dm vdo wait-queue: rename to vdo_waitq_dequeue_waiter

Rename vdo_waitq_dequeue_next_waiter to vdo_waitq_dequeue_waiter.  The
"next" aspect of returned waiter is implied. "next" also isn't
informative ("oldest" would be). Removing "next_" adds symmetry to
vdo_waitq_enqueue_waiter().

Also fix whitespace and comments from previous waitq commit.

Reviewed-by: Ken Raeburn <raeburn@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Matthew Sakai <msakai@redhat.com>

drivers/md/dm-vdo/block-map.c

@@ -913,7 +913,7 @@ static void allocate_free_page(struct page_info *info)
 
 	/*
 	 * Remove all entries which match the page number in question and push them onto the page
-	 * info's wait queue.
+	 * info's waitq.
 	 */
 	vdo_waitq_dequeue_matching_waiters(&cache->free_waiters, completion_needs_page,
 					   &pbn, &info->waiting);
@@ -1593,9 +1593,8 @@ static void finish_page_write(struct vdo_completion *completion)
 		enqueue_page(page, zone);
 	} else if ((zone->flusher == NULL) && vdo_waitq_has_waiters(&zone->flush_waiters) &&
 		   attempt_increment(zone)) {
-		zone->flusher =
-			container_of(vdo_waitq_dequeue_next_waiter(&zone->flush_waiters),
-				     struct tree_page, waiter);
+		zone->flusher = container_of(vdo_waitq_dequeue_waiter(&zone->flush_waiters),
+					     struct tree_page, waiter);
 		write_page(zone->flusher, pooled);
 		return;
 	}

drivers/md/dm-vdo/data-vio.c

@@ -1191,7 +1191,7 @@ static void transfer_lock(struct data_vio *data_vio, struct lbn_lock *lock)
 
 	/* Another data_vio is waiting for the lock, transfer it in a single lock map operation. */
 	next_lock_holder =
-		vdo_waiter_as_data_vio(vdo_waitq_dequeue_next_waiter(&lock->waiters));
+		vdo_waiter_as_data_vio(vdo_waitq_dequeue_waiter(&lock->waiters));
 
 	/* Transfer the remaining lock waiters to the next lock holder. */
 	vdo_waitq_transfer_all_waiters(&lock->waiters,

drivers/md/dm-vdo/dedupe.c

@@ -413,14 +413,14 @@ static void set_duplicate_lock(struct hash_lock *hash_lock, struct pbn_lock *pbn
 }
 
 /**
- * dequeue_lock_waiter() - Remove the first data_vio from the lock's wait queue and return it.
+ * dequeue_lock_waiter() - Remove the first data_vio from the lock's waitq and return it.
  * @lock: The lock containing the wait queue.
  *
  * Return: The first (oldest) waiter in the queue, or NULL if the queue is empty.
  */
 static inline struct data_vio *dequeue_lock_waiter(struct hash_lock *lock)
 {
-	return vdo_waiter_as_data_vio(vdo_waitq_dequeue_next_waiter(&lock->waiters));
+	return vdo_waiter_as_data_vio(vdo_waitq_dequeue_waiter(&lock->waiters));
 }
 
 /**

drivers/md/dm-vdo/flush.c

@@ -196,7 +196,7 @@ static void finish_notification(struct vdo_completion *completion)
 	assert_on_flusher_thread(flusher, __func__);
 
 	vdo_waitq_enqueue_waiter(&flusher->pending_flushes,
-				 vdo_waitq_dequeue_next_waiter(&flusher->notifiers));
+				 vdo_waitq_dequeue_waiter(&flusher->notifiers));
 	vdo_complete_flushes(flusher);
 	if (vdo_waitq_has_waiters(&flusher->notifiers))
 		notify_flush(flusher);
@@ -335,7 +335,7 @@ void vdo_complete_flushes(struct flusher *flusher)
 				"acknowledged next expected flush, %llu, was: %llu",
 				(unsigned long long) flusher->first_unacknowledged_generation,
 				(unsigned long long) flush->flush_generation);
-		vdo_waitq_dequeue_next_waiter(&flusher->pending_flushes);
+		vdo_waitq_dequeue_waiter(&flusher->pending_flushes);
 		vdo_complete_flush(flush);
 		flusher->first_unacknowledged_generation++;
 	}

