi_device *sdev)
 	sdev->max_device_blocked = 1;
 }
 
-static void ata_scsi_dev_config(struct scsi_device *sdev,
-				struct ata_device *dev)
+static int ata_scsi_dev_config(struct scsi_device *sdev,
+			       struct ata_device *dev)
 {
 	/* configure max sectors */
 	blk_queue_max_sectors(sdev->request_queue, dev->max_sectors);
@@ -839,6 +839,16 @@ static void ata_scsi_dev_config(struct scsi_device *sdev,
 		sdev->manage_start_stop = 1;
 	}
 
+	if (dev->class == ATA_DEV_ATAPI) {
+		struct request_queue *q = sdev->request_queue;
+		void *buf = kmalloc(ATAPI_MAX_DRAIN, GFP_KERNEL);
+		if (!buf) {
+			sdev_printk(KERN_ERR, sdev, "drain buffer allocation failed\n");
+			return -ENOMEM;
+		}
+		blk_queue_dma_drain(q, buf, ATAPI_MAX_DRAIN);
+	}
+
 	if (dev->flags & ATA_DFLAG_AN)
 		set_bit(SDEV_EVT_MEDIA_CHANGE, sdev->supported_events);
 
@@ -849,6 +859,8 @@ static void ata_scsi_dev_config(struct scsi_device *sdev,
 		depth = min(ATA_MAX_QUEUE - 1, depth);
 		scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, depth);
 	}
+
+	return 0;
 }
 
 /**
@@ -867,13 +879,14 @@ int ata_scsi_slave_config(struct scsi_device *sdev)
 {
 	struct ata_port *ap = ata_shost_to_port(sdev->host);
 	struct ata_device *dev = __ata_scsi_find_dev(ap, sdev);
+	int rc = 0;
 
 	ata_scsi_sdev_config(sdev);
 
 	if (dev)
-		ata_scsi_dev_config(sdev, dev);
+		rc = ata_scsi_dev_config(sdev, dev);
 
-	return 0;
+	return rc;
 }
 
 /**
@@ -895,6 +908,7 @@ void ata_scsi_slave_destroy(struct scsi_device *sdev)
 	struct ata_port *ap = ata_shost_to_port(sdev->host);
 	unsigned long flags;
 	struct ata_device *dev;
+	struct request_queue *q = sdev->request_queue;
 
 	if (!ap->ops->error_handler)
 		return;
@@ -908,6 +922,10 @@ void ata_scsi_slave_destroy(struct scsi_device *sdev)
 		ata_port_schedule_eh(ap);
 	}
 	spin_unlock_irqrestore(ap->lock, flags);
+
+	kfree(q->dma_drain_buffer);
+	q->dma_drain_buffer = NULL;
+	q->dma_drain_size = 0;
 }
 
 /**
-- 
1.5.3.8

Re: [PATCH RESEND] libata: implement drain buffers

[Jeff Garzik]

James Bottomley wrote:
> From: James Bottomley <James.Bottomley@HansenPartnership.com>
> Date: Thu, 10 Jan 2008 11:42:50 -0600
> Subject: libata: implement drain buffers
> 
> This just updates the libata slave configure routine to take advantage
> of the block layer drain buffers.
> 
> I suspect I should also be checking for AHCI as well as ATA_DEV_ATAPI,
> but I couldn't see how to do that easily.
> 
> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
> ---
>  drivers/ata/libata-scsi.c |   26 ++++++++++++++++++++++----
>  1 files changed, 22 insertions(+), 4 deletions(-)

Tejun's persistent comment/objection with these works is that you need 
two sizes, for ATAPI, the raw size and the buffered size.

	Jeff

Re: [PATCH RESEND] libata: implement drain buffers

[James Bottomley]

On Fri, 2008-02-01 at 15:02 -0500, Jeff Garzik wrote:
> James Bottomley wrote:
> > From: James Bottomley <James.Bottomley@HansenPartnership.com>
> > Date: Thu, 10 Jan 2008 11:42:50 -0600
> > Subject: libata: implement drain buffers
> > 
> > This just updates the libata slave configure routine to take advantage
> > of the block layer drain buffers.
> > 
> > I suspect I should also be checking for AHCI as well as ATA_DEV_ATAPI,
> > but I couldn't see how to do that easily.
> > 
> > Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
> > ---
> >  drivers/ata/libata-scsi.c |   26 ++++++++++++++++++++++----
> >  1 files changed, 22 insertions(+), 4 deletions(-)
> 
> Tejun's persistent comment/objection with these works is that you need 
> two sizes, for ATAPI, the raw size and the buffered size.

This should be independent of the drain patch.  All this one does is
eliminate the unnecessary extra segment for alignment.  DMA drain for
ATAPI is something separate (and it's also something that isn't upstream
in any form).

James