Re: [PATCH v3] erofs: fix file handle encoding for 64-bit NIDs

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

On 2025/5/7 09:53, Hongbo Li wrote:
> 
> 
> On 2025/5/6 23:10, Gao Xiang wrote:
>> Hi Hongbo,
>>
>> On 2025/4/29 21:42, Hongbo Li wrote:
>>> In erofs, the inode number has the location information of
>>> files. The default encode_fh uses the ino32, this will lack
>>> of some information when the file is too big. So we need
>>> the internal helpers to encode filehandle.
>>
>> EROFS uses NID to indicate the on-disk inode offset, which can
>> exceed 32 bits. However, the default encode_fh uses the ino32,
>> thus it doesn't work if the image is large than 128GiB.
>>
> Thanks for helping me correct my description.
> 
> Here, an image larger than 128GiB won't trigger NID reversal. It requires a 128GiB file inside, and the NID of the second file may exceed U32 during formatting. So here can we change it to "However, the default encode_fh uses the ino32, thus it may not work if there exist a file which is large than 128GiB." ?

Why? Currently EROFS doesn't arrange inode metadata
together, but close to its data (or its directory)
if possible for data locality.

So NIDs can exceed 32-bit for images larger than
128 GiB.

Thanks,
Gao Xiang

> 
> Thanks,
> Hongbo
>