[LU-8288] handle error due to file with "no stripe info" rewritten before lfsck is run

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.10.0
• Affects Version/s: Lustre 2.7.0
• Severity: 3
• Assignee: nasf (Inactive)
• Reporter: Nathan Dauchy (Inactive)

Description

This is a followup on the filesystem recovery efforts from LU-8071, in particular the comment:

If you think that the layout LFSCK made wrong decision when re-generated the
"nagtest.toobig.stripes" LOV EA, we need to make new patch to recover it. 

More than just making a wrong decision, lfsck can actually corrupt files when it is run. The case is where the MDT loses stripe information, and then the file is rewritten (or appeneded to?), and then lfsck is run.

In general, it would be good if lfsck can handle "conflicts" more gracefully. I understand that it may not know which object is the right one, but it should not pick them arbitrarily since that can result in a mixed-data file. Additionally, at the time when lfsck is run, it has information about what file an object is associated with, and that could be exposed to the user in the name of the file placed in lost+found.

Issue Links

• is related to: LU-4615 LFSCK 5: OST index verification during the LFSCK_LAYOUT

Comments

[Minh Diep]

Landed for 2.10

[Jay Lan (Inactive)]

Could you port this patch to b2_7_fe and land to b2_9_fe? Thanks!

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/21562/
Subject: LU-8288 lfsck: handle dangling LOV EA reference
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 17cc912fd5b40965d14a89a268cbf2d63b2fe21b

[Andreas Dilger]

Per earlier discussion in this ticket, it would be worthwhile to backport the PFL patches to increase the MDT and OST inode size, as well as the patch to improve the fid xattr to store the total stripe count and stripe size on each OST object. That would allow LFSCK to reconstruct the layout properly, even in the case where some OST objects are totally missing. Having clients send this information with each write will ensure that this information is stored on each OST object for later use if needed.

[Peter Jones]

That matches my understanding Nathan

[Nathan Dauchy (Inactive)]

It looks like there were many iterations on this patch, but it is ready for final review and then landing. Please confirm.

Also, once the patch is finalized, we will need a backport to the 2.7 FE branch as well as master. Thanks!

[Gerrit Updater]

Fan Yong ([e-mail]) uploaded a new patch: http://review.whamcloud.com/21562
Subject: LU-8288 lfsck: handle dangling LOV EA reference
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 61dc2ac65258fceb30bf0549e76b8ff7eace2d29