staging: lustre: llite: fix ll_statahead_thread() problems on failure

When ll_prep_md_op_data() fails, ll_statahead_thread() does not
release reference of sai and parent dentry. It does not wake
up parent thread either. This patch fixes these problems.
Signed-off-by: Li Xi <lixi@ddn.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5274
Reviewed-on: http://review.whamcloud.com/10940Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Lai Siyao <lai.siyao@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/llite/statahead.c

@@ -1050,8 +1050,10 @@ static int ll_statahead_thread(void *arg)
 
 	op_data = ll_prep_md_op_data(NULL, dir, dir, NULL, 0, 0,
 				     LUSTRE_OPC_ANY, dir);
-	if (IS_ERR(op_data))
-		return PTR_ERR(op_data);
+	if (IS_ERR(op_data)) {
+		rc = PTR_ERR(op_data);
+		goto out_put;
+	}
 
 	op_data->op_max_pages = ll_i2sbi(dir)->ll_md_brw_pages;
 
@@ -1239,7 +1241,9 @@ static int ll_statahead_thread(void *arg)
 		}
 	}
 out:
+	ll_dir_chain_fini(&chain);
 	ll_finish_md_op_data(op_data);
+out_put:
 	if (sai->sai_agl_valid) {
 		spin_lock(&plli->lli_agl_lock);
 		thread_set_flags(agl_thread, SVC_STOPPING);
@@ -1255,7 +1259,6 @@ static int ll_statahead_thread(void *arg)
 		/* Set agl_thread flags anyway. */
 		thread_set_flags(&sai->sai_agl_thread, SVC_STOPPED);
 	}
-	ll_dir_chain_fini(&chain);
 	spin_lock(&plli->lli_sa_lock);
 	if (!list_empty(&sai->sai_entries_received)) {
 		thread_set_flags(thread, SVC_STOPPING);
@@ -1272,9 +1275,9 @@ static int ll_statahead_thread(void *arg)
 	wake_up(&sai->sai_waitq);
 	wake_up(&thread->t_ctl_waitq);
 	ll_sai_put(sai);
-	dput(parent);
 	CDEBUG(D_READA, "statahead thread stopped: sai %p, parent %pd\n",
 	       sai, parent);
+	dput(parent);
 	return rc;
 }