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bcache: acquire bch_register_lock later in cached_dev_detach_finish()

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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>
This commit is contained in:
Coly Li 2019-06-28 19:59:47 +08:00 committed by Jens Axboe
parent a59ff6ccc2
commit 97ba3b816e
1 changed files with 2 additions and 1 deletions
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3
drivers/md/bcache/super.c
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@ -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);