From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Woodhouse <dwmw2@infradead.org>
Subject: Re: [PATCH 2/5] [FAT] Let the block device know when sectors can
	be discarded
Date: Wed, 06 Aug 2008 22:37:49 +0100
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Cc: Jens Axboe <jens.axboe@oracle.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ric Wheeler <ricwheeler@gmail.com>,
	linux-fsdevel@vger.kernel.org, gilad@codefidence.com
To: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
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On Thu, 2008-08-07 at 04:10 +0900, OGAWA Hirofumi wrote:
> David Woodhouse <dwmw2@infradead.org> writes:
> 
> > On Thu, 2008-08-07 at 01:40 +0900, OGAWA Hirofumi wrote:
> >> Perhaps, after checking cluster-chain corruption is better. Thanks.
> >
> > That can be done, but not like that, I think. At the point you added the
> > blkdev_issue_discard() call, the value of 'cluster' has already changed.
> >
> > So if the chain being freed is clusters 10, 11 and 12, your version of
> > the patch will attempt to discard clusters 11, 12 and 0xFFFF (EOF).
> 
> +				     fat_clus_to_blknr(sbi, fatent.entry),
> 
> No, no. I used fatent.entry, not cluster.

Ah, OK. Sorry, I misread it :)

> > On Thu, 2008-08-07 at 02:14 +0900, OGAWA Hirofumi wrote:
> >> Ah, blkdev_issue_discard() assumes blocksize is 512bytes, um...
> >
> > Doesn't everything? I did consider using q->hardsect_size, but decided
> > that was probably the wrong thing to do. I don't know. Jens?
> 
> My point is fs-blocksize vs hard sector size.
> 
> In FAT patch, it's passing the number of fs-blocks, not number of hard
> sectors.
> 
> >> blkdev_issue_discard() takes bytes,
> >
> > -EPARSE. It takes sectors at the moment -- do you mean you _want_ it to
> > take bytes? 
> 
> Yes and no. I guess bytes or _fs_-blocksize is good interface for fs.

OK. I'll do the latter; thank you.

-- 
dwmw2