[linux-lvm] cache_check --clear-needs-check-flag does not clear needs_check flag?

[Dennis Schridde]

On Sonntag, 6. Dezember 2020 22:01:37 CET Dennis Schridde wrote:
> [...]
> $ sudo lvchange -ay vg_ernie/lv_cache
> Do you want to activate component LV in read-only mode? [y/n]: y
>    Allowing activation of component LV.
> [...]
> Is it possible that `cache_check --clear-needs-check-flag does not clear
> needs_check flag` does not actually clear the needs_check flag in my case?

I suspect that this has something to do with the read only status of the LV...

What if the superblock gets changed, but is then not written back to the LV,
because it is read only, and failure to write it back was not treated as an
error?  I dd-ed lv_cache into a file, ran cache_check --clear-needs-check-flag
on it, and then tried to dd it back to the LV.  Sadly that results in a
permission denied error.  I was not able to figure out how to force writing it
back.

--Dennis
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