File system query

Alexandru Juncu alexj at
Tue Jun 25 02:56:43 EDT 2013

On 23 June 2013 17:18, Dibyayan Chakraborty <dib.coolguy at> wrote:
> Hi,
> I came by a really weird macro code in linux/jbd.h which is
> BUFFER_TRACE(bh,info)  do{} while(0).
> Please explain the necessity of this.

I'm not familiar with that specific code, but it looks like a "no op"
macro. Maybe the definition is the to ensure backwards or forward
compatibility for the code that calls the macro , but now it doesn't
do anything.

For the reason why there is a while(0), instead of just no code there,
take a look at this:

Hope this helps.

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