Callbacks provided for module parameters are executed both
after the module is loaded, when a user alters it via sysfs, e.g
echo bar > /sys/modules/zfs/parameters/foo
as well as when the module is loaded with an argument, e.g.
modprobe zfs foo=bar
In the latter case, the init functions likely have not run yet,
including spa_init() which initializes the namespace lock so it is safe
to use.
Instead of immediately taking the namespace lock and attemping to
iterate over initialized spa structures, check whether spa_mode_global
is nonzero. This is set by spa_init() after it has initialized the
namespace lock.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#7496Closes#7521
vdev_count_leaves() in the denominator may return 0, caught by Coverity.
Introduced by
* 533ea04 Update mmp_delay on sync or skipped, failed write
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#7391
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
When the pool is suspended, record whether it was due to an I/O error or
due to MMP writes failing to succeed within the required time.
Change spa_suspended from uint8_t to zio_suspend_reason_t to store the
reason.
When userspace queries pool status via spa_tryimport(), report the
reason the pool was suspended in a new key,
ZPOOL_CONFIG_SUSPENDED_REASON.
In libzfs, when interpreting the returned config nvlist, report
suspension due to MMP with a new pool status enum value,
ZPOOL_STATUS_IO_FAILURE_MMP.
In status_callback(), which generates and emits the message when 'zpool
status' is executed, add a case to print an appropriate message for the
new pool status enum value.
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#7296
Once per pass through the MMP thread's loop, the vdev tree is walked to
find a suitable leaf to write the next MMP block to. If no such leaf is
found, the thread sleeps for a while and resumes at the top of the loop.
Add an entry to multihost_history when no leaf can be found, and record
the reason in the error column. The error code for such entries is a
bitfield, displayed in hex:
0x1 At least one vdev (interior or leaf) was not writeable.
0x2 At least one writeable leaf vdev was found, but it had a pending
MMP write.
timestamp = the time in seconds since the epoch when no leaf could be
found originally.
duration = the time (in ns) during which no MMP block was written for
this reason. This does not include the preceeding inter-write period
nor the following inter-write period.
vdev_guid = the number of sequential cycles of the MMP thread looop when
this occurred.
Sample output, truncated to fit:
For records of skipped MMP writes the right-most column, vdev_path, is
reported as "-".
id txg timestamp error duration mmp_delay vdev_guid ...
936 11 1520036441 0 146264 891422313 1740883117838 ...
937 11 1520036441 0 163956 888356657 7320395061548 ...
938 11 1520036442 0 130690 885314969 7320395061548 ...
939 11 1520036442 0 2001068577 882296582 1740883117838 ...
940 11 1520036443 0 161806 882296582 7320395061548 ...
941 11 1520036443 0x2 0 998020546 1 ...
942 11 1520036444 0 136585 998020546 7320395061548 ...
943 11 1520036444 0x2 0 998020257 1 ...
944 11 1520036445 5 2002662964 994160219 1740883117838 ...
945 11 1520036445 0x2 998073118 994160219 3 ...
946 11 1520036447 0 247136 994160219 7320395061548 ...
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#7212
When a single pool contains more vdevs than the CONFIG_HZ for
for the kernel the mmp thread will not delay properly. Switch
to using cv_timedwait_sig_hires() to handle higher resolution
delays.
This issue was reported on Arch Linux where HZ defaults to only
100 and this could be fairly easily reproduced with a reasonably
large pool. Most distribution kernels set CONFIG_HZ=250 or
CONFIG_HZ=1000 and thus are unlikely to be impacted.
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Olaf Faaland <faaland1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#7205Closes#7289
When multihost is disabled on a pool, and the pool is resumed via zpool
clear, within a single cycle of the mmp thread's loop (e.g. while it's
in the cv_timedwait call), both mmp_last_write and mmp_delay should be
updated.
The original code mistakenly treated the two cases as if they could not
occur at the same time.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#7286
If something holds the config lock as a writer for too long, MMP will
fail to issue MMP writes in a timely manner. This will result either in
the pool being suspended, or in an extreme case, in the pool not being
protected.
If the time to acquire the config lock exceeds 1/10 of the minimum
zfs_multihost_interval, report it in the zfs debug log.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#7212
While the pool is suspended on host A, it may be imported on host B.
If host A continued to write MMP blocks, it would be blindly
overwriting MMP blocks written by host B, and the blocks written by
host A would have outdated txg information.
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#7182
mmp_write_uberblock() and mmp_write_done() should the same tag
for spa_config_locks.
Reviewed-by: Olaf Faaland <faaland1@llnl.gov>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Sanjeev Bagewadi <sanjeev.bagewadi@gmail.com>
Closes#6530Closes#7155
In mmp_thread(), emit an MMP specific error message before calling
zio_suspend() so that the administrator will understand why the pool
is being suspended.
