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Subject: Re: [PATCH v4] erofs: avoid using generic_block_bmap
To:     Gao Xiang <hsiangkao@redhat.com>, Chao Yu <yuchao0@huawei.com>
Cc:     linux-erofs@lists.ozlabs.org, zhangshiming@oppo.com,
        guoweichao@oppo.com, linux-kernel@vger.kernel.org
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From:   Huang Jianan <huangjianan@oppo.com>
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Date:   Wed, 9 Dec 2020 19:54:05 +0800
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Thanks for review, i will update it soon.

在 2020/12/9 19:39, Gao Xiang 写道:
> 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@oppo.com>
>>> Signed-off-by: Guo Weichao <guoweichao@oppo.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@huawei.com>
>>
>> Thanks,
>>
>>>    }
>>>    /* for uncompressed (aligned) files and raw access for other files */
>>>