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: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20211027022223.183838-3-damien.lemoal@wdc.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index d8f6add416c0aa04430e71844d1b12a7c7a01de2..55c0d951a446e0a520299f44c985988c4cf8ac28 100644 (file)
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -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);
        }
 
        /*

diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index b59136c4125ba03b6fd0592360b82e3572772f65..2e5932bde43d12bbb5c26a1d147c72147751c2ea 100644 (file)
--- 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 */