Reviewed-by: Olaf Faaland <faaland1@llnl.gov>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: John L. Hammond <john.hammond@intel.com>
Closes#7048
Rename it as mmp_random_leaf() since it is defined in mmp.c.
The earlier implementation could end up spinning forever if a pool had a
vdev marked writeable, none of whose children were writeable. It also
did not guarantee that if a writeable leaf vdev existed, it would be
found.
Reimplement to recursively walk the device tree to select the leaf. It
searches the entire tree, so that a return value of (NULL) indicates
there were no usable leaves in the pool; all were either not writeable
or had pending mmp writes.
It still chooses the starting child randomly at each level of the tree,
so if the pool's devices are healthy, the mmp writes go to random leaves
with an even distribution. This was verified by testing using
zfs_multihost_history enabled.
Reviewed by: Thomas Caputi <tcaputi@datto.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#6631Closes#6665
Add a callback to wake all running mmp threads when
zfs_multihost_interval is changed.
This is necessary when the interval is changed from a very large value
to a significantly lower one, while pools are imported that have the
multihost property enabled.
Without this commit, the mmp thread does not wake up and detect the new
interval until after it has waited the old multihost interval time. A
user monitoring mmp writes via the provided kstat would be led to
believe that the changed setting did not work.
Added a test in the ZTS under mmp to verify the new functionality is
working.
Added a test to ztest which starts and stops mmp threads, and calls into
the code to signal sleeping mmp threads, to test for deadlocks or
similar locking issues.
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#6387
The config lock must be held for the duration of the MMP write.
Since the I/Os are executed via map_nowait(), the done function
is the only place where we know the write has completed.
Since SCL_STATE is taken as reader, overlapping I/Os do not
create a deadlock. The refcount is simply increased when new
I/Os are queued and decreased when I/Os complete.
Test case added which exercises the probe IO call path to
verify the fix and prevent a regression.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#6394
Commit 379ca9c Multi-modifier protection (MMP) used HZ to convert
nanoseconds to ticks for use with cv_timedwait() and ddi_get_lbolt().
The correct macro is hz, which is defined within the SPL for kernel
space, and within zfs_context.h for user space.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#6357Closes#6360
CID 165755: Division or modulo by zero (DIVIDE_BY_ZERO)
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Olaf Faaland <faaland1@llnl.gov>
Signed-off-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Closes#6352
Add multihost=on|off pool property to control MMP. When enabled
a new thread writes uberblocks to the last slot in each label, at a
set frequency, to indicate to other hosts the pool is actively imported.
These uberblocks are the last synced uberblock with an updated
timestamp. Property defaults to off.
During tryimport, find the "best" uberblock (newest txg and timestamp)
repeatedly, checking for change in the found uberblock. Include the
results of the activity test in the config returned by tryimport.
These results are reported to user in "zpool import".
Allow the user to control the period between MMP writes, and the
duration of the activity test on import, via a new module parameter
zfs_multihost_interval. The period is specified in milliseconds. The
activity test duration is calculated from this value, and from the
mmp_delay in the "best" uberblock found initially.
Add a kstat interface to export statistics about Multiple Modifier
Protection (MMP) updates. Include the last synced txg number, the
timestamp, the delay since the last MMP update, the VDEV GUID, the VDEV
label that received the last MMP update, and the VDEV path. Abbreviated
output below.
$ cat /proc/spl/kstat/zfs/mypool/multihost
31 0 0x01 10 880 105092382393521 105144180101111
txg timestamp mmp_delay vdev_guid vdev_label vdev_path
20468 261337 250274925 68396651780 3 /dev/sda
20468 261339 252023374 6267402363293 1 /dev/sdc
20468 261340 252000858 6698080955233 1 /dev/sdx
20468 261341 251980635 783892869810 2 /dev/sdy
20468 261342 253385953 8923255792467 3 /dev/sdd
20468 261344 253336622 042125143176 0 /dev/sdab
20468 261345 253310522 1200778101278 2 /dev/sde
20468 261346 253286429 0950576198362 2 /dev/sdt
20468 261347 253261545 96209817917 3 /dev/sds
20468 261349 253238188 8555725937673 3 /dev/sdb
Add a new tunable zfs_multihost_history to specify the number of MMP
updates to store history for. By default it is set to zero meaning that
no MMP statistics are stored.
When using ztest to generate activity, for automated tests of the MMP
function, some test functions interfere with the test. For example, the
pool is exported to run zdb and then imported again. Add a new ztest
function, "-M", to alter ztest behavior to prevent this.
Add new tests to verify the new functionality. Tests provided by
Giuseppe Di Natale.
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Ned Bass <bass6@llnl.gov>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes#745Closes#6279
