[LU-7759] umount hanging in modern distros when OST is unavailable

• Type: Bug
• Resolution: Fixed
• Priority: Major
• Fix Version/s: Lustre 2.9.0
• Affects Version/s: Lustre 2.8.0, Lustre 2.9.0
• Labels: easy sles12
• Severity: 3
• Assignee: Yang Sheng
• Reporter: Oleg Drokin

Description

It looks like modern distros: SLES12, Fedora 21+ (possibly earlier) always do statfs on the mountpoint before issuing the umount call.

In case one of the OSTs is not available at that time - the statfs will hang.

In our tests there's a bunch of tests in conf-sanity that have this problem and it was "dealt with" in LU-5472 by just adding the -f umount option.
But this still leaves palces like recovery-single test 89 and something in recovery-small at the very least.

And most of all regular users would be affected too. So I wonder if we should deal with this issue somewhat more intelligently so that the unmount does not really hang in such a case?

Issue Links

• is related to: LU-4039 Failure on test suite replay-single test_90: wrong stripe: f0, uuid: lustre-OST0000_UUID
• is related to: LU-8544 recovery-double-scale test_pairwise_fail: start client on trevis-54vm5 failed
• is related to: LU-8731 lfs df exits with status 0 on failures
• is related to: LU-6233 recovery-small test_10d failed with 'file contents differ'
• is related to: LU-8069 Allow remount to include "flock" and "localflock", as well as "lazystatfs" and "nolazystatfs"
• is related to: LU-5472 conf-sanity test_32a: failed with 1