7938 Port ZOL #3712 disable LBA weighting on files and SSDs

@@ -21,10 +21,11 @@
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
  * Copyright 2016 Nexenta Systems, Inc.  All rights reserved.
  * Copyright (c) 2013 Joyent, Inc.  All rights reserved.
+ * Copyright (c) 2017 James S Blachly, MD <james.blachly@gmail.com>
  */
 
 #include <sys/zfs_context.h>
 #include <sys/spa_impl.h>
 #include <sys/refcount.h>

@@ -269,10 +270,12 @@
         dev_t dev;
         int otyp;
         boolean_t validate_devid = B_FALSE;
         ddi_devid_t devid;
         uint64_t capacity = 0, blksz = 0, pbsize;
+        int device_solid_state;
+        char *vendorp;  /* will point to inquiry-vendor-id */
 
         /*
          * We must have a pathname, and it must be absolute.
          */
         if (vd->vdev_path == NULL || vd->vdev_path[0] != '/') {

@@ -541,10 +544,32 @@
                 (void) ldi_ioctl(dvd->vd_lh, DKIOCSETWCE, (intptr_t)&wce,
                     FKIOCTL, kcred, NULL);
         }
 
         /*
+         * Inform the ZIO pipeline if we are non-rotational:
+         * 1. Check if device is SSD
+         * 2. If not SSD, check if device is Virtio
+         */
+        device_solid_state = ldi_prop_get_int(dvd->vd_lh, LDI_DEV_T_ANY,
+            "device-solid-state", 0);
+        vd->vdev_nonrot = (device_solid_state ? B_TRUE : B_FALSE);
+
+        if (device_solid_state == 0 &&
+            ldi_prop_exists(dvd->vd_lh, LDI_DEV_T_ANY, "inquiry-vendor-id")) {
+                ldi_prop_lookup_string(dvd->vd_lh, LDI_DEV_T_ANY,
+                    "inquiry-vendor-id", &vendorp);
+                if (strncmp(vendorp, "Virtio", 6) == 0)
+                    vd->vdev_nonrot = B_TRUE;
+                ddi_prop_free(vendorp);
+        }
+
+        cmn_err(CE_NOTE, "[vdev_disk_open] %s :: device-solid-state "
+            "== %d :: vd->vdev_nonrot == %d\n", vd->vdev_path,
+            device_solid_state, (int) vd->vdev_nonrot);
+
+        /*
          * Clear the nowritecache bit, so that on a vdev_reopen() we will
          * try again.
          */
         vd->vdev_nowritecache = B_FALSE;