linux-kernel - RE: [PATCH 1/4] f2fs: limit b_size of mapped bh in f2fs_map

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Message-id: <003301d065ef$c78b03f0$56a10bd0$@samsung.com>
Date:	Tue, 24 Mar 2015 13:02:04 +0800
From:	Chao Yu <chao2.yu@...sung.com>
To:	'Jaegeuk Kim' <jaegeuk@...nel.org>
Cc:	'Changman Lee' <cm224.lee@...sung.com>,
	linux-f2fs-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org
Subject: RE: [PATCH 1/4] f2fs: limit b_size of mapped bh in f2fs_map_bh

Hi Jaegeuk,

> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk@...nel.org]
> Sent: Tuesday, March 24, 2015 12:42 PM
> To: Chao Yu
> Cc: Changman Lee; linux-f2fs-devel@...ts.sourceforge.net; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH 1/4] f2fs: limit b_size of mapped bh in f2fs_map_bh
> 
> Hi Chao,
> 
> On Mon, Mar 23, 2015 at 10:28:00AM +0800, Chao Yu wrote:
> > Map bh over max size which caller defined is not needed, limit it in
> > f2fs_map_bh.
> >
> > Signed-off-by: Chao Yu <chao2.yu@...sung.com>
> > ---
> >  fs/f2fs/data.c | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > index f0a18a0..a99bc7f 100644
> > --- a/fs/f2fs/data.c
> > +++ b/fs/f2fs/data.c
> > @@ -255,15 +255,16 @@ static void f2fs_map_bh(struct super_block *sb, pgoff_t pgofs,
> >  			struct extent_info *ei, struct buffer_head *bh_result)
> >  {
> >  	unsigned int blkbits = sb->s_blocksize_bits;
> > +	unsigned int maxblocks = bh_result->b_size >> blkbits;
> >  	size_t count;
> >
> >  	clear_buffer_new(bh_result);
> >  	map_bh(bh_result, sb, ei->blk + pgofs - ei->fofs);
> >  	count = ei->fofs + ei->len - pgofs;
> > -	if (count < (UINT_MAX >> blkbits))
> > -		bh_result->b_size = (count << blkbits);
> > +	if (count > maxblocks)
> > +		bh_result->b_size = maxblocks << blkbits;
> >  	else
> > -		bh_result->b_size = UINT_MAX;
> > +		bh_result->b_size = count << blkbits;
> 
> How about using min()?

Better, I will do it. :)

Thanks,

> 
> Thanks,
> 
> >  }
> >
> >  static bool lookup_extent_info(struct inode *inode, pgoff_t pgofs,
> > --
> > 2.3.3

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