Re: ext4: cache all of an extent tree's leaf block upon reading

From: Theodore Ts'o
Date: Thu Sep 05 2013 - 15:08:55 EST


On Thu, Sep 05, 2013 at 11:14:57AM -0400, Dave Jones wrote:
> > So the only reason to add a line explicitly setting es_pblk to zero
> > would be to suppress a warning from some insufficiently smart static
> > code analysis tool. I didn't see a warning from gcc, but it's
> > possible that this is something which is causing Coverity or some
> > other code scanner heartburn.
>
> Yep, that's what picked it up. I'll add a 'not a bug' annotation to stop
> it getting flagged again. This was the only ext* issue that Coverity
> picked up from yesterdays merge btw, which I guess is good news ;)

Indeed.

Hmm... I could add a new inline function
"ext4_es_store_pblock_status()" which sets both parts of the es_pblk
word at once, and which doesn't depend looking at its original value
at all. I doubt we would never measure a difference in performance,
but in theory it would be more efficient. And if it eliminates a
potential static code analysis complaint, maybe the two justifications
is good enough to add the new function.

Thanks for checking the coverity results!!

- Ted
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