libata: set queue DMA alignment to sector size for ATAPI too (729a6a30) · Commits · 戴 / test

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 <tj@kernel.org> Reported-by:

John Stanley <jpsinthemix@verizon.net> Tested-by:

John Stanley <jpsinthemix@verizon.net> Cc: stable@kernel.org Signed-off-by:

Jeff Garzik <jgarzik@redhat.com>

drivers/ata/libata-scsi.c

+18 −6

Original line number	Diff line number	Diff line
		@@ -1099,9 +1099,9 @@ static int ata_scsi_dev_config(struct scsi_device *sdev,
		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);
		sdev->sector_size = ATA_SECT_SIZE;

		/* set DMA padding */
		blk_queue_update_dma_pad(sdev->request_queue,
		ATA_DMA_PAD_SZ - 1);

		@@ -1115,13 +1115,25 @@ static int ata_scsi_dev_config(struct scsi_device *sdev,

		blk_queue_dma_drain(q, atapi_drain_needed, buf, ATAPI_MAX_DRAIN);
		} else {
		/* ATA devices must be sector aligned */
		sdev->sector_size = ata_id_logical_sector_size(dev->id);
		blk_queue_update_dma_alignment(sdev->request_queue,
		sdev->sector_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);

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