linux-kernel - [ 086/115] LOCKD: Ensure that nlmclnt_block resets block->b

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Message-Id: <20130506203104.432400899@linuxfoundation.org>
Date:	Mon,  6 May 2013 13:45:22 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Marc Eshel <eshel@...ibm.com>,
	Trond Myklebust <Trond.Myklebust@...app.com>
Subject: [ 086/115] LOCKD: Ensure that nlmclnt_block resets block->b_status after a server reboot

3.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Trond Myklebust <Trond.Myklebust@...app.com>

commit 1dfd89af8697a299e7982ae740d4695ecd917eef upstream.

After a server reboot, the reclaimer thread will recover all the existing
locks. For locks that are blocked, however, it will change the value
of block->b_status to nlm_lck_denied_grace_period in order to signal that
they need to wake up and resend the original blocking lock request.

Due to a bug, however, the block->b_status never gets reset after the
blocked locks have been woken up, and so the process goes into an
infinite loop of resends until the blocked lock is satisfied.

Reported-by: Marc Eshel <eshel@...ibm.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@...app.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/lockd/clntlock.c |    3 +++
 fs/lockd/clntproc.c |    3 ---
 2 files changed, 3 insertions(+), 3 deletions(-)

--- a/fs/lockd/clntlock.c
+++ b/fs/lockd/clntlock.c
@@ -144,6 +144,9 @@ int nlmclnt_block(struct nlm_wait *block
 			timeout);
 	if (ret < 0)
 		return -ERESTARTSYS;
+	/* Reset the lock status after a server reboot so we resend */
+	if (block->b_status == nlm_lck_denied_grace_period)
+		block->b_status = nlm_lck_blocked;
 	req->a_res.status = block->b_status;
 	return 0;
 }
--- a/fs/lockd/clntproc.c
+++ b/fs/lockd/clntproc.c
@@ -550,9 +550,6 @@ again:
 		status = nlmclnt_block(block, req, NLMCLNT_POLL_TIMEOUT);
 		if (status < 0)
 			break;
-		/* Resend the blocking lock request after a server reboot */
-		if (resp->status ==  nlm_lck_denied_grace_period)
-			continue;
 		if (resp->status != nlm_lck_blocked)
 			break;
 	}


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