This is a note to let you know that I've just added the patch titled
libata: set queue DMA alignment to sector size for ATAPI too
to the 2.6.33-longterm tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/longterm/longterm-queue-2.6.33.git;a=summary
The filename of the patch is:
libata-set-queue-dma-alignment-to-sector-size-for-atapi-too.patch
and it can be found in the queue-2.6.33 subdirectory.
If you, or anyone else, feels it should not be added to the 2.6.33 longterm
tree,
please let <[email protected]> know about it.
>From 729a6a300e628a48cf12bac93a964a535e83cd1d Mon Sep 17 00:00:00 2001
From: Tejun Heo <[email protected]>
Date: Thu, 20 Jan 2011 13:59:06 +0100
Subject: libata: set queue DMA alignment to sector size for ATAPI too
From: Tejun Heo <[email protected]>
commit 729a6a300e628a48cf12bac93a964a535e83cd1d upstream.
ata_pio_sectors() expects buffer for each sector to be contained in a
single page; otherwise, it ends up overrunning the first page. This
is achieved by setting queue DMA alignment. If sector_size is smaller
than PAGE_SIZE and all buffers are sector_size aligned, buffer for
each sector is always contained in a single page.
This wasn't applied to ATAPI devices but IDENTIFY_PACKET is executed
as ATA_PROT_PIO and thus uses ata_pio_sectors(). Newer versions of
udev issue IDENTIFY_PACKET with unaligned buffer triggering the
problem and causing oops.
This patch fixes the problem by setting sdev->sector_size to
ATA_SECT_SIZE on ATATPI devices and always setting DMA alignment to
sector_size. While at it, add a warning for the unlikely but still
possible scenario where sector_size is larger than PAGE_SIZE, in which
case the alignment wouldn't be enough.
Signed-off-by: Tejun Heo <[email protected]>
Reported-by: John Stanley <[email protected]>
Tested-by: John Stanley <[email protected]>
Signed-off-by: Jeff Garzik <[email protected]>
Signed-off-by: Jonathan Liu <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/ata/libata-scsi.c | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -1099,13 +1099,13 @@ static int ata_scsi_dev_config(struct sc
/* configure max sectors */
blk_queue_max_sectors(sdev->request_queue, dev->max_sectors);
+ sdev->sector_size = ATA_SECT_SIZE;
+
if (dev->class == ATA_DEV_ATAPI) {
struct request_queue *q = sdev->request_queue;
void *buf;
- /* set the min alignment and padding */
- blk_queue_update_dma_alignment(sdev->request_queue,
- ATA_DMA_PAD_SZ - 1);
+ /* set DMA padding */
blk_queue_update_dma_pad(sdev->request_queue,
ATA_DMA_PAD_SZ - 1);
@@ -1119,12 +1119,24 @@ static int ata_scsi_dev_config(struct sc
blk_queue_dma_drain(q, atapi_drain_needed, buf,
ATAPI_MAX_DRAIN);
} else {
- /* ATA devices must be sector aligned */
- blk_queue_update_dma_alignment(sdev->request_queue,
- ATA_SECT_SIZE - 1);
sdev->manage_start_stop = 1;
}
+ /*
+ * ata_pio_sectors() expects buffer for each sector to not cross
+ * page boundary. Enforce it by requiring buffers to be sector
+ * aligned, which works iff sector_size is not larger than
+ * PAGE_SIZE. ATAPI devices also need the alignment as
+ * IDENTIFY_PACKET is executed as ATA_PROT_PIO.
+ */
+ if (sdev->sector_size > PAGE_SIZE)
+ ata_dev_printk(dev, KERN_WARNING,
+ "sector_size=%u > PAGE_SIZE, PIO may malfunction\n",
+ sdev->sector_size);
+
+ blk_queue_update_dma_alignment(sdev->request_queue,
+ sdev->sector_size - 1);
+
if (dev->flags & ATA_DFLAG_AN)
set_bit(SDEV_EVT_MEDIA_CHANGE, sdev->supported_events);
Patches currently in longterm-queue-2.6.33 which might be from [email protected]
are
/home/gregkh/linux/longterm/longterm-queue-2.6.33/queue-2.6.33/libata-set-queue-dma-alignment-to-sector-size-for-atapi-too.patch
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