Re: [PATCH v2] erofs: fix file-backed mounts over FUSE

[Gao Xiang <hsiangkao@linux.alibaba.com>]

On 2024/11/15 00:18, Al Viro wrote:
> On Thu, Nov 14, 2024 at 05:01:09PM +0800, Gao Xiang wrote:
>> --- a/fs/erofs/data.c
>> +++ b/fs/erofs/data.c
>> @@ -38,7 +38,9 @@ void *erofs_bread(struct erofs_buf *buf, erofs_off_t offset,
>>   	}
>>   	if (!folio || !folio_contains(folio, index)) {
>>   		erofs_put_metabuf(buf);
>> -		folio = read_mapping_folio(buf->mapping, index, NULL);
>> +		folio = buf->file ? read_mapping_folio(buf->file->f_mapping,
>> +					index, buf->file) :
>> +			read_mapping_folio(buf->mapping, index, NULL);
>>   		if (IS_ERR(folio))
>>   			return folio;
>>   	}
>> @@ -61,8 +63,8 @@ void erofs_init_metabuf(struct erofs_buf *buf, struct super_block *sb)
>>   {
>>   	struct erofs_sb_info *sbi = EROFS_SB(sb);
>>   
>> -	if (erofs_is_fileio_mode(sbi))
>> -		buf->mapping = file_inode(sbi->fdev)->i_mapping;
>> +	if (erofs_is_fileio_mode(sbi))	/* some fs like FUSE needs it */
>> +		buf->file = sbi->fdev;
> 
> Would be easier to set *both* ->mapping and ->file at that point, so that
> erofs_bread() would just have read_mapping_folio(buf->mapping, index, buf->file),
> unconditionally...

Ok, will do the next version.

Thanks,
Gao Xiang