Re: xfs_check refuses to work on readonly fs

["CN" <cnliou9@fastmail.fm>]

Hi! Hedi,

> Based on the info you provided I infer that you're running Linux.

Yes. I forgot to mention this.

> | # init 1
> | # mount -o ro,remount /
> | # mount
> | /dev/hda1 on / type xfs (rw)
> | # xfs_check /dev/hda1
> | xfs_check: /dev/hda1 contains a mounted and writable filesystem
> |
> | xfs_check/xfs_repair are willing to work only when I boot from a disk
> | and check/repair the other unmounted disk.
> |
> | Why "mount" shows (rw) instead of (ro) even "mount -o ro,remount /" is
> | issued?
> 
> Because mount is relying on /etc/mtab which couldn't be updated
> precisely because / was remounted ro.
> 
> You'll need a recent xfsprogs version, at least 2.7.17 IIRC, one
> that uses that uses /proc/mounts instead of /etc/mtab to check
> filesystem status.
> 
> Or you can use a dirty and quick hack
> 
>     - prior to remounting ro, edit /etc/mtab and change the root fs entry
>     from
>     rw to ro.
>     - remount ro
>     - run your xfs_check/xfs_repair in dangerous mode.
> 
> FWIW the safe thing to do after a repair on a mounted root FS is to
> reboot.

I upgraded xfsprogs to 2.8.4 and have tried both approaches you provided
but still have no luck. Only one thing is different: "mount" now reports
"ro" if I edit /etc/mtab as you instructed.

Regards,

CN

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