linux-kernel - [PATCH] ocfs2: insure dlm lockspace is created by kernel module

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Date:	Fri, 20 May 2016 16:12:20 +0800
From:	Gang He <ghe@...e.com>
To:	mfasheh@...e.com, rgoldwyn@...e.de, ghe@...e.com
Cc:	linux-kernel@...r.kernel.org, ocfs2-devel@....oracle.com,
	akpm@...ux-foundation.org
Subject: [PATCH] ocfs2: insure dlm lockspace is created by kernel module

This patch will be used to insure the dlm lockspace is created by kernel
module when mounting a ocfs2 file system. There are two ways to create a
lockspace, from user space and kernel space, but the same name lockspaces
probably have different lvblen lengths/flags.
To avoid this mix using, we add one more flag DLM_LSFL_NEWEXCL, it will make
sure the dlm lockspace is created by kernel module when mounting.
Secondly, if a user space program (ocfs2-tools) is running on a file system,
the user tries to mount this file system in the cluster, DLM module will return
a -EEXIST or -EPROTO errno, we should give the user a obvious error message,
then, the user can let that user space tool exit before mounting the file
system again.

Signed-off-by: Gang He <ghe@...e.com>
---
 fs/ocfs2/stack_user.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/fs/ocfs2/stack_user.c b/fs/ocfs2/stack_user.c
index ced70c8..c9e828e 100644
--- a/fs/ocfs2/stack_user.c
+++ b/fs/ocfs2/stack_user.c
@@ -1007,10 +1007,17 @@ static int user_cluster_connect(struct ocfs2_cluster_connection *conn)
 	lc->oc_type = NO_CONTROLD;

 	rc = dlm_new_lockspace(conn->cc_name, conn->cc_cluster_name,
-			       DLM_LSFL_FS, DLM_LVB_LEN,
+			       DLM_LSFL_FS | DLM_LSFL_NEWEXCL, DLM_LVB_LEN,
 			       &ocfs2_ls_ops, conn, &ops_rv, &fsdlm);
-	if (rc)
+	if (rc) {
+		if (rc == -EEXIST || rc == -EPROTO)
+			printk(KERN_ERR "ocfs2: Unable to create the "
+				"lockspace %s (%d), because a ocfs2-tools "
+				"program is running on this file system "
+				"with the same name lockspace\n",
+				conn->cc_name, rc);
 		goto out;
+	}

 	if (ops_rv == -EOPNOTSUPP) {
 		lc->oc_type = WITH_CONTROLD;
-- 
1.8.5.6