[PATCH 3/3] xfs: event tracing support

[Alex Elder]

Christoph Hellwig wrote:
> On Mon, Dec 14, 2009 at 04:40:36PM -0600, Alex Elder wrote:
>> There is a problem with trace_xfs_bmap_insert().  It is
>> referenced once (in xfs_bmap_trace_exlist()), but never defined.
>> The reference does not match the prototype defined for the other bmap tracepoints either.
>> 
>> Rather than trying to figure out what you intended I thought I'd
>> give you a chance to offer a fix.  If you do, please just send me
>> an update of that portion of the code if possible.  Meanwhile
>> I've commented out that reference and am going to try to complete
>> my review of this patch shortly.
>> 
>> Details are in the excerpts below.  I didn't add any commentary,
>> I'm just calling attention to the code I'm referring to.
> 
> Yeah, that was some debug build that got missed in the last iteration of
> the patch.  Updated version below:

OK, this looks good.  Compared to the first time around, I gave
it a very cursory review.  But we'll get it in.

Signed-off-by: Alex Elder <aelder at sgi.com>

> Subject: xfs: event tracing support
> From: Christoph Hellwig <hch at lst.de>
> 
> Convert the old xfs tracing support that could only be used with the out
> of tree kdb and xfsidbg patches to use the generic event tracer.
> 
> To use it make sure CONFIG_EVENT_TRACING is enabled and then enable all
> xfs trace channels by:
> 
>    echo 1 > /sys/kernel/debug/tracing/events/xfs/enable
> 
> or alternatively enable single events by just doing the same in one
> event subdirectory, e.g.
> 
>    echo 1 > /sys/kernel/debug/tracing/events/xfs/xfs_ihold/enable
> 
> or set more complex filters, etc. In Documentation/trace/events.txt all

. . .