Stop upgrade thread at the end of 'zfs recv'

'zfs recv' could disown a living objset without calling
dmu_objset_disown(). This will cause the problem that the objset
would be released while upgrading thread is still running.

This patch calls dmu_objset_upgrade_stop() in dmu_recv_end().

ZoL-bug-id: #5295

Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>

include/sys/dmu_objset.h

@@ -181,6 +181,7 @@ void dmu_objset_evict(objset_t *os);
 void dmu_objset_do_userquota_updates(objset_t *os, dmu_tx_t *tx);
 void dmu_objset_userquota_get_ids(dnode_t *dn, boolean_t before, dmu_tx_t *tx);
 boolean_t dmu_objset_userused_enabled(objset_t *os);
+void dmu_objset_upgrade_stop(objset_t *os);
 int dmu_objset_userspace_upgrade(objset_t *os);
 boolean_t dmu_objset_userspace_present(objset_t *os);
 boolean_t dmu_objset_userobjused_enabled(objset_t *os);

module/zfs/dmu_objset.c

@@ -80,7 +80,6 @@ int dmu_rescan_dnode_threshold = 1 << DN_MAX_INDBLKSHIFT;
 static void dmu_objset_find_dp_cb(void *arg);
 
 static void dmu_objset_upgrade(objset_t *os, dmu_objset_upgrade_cb_t cb);
-static void dmu_objset_upgrade_stop(objset_t *os);
 
 void
 dmu_objset_init(void)
@@ -1124,7 +1123,7 @@ dmu_objset_upgrade(objset_t *os, dmu_objset_upgrade_cb_t cb)
 	mutex_exit(&os->os_upgrade_lock);
 }
 
-static void
+void
 dmu_objset_upgrade_stop(objset_t *os)
 {
 	mutex_enter(&os->os_upgrade_lock);

module/zfs/dmu_send.c

@@ -3347,6 +3347,11 @@ dmu_recv_new_end(dmu_recv_cookie_t *drc)
 int
 dmu_recv_end(dmu_recv_cookie_t *drc, void *owner)
 {
+	objset_t *os;
+
+	VERIFY0(dmu_objset_from_ds(drc->drc_ds, &os));
+	dmu_objset_upgrade_stop(os);
+
 	drc->drc_owner = owner;
 
 	if (drc->drc_newfs)