Re: [f2fs-dev] [PATCH 2/3] f2fs: introduce FITRIM in f2fs_ioctl

[Jaegeuk Kim]

On Tue, Sep 30, 2014 at 02:01:58PM +0800, Chao Yu wrote:
> > -----Original Message-----
> > From: Jaegeuk Kim [mailto:jaegeuk@xxxxxxxxxx]
> > Sent: Tuesday, September 23, 2014 12:53 PM
> > To: linux-kernel@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx;
> > linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
> > Cc: Jaegeuk Kim
> > Subject: [f2fs-dev] [PATCH 2/3] f2fs: introduce FITRIM in f2fs_ioctl
> > 
> > This patch introduces FITRIM in f2fs_ioctl.
> > In this case, f2fs will issue small discards and prefree discards as many as
> > possible for the given area.
> > 
> > Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> 
> Looks good!
> 
> Reviewed-by: Chao Yu <chao2.yu@xxxxxxxxxxx>
> 
> > +
> >  	/* zero block will be discarded through the prefree list */
> >  	if (!se->valid_blocks || se->valid_blocks == max_blocks)
> >  		return;
> > 
> > +	dmap = kzalloc(SIT_VBLOCK_MAP_SIZE, GFP_KERNEL);
> 
> We can afford 64 bytes allocation in stack, how about altering dmap to a local
> array to reduce memory pressure at that moment and avoid delay of allocation?

It's not a big deal.
Fixed.
Thanks,

> 
> > +	if (!dmap)
> > +		return;
> > +
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