linux-kernel - Re: [PATCH 5/5] libata: Add support for TRIM

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Date:	Thu, 02 Apr 2009 13:20:01 -0400
From:	Mark Lord <liml@....ca>
To:	Matthew Wilcox <willy@...ux.intel.com>
Cc:	linux-ide@...r.kernel.org, linux-kernel@...r.kernel.org,
	jgarzik@...hat.com
Subject: Re: [PATCH 5/5] libata: Add support for TRIM

Matthew Wilcox wrote:
> Signed-off-by: Matthew Wilcox <willy@...ux.intel.com>
> ---
>  drivers/ata/libata-scsi.c |   46 +++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 46 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index b9747fa..d4c8b8b 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
> @@ -1029,6 +1029,46 @@ static void ata_gen_ata_sense(struct ata_queued_cmd *qc)
>  	desc[11] = block;
>  }
>  
> +static int ata_discard_fn(struct request_queue *q, struct request *req,
> +							struct bio *bio)
> +{
> +	unsigned size;
> +	struct page *page = alloc_page(GFP_KERNEL);
> +	if (!page)
> +		goto error;
> +
> +	size = ata_set_lba_range_entries(page_address(page), PAGE_SIZE / 8,
> +					bio->bi_sector, bio_sectors(bio));
> +	bio->bi_size = 0;
> +	if (bio_add_pc_page(q, bio, page, size, 0) < size)
> +		goto free_page;
> +
> +	req->cmd_type = REQ_TYPE_BLOCK_PC;
> +	req->cmd_len = 16;
> +	req->cmd[0] = ATA_16;
> +	req->cmd[1] = (6 << 1) | 1;		/* dma, 48-bit */
> +	req->cmd[2] = 0x6;			/* length, direction */
> +	req->cmd[3] = 0;			/* feature high */
> +	req->cmd[4] = ATA_DSM_TRIM;		/* feature low */
> +	req->cmd[5] = (size / 512) >> 8;	/* nsect high */
> +	req->cmd[6] = size / 512;		/* nsect low */
> +	req->cmd[7] = 0;			/* lba */
> +	req->cmd[8] = 0;			/* lba */
> +	req->cmd[9] = 0;			/* lba */
> +	req->cmd[10] = 0;			/* lba */
> +	req->cmd[11] = 0;			/* lba */
> +	req->cmd[12] = 0;			/* lba */
> +	req->cmd[13] = ATA_LBA;			/* device */
> +	req->cmd[14] = ATA_CMD_DSM;		/* command */
> +	req->cmd[15] = 0;			/* control */
> +
> +	return 0;
> + free_page:
> +	__free_page(page);
> + error:
> +	return -ENOMEM;
> +}
> +
>  static void ata_scsi_sdev_config(struct scsi_device *sdev)
>  {
>  	sdev->use_10_for_rw = 1;
> @@ -1077,6 +1117,9 @@ static int ata_scsi_dev_config(struct scsi_device *sdev,
>  	/* configure max sectors */
>  	blk_queue_max_sectors(sdev->request_queue, dev->max_sectors);
>  
> +	if (ata_id_has_trim(dev->id))
> +		blk_queue_set_discard(sdev->request_queue, ata_discard_fn);
> +
>  	if (dev->class == ATA_DEV_ATAPI) {
>  		struct request_queue *q = sdev->request_queue;
>  		void *buf;
> @@ -2385,6 +2428,9 @@ static unsigned int ata_scsiop_read_cap(struct ata_scsi_args *args, u8 *rbuf)
>  		/* sector size */
>  		rbuf[10] = ATA_SECT_SIZE >> 8;
>  		rbuf[11] = ATA_SECT_SIZE & 0xff;
> +
> +		if (ata_id_has_trim(args->id))
> +			rbuf[14] = 0x80;
>  	}
>  
>  	return 0;
..

Now we just need an implementation of ata_discard_fn()
that issues the CFA ERASE SECTORS command instead of TRIM
when speaking to a CFA device.

Ah, life is good!
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