Update rsend_014_pos and send-c_volume test cases

The send-c_volume test case has been observed to occasionally
fail on 32-bit systems.  Until this issue is fully understood
disable this test case.

The rsend_014_pos test case can occasionally fail due to an
EBUSY during export.  This can lead to subsequent test failures.
Resolve the issue by retrying the export on EBUSY.  Additionally,
remove the gratuitous use of eval.

Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #6088

tests/zfs-tests/tests/functional/rsend/rsend_014_pos.ksh

@@ -33,8 +33,8 @@ verify_runnable "both"
 log_assert "zfs send will work on filesystems and volumes in a read-only pool."
 log_onexit cleanup_pool $POOL2
 
-log_must eval "zpool export $POOL"
-log_must eval "zpool import -o readonly=on $POOL"
+log_must zpool export $POOL
+log_must zpool import -o readonly=on $POOL
 log_must eval "zfs send -R $POOL@final > $BACKDIR/pool-final-R"
 log_must eval "zfs receive -d -F $POOL2 < $BACKDIR/pool-final-R"
 
@@ -46,9 +46,8 @@ log_must cleanup_pool $POOL2
 
 log_must eval "zfs send -R $POOL/$FS@final > $BACKDIR/fs-final-R"
 log_must eval "zfs receive -d $POOL2 < $BACKDIR/fs-final-R"
-block_device_wait
-log_must eval "zpool export $POOL"
-log_must eval "zpool import $POOL"
+log_must_busy zpool export $POOL
+log_must zpool import $POOL
 
 dstds=$(get_dst_ds $POOL/$FS $POOL2)
 log_must cmp_ds_subs $POOL/$FS $dstds

tests/zfs-tests/tests/functional/rsend/send-c_volume.ksh

@@ -35,6 +35,11 @@ function cleanup
 
 verify_runnable "both"
 
+# See issue: https://github.com/zfsonlinux/zfs/issues/6087
+if is_32bit; then
+	log_unsupported "Test case occasionally fails on 32-bit systems"
+fi
+
 log_assert "Verify compressed send works with volumes"
 log_onexit cleanup