From stable-bounces@linux.kernel.org  Tue May 15 20:55:43 2007
From: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
To: stable@kernel.org
Date: Tue, 15 May 2007 22:53:36 -0500
Message-Id: <1179287616.8339.8.camel@kleikamp.austin.ibm.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
Subject: JFS: Fix race waking up jfsIO kernel thread

It's possible for a journal I/O request to be added to the log_redrive
queue and the jfsIO thread to be awakened after the thread releases
log_redrive_lock but before it sets its state to TASK_INTERRUPTIBLE.

The jfsIO thread should set the state before giving up the spinlock, so
the waking thread will really wake it.

Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
 fs/jfs/jfs_logmgr.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
--- linux-2.6.21.1.orig/fs/jfs/jfs_logmgr.c
+++ linux-2.6.21.1/fs/jfs/jfs_logmgr.c
@@ -2354,12 +2354,13 @@ int jfsIOWait(void *arg)
 			lbmStartIO(bp);
 			spin_lock_irq(&log_redrive_lock);
 		}
-		spin_unlock_irq(&log_redrive_lock);
 
 		if (freezing(current)) {
+			spin_unlock_irq(&log_redrive_lock);
 			refrigerator();
 		} else {
 			set_current_state(TASK_INTERRUPTIBLE);
+			spin_unlock_irq(&log_redrive_lock);
 			schedule();
 			current->state = TASK_RUNNING;
 		}