inode: port __I_NEW to var event

Port the __I_NEW mechanism to use the new var event mechanism.

Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Josef Bacik <[e-mail]>
Reviewed-by: Jan Kara <[e-mail]>
Signed-off-by: Christian Brauner <[e-mail]>

fs/bcachefs/fs.c

···
 				break;
 			}
 		} else if (clean_pass && this_pass_clean) {
-			wait_queue_head_t *wq = bit_waitqueue(&inode->v.i_state, __I_NEW);
-			DEFINE_WAIT_BIT(wait, &inode->v.i_state, __I_NEW);
+			struct wait_bit_queue_entry wqe;
+			struct wait_queue_head *wq_head;
 
-			prepare_to_wait(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE);
+			wq_head = inode_bit_waitqueue(&wqe, &inode->v, __I_NEW);
+			prepare_to_wait_event(wq_head, &wqe.wq_entry,
+					      TASK_UNINTERRUPTIBLE);
 			mutex_unlock(&c->vfs_inodes_lock);
 
 			schedule();
-			finish_wait(wq, &wait.wq_entry);
+			finish_wait(wq_head, &wqe.wq_entry);
 			goto again;
 		}
 	}

fs/dcache.c

···
 	__d_instantiate(entry, inode);
 	WARN_ON(!(inode->i_state & I_NEW));
 	inode->i_state &= ~I_NEW & ~I_CREATING;
+	/*
+	 * Pairs with the barrier in prepare_to_wait_event() to make sure
+	 * ___wait_var_event() either sees the bit cleared or
+	 * waitqueue_active() check in wake_up_var() sees the waiter.
+	 */
 	smp_mb();
-	wake_up_bit(&inode->i_state, __I_NEW);
+	inode_wake_up_bit(inode, __I_NEW);
 	spin_unlock(&inode->i_lock);
 }
 EXPORT_SYMBOL(d_instantiate_new);

fs/inode.c

···
 	 * used as an indicator whether blocking on it is safe.
 	 */
 	spin_lock(&inode->i_lock);
-	wake_up_bit(&inode->i_state, __I_NEW);
+	/*
+	 * Pairs with the barrier in prepare_to_wait_event() to make sure
+	 * ___wait_var_event() either sees the bit cleared or
+	 * waitqueue_active() check in wake_up_var() sees the waiter.
+	 */
+	smp_mb();
+	inode_wake_up_bit(inode, __I_NEW);
 	BUG_ON(inode->i_state != (I_FREEING | I_CLEAR));
 	spin_unlock(&inode->i_lock);
 
···
 	spin_lock(&inode->i_lock);
 	WARN_ON(!(inode->i_state & I_NEW));
 	inode->i_state &= ~I_NEW & ~I_CREATING;
+	/*
+	 * Pairs with the barrier in prepare_to_wait_event() to make sure
+	 * ___wait_var_event() either sees the bit cleared or
+	 * waitqueue_active() check in wake_up_var() sees the waiter.
+	 */
 	smp_mb();
-	wake_up_bit(&inode->i_state, __I_NEW);
+	inode_wake_up_bit(inode, __I_NEW);
 	spin_unlock(&inode->i_lock);
 }
 EXPORT_SYMBOL(unlock_new_inode);
···
 	spin_lock(&inode->i_lock);
 	WARN_ON(!(inode->i_state & I_NEW));
 	inode->i_state &= ~I_NEW;
+	/*
+	 * Pairs with the barrier in prepare_to_wait_event() to make sure
+	 * ___wait_var_event() either sees the bit cleared or
+	 * waitqueue_active() check in wake_up_var() sees the waiter.
+	 */
 	smp_mb();
-	wake_up_bit(&inode->i_state, __I_NEW);
+	inode_wake_up_bit(inode, __I_NEW);
 	spin_unlock(&inode->i_lock);
 	iput(inode);
 }
···
  */
 static void __wait_on_freeing_inode(struct inode *inode, bool is_inode_hash_locked)
 {
-	wait_queue_head_t *wq;
-	DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW);
+	struct wait_bit_queue_entry wqe;
+	struct wait_queue_head *wq_head;
 
 	/*
 	 * Handle racing against evict(), see that routine for more details.
···
 		return;
 	}
 
-	wq = bit_waitqueue(&inode->i_state, __I_NEW);
-	prepare_to_wait(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE);
+	wq_head = inode_bit_waitqueue(&wqe, inode, __I_NEW);
+	prepare_to_wait_event(wq_head, &wqe.wq_entry, TASK_UNINTERRUPTIBLE);
 	spin_unlock(&inode->i_lock);
 	rcu_read_unlock();
 	if (is_inode_hash_locked)
 		spin_unlock(&inode_hash_lock);
 	schedule();
-	finish_wait(wq, &wait.wq_entry);
+	finish_wait(wq_head, &wqe.wq_entry);
 	if (is_inode_hash_locked)
 		spin_lock(&inode_hash_lock);
 	rcu_read_lock();

include/linux/writeback.h

···
 /* writeback.h requires fs.h; it, too, is not included from here. */
 static inline void wait_on_inode(struct inode *inode)
 {
-	wait_on_bit(&inode->i_state, __I_NEW, TASK_UNINTERRUPTIBLE);
+	wait_var_event(inode_state_wait_address(inode, __I_NEW),
+		       !(READ_ONCE(inode->i_state) & I_NEW));
 }
 
 #ifdef CONFIG_CGROUP_WRITEBACK