Re: [PATCH RFC] fs: xfs: Fix xfs_trans_read_buf event tracing

Brian Foster
2015-02-19T17:20:39Z

On Thu, Feb 19, 2015 at 06:54:33PM +0530, Pratyush Anand wrote:
> My root file system is xfs. As soon as I enable event for
> xfs_trans_read_buf `echo xfs:xfs_trans_read_buf >>
> /sys/kernel/debug/tracing/set_event`, I see a kernel panic.
>
> A little bit of debugging shows that bp->b_fspriv is NULL many a time
> when trace_xfs_trans_read_buf(bp->b_fspriv) is called.
>
> I do not have any idea about xfs filesystem. So, I am not sure, if it
> is expected to have bp->b_fspriv = NULL at this location.
>
> This patch fixes the issue, until we have a better fix.
>
> Signed-off-by: Pratyush Anand <panand@redhat.com>
> ---

A fix for this has been posted here:

http://oss.sgi.com/archives/xfs/2015-02/msg00101.html

Brian

> fs/xfs/xfs_trans_buf.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_trans_buf.c b/fs/xfs/xfs_trans_buf.c
> index 0a4d4ab6d9a9..0b67a20643bf 100644
> --- a/fs/xfs/xfs_trans_buf.c
> +++ b/fs/xfs/xfs_trans_buf.c
> @@ -329,7 +329,8 @@ xfs_trans_read_buf_map(
>
> if (tp)
> _xfs_trans_bjoin(tp, bp, 1);
> - trace_xfs_trans_read_buf(bp->b_fspriv);
> + if (bp->b_fspriv)
> + trace_xfs_trans_read_buf(bp->b_fspriv);
> *bpp = bp;
> return 0;
>
> --
> 2.1.0
>
> _______________________________________________
> xfs mailing list
> xfs@oss.sgi.com
> http://oss.sgi.com/mailman/listinfo/xfs