Author: asomers
Date: Mon May 22 15:12:49 2017
New Revision: 318648
URL: https://svnweb.freebsd.org/changeset/base/318648

Log:
  MFC r318189:
  
  vdev_geom may associate multiple vdevs per g_consumer
  
  vdev_geom.c currently uses the g_consumer's private field to point to a
  vdev_t. That way, a GEOM event can cause a change to a ZFS vdev. For
  example, when you remove a disk, the vdev's status will change to REMOVED.
  However, vdev_geom will sometimes attach multiple vdevs to the same GEOM
  consumer. If this happens, then geom events will only be propagated to one
  of the vdevs.
  
  Fix this by storing a linked list of vdevs in g_consumer's private field.
  
  sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c
  
  * g_consumer.private now stores a linked list of vdev pointers associated
    with the consumer instead of just a single vdev pointer.
  
  * Change vdev_geom_set_physpath's signature to more closely match
    vdev_geom_set_rotation_rate
  
  * Don't bother calling g_access in vdev_geom_set_physpath. It's guaranteed
    that we've already accessed the consumer by the time we get here.
  
  * Don't call vdev_geom_set_physpath in vdev_geom_attach. Instead, call it
    in vdev_geom_open, after we know that the open has succeeded.
  
  PR:           218634
  Reviewed by:  gibbs
  Sponsored by: Spectra Logic Corp
  Differential Revision:        https://reviews.freebsd.org/D10391

Modified:
  stable/11/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c
==============================================================================
--- stable/11/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c        
Mon May 22 14:46:13 2017        (r318647)
+++ stable/11/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c        
Mon May 22 15:12:49 2017        (r318648)
@@ -49,6 +49,16 @@ struct g_class zfs_vdev_class = {
        .attrchanged = vdev_geom_attrchanged,
 };
 
+struct consumer_vdev_elem {
+       SLIST_ENTRY(consumer_vdev_elem) elems;
+       vdev_t                          *vd;
+};
+
+SLIST_HEAD(consumer_priv_t, consumer_vdev_elem);
+_Static_assert(sizeof(((struct g_consumer*)NULL)->private)
+    == sizeof(struct consumer_priv_t*),
+    "consumer_priv_t* can't be stored in g_consumer.private");
+
 DECLARE_GEOM_CLASS(zfs_vdev_class, zfs_vdev);
 
 SYSCTL_DECL(_vfs_zfs_vdev);
@@ -85,21 +95,16 @@ vdev_geom_set_rotation_rate(vdev_t *vd, 
 }
 
 static void
-vdev_geom_set_physpath(struct g_consumer *cp, boolean_t do_null_update)
+vdev_geom_set_physpath(vdev_t *vd, struct g_consumer *cp,
+                      boolean_t do_null_update)
 {
        boolean_t needs_update = B_FALSE;
-       vdev_t *vd;
        char *physpath;
        int error, physpath_len;
 
-       if (g_access(cp, 1, 0, 0) != 0)
-               return;
-
-       vd = cp->private;
        physpath_len = MAXPATHLEN;
        physpath = g_malloc(physpath_len, M_WAITOK|M_ZERO);
        error = g_io_getattr("GEOM::physpath", cp, &physpath_len, physpath);
-       g_access(cp, -1, 0, 0);
        if (error == 0) {
                char *old_physpath;
 
@@ -130,37 +135,40 @@ vdev_geom_set_physpath(struct g_consumer
 static void
 vdev_geom_attrchanged(struct g_consumer *cp, const char *attr)
 {
-       vdev_t *vd;
        char *old_physpath;
+       struct consumer_priv_t *priv;
+       struct consumer_vdev_elem *elem;
        int error;
 
-       vd = cp->private;
-       if (vd == NULL)
+       priv = (struct consumer_priv_t*)&cp->private;
+       if (SLIST_EMPTY(priv))
                return;
 
-       if (strcmp(attr, "GEOM::rotation_rate") == 0) {
-               vdev_geom_set_rotation_rate(vd, cp);
-               return;
-       }
-
-       if (strcmp(attr, "GEOM::physpath") == 0) {
-               vdev_geom_set_physpath(cp, /*do_null_update*/B_TRUE);
-               return;
+       SLIST_FOREACH(elem, priv, elems) {
+               vdev_t *vd = elem->vd;
+               if (strcmp(attr, "GEOM::rotation_rate") == 0) {
+                       vdev_geom_set_rotation_rate(vd, cp);
+                       return;
+               }
+               if (strcmp(attr, "GEOM::physpath") == 0) {
+                       vdev_geom_set_physpath(vd, cp, /*null_update*/B_TRUE);
+                       return;
+               }
        }
 }
 
 static void
 vdev_geom_orphan(struct g_consumer *cp)
 {
-       vdev_t *vd;
+       struct consumer_priv_t *priv;
+       struct consumer_vdev_elem *elem;
 
        g_topology_assert();
 
