Resilver restarts unnecessarily when it encounters errors

When a resilver finishes, vdev_dtl_reassess is called to hopefully
excise DTL_MISSING (amongst other things). If there are errors during
the resilver, they are tracked in DTL_SCRUB, as spelled out in the
block comment in vdev.c. DTL_SCRUB is in-core only, so it can only
be used if the pool was online for the whole resilver. This state is
tracked with the spa_scrub_started flag, which only gets set when
the scan is initialized. Unfortunately, this flag gets cleared right
before vdev_dtl_reassess gets called, so if there are any errors
during the scan, DTL_MISSING will never get excised and the resilver
will just continually restart. This fix simply moves clearing that
flag until after the call to vdev_dtl_reasses.

In addition, if a pool is imported and already has scn_errors > 0,
this change will restart the resilver immediately instead of doing
the rest of the scan and then restarting it from the beginning. On
the other hand, if scn_errors == 0 at import, then no errors have
been encountered so far, so the spa_scrub_started flag can be safely
set.

A test has been added to verify that resilver does not restart when
relevant DTL's are available.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Paul Zuchowski <pzuchowski@datto.com>
Signed-off-by: John Poduska <jpoduska@datto.com>
Closes #10291
This commit is contained in:
John Poduska
2020-05-13 13:54:27 -04:00
committed by GitHub
parent b29e31d80d
commit 41035a0496
6 changed files with 149 additions and 4 deletions
+1
View File
@@ -59,6 +59,7 @@ OVERRIDE_ESTIMATE_RECORDSIZE send.override_estimate_recordsize zfs_override_esti
REMOVAL_SUSPEND_PROGRESS removal_suspend_progress zfs_removal_suspend_progress
REMOVE_MAX_SEGMENT remove_max_segment zfs_remove_max_segment
RESILVER_MIN_TIME_MS resilver_min_time_ms zfs_resilver_min_time_ms
SCAN_LEGACY scan_legacy zfs_scan_legacy
SCAN_SUSPEND_PROGRESS scan_suspend_progress zfs_scan_suspend_progress
SCAN_VDEV_LIMIT scan_vdev_limit zfs_scan_vdev_limit
SEND_HOLES_WITHOUT_BIRTH_TIME send_holes_without_birth_time send_holes_without_birth_time