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

[Don Dutile]

On 02/19/2015 04:37 PM, Dave Chinner wrote:
> On Thu, Feb 19, 2015 at 12:20:28PM -0500, Brian Foster wrote:
>> 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 at redhat.com>
>>> ---
>>
>> A fix for this has been posted here:
>>
>> http://oss.sgi.com/archives/xfs/2015-02/msg00101.html
>
> It's already in the 3.20-rc0 kernel, and it was marked as a stable
> patch so should be fixed in the next 3.19 stable kernel.
>
We (RHELSA) are not tracking 3.19 stable; just rebased to 3.19-final (from -rc5).
But, you make me think we *should* track 3.19 stable now (our Beta kernel base).

> Cheers,
>
> Dave.
>