[LU-9543] Deadlock in ofd fiemap code leads to client eviction

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.11.0
• Labels: patch
• Severity: 3
• Assignee: WC Triage
• Reporter: Andriy Skulysh

Description

When fiemap is used with FIEMAP_FLAG_SYNC flag OST locks all spare regions one by one. It may lead to a deadlock with another client which tries to get write lock on a region covering 2 spare regions.
So scenario is following :
1) client 1 calls fiemap, OST locks first spare region
2) client 2 enqueues PW lock on whole file, it conflicts with first spare region
3) OST tries to lock second spare region, but it conflicts with PW waiting lock.

Comments

[Peter Jones]

Landed for 2.11

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/27224/
Subject: LU-9543 ofd: fiemap deadlock
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 4eac5c85d3a4ddda5833af2f15cd8d614d1e3996

[Gerrit Updater]

Andriy Skulysh ([e-mail]) uploaded a new patch: https://review.whamcloud.com/27224
Subject: LU-9543 ofd: fiemap deadlock
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 4e95ce002d560ac28badcb11c6e05dfdf1b63d01