[PATCH] Check if AIL has been started before stopping it

[PATCH] Check if AIL has been started before stopping it

[Lachlan McIlroy]

A failure during mount can result in shutting down the AIL when
it may not have been started up yet.

Index: xfs-patch/fs/xfs/linux-2.6/xfs_super.c
===================================================================
--- xfs-patch.orig/fs/xfs/linux-2.6/xfs_super.c
+++ xfs-patch/fs/xfs/linux-2.6/xfs_super.c
@@ -913,7 +913,8 @@ void
  xfsaild_stop(
  	struct xfs_ail	*ailp)
  {
-	kthread_stop(ailp->xa_task);
+	if (ailp->xa_task)
+		kthread_stop(ailp->xa_task);
  }


Index: xfs-patch/fs/xfs/xfs_trans_ail.c
===================================================================
--- xfs-patch.orig/fs/xfs/xfs_trans_ail.c
+++ xfs-patch/fs/xfs/xfs_trans_ail.c
@@ -598,8 +598,10 @@ xfs_trans_ail_destroy(
  {
  	struct xfs_ail	*ailp = mp->m_ail;

-	xfsaild_stop(ailp);
-	kmem_free(ailp);
+	if (ailp) {
+		xfsaild_stop(ailp);
+		kmem_free(ailp);
+	}
  }

  /*

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Re: [PATCH] Check if AIL has been started before stopping it

[Christoph Hellwig]

On Tue, Feb 10, 2009 at 12:27:06PM +1100, Lachlan McIlroy wrote:
> A failure during mount can result in shutting down the AIL when
> it may not have been started up yet.

The right fix is to not call xfsaild_stop in that case.

Something like this should fix your problem:


Index: xfs/fs/xfs/xfs_log.c
===================================================================
--- xfs.orig/fs/xfs/xfs_log.c	2009-02-10 11:10:41.804069754 +0100
+++ xfs/fs/xfs/xfs_log.c	2009-02-10 11:10:58.339943990 +0100
@@ -575,7 +575,7 @@ xfs_log_mount(
 	error = xfs_trans_ail_init(mp);
 	if (error) {
 		cmn_err(CE_WARN, "XFS: AIL initialisation failed: error %d", error);
-		goto error;
+		goto out_free_log;
 	}
 	mp->m_log->l_ailp = mp->m_ail;
 
@@ -595,20 +595,22 @@ xfs_log_mount(
 			mp->m_flags |= XFS_MOUNT_RDONLY;
 		if (error) {
 			cmn_err(CE_WARN, "XFS: log mount/recovery failed: error %d", error);
-			goto error;
+			goto out_destroy_ail;
 		}
 	}
 
 	/* Normal transactions can now occur */
 	mp->m_log->l_flags &= ~XLOG_ACTIVE_RECOVERY;
 
-	/* End mounting message in xfs_log_mount_finish */
 	return 0;
-error:
-	xfs_log_unmount_dealloc(mp);
+
+out_destroy_ail:
+	xfs_trans_ail_destroy(mp);
+out_free_log:
+	xlog_dealloc_log(mp->m_log);
 out:
 	return error;
-}	/* xfs_log_mount */
+}
 
 /*
  * Finish the recovery of the file system.  This is separate from

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Re: [PATCH] Check if AIL has been started before stopping it

[Dave Chinner]

On Tue, Feb 10, 2009 at 12:27:06PM +1100, Lachlan McIlroy wrote:
> A failure during mount can result in shutting down the AIL when
> it may not have been started up yet.

The ail init/destroy are supposed to be called symmetrically. if the
destroy is being called when the init has not been run or completed,
then the bug is at the caller.

Reading between the lines of your brief description of the problem,
xfs_trans_ail_init() has failed with ENOMEM, and that has called
xfs_trans_ail_destroy() erroneously. The correct fix is to call
xlog_dealloc_log() when xfs_trans_ail_init() fails, not
xfs_log_unmount_dealloc() which calls xfs_trans_ail_destroy() before
calling xlog_dealloc_log().

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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