Re: md: raid 10 supports TRIM

[NeilBrown <neilb@suse.de>]

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On Fri, 17 Aug 2012 12:00:15 +0800 Shaohua Li <shli@kernel.org> wrote:

> > 
> > This is a semi-automatic email about new static checker warnings.
> > 
> > The patch d61b764704ca: "md: raid 10 supports TRIM" from Aug 15,
> > 2012, leads to the following Smatch complaint:
> > 
> > drivers/md/raid10.c:3510 run()
> > 	 warn: variable dereferenced before check 'mddev->queue' (see line 3508)
> > 
> > drivers/md/raid10.c
> >   3507	
> >   3508		blk_queue_max_discard_sectors(mddev->queue, mddev->chunk_sectors);
> >                                               ^^^^^^^^^^^^
> > New dereference.
> > 
> >   3509		chunk_size = mddev->chunk_sectors<<  9;
> >   3510		if (mddev->queue) {
> >                     ^^^^^^^^^^^^
> > Old check.
> > 
> >   3511			blk_queue_io_min(mddev->queue, chunk_size);
> >   3512			if (conf->geo.raid_disks % conf->geo.near_copies)
> 
> Thanks! Neil, this is the updated patch. If you prefer a fix against original
> patch, please let me know. 
> 
> 
> Subject: md: raid 10 supports TRIM
> 
> This makes md raid 10 support TRIM.
> If one disk supports discard and another not, or one has discard_zero_data and
> another not, there could be inconsistent between data from such disks. But this
> should not matter, discarded data is useless. This will add extra copy in rebuild
> though.
> 
> Signed-off-by: Shaohua Li <shli@fusionio.com>


Applied, thanks.

NeilBrown

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