-       vd = cp->private;
-       if (vd == NULL) {
+       priv = (struct consumer_priv_t*)&cp->private;
+       if (SLIST_EMPTY(priv))
                /* Vdev close in progress.  Ignore the event. */
                return;
-       }
 
        /*
         * Orphan callbacks occur from the GEOM event thread.
@@ -176,8 +184,12 @@ vdev_geom_orphan(struct g_consumer *cp)
         * async removal support to invoke a close on this
         * vdev once it is safe to do so.
         */
-       vd->vdev_remove_wanted = B_TRUE;
-       spa_async_request(vd->vdev_spa, SPA_ASYNC_REMOVE);
+       SLIST_FOREACH(elem, priv, elems) {
+               vdev_t *vd = elem->vd;
+
+               vd->vdev_remove_wanted = B_TRUE;
+               spa_async_request(vd->vdev_spa, SPA_ASYNC_REMOVE);
+       }
 }
 
 static struct g_consumer *
@@ -265,21 +277,8 @@ vdev_geom_attach(struct g_provider *pp, 
                }
        }
 
-       /* 
-        * BUG: cp may already belong to a vdev.  This could happen if:
-        * 1) That vdev is a shared spare, or
-        * 2) We are trying to reopen a missing vdev and we are scanning by
-        *    guid.  In that case, we'll ultimately fail to open this consumer,
-        *    but not until after setting the private field.
-        * The solution is to:
-        * 1) Don't set the private field until after the open succeeds, and
-        * 2) Set it to a linked list of vdevs, not just a single vdev
-        */
-       cp->private = vd;
-       if (vd != NULL) {
+       if (vd != NULL)
                vd->vdev_tsd = cp;
-               vdev_geom_set_physpath(cp, /*do_null_update*/B_FALSE);
-       }
 
        cp->flags |= G_CF_DIRECT_SEND | G_CF_DIRECT_RECEIVE;
        return (cp);
@@ -289,16 +288,12 @@ static void
 vdev_geom_detach(struct g_consumer *cp, boolean_t open_for_read)
 {
        struct g_geom *gp;
-       vdev_t *vd;
 
        g_topology_assert();
 
        ZFS_LOG(1, "Detaching from %s.",
            cp->provider && cp->provider->name ? cp->provider->name : "NULL");
 
-       vd = cp->private;
-       cp->private = NULL;
-
        gp = cp->geom;
        if (open_for_read)
                g_access(cp, -1, 0, -1);
@@ -324,16 +319,26 @@ static void
 vdev_geom_close_locked(vdev_t *vd)
 {
        struct g_consumer *cp;
+       struct consumer_priv_t *priv;
+       struct consumer_vdev_elem *elem, *elem_temp;
 
        g_topology_assert();
 
        cp = vd->vdev_tsd;
-       vd->vdev_tsd = NULL;
        vd->vdev_delayed_close = B_FALSE;
        if (cp == NULL)
                return;
 
        ZFS_LOG(1, "Closing access to %s.", cp->provider->name);
+       KASSERT(cp->private != NULL, ("%s: cp->private is NULL", __func__));
+       priv = (struct consumer_priv_t*)&cp->private;
+       vd->vdev_tsd = NULL;
+       SLIST_FOREACH_SAFE(elem, priv, elems, elem_temp) {
+               if (elem->vd == vd) {
+                       SLIST_REMOVE(priv, elem, consumer_vdev_elem, elems);
+                       g_free(elem);
+               }
+       }
 
        vdev_geom_detach(cp, B_TRUE);
 }
@@ -870,11 +875,27 @@ vdev_geom_open(vdev_t *vd, uint64_t *psi
                        cp = NULL;
                }
        }
+       if (cp != NULL) {
+               struct consumer_priv_t *priv;
+               struct consumer_vdev_elem *elem;
+
+               priv = (struct consumer_priv_t*)&cp->private;
+               if (cp->private == NULL)
+                       SLIST_INIT(priv);
+               elem = g_malloc(sizeof(*elem), M_WAITOK|M_ZERO);
+               elem->vd = vd;
+               SLIST_INSERT_HEAD(priv, elem, elems);
+       }
 
        /* Fetch initial physical path information for this device. */
-       if (cp != NULL)
+       if (cp != NULL) {
                vdev_geom_attrchanged(cp, "GEOM::physpath");
        
+               /* Set other GEOM characteristics */
+               vdev_geom_set_physpath(vd, cp, /*do_null_update*/B_FALSE);
+               vdev_geom_set_rotation_rate(vd, cp);
+       }
+
        g_topology_unlock();
        PICKUP_GIANT();
        if (cp == NULL) {
@@ -905,11 +926,6 @@ skip_open:
         */
        vd->vdev_nowritecache = B_FALSE;
 
-       /*
-        * Determine the device's rotation rate.
-        */
-       vdev_geom_set_rotation_rate(vd, cp);
-
        return (0);
 }
 
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