mirror_zfs/module
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
..
avl Replace dead opensolaris.org license link 2022-07-11 14:16:13 -07:00
icp Fix Clang 15 compilation errors 2022-11-30 13:46:26 -08:00
lua Fix Clang 15 compilation errors 2022-11-30 13:46:26 -08:00
nvpair Replace dead opensolaris.org license link 2022-07-11 14:16:13 -07:00
os FreeBSD: Remove stray debug printf 2022-12-13 17:35:07 -08:00
unicode Replace dead opensolaris.org license link 2022-07-11 14:16:13 -07:00
zcommon Micro-optimize fletcher4 calculations 2022-12-05 11:00:34 -08:00
zfs deadlock between spa_errlog_lock and dp_config_rwlock 2022-12-22 11:48:49 -08:00
zstd zstd: Refactor prefetching for the decoding loop 2022-11-29 10:05:30 -08:00
.gitignore FreeBSD: Ignore symlink to i386 includes 2022-08-02 16:34:23 -07:00
Kbuild.in Fix Clang 15 compilation errors 2022-11-30 13:46:26 -08:00
Makefile.bsd Cleanup dead spa_boot code 2022-09-13 16:40:10 -07:00
Makefile.in autoconf: use include directives instead of recursing down lib 2022-05-10 10:18:11 -07:00