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@xxxxxxx>
---
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
