Re: [linux-lvm] LVM and RO device/partition(s
Zdenek Kabelac <[email protected]>
| Newsgroups | dev.linux.lists.linux-lvm |
|---|---|
| Message-ID | <[email protected]> |
Dne 20. 03. 23 v 17:37 lacsaP Patatetom napsal(a): > hi, > > I come back to you with the memo mentioned : > https://github.com/patatetom/lvm-on-readonly-block-device > <https://github.com/patatetom/lvm-on-readonly-block-device> > I hope that it will allow you to better understand this problem of alteration > of the disk. > > as I mentioned, LVM should normally/theoretically not touch the disk as long > as it is read-only, but what bothers me the most is the fact that I can't > "catch up" by correcting the new 6.1.15 kernel as I did before. > > regards, lacsaP. > > Le lun. 20 mars 2023 à 15:15, lacsaP Patatetom <[email protected] Hi So I'm possibly finally starting to understand your problem here. You are using your own patched kernel - where you were reverting a32e236eb93e62a0f692e79b7c3c9636689559b9 linux kernel patch. without likely understanding the consequences. With kernel 6.X there is commit bdb7d420c6f6d2618d4c907cd7742c3195c425e2 modifying bio_check_ro() to return void - so your 'reverting' patch is no longer usable the way it's been created. From your github report it seems you are creating 'raid' across 3 sdb drives. So with normal kernel - it happens to be that 'dm' drives are allowed to bypass any 'read-only' protection set on a device. So when you actually creating raid LV on loop0 & loop1 - deactivate, then you make loop0 & loop1 read-only, active raid LV - then you can easily call 'mkfs' and it will normally work. Raid device consist or '_rimage' & '_rmeta' LV per leg - where _rmeta is metadata device updated with activation of raid LV. So when your local 'revert' patch for 6.X kernel no longer works - there is no surprise that your 'sdbX' drives are being actually modified - since ATM dm targets are allowed to bypass read-only protection. Since the reason for the 'bypass' (snapshot read-only activation) was fixed 5 years ago we should probably build some better way how to restore to 'read-only' protection - and allow to disable it only when user requests such behavior due to use of old user-space tooling. Regards Zdenek _______________________________________________ linux-lvm mailing list [email protected] https://listman.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/