UBI scrubbing behavior when readonly

[Zhihao Cheng]

在 2023/12/8 1:56, Chuck Meade 写道:
> Hello,
>
> Does UBI scrubbing (moving data to new PEB when read operations report 
> ECC
> bitflips) still occur when a UBIFS mounted on the UBI volume is 
> readonly, in
> terms of Linux filesystem permissions?
>
> I have looked at the UBI source for scrubbing, and it appears that it 
> will not
> occur when the UBI device (or MTD partition to which the device is 
> attached)
> is in readonly mode. But what if the UBI device is in read/write mode, 
> but the
> UBIFS mounted on the device is in readonly mode?
>
Does 'UBI scrubbing' mean the wear_leveling_worker(e1 comes from 
ubi->scrub)? If so, I think it still work when UBI is rw mode and ubifs 
is readonly. For example: ubifs_leb_read -> ubi_leb_read -> 
ubi_eba_read_leb -> ubi_wl_scrub_peb: wl_tree_add(e, &ubi->scrub)  && 
ensure_wear_leveling
> I am trying to create a configuration where the UBIFS is readonly at 
> the Linux
> filesystem permissions level, but UBI scrubbing still occurs when read
> operations report enough ECC bitflips.  So no Linux userspace programs 
> may
> modify the filesystem due to permissions, but UBI scrubbing still 
> would occur.
>
> Is this possible, or am I missing something in the UBI source code?
>
> Thanks,
> Chuck
>
>
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