btrfs: switch extent_buffer spinning_writers from atomic to int

The spinning_writers is either 0 or 1 and always updated under the lock,
so we don't need the atomic_t semantics.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -4876,7 +4876,7 @@ __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start,
 	BUG_ON(len > MAX_INLINE_EXTENT_BUFFER_SIZE);
 
 #ifdef CONFIG_BTRFS_DEBUG
-	atomic_set(&eb->spinning_writers, 0);
+	eb->spinning_writers = 0;
 	atomic_set(&eb->spinning_readers, 0);
 	atomic_set(&eb->read_locks, 0);
 	atomic_set(&eb->write_locks, 0);

fs/btrfs/extent_io.h

@@ -187,7 +187,7 @@ 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;
+	int spinning_writers;
 	atomic_t spinning_readers;
 	atomic_t read_locks;
 	atomic_t write_locks;

fs/btrfs/locking.c

@@ -15,19 +15,19 @@
 #ifdef CONFIG_BTRFS_DEBUG
 static void btrfs_assert_spinning_writers_get(struct extent_buffer *eb)
 {
-	WARN_ON(atomic_read(&eb->spinning_writers));
-	atomic_inc(&eb->spinning_writers);
+	WARN_ON(eb->spinning_writers);
+	eb->spinning_writers++;
 }
 
 static void btrfs_assert_spinning_writers_put(struct extent_buffer *eb)
 {
-	WARN_ON(atomic_read(&eb->spinning_writers) != 1);
-	atomic_dec(&eb->spinning_writers);
+	WARN_ON(eb->spinning_writers != 1);
+	eb->spinning_writers--;
 }
 
 static void btrfs_assert_no_spinning_writers(struct extent_buffer *eb)
 {
-	WARN_ON(atomic_read(&eb->spinning_writers));
+	WARN_ON(eb->spinning_writers);
 }
 
 static void btrfs_assert_spinning_readers_get(struct extent_buffer *eb)

fs/btrfs/print-tree.c

@@ -157,7 +157,7 @@ static void print_eb_refs_lock(struct extent_buffer *eb)
 		   atomic_read(&eb->read_locks),
 		   eb->blocking_writers,
 		   atomic_read(&eb->blocking_readers),
-		   atomic_read(&eb->spinning_writers),
+		   eb->spinning_writers,
 		   atomic_read(&eb->spinning_readers),
 		   eb->lock_owner, current->pid);
 #endif