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

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Message-ID: <20130905151457.GA24177@redhat.com>
Date:	Thu, 5 Sep 2013 11:14:57 -0400
From:	Dave Jones <davej@...hat.com>
To:	"Theodore Ts'o" <tytso@....edu>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: ext4: cache all of an extent tree's leaf block upon reading

On Thu, Sep 05, 2013 at 10:53:34AM -0400, Theodore Ts'o wrote:

 > > ext4_es_store_pblock or's the pblk with the existing contents of the struct member.
 > > (albeit masked with ES_MASK)
 > > 
 > > Should there be a 
 > > 
 > > 	newes.es_pblk = 0;
 > > 
 > > up there too ?
 > 
 > The next line after ext4_es_store_pblock() is:
 > 
 >         ext4_es_store_status(&newes, status);
 > 
 > This will set remaining ES_WRITTEN | ES_UNWRITTEN... bits.
 > 
 > 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 ;)

	Dave

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