[PATCH] erofs: introduce nolargefolio mount option

[Gao Xiang]

On 2026/3/10 14:43, Chao Yu wrote:
> Xiang,
> 
> On 3/9/26 11:03, Gao Xiang wrote:
>> Hi Chao,
>>
>> (+cc -fsdevel, willy, Jan kara)
>>
>> On 2026/3/9 10:30, Chao Yu wrote:
>>> This patch introduces a new mount option 'nolargefolio' for EROFS.
>>> When this option is specified, large folio will be disabled by
>>> default for all inodes, this option can be used for environments
>>> where large folio resources are limited, it's necessary to only
>>> let specified user to allocate large folios on demand.
>>
>> For this kind of options, I think more real backgrounds
>> about avoiding high-order allocations are needed in the
>> commit message (at least for later reference) also like
>> what I observed in:
>> https://android-review.googlesource.com/c/kernel/common/+/3877981
> 
> Basically, the background is about contention scenario on large folio allocation,
> it's among multiple users including EROFS in Android-system, as it's related to
> internal scene of product, so I can not provide more details now, I'm sorry
> about that, but I'm glad to discuss based on the background and pain point once
> if I can share more, let's see. :)

Understood, but I think it's hard to justify an upstream
solution without a public load for discussion.  Anyway,
I can imagine some real workloads which large folios could
cause unnecessary pressure since I once worked for Android,
but I think others need an explicit one anyway to justify
this.

As Matthew and Jan mentioned, it's hard to add a per-fs
knob like this.  If it's Android-specific and no possible
public infos, I suggest leaving the changes Android
downstream for now, until the workloads can be made public.

Thanks,
Gao Xiang