mirror_zfs/cmd/zpool
Matthew Ahrens 018f26041d
deadlock between spa_errlog_lock and dp_config_rwlock
There is a lock order inversion deadlock between `spa_errlog_lock` and
`dp_config_rwlock`:

A thread in `spa_delete_dataset_errlog()` is running from a sync task.
It is holding the `dp_config_rwlock` for writer (see
`dsl_sync_task_sync()`), and waiting for the `spa_errlog_lock`.

A thread in `dsl_pool_config_enter()` is holding the `spa_errlog_lock`
(see `spa_get_errlog_size()`) and waiting for the `dp_config_rwlock` (as
reader).

Note that this was introduced by #12812.

This commit address this by defining the lock ordering to be
dp_config_rwlock first, then spa_errlog_lock / spa_errlist_lock.
spa_get_errlog() and spa_get_errlog_size() can acquire the locks in this
order, and then process_error_block() and get_head_and_birth_txg() can
verify that the dp_config_rwlock is already held.

Additionally, a buffer overrun in `spa_get_errlog()` is corrected.  Many
code paths didn't check if `*count` got to zero, instead continuing to
overwrite past the beginning of the userspace buffer at `uaddr`.

Tested by having some errors in the pool (via `zinject -t data
/path/to/file`), one thread running `zpool iostat 0.001`, and another
thread runs `zfs destroy` (in a loop, although it hits the first time).
This reproduces the problem easily without the fix, and works with the
fix.

Reviewed-by: Mark Maybee <mark.maybee@delphix.com>
Reviewed-by: George Amanakis <gamanakis@gmail.com>
Reviewed-by: George Wilson <gwilson@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #14239
Closes #14289
2022-12-22 11:48:49 -08:00
..
compatibility.d Add compatibility file sets (ZoL 0.6.1, 0.6.4, OpenZFS 2.1) 2021-03-31 09:40:25 -07:00
os Replace dead opensolaris.org license link 2022-07-11 14:16:13 -07:00
zpool.d Workaround broken VDEV_UPATH 2022-05-10 10:14:07 -07:00
Makefile.am Replace EXTRA_DIST with dist_noinst_DATA 2022-05-26 09:24:50 -07:00
zpool_iter.c Replace dead opensolaris.org license link 2022-07-11 14:16:13 -07:00
zpool_main.c deadlock between spa_errlog_lock and dp_config_rwlock 2022-12-22 11:48:49 -08:00
zpool_util.c Replace dead opensolaris.org license link 2022-07-11 14:16:13 -07:00
zpool_util.h Replace dead opensolaris.org license link 2022-07-11 14:16:13 -07:00
zpool_vdev.c zpool: fix redundancy check after vdev removal 2022-08-04 17:02:57 -07:00