This is primarily of use when a pool has lost its disk, while the user
doesn't care about any pending (or otherwise) transactions.
Implement various control methods to make this feasible:
- txg_wait can now take a NOSUSPEND flag, in which case the caller will
be alerted if their txg can't be committed. This is primarily of
interest for callers that would normally pass TXG_WAIT, but don't want
to wait if the pool becomes suspended, which allows unwinding in some
cases, specifically when one is attempting a non-forced export.
Without this, the non-forced export would preclude a forced export
by virtue of holding the namespace lock indefinitely.
- txg_wait also returns failure for TXG_WAIT users if a pool is actually
being force exported. Adjust most callers to tolerate this.
- spa_config_enter_flags now takes a NOSUSPEND flag to the same effect.
- DMU objset initiator which may be set on an objset being forcibly
exported / unmounted.
- SPA export initiator may be set on a pool being forcibly exported.
- DMU send/recv now use an interruption mechanism which relies on the
SPA export initiator being able to enumerate datasets and closing any
send/recv streams, causing their EINTR paths to be invoked.
- ZIO now has a cancel entry point, which tells all suspended zios to
fail, and which suppresses the failures for non-CANFAIL users.
- metaslab, etc. cleanup, which consists of simply throwing away any
changes that were not able to be synced out.
- Linux specific: introduce a new tunable,
zfs_forced_export_unmount_enabled, which allows the filesystem to
remain in a modified 'unmounted' state upon exiting zpl_umount_begin,
to achieve parity with FreeBSD and illumos,
which have VFS-level support for yanking filesystems out from under
users. However, this only helps when the user is actively performing
I/O, while not sitting on the filesystem. In particular, this allows
test #3 below to pass on Linux.
- Add basic logic to zpool to indicate a force-exporting pool, instead
of crashing due to lack of config, etc.
Add tests which cover the basic use cases:
- Force export while a send is in progress
- Force export while a recv is in progress
- Force export while POSIX I/O is in progress
This change modifies the libzfs ABI:
- New ZPOOL_STATUS_FORCE_EXPORTING zpool_status_t enum value.
- New field libzfs_force_export for libzfs_handle.
Signed-off-by: Will Andrews <will@firepipe.net>
Signed-off-by: Allan Jude <allan@klarasystems.com>
Signed-off-by: Mariusz Zaborski <mariusz.zaborski@klarasystems.com>
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Sponsored-by: Klara, Inc.
Sponsored-by: Catalogics, Inc.
Sponsored-by: Wasabi Technology, Inc.
Closes#3461
(cherry picked from commit 852e633772217d779a63e8c46fe3c5f81dd8960e)
40a9efd0e8