[LU-2877] sanity test_34h failed Multiop blocked on ftruncate, pid=

• Type: Bug
• Resolution: Fixed
• Priority: Critical
• Fix Version/s: Lustre 2.4.0
• Affects Version/s: Lustre 2.4.1
• Labels: mq313
• Severity: 3
• Assignee: Oleg Drokin
• Reporter: Oleg Drokin

Description

Happens pretty frequently in maloo since April 2012.
Sample failures:
https://maloo.whamcloud.com/test_sets/33b06c22-8065-11e2-9b82-52540035b04c

https://maloo.whamcloud.com/sub_tests/9ccebafe-807b-11e2-b777-52540035b04c

I think the underlying problem is that multiop as written can block on not just truncate lock, but also at group lock getting time it can block on cache flush.

        dd if=/dev/zero of=$DIR/$tfile bs=1M count=10 || error
        $MULTIOP $DIR/$tfile OG${gid}T${sz}g${gid}c &
        MULTIPID=$!
        sleep 2

Co perhaps we need to add sync or other way of cache flush after dd before doing multiop.