Re: [xfs-masters] Re: mm snapshot broken-out-2007-04-11-02-24.tar.gz uploaded

[Timothy Shimmin <tes@sgi.com>]

> There's a couple of different ways I can see to fix the problem -
> the first is to not reference the buffer in xlog_iodone() after
> running the callbacks that may trigger it being freed. I'd prfer to
> see if this fixes the problem before having to do more invasive
> surgery.  Can you try the patch below to see if it fixes the
> problem?
>
>  fs/xfs/xfs_log.c |   11 ++++-------
>  1 file changed, 4 insertions(+), 7 deletions(-)
>
> Index: 2.6.x-xfs-new/fs/xfs/xfs_log.c
> ===================================================================
> --- 2.6.x-xfs-new.orig/fs/xfs/xfs_log.c	2007-04-03 09:09:36.000000000 +1000
> +++ 2.6.x-xfs-new/fs/xfs/xfs_log.c	2007-04-16 11:40:21.655306665 +1000
> @@ -988,14 +988,11 @@ xlog_iodone(xfs_buf_t *bp)
>  	} else if (iclog->ic_state & XLOG_STATE_IOERROR) {
>  		aborted = XFS_LI_ABORTED;
>  	}
> +	/* log I/O is always issued ASYNC, so we should see that here */

I guess this is a left over because at a prior time
xlog_sync() took an extra flags param (which could have XFS_LOG_SYNC set)
which could do a SYNC write of the iclog.
IIRC, we took this extra param out because nobody was ever calling with
it set for xlog_sync().

> +	WARN_ON(!(XFS_BUF_ISASYNC(bp)));
>  	xlog_state_done_syncing(iclog, aborted);
> -	if (!(XFS_BUF_ISASYNC(bp))) {
> -		/*
> -		 * Corresponding psema() will be done in bwrite().  If we don't
> -		 * vsema() here, panic.
> -		 */
> -		XFS_BUF_V_IODONESEMA(bp);
> -	}
> +	/* do not reference bp here - it may have been freed during unmount */
> +
>  }	/* xlog_iodone */
>
>  /*

--Tim


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