drivers/md/dm-vdo/recovery-journal.c

@@ -1332,7 +1332,7 @@ static void add_queued_recovery_entries(struct recovery_journal_block *block)
 {
 	while (vdo_waitq_has_waiters(&block->entry_waiters)) {
 		struct data_vio *data_vio =
-			vdo_waiter_as_data_vio(vdo_waitq_dequeue_next_waiter(&block->entry_waiters));
+			vdo_waiter_as_data_vio(vdo_waitq_dequeue_waiter(&block->entry_waiters));
 		struct tree_lock *lock = &data_vio->tree_lock;
 		struct packed_recovery_journal_entry *packed_entry;
 		struct recovery_journal_entry new_entry;

drivers/md/dm-vdo/wait-queue.c

@@ -135,7 +135,7 @@ void vdo_waitq_dequeue_matching_waiters(struct vdo_wait_queue *waitq,
 	vdo_waitq_transfer_all_waiters(waitq, &iteration_waitq);
 
 	while (vdo_waitq_has_waiters(&iteration_waitq)) {
-		struct vdo_waiter *waiter = vdo_waitq_dequeue_next_waiter(&iteration_waitq);
+		struct vdo_waiter *waiter = vdo_waitq_dequeue_waiter(&iteration_waitq);
 
 		vdo_waitq_enqueue_waiter((waiter_match(waiter, match_context) ?
 					  matched_waitq : waitq), waiter);
@@ -143,15 +143,15 @@ void vdo_waitq_dequeue_matching_waiters(struct vdo_wait_queue *waitq,
 }
 
 /**
- * vdo_waitq_dequeue_next_waiter() - Remove the first waiter from the head end of a waitq.
+ * vdo_waitq_dequeue_waiter() - Remove the first (oldest) waiter from a waitq.
  * @waitq: The vdo_wait_queue from which to remove the first entry.
  *
- * The caller will be responsible for waking the waiter by invoking the correct callback function
- * to resume its execution.
+ * The caller will be responsible for waking the waiter by continuing its
+ * execution appropriately.
  *
  * Return: The first (oldest) waiter in the waitq, or NULL if the waitq is empty.
  */
-struct vdo_waiter *vdo_waitq_dequeue_next_waiter(struct vdo_wait_queue *waitq)
+struct vdo_waiter *vdo_waitq_dequeue_waiter(struct vdo_wait_queue *waitq)
 {
 	struct vdo_waiter *first_waiter = vdo_waitq_get_first_waiter(waitq);
 	struct vdo_waiter *last_waiter = waitq->last_waiter;
@@ -160,12 +160,12 @@ struct vdo_waiter *vdo_waitq_dequeue_next_waiter(struct vdo_wait_queue *waitq)
 		return NULL;
 
 	if (first_waiter == last_waiter) {
-		/* The waitq has a single entry, so just empty it out by nulling the tail. */
+		/* The waitq has a single entry, so empty it by nulling the tail. */
 		waitq->last_waiter = NULL;
 	} else {
 		/*
-		 * The waitq has more than one entry, so splice the first waiter out of the
-		 * circular waitq.
+		 * The waitq has multiple waiters, so splice the first waiter out
+		 * of the circular waitq.
 		 */
 		last_waiter->next_waiter = first_waiter->next_waiter;
 	}
@@ -192,7 +192,7 @@ struct vdo_waiter *vdo_waitq_dequeue_next_waiter(struct vdo_wait_queue *waitq)
 bool vdo_waitq_notify_next_waiter(struct vdo_wait_queue *waitq,
 				  vdo_waiter_callback_fn callback, void *context)
 {
-	struct vdo_waiter *waiter = vdo_waitq_dequeue_next_waiter(waitq);
+	struct vdo_waiter *waiter = vdo_waitq_dequeue_waiter(waitq);
 
 	if (waiter == NULL)
 		return false;

drivers/md/dm-vdo/wait-queue.h

@@ -106,6 +106,8 @@ static inline bool __must_check vdo_waitq_has_waiters(const struct vdo_wait_queu
 void vdo_waitq_enqueue_waiter(struct vdo_wait_queue *waitq,
 			      struct vdo_waiter *waiter);
 
+struct vdo_waiter *vdo_waitq_dequeue_waiter(struct vdo_wait_queue *waitq);
+
 void vdo_waitq_notify_all_waiters(struct vdo_wait_queue *waitq,
 				  vdo_waiter_callback_fn callback, void *context);
 
@@ -122,8 +124,6 @@ void vdo_waitq_dequeue_matching_waiters(struct vdo_wait_queue *waitq,
 					void *match_context,
 					struct vdo_wait_queue *matched_waitq);
 
-struct vdo_waiter *vdo_waitq_dequeue_next_waiter(struct vdo_wait_queue *waitq);
-
 /**
  * vdo_waitq_num_waiters() - Return the number of waiters in a vdo_wait_queue.
  * @waitq: The vdo_wait_queue to query.