Commit e815d365 authored by Damien Le Moal's avatar Damien Le Moal Committed by Jens Axboe
Browse files

scsi: sd: add concurrent positioning ranges support 



Add the sd_read_cpr() function to the sd scsi disk driver to discover
if a device has multiple concurrent positioning ranges (i.e. multiple
actuators on an HDD). The existence of VPD page B9h indicates if a
device has multiple concurrent positioning ranges. The page content
describes each range supported by the device.

sd_read_cpr() is called from sd_revalidate_disk() and uses the block
layer functions disk_alloc_independent_access_ranges() and
disk_set_independent_access_ranges() to represent the set of actuators
of the device as independent access ranges.

The format of the Concurrent Positioning Ranges VPD page B9h is defined
in section 6.6.6 of SBC-5.

Signed-off-by: default avatarDamien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Reviewed-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: default avatarKeith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20211027022223.183838-3-damien.lemoal@wdc.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent a2247f19

drivers/scsi/sd.c

+81 −0
Original line number Diff line number Diff line
@@ -3088,6 +3088,86 @@ static void sd_read_security(struct scsi_disk *sdkp, unsigned char *buffer) 
		sdkp->security = 1;

}



static inline sector_t sd64_to_sectors(struct scsi_disk *sdkp, u8 *buf)

{

	return logical_to_sectors(sdkp->device, get_unaligned_be64(buf));

}



/**

 * sd_read_cpr - Query concurrent positioning ranges

 * @sdkp:	disk to query

 */

static void sd_read_cpr(struct scsi_disk *sdkp)

{

	struct blk_independent_access_ranges *iars = NULL;

	unsigned char *buffer = NULL;

	unsigned int nr_cpr = 0;

	int i, vpd_len, buf_len = SD_BUF_SIZE;

	u8 *desc;



	/*

	 * We need to have the capacity set first for the block layer to be

	 * able to check the ranges.

	 */

	if (sdkp->first_scan)

		return;



	if (!sdkp->capacity)

		goto out;



	/*

	 * Concurrent Positioning Ranges VPD: there can be at most 256 ranges,

	 * leading to a maximum page size of 64 + 256*32 bytes.

	 */

	buf_len = 64 + 256*32;

	buffer = kmalloc(buf_len, GFP_KERNEL);

	if (!buffer || scsi_get_vpd_page(sdkp->device, 0xb9, buffer, buf_len))

		goto out;



	/* We must have at least a 64B header and one 32B range descriptor */

	vpd_len = get_unaligned_be16(&buffer[2]) + 3;

	if (vpd_len > buf_len || vpd_len < 64 + 32 || (vpd_len & 31)) {

		sd_printk(KERN_ERR, sdkp,

			  "Invalid Concurrent Positioning Ranges VPD page\n");

		goto out;

	}



	nr_cpr = (vpd_len - 64) / 32;

	if (nr_cpr == 1) {

		nr_cpr = 0;

		goto out;

	}



	iars = disk_alloc_independent_access_ranges(sdkp->disk, nr_cpr);

	if (!iars) {

		nr_cpr = 0;

		goto out;

	}



	desc = &buffer[64];

	for (i = 0; i < nr_cpr; i++, desc += 32) {

		if (desc[0] != i) {

			sd_printk(KERN_ERR, sdkp,

				"Invalid Concurrent Positioning Range number\n");

			nr_cpr = 0;

			break;

		}



		iars->ia_range[i].sector = sd64_to_sectors(sdkp, desc + 8);

		iars->ia_range[i].nr_sectors = sd64_to_sectors(sdkp, desc + 16);

	}



out:

	disk_set_independent_access_ranges(sdkp->disk, iars);

	if (nr_cpr && sdkp->nr_actuators != nr_cpr) {

		sd_printk(KERN_NOTICE, sdkp,

			  "%u concurrent positioning ranges\n", nr_cpr);

		sdkp->nr_actuators = nr_cpr;

	}



	kfree(buffer);

}



/*

 * Determine the device's preferred I/O size for reads and writes

 * unless the reported value is unreasonably small, large, not a
@@ -3203,6 +3283,7 @@ static int sd_revalidate_disk(struct gendisk *disk) 
		sd_read_app_tag_own(sdkp, buffer);

		sd_read_write_same(sdkp, buffer);

		sd_read_security(sdkp, buffer);

		sd_read_cpr(sdkp);

	}



	/*

drivers/scsi/sd.h

+1 −0
Original line number Diff line number Diff line
@@ -106,6 +106,7 @@ struct scsi_disk { 
	u8		protection_type;/* Data Integrity Field */

	u8		provisioning_mode;

	u8		zeroing_mode;

	u8		nr_actuators;		/* Number of actuators */

	unsigned	ATO : 1;	/* state of disk ATO bit */

	unsigned	cache_override : 1; /* temp override of WCE,RCD */

	unsigned	WCE : 1;	/* state of disk WCE bit */