linux-kernel - Re: [PATCH 2/6] Adjust block device size after an online resize of a disk.

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Message-ID: <20080905175536.GD3795@skl-net.de>
Date:	Fri, 5 Sep 2008 19:55:36 +0200
From:	Andre Noll <maan@...temlinux.org>
To:	Andrew Patterson <andrew.patterson@...com>
Cc:	linux-scsi@...r.kernel.org, James.Bottomley@...senPartnership.com,
	linux-kernel@...r.kernel.org, viro@...iv.linux.org.uk,
	axboe@...nel.dk, andmike@...ux.vnet.ibm.com, mike.miller@...com,
	genanr@...phone.com, jmoyer@...hat.com
Subject: Re: [PATCH 2/6] Adjust block device size after an online resize of a disk.

On 09:36, Andrew Patterson wrote:
> On Fri, 2008-09-05 at 15:12 +0200, Andre Noll wrote:
> > On 14:27, Andrew Patterson wrote:
> > >  int revalidate_disk(struct gendisk *disk)
> > >  {
> > > +	struct block_device *bdev;
> > >  	int ret = 0;
> > >  
> > >  	if (disk->fops->revalidate_disk)
> > >  		ret = disk->fops->revalidate_disk(disk);
> > 
> > Maybe we should return early at this point if revalidate_disk()
> > failed or fops->revalidate_disk is NULL.
> 
> We won't run check_disk_size_change() if we return early here. So the
> question is would anyone ever make this call if they didn't have a
> revalidate_disk routine?

I'd say no. In case someone ever does, it seems natural to do nothing
and return early.

> > > +	bdev = bdget_disk(disk, 0);
> > > +	if (!bdev)
> > > +		return ret;
> > 
> > We might return success here even if bdev is NULL. OTOH, as the callers
> > of revalidate_disk() do not check the return value anyway (although at
> > least tapeblock_revalidate_disk() might return a negative value) it's
> > probably also an option to change the return type of revalidate_disk()
> > to void.
> > 
> 
> The revalidate_disk() wrapper tries to maintain compatibility with the
> current interface. It might make sense to change it given no one
> actually really seems to use the return value. I guess I am very wary
> about effectively changing the interface of the lower-level
> revalidate_disk() routines, at least in this particular patchset.

Agreed, that should be done later in a different patchset. It just
looked a bit odd to introduce a new function returning int with none
of its callers actually caring about the return value.

Thanks
Andre
-- 
The only person who always got his work done by Friday was Robinson Crusoe

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