mainline inclusion from mainline-5.3-rc1 commit 97ba3b816e2cdea798398bc8486125f79f2453c1 category: backport
Now there is variable bcache_is_reboot to prevent device register or unregister during reboot, it is unncessary to still hold mutex lock bch_register_lock before stopping writeback_rate_update kworker and writeback kthread. And if the stopping kworker or kthread holding bch_register_lock inside their routine (we used to have such problem in writeback thread, thanks to Junhui Wang fixed it), it is very easy to introduce deadlock during reboot/shutdown procedure.
Therefore in this patch, the location to acquire bch_register_lock is moved to the location before calling calc_cached_dev_sectors(). Which is later then original location in cached_dev_detach_finish().
Signed-off-by: Coly Li colyli@suse.de Signed-off-by: Jens Axboe axboe@kernel.dk --- drivers/md/bcache/super.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index ec75ac2ca5d0..a8ea4e2086a9 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -1018,7 +1018,6 @@ static void cached_dev_detach_finish(struct work_struct *w) BUG_ON(!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags)); BUG_ON(refcount_read(&dc->count));
- mutex_lock(&bch_register_lock);
if (test_and_clear_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags)) cancel_writeback_rate_update_dwork(dc); @@ -1034,6 +1033,8 @@ static void cached_dev_detach_finish(struct work_struct *w) bch_write_bdev_super(dc, &cl); closure_sync(&cl);
+ mutex_lock(&bch_register_lock); + calc_cached_dev_sectors(dc->disk.c); bcache_device_detach(&dc->disk); list_move(&dc->list, &uncached_devices);