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From: Damien Le Moal <damien.lemoal@wdc.com>
To: Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org, linux-ide@vger.kernel.org,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	linux-scsi@vger.kernel.org
Subject: [PATCH v7 2/5] scsi: sd: add concurrent positioning ranges support
Date: Mon,  6 Sep 2021 10:58:07 +0900	[thread overview]
Message-ID: <20210906015810.732799-3-damien.lemoal@wdc.com> (raw)
In-Reply-To: <20210906015810.732799-1-damien.lemoal@wdc.com>

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_iaranges() and disk_set_iaranges() 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: Damien Le Moal <damien.lemoal@wdc.com>
---
 drivers/scsi/sd.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++
 drivers/scsi/sd.h |  1 +
 2 files changed, 82 insertions(+)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 610ebba0d66e..1bb49d74c3db 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3126,6 +3126,86 @@ 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_iaranges(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->iarange[i].sector = sd64_to_sectors(sdkp, desc + 8);
+		iars->iarange[i].nr_sectors = sd64_to_sectors(sdkp, desc + 16);
+	}
+
+out:
+	disk_set_iaranges(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
@@ -3241,6 +3321,7 @@ 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);
 	}
 
 	/*
diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index b59136c4125b..2e5932bde43d 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -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 */
-- 
2.31.1


  parent reply	other threads:[~2021-09-06  1:58 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-06  1:58 [PATCH v7 0/5] Initial support for multi-actuator HDDs Damien Le Moal
2021-09-06  1:58 ` [PATCH v7 1/5] block: Add independent access ranges support Damien Le Moal
2021-09-06  8:14   ` Hannes Reinecke
2021-09-06 17:38   ` Jens Axboe
2021-09-06 22:31     ` Damien Le Moal
2021-09-06  1:58 ` Damien Le Moal [this message]
2021-09-06  8:35   ` [PATCH v7 2/5] scsi: sd: add concurrent positioning " Hannes Reinecke
2021-09-06  1:58 ` [PATCH v7 3/5] libata: support concurrent positioning ranges log Damien Le Moal
2021-09-06  1:58 ` [PATCH v7 4/5] doc: document sysfs queue/independent_access_ranges attributes Damien Le Moal
2021-09-06  8:37   ` Hannes Reinecke
2021-09-06  1:58 ` [PATCH v7 5/5] doc: Fix typo in request queue sysfs documentation Damien Le Moal
2021-09-06  8:37   ` Hannes Reinecke

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