Re: [Lsf-pc] [LSF/MM/BPF TOPIC] Where is fuse going? API cleanup, restructuring and more

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

On 2026/3/23 18:14, Jan Kara wrote:
> Hi Gao!
> 
> On Mon 23-03-26 18:05:17, Gao Xiang wrote:
>> On 2026/3/23 17:43, Jan Kara wrote:
>>> And yes, when you have immutable filesystem, things are much simpler
>>> because the data structures and algorithms can be much simpler and as you
>>> wrote a lot of these inconsistencies don't matter (at least for the
>>> kernel). But once you add ability to modify the filesystem - here I don't
>>> think it matters whether through CoW or other means - things get
>>> complicated quickly and it gets much more complex to make your code
>>> resilient to all kinds of inconsistencies...
>>
>> I only consider the COW approach using OverlayFS for example,
>> it just copies up (meta)data into another filesystem (the
>> semantics is just like copy the file in the userspace) and
>> the immutable filesystem image won't change in any case.
>>
>> Overlayfs write goes through normal user write and the
>> writable filesystem is consistent, so I don't think it does
>> matter.  Or am I missing something? (e.g could you point
>> out some case which OverlayFS cannot handle properly?)
> 
> No, you are correct. For the usecases where immutable fs + overlayfs +
> empty initial writeable filesystem works, this is a safe design.

(Just BTW, not only to empty initial writable filesystems
  but also to previously mounted, consistent trusted local
  filesystems used as upper layers, as they are typical
  cases for containers.)

Thanks,
Gao Xiang

> 
> 								Honza