Date: Fri, 23 Apr 2010 08:27:02 -0700 (PDT)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Josef Bacik <josef@redhat.com>
cc: akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org,
       linux-kernel@vger.kernel.org, randy.dunlap@oracle.com
Subject: Re: [PATCH] cleanup block based fiemap
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On Fri, 23 Apr 2010, Josef Bacik wrote:
> 
> __generic_block_fiemap is called by generic_block_fiemap which takes the
> i_mutex.  The only reason we have __generic_block_fiemap is because gfs2 needs
> to do its own locking magic before we go calling get_block.  The idea is that
> the file size doesn't change while we're doing this.

Ok, maybe just a comment then..

> As for reading the size several times, I can read it once and store it in a
> local variable if you prefer, but theres no way to know if len is smaller than
> the size or not, which is why I'm constantly doing i_size_read().  If thats what
> you would prefer I can do that, just let me know.

.. or a comment _and_ a "read size once into a variable". Not a big deal, 
it just wasn't entirely clear to me and I hadn't checked the callchain.

> > Issue #2: "blk_to_logical(inode, 0)"? WTF? Since when has shifting zero 
> > ever resulted in anything interesting or relevant? There's at least two of 
> > those things.
> > 
> 
> Umm, yeah I'm sorry?  I have no idea why I did that.  I think its because I was
> getting the logical offset of the first block + size, which is just stupid
> because the logical offset is 0, so all I can say is I'm sorry that me a year
> ago was alot dumber than me now :).  Thanks,

Ok, fix that, and I think the patch will be a clear improvement.

		Linus
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