Re: mdadm --misc --readonly -> ENODEV indefinitely

[NeilBrown <neilb@suse.com>]

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On Sun, May 28 2017, Nix wrote:

> So I was trying to flip on the RAID journal now I'd fully populated my
> array and cut over to it. So, from early userspace, I did
>
>    # first line done by initramfs scripting
>    /sbin/mdadm --assemble --scan --auto=md --freeze-reshape
>    mdadm --misc --readonly /dev/md/fast
>    mdadm --manage /dev/md/fast --add-journal /dev/ssd1
>    mdadm --misc --readwrite /dev/md/fast
>
> This did not work as planned, or indeed at all. After the first
> --readonly, all requests for /dev/md/fast report "No such device or
> address" until a reboot, though /proc/mdstat says the thing is still
> there and /sys/block/md125/dev reports no change in major/minor numbers.
> (I don't have udev in my early-userspace environment, but mdev reports
> no change, either.)
>
> It's a bit hard to do anything else after that, like, say, turn the
> journal on.
>
> ... maybe an mdadm --assemble --scan --auto=md --readonly in one go
> would work better, rather than starting with the default (?read-mostly?)
> and flipping it? I'll give that a try later.
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Commit: 065e519e71b2 ("md: MD_CLOSING needs to be cleared after called md_set_readonly or do_md_stop")

Broken in v4.9-rc1
Fixed in v4.12-rc1

NeilBrown

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