OpenZFS 6877 - zfs_rename_006_pos fails due to missing zvol snapshot device file

Authored by: Akash Ayare <aayare@delphix.com>
Reviewed by: John Kennedy <john.kennedy@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed-by: luozhengzheng <luo.zhengzheng@zte.com.cn>
Reviewed-by: yuxiang <guo.yong33@zte.com.cn>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>

Bug was caused due to a change in functionality. At some point, ZFS
snapshots no longer created associated device files which were being
used in the test. To resolve this issue, a clone of the snapshot can be
produced which will also create the expected device files; then, the
test will behave as it did historically.

OpenZFS-issue: https://www.illumos.org/issues/6877
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/2200f27
Closes #5275

Porting Notes:
- Hardcoded /dev/zvol/rdsk changed to $ZVOL_RDEVDIR for compatibility.
- Enabled in linux runfile.

tests/zfs-tests/tests/functional/cli_root/zfs_rename/zfs_rename_006_pos.ksh

@@ -24,6 +24,10 @@
 # Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 # Use is subject to license terms.
 #
+
+#
+# Copyright (c) 2015 by Delphix. All rights reserved.
+#
 . $STF_SUITE/include/libtest.shlib
 . $STF_SUITE/tests/functional/cli_root/zfs_rename/zfs_rename.kshlib
 
@@ -35,6 +39,7 @@
 #       1. Create a snapshot of volume.
 #       2. Rename volume snapshot to a new one.
 #	3. Rename volume to a new one.
+#       4. Create a clone of the snapshot.
 #       5. Verify that the rename operations are successful and zfs list can
 #	   list them.
 #
@@ -62,14 +67,18 @@ rename_dataset $vol ${vol}-new
 rename_dataset ${vol}-new@${snap}-new ${vol}-new@$snap
 rename_dataset ${vol}-new $vol
 
+clone=$TESTPOOL/${snap}_clone
+create_clone $vol@$snap $clone
+
 #verify data integrity
-for input in $VOL_R_PATH ${VOL_R_PATH}@$snap; do
+for input in $VOL_R_PATH $ZVOL_RDEVDIR/$clone; do
 	log_must eval "$DD if=$input of=$VOLDATA bs=$BS count=$CNT >/dev/null 2>&1"
 	if ! cmp_data $VOLDATA $DATA ; then
 		log_fail "$input gets corrupted after rename operation."
 	fi
 done
 
+destroy_clone $clone
 log_must $ZFS destroy $vol@$snap
 
 log_pass "'zfs rename' can rename volume snapshot as expected."