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six locks: Centralize setting of waiting bit

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Originally, the waiting bit was always set by trylock() on failure:
however, it's now set by __six_lock_type_slowpath(), with wait_lock held
- which is the more correct place to do it.

That made setting the waiting bit in trylock redundant, so this patch
deletes that.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet
2023-05-20 20:37:53 -04:00
parent 0157f9c5a7
commit d2c86b77de
1 changed files with 3 additions and 12 deletions
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15
fs/bcachefs/six.c
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@ -151,14 +151,6 @@ static int __do_six_trylock_type(struct six_lock *lock,
atomic64_add(__SIX_VAL(write_locking, 1), atomic64_add(__SIX_VAL(write_locking, 1),
&lock->state.counter); &lock->state.counter);
smp_mb__after_atomic(); smp_mb__after_atomic();
} else if (!(lock->state.waiters & (1 << SIX_LOCK_write))) {
atomic64_add(__SIX_VAL(waiters, 1 << SIX_LOCK_write),
&lock->state.counter);
/*
* pairs with barrier after unlock and before checking
* for readers in unlock path
*/
smp_mb__after_atomic();
} }
ret = !pcpu_read_count(lock); ret = !pcpu_read_count(lock);
@ -190,10 +182,9 @@ static int __do_six_trylock_type(struct six_lock *lock,
if (type == SIX_LOCK_write) if (type == SIX_LOCK_write)
new.write_locking = 0; new.write_locking = 0;
} else if (!try && !(new.waiters & (1 << type))) } else {
new.waiters |= 1 << type; break;
else }
break; /* waiting bit already set */
} while ((v = atomic64_cmpxchg_acquire(&lock->state.counter, } while ((v = atomic64_cmpxchg_acquire(&lock->state.counter,
old.v, new.v)) != old.v); old.v, new.v)) != old.v);