target: Implement Block Device Characteristics VPD page

Implement page B1h, Block Device Characteristics, so that we can report
a medium rotation rate of 1 (non-rotating / solid state) if the
is_nonrot device attribute is set; we update the iblock backend to set
this attribute if the underlying Linux block device has its nonrot
flag set.

Signed-off-by: Roland Dreier <roland@purestorage.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

4 files changed, 37 insertions, 0 deletions

diff --git a/drivers/target/target_core_cdb.c b/drivers/target/target_core_cdb.c
index 1157e0c6dba..432253034de 100644
--- a/drivers/target/target_core_cdb.c
+++ b/drivers/target/target_core_cdb.c
@@ -535,6 +535,22 @@ target_emulate_evpd_b0(struct se_cmd *cmd, unsigned char *buf)
         return 0;
 }
 
+/* Block Device Characteristics VPD page */
+static int
+target_emulate_evpd_b1(struct se_cmd *cmd, unsigned char *buf)
+{
+        struct se_device *dev = cmd->se_dev;
+
+        buf[0] = dev->transport->get_device_type(dev);
+        buf[3] = 0x3c;
+
+        if (cmd->data_length >= 5 &&
+            dev->se_sub_dev->se_dev_attrib.is_nonrot)
+                buf[5] = 1;
+
+        return 0;
+}
+
 /* Thin Provisioning VPD */
 static int
 target_emulate_evpd_b2(struct se_cmd *cmd, unsigned char *buf)
@@ -599,6 +615,7 @@ static struct {
         { .page = 0x83, .emulate = target_emulate_evpd_83 },
         { .page = 0x86, .emulate = target_emulate_evpd_86 },
         { .page = 0xb0, .emulate = target_emulate_evpd_b0 },
+        { .page = 0xb1, .emulate = target_emulate_evpd_b1 },
         { .page = 0xb2, .emulate = target_emulate_evpd_b2 },
 };
 
diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index 8d2aba51fc8..6b00810b8dc 100644
--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -698,6 +698,9 @@ SE_DEV_ATTR(emulate_tpws, S_IRUGO | S_IWUSR);
 DEF_DEV_ATTRIB(enforce_pr_isids);
 SE_DEV_ATTR(enforce_pr_isids, S_IRUGO | S_IWUSR);
 
+DEF_DEV_ATTRIB(is_nonrot);
+SE_DEV_ATTR(is_nonrot, S_IRUGO | S_IWUSR);
+
 DEF_DEV_ATTRIB_RO(hw_block_size);
 SE_DEV_ATTR_RO(hw_block_size);
 
@@ -746,6 +749,7 @@ static struct configfs_attribute *target_core_dev_attrib_attrs[] = {
         &target_core_dev_attrib_emulate_tpu.attr,
         &target_core_dev_attrib_emulate_tpws.attr,
         &target_core_dev_attrib_enforce_pr_isids.attr,
+        &target_core_dev_attrib_is_nonrot.attr,
         &target_core_dev_attrib_hw_block_size.attr,
         &target_core_dev_attrib_block_size.attr,
         &target_core_dev_attrib_hw_max_sectors.attr,
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index f13e2941936..440e6b69d47 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -853,6 +853,7 @@ void se_dev_set_default_attribs(
         dev->se_sub_dev->se_dev_attrib.emulate_reservations = DA_EMULATE_RESERVATIONS;
         dev->se_sub_dev->se_dev_attrib.emulate_alua = DA_EMULATE_ALUA;
         dev->se_sub_dev->se_dev_attrib.enforce_pr_isids = DA_ENFORCE_PR_ISIDS;
+        dev->se_sub_dev->se_dev_attrib.is_nonrot = DA_IS_NONROT;
         /*
          * The TPU=1 and TPWS=1 settings will be set in TCM/IBLOCK
          * iblock_create_virtdevice() from struct queue_limits values
@@ -1117,6 +1118,18 @@ int se_dev_set_enforce_pr_isids(struct se_device *dev, int flag)
         return 0;
 }
 
+int se_dev_set_is_nonrot(struct se_device *dev, int flag)
+{
+        if ((flag != 0) && (flag != 1)) {
+                printk(KERN_ERR "Illegal value %d\n", flag);
+                return -EINVAL;
+        }
+        dev->se_sub_dev->se_dev_attrib.is_nonrot = flag;
+        printk(KERN_INFO "dev[%p]: SE Device is_nonrot bit: %d\n",
+               dev, flag);
+        return 0;
+}
+
 /*
  * Note, this can only be called on unexported SE Device Object.
  */
diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index 160c484fd3d..392e75fb108 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -196,6 +196,9 @@ static struct se_device *iblock_create_virtdevice(
                                 " disabled by default\n");
         }
 
+        if (blk_queue_nonrot(q))
+                dev->se_sub_dev->se_dev_attrib.is_nonrot = 1;
+
         return dev;
 
 failed: