linux-kernel - Re: [PATCH v4] erofs: avoid using generic_block

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Date:   Wed, 9 Dec 2020 19:39:41 +0800
From:   Gao Xiang <hsiangkao@...hat.com>
To:     Huang Jianan <huangjianan@...o.com>
Cc:     Chao Yu <yuchao0@...wei.com>, linux-erofs@...ts.ozlabs.org,
        zhangshiming@...o.com, guoweichao@...o.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] erofs: avoid using generic_block_bmap

Hi Jianan,

On Wed, Dec 09, 2020 at 06:08:41PM +0800, Chao Yu wrote:
> On 2020/12/9 10:39, Huang Jianan wrote:
> > iblock indicates the number of i_blkbits-sized blocks rather than
> > sectors.
> > 
> > In addition, considering buffer_head limits mapped size to 32-bits,
> > should avoid using generic_block_bmap.
> > 
> > Fixes: 9da681e017a3 ("staging: erofs: support bmap")
> > Signed-off-by: Huang Jianan <huangjianan@...o.com>
> > Signed-off-by: Guo Weichao <guoweichao@...o.com>

Could you send out an updated version? I might get a point to freeze
dev branch since it needs some time on linux-next....

Thanks,
Gao Xiang

> > ---
> >   fs/erofs/data.c | 30 ++++++++++--------------------
> >   1 file changed, 10 insertions(+), 20 deletions(-)
> > 
> > diff --git a/fs/erofs/data.c b/fs/erofs/data.c
> > index 347be146884c..d6ea0a216b57 100644
> > --- a/fs/erofs/data.c
> > +++ b/fs/erofs/data.c
> > @@ -312,36 +312,26 @@ static void erofs_raw_access_readahead(struct readahead_control *rac)
> >   		submit_bio(bio);
> >   }
> > -static int erofs_get_block(struct inode *inode, sector_t iblock,
> > -			   struct buffer_head *bh, int create)
> > -{
> > -	struct erofs_map_blocks map = {
> > -		.m_la = iblock << 9,
> > -	};
> > -	int err;
> > -
> > -	err = erofs_map_blocks(inode, &map, EROFS_GET_BLOCKS_RAW);
> > -	if (err)
> > -		return err;
> > -
> > -	if (map.m_flags & EROFS_MAP_MAPPED)
> > -		bh->b_blocknr = erofs_blknr(map.m_pa);
> > -
> > -	return err;
> > -}
> > -
> >   static sector_t erofs_bmap(struct address_space *mapping, sector_t block)
> >   {
> >   	struct inode *inode = mapping->host;
> > +	struct erofs_map_blocks map = {
> > +		.m_la = blknr_to_addr(block),
> > +	};
> > +	sector_t blknr = 0;
> 
> It could be removed?
> 
> >   	if (EROFS_I(inode)->datalayout == EROFS_INODE_FLAT_INLINE) {
> >   		erofs_blk_t blks = i_size_read(inode) >> LOG_BLOCK_SIZE;
> >   		if (block >> LOG_SECTORS_PER_BLOCK >= blks)
> > -			return 0;
> 
> return 0;
> 
> > +			goto out;
> >   	}
> > -	return generic_block_bmap(mapping, block, erofs_get_block);
> > +	if (!erofs_map_blocks(inode, &map, EROFS_GET_BLOCKS_RAW))
> > +		blknr = erofs_blknr(map.m_pa);
> 
> return erofs_blknr(map.m_pa);
> 
> > +
> > +out:
> > +	return blknr;
> 
> return 0;
> 
> Anyway, LGTM.
> 
> Reviewed-by: Chao Yu <yuchao0@...wei.com>
> 
> Thanks,
> 
> >   }
> >   /* for uncompressed (aligned) files and raw access for other files */
> > 
>