btrfs: use assertion helpers for spinning writers

Use the helpers where open coded. On non-debug builds, the warnings will
not trigger and extent_buffer::spining_writers become unused and can be
moved to the appropriate section, saving a few bytes.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -4682,7 +4682,6 @@ __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start,
 	atomic_set(&eb->blocking_readers, 0);
 	atomic_set(&eb->blocking_writers, 0);
 	atomic_set(&eb->spinning_readers, 0);
-	atomic_set(&eb->spinning_writers, 0);
 	eb->lock_nested = 0;
 	init_waitqueue_head(&eb->write_lock_wq);
 	init_waitqueue_head(&eb->read_lock_wq);
@@ -4700,6 +4699,10 @@ __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start,
 		> MAX_INLINE_EXTENT_BUFFER_SIZE);
 	BUG_ON(len > MAX_INLINE_EXTENT_BUFFER_SIZE);
 
+#ifdef CONFIG_BTRFS_DEBUG
+	atomic_set(&eb->spinning_writers, 0);
+#endif
+
 	return eb;
 }
 

fs/btrfs/extent_io.h

@@ -166,7 +166,6 @@ struct extent_buffer {
 	atomic_t blocking_writers;
 	atomic_t blocking_readers;
 	atomic_t spinning_readers;
-	atomic_t spinning_writers;
 	short lock_nested;
 	/* >= 0 if eb belongs to a log tree, -1 otherwise */
 	short log_index;
@@ -185,6 +184,7 @@ struct extent_buffer {
 	wait_queue_head_t read_lock_wq;
 	struct page *pages[INLINE_EXTENT_BUFFER_PAGES];
 #ifdef CONFIG_BTRFS_DEBUG
+	atomic_t spinning_writers;
 	struct list_head leak_list;
 #endif
 };

fs/btrfs/locking.c

@@ -64,8 +64,7 @@ void btrfs_set_lock_blocking_write(struct extent_buffer *eb)
 	if (eb->lock_nested && current->pid == eb->lock_owner)
 		return;
 	if (atomic_read(&eb->blocking_writers) == 0) {
-		WARN_ON(atomic_read(&eb->spinning_writers) != 1);
-		atomic_dec(&eb->spinning_writers);
+		btrfs_assert_spinning_writers_put(eb);
 		btrfs_assert_tree_locked(eb);
 		atomic_inc(&eb->blocking_writers);
 		write_unlock(&eb->lock);
@@ -101,8 +100,7 @@ void btrfs_clear_lock_blocking_write(struct extent_buffer *eb)
 		return;
 	BUG_ON(atomic_read(&eb->blocking_writers) != 1);
 	write_lock(&eb->lock);
-	WARN_ON(atomic_read(&eb->spinning_writers));
-	atomic_inc(&eb->spinning_writers);
+	btrfs_assert_spinning_writers_get(eb);
 	/* atomic_dec_and_test implies a barrier */
 	if (atomic_dec_and_test(&eb->blocking_writers))
 		cond_wake_up_nomb(&eb->write_lock_wq);
@@ -200,7 +198,7 @@ int btrfs_try_tree_write_lock(struct extent_buffer *eb)
 		return 0;
 	}
 	atomic_inc(&eb->write_locks);
-	atomic_inc(&eb->spinning_writers);
+	btrfs_assert_spinning_writers_get(eb);
 	eb->lock_owner = current->pid;
 	return 1;
 }
@@ -266,8 +264,7 @@ void btrfs_tree_lock(struct extent_buffer *eb)
 		write_unlock(&eb->lock);
 		goto again;
 	}
-	WARN_ON(atomic_read(&eb->spinning_writers));
-	atomic_inc(&eb->spinning_writers);
+	btrfs_assert_spinning_writers_get(eb);
 	atomic_inc(&eb->write_locks);
 	eb->lock_owner = current->pid;
 }
@@ -286,14 +283,13 @@ void btrfs_tree_unlock(struct extent_buffer *eb)
 	atomic_dec(&eb->write_locks);
 
 	if (blockers) {
-		WARN_ON(atomic_read(&eb->spinning_writers));
+		btrfs_assert_no_spinning_writers(eb);
 		atomic_dec(&eb->blocking_writers);
 		/* Use the lighter barrier after atomic */
 		smp_mb__after_atomic();
 		cond_wake_up_nomb(&eb->write_lock_wq);
 	} else {
-		WARN_ON(atomic_read(&eb->spinning_writers) != 1);
-		atomic_dec(&eb->spinning_writers);
+		btrfs_assert_spinning_writers_put(eb);
 		write_unlock(&eb->lock);
 	}
 }