[PATCH] staging: erofs: support bmap

[Chao Yu]

On 2019/7/16 15:37, Gao Xiang wrote:
> 
> 
> On 2019/7/16 15:35, Chao Yu wrote:
>> Hi Xiang,
>>
>> On 2019/7/16 15:19, Gao Xiang wrote:
>>> Hi Chao,
>>>
>>> On 2019/7/16 15:05, Chao Yu wrote:
>>>> Add erofs_bmap() to support FIBMAP ioctl on flatmode inode.
>>>>
>>>> Signed-off-by: Chao Yu <yuchao0 at huawei.com>
>>>> ---
>>>>  drivers/staging/erofs/data.c | 29 +++++++++++++++++++++++++++++
>>>>  1 file changed, 29 insertions(+)
>>>>
>>>> diff --git a/drivers/staging/erofs/data.c b/drivers/staging/erofs/data.c
>>>> index fbce71403d87..03da57f04347 100644
>>>> --- a/drivers/staging/erofs/data.c
>>>> +++ b/drivers/staging/erofs/data.c
>>>> @@ -308,9 +308,38 @@ static int erofs_raw_access_readpages(struct file *filp,
>>>>  	return iomap_readpages(mapping, pages, nr_pages, &erofs_iomap_ops);
>>>>  }
>>>>  
>>>> +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;
>>>> +
>>>> +	if (is_inode_flat_inline(inode))
>>>> +		return 0;
>>>
>>> could we support flat_inline as well? some difficulty on this?
>>
>> I think we can support partial of this on inline inode, e.g.:
>>
>> [0, 4k] mapped
>> [4k, 5k] inline
>>
>> We can find and return the physical block address for first block, but for last
>> block locating in metadata, we should just return 0 (0 indicate bmap has failed
>> to get mapped block address).
> 
> I think that is fine (in the long term, FIEMAP is preferred of course.)

Right, I can take a look at fiemap() implementation.

Thanks,

> 
> Thanks,
> Gao Xiang
> .
>