From 4b5b13da527b1ce02ee9a96382684496e8d83696 Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Mon, 6 Mar 2023 07:57:51 -0500 Subject: [PATCH] six locks: be more careful about lost wakeups This is a workaround for a lost wakeup bug we've been seeing - we still need to discover the actual bug. Signed-off-by: Kent Overstreet --- fs/bcachefs/six.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/fs/bcachefs/six.c b/fs/bcachefs/six.c index e1e9df0368b6c..b54a2ac480c8e 100644 --- a/fs/bcachefs/six.c +++ b/fs/bcachefs/six.c @@ -142,8 +142,17 @@ static int __do_six_trylock_type(struct six_lock *lock, * lock, issue a wakeup because we might have caused a * spurious trylock failure: */ +#if 0 + /* + * This code should be sufficient, but we're seeing unexplained + * lost wakeups: + */ if (old.write_locking) ret = -1 - SIX_LOCK_write; +#else + if (!ret) + ret = -1 - SIX_LOCK_write; +#endif } else if (type == SIX_LOCK_write && lock->readers) { if (try) { atomic64_add(__SIX_VAL(write_locking, 1), @@ -319,11 +328,10 @@ static bool __six_relock_type(struct six_lock *lock, enum six_lock_type type, * Similar to the lock path, we may have caused a spurious write * lock fail and need to issue a wakeup: */ - if (old.write_locking) - six_lock_wakeup(lock, old, SIX_LOCK_write); - if (ret) six_acquire(&lock->dep_map, 1, type == SIX_LOCK_read, ip); + else + six_lock_wakeup(lock, old, SIX_LOCK_write); return ret; } -- 2.30.2