Update mmp_delay on skipped/failed writes and on txg syncs #7330
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@@ Coverage Diff @@
## master #7330 +/- ##
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- Coverage 76.38% 76.32% -0.06%
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Files 329 329
Lines 104214 104200 -14
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- Hits 79606 79533 -73
- Misses 24608 24667 +59
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| @@ -163,17 +163,29 @@ function mmp_pool_set_hostid # pool hostid | |||
| return 0 | |||
| } | |||
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| function activity_check_duration | |||
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Can you comment this function's return value, or give it a more verbose name like total_seconds_mmp_has_been_active?
When an MMP write is skipped, or fails, and time since mts->mmp_last_write is already greater than mts->mmp_delay, increase mts->mmp_delay. The original code only updated mts->mmp_delay when a write succeeded, but this results in the write(s) after delays and failed write(s) reporting an ub_mmp_delay which is too low. Update mmp_last_write and mmp_delay if a txg sync was successful. At least one uberblock was written, thus extending the time we can be sure the pool will not be imported by another host. Do not allow mmp_delay to go below (MSEC2NSEC(zfs_multihost_interval) / vdev_count_leaves()) so that a period of frequent successful MMP writes, e.g. due to frequent txg syncs, does not result in an import activity check so short it is not reliable based on mmp thread writes alone. Remove unnecessary local variable, start. We do not use the start time of the loop iteration. Add a debug message in spa_activity_check() to allow verification of the import_delay value and to prove the activity check occurred. Alter the tests that import pools and attempt to detect an activity check. Calculate the expected duration of spa_activity_check() based on module parameters at the time the import is performed, rather than a fixed time set in mmp.cfg. The fixed time may be wrong. Also, use the default zfs_multihost_interval value so the activity check is longer and easier to recognize. Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
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When an MMP write is skipped, or fails, and time since mts->mmp_last_write is already greater than mts->mmp_delay, increase mts->mmp_delay. The original code only updated mts->mmp_delay when a write succeeded, but this results in the write(s) after delays and failed write(s) reporting an ub_mmp_delay which is too low. Update mmp_last_write and mmp_delay if a txg sync was successful. At least one uberblock was written, thus extending the time we can be sure the pool will not be imported by another host. Do not allow mmp_delay to go below (MSEC2NSEC(zfs_multihost_interval) / vdev_count_leaves()) so that a period of frequent successful MMP writes, e.g. due to frequent txg syncs, does not result in an import activity check so short it is not reliable based on mmp thread writes alone. Remove unnecessary local variable, start. We do not use the start time of the loop iteration. Add a debug message in spa_activity_check() to allow verification of the import_delay value and to prove the activity check occurred. Alter the tests that import pools and attempt to detect an activity check. Calculate the expected duration of spa_activity_check() based on module parameters at the time the import is performed, rather than a fixed time set in mmp.cfg. The fixed time may be wrong. Also, use the default zfs_multihost_interval value so the activity check is longer and easier to recognize. Reviewed-by: Tony Hutter <hutter2@llnl.gov> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov> Signed-off-by: Olaf Faaland <faaland1@llnl.gov> Closes openzfs#7330
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When an MMP write is skipped, or fails, and time since mts->mmp_last_write is already greater than mts->mmp_delay, increase mts->mmp_delay. The original code only updated mts->mmp_delay when a write succeeded, but this results in the write(s) after delays and failed write(s) reporting an ub_mmp_delay which is too low. Update mmp_last_write and mmp_delay if a txg sync was successful. At least one uberblock was written, thus extending the time we can be sure the pool will not be imported by another host. Do not allow mmp_delay to go below (MSEC2NSEC(zfs_multihost_interval) / vdev_count_leaves()) so that a period of frequent successful MMP writes, e.g. due to frequent txg syncs, does not result in an import activity check so short it is not reliable based on mmp thread writes alone. Remove unnecessary local variable, start. We do not use the start time of the loop iteration. Add a debug message in spa_activity_check() to allow verification of the import_delay value and to prove the activity check occurred. Alter the tests that import pools and attempt to detect an activity check. Calculate the expected duration of spa_activity_check() based on module parameters at the time the import is performed, rather than a fixed time set in mmp.cfg. The fixed time may be wrong. Also, use the default zfs_multihost_interval value so the activity check is longer and easier to recognize. Reviewed-by: Tony Hutter <hutter2@llnl.gov> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov> Signed-off-by: Olaf Faaland <faaland1@llnl.gov> Closes openzfs#7330
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When an MMP write is skipped, or fails, and time since mts->mmp_last_write is already greater than mts->mmp_delay, increase mts->mmp_delay. The original code only updated mts->mmp_delay when a write succeeded, but this results in the write(s) after delays and failed write(s) reporting an ub_mmp_delay which is too low. Update mmp_last_write and mmp_delay if a txg sync was successful. At least one uberblock was written, thus extending the time we can be sure the pool will not be imported by another host. Do not allow mmp_delay to go below (MSEC2NSEC(zfs_multihost_interval) / vdev_count_leaves()) so that a period of frequent successful MMP writes, e.g. due to frequent txg syncs, does not result in an import activity check so short it is not reliable based on mmp thread writes alone. Remove unnecessary local variable, start. We do not use the start time of the loop iteration. Add a debug message in spa_activity_check() to allow verification of the import_delay value and to prove the activity check occurred. Alter the tests that import pools and attempt to detect an activity check. Calculate the expected duration of spa_activity_check() based on module parameters at the time the import is performed, rather than a fixed time set in mmp.cfg. The fixed time may be wrong. Also, use the default zfs_multihost_interval value so the activity check is longer and easier to recognize. Reviewed-by: Tony Hutter <hutter2@llnl.gov> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov> Signed-off-by: Olaf Faaland <faaland1@llnl.gov> Closes #7330
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Description
When an MMP write is skipped, or fails, and time since mts->mmp_last_write is already greater than mts->mmp_delay, increase mts->mmp_delay. The original code only updated mts->mmp_delay when a write succeeded, but this results in the write(s) after delays and failed write(s) reporting an ub_mmp_delay which is too low.
Update mmp_last_write and mmp_delay if a txg sync was successful. At least one uberblock was written, thus extending the time we can be sure the pool will not be imported by another host.
Do not allow mmp_delay to go below (MSEC2NSEC(zfs_multihost_interval) / vdev_count_leaves()) so that a period of frequent successful MMP writes, e.g. due to frequent txg syncs, does not result in an import activity check so short it is not reliable based on mmp thread writes alone.
Remove unnecessary local variable, start. We do not use the start time of the loop iteration.
Add a debug message in spa_activity_check() to allow verification of the import_delay value and to prove the activity check occurred.
Alter the tests that import pools and attempt to detect an activity check. Calculate the expected duration of spa_activity_check() based on module parameters at the time the import is performed, rather than a fixed time set in mmp.cfg. The fixed time may be wrong. Also, use the default zfs_multihost_interval value so the activity check is longer and easier to recognize.
Motivation and Context
Under some circumstances, the mmp_delay value written in uberblocks was low due to being out-of-date. In others, the uberblock writes during txg sync were not being taken into account even though their uberblocks act as MMP writes.
Misc fixes to clean up minor issues found during testing.
How Has This Been Tested?
Ran zloop and the mmp portion of the test suite locally. Examined debug logs to verify the spa activity check's import_delay was set appropriately and that the test change more closely matches the real behavior.
Types of changes
Checklist:
Signed-off-by.