btrfs: tree-log: factor out a clean_log_buffer helper

The tree-log code has three almost identical copies for the accounting on
an extent_buffer that doesn't need to be written any more.  The only
difference is that walk_down_log_tree passed the bytenr used to find the
buffer instead of extent_buffer.start and calculates the length using the
nodesize, while the other two callers look at the extent_buffer.len
field that must always be equivalent to the nodesize.

Factor the code into a common helper.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/tree-log.c

@@ -2563,6 +2563,28 @@ static void unaccount_log_buffer(struct btrfs_fs_info *fs_info, u64 start)
 	btrfs_put_block_group(cache);
 }
 
+static int clean_log_buffer(struct btrfs_trans_handle *trans,
+			    struct extent_buffer *eb)
+{
+	int ret;
+
+	btrfs_tree_lock(eb);
+	btrfs_clear_buffer_dirty(trans, eb);
+	wait_on_extent_buffer_writeback(eb);
+	btrfs_tree_unlock(eb);
+
+	if (trans) {
+		ret = btrfs_pin_reserved_extent(trans, eb->start, eb->len);
+		if (ret)
+			return ret;
+		btrfs_redirty_list_add(trans->transaction, eb);
+	} else {
+		unaccount_log_buffer(eb->fs_info, eb->start);
+	}
+
+	return 0;
+}
+
 static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans,
 				   struct btrfs_root *root,
 				   struct btrfs_path *path, int *level,
@@ -2573,7 +2595,6 @@ static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans,
 	u64 ptr_gen;
 	struct extent_buffer *next;
 	struct extent_buffer *cur;
-	u32 blocksize;
 	int ret = 0;
 
 	while (*level > 0) {
@@ -2593,7 +2614,6 @@ static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans,
 		check.level = *level - 1;
 		check.has_first_key = true;
 		btrfs_node_key_to_cpu(cur, &check.first_key, path->slots[*level]);
-		blocksize = fs_info->nodesize;
 
 		next = btrfs_find_create_tree_block(fs_info, bytenr,
 						    btrfs_header_owner(cur),
@@ -2617,23 +2637,11 @@ static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans,
 					return ret;
 				}
 
-				btrfs_tree_lock(next);
-				btrfs_clear_buffer_dirty(trans, next);
-				wait_on_extent_buffer_writeback(next);
-				btrfs_tree_unlock(next);
-
-				if (trans) {
-					ret = btrfs_pin_reserved_extent(trans,
-							bytenr, blocksize);
+				ret = clean_log_buffer(trans, next);
 				if (ret) {
 					free_extent_buffer(next);
 					return ret;
 				}
-					btrfs_redirty_list_add(
-						trans->transaction, next);
-				} else {
-					unaccount_log_buffer(fs_info, bytenr);
-				}
 			}
 			free_extent_buffer(next);
 			continue;
@@ -2662,7 +2670,6 @@ static noinline int walk_up_log_tree(struct btrfs_trans_handle *trans,
 				 struct btrfs_path *path, int *level,
 				 struct walk_control *wc)
 {
-	struct btrfs_fs_info *fs_info = root->fs_info;
 	int i;
 	int slot;
 	int ret;
@@ -2682,27 +2689,9 @@ static noinline int walk_up_log_tree(struct btrfs_trans_handle *trans,
 				return ret;
 
 			if (wc->free) {
-				struct extent_buffer *next;
-
-				next = path->nodes[*level];
-
-				btrfs_tree_lock(next);
-				btrfs_clear_buffer_dirty(trans, next);
-				wait_on_extent_buffer_writeback(next);
-				btrfs_tree_unlock(next);
-
-				if (trans) {
-					ret = btrfs_pin_reserved_extent(trans,
-						     path->nodes[*level]->start,
-						     path->nodes[*level]->len);
+				ret = clean_log_buffer(trans, path->nodes[*level]);
 				if (ret)
 					return ret;
-					btrfs_redirty_list_add(trans->transaction,
-							       next);
-				} else {
-					unaccount_log_buffer(fs_info,
-						path->nodes[*level]->start);
-				}
 			}
 			free_extent_buffer(path->nodes[*level]);
 			path->nodes[*level] = NULL;
@@ -2720,7 +2709,6 @@ static noinline int walk_up_log_tree(struct btrfs_trans_handle *trans,
 static int walk_log_tree(struct btrfs_trans_handle *trans,
 			 struct btrfs_root *log, struct walk_control *wc)
 {
-	struct btrfs_fs_info *fs_info = log->fs_info;
 	int ret = 0;
 	int wret;
 	int level;
@@ -2762,26 +2750,8 @@ static int walk_log_tree(struct btrfs_trans_handle *trans,
 			 orig_level);
 		if (ret)
 			goto out;
-		if (wc->free) {
-			struct extent_buffer *next;
-
-			next = path->nodes[orig_level];
-
-			btrfs_tree_lock(next);
-			btrfs_clear_buffer_dirty(trans, next);
-			wait_on_extent_buffer_writeback(next);
-			btrfs_tree_unlock(next);
-
-			if (trans) {
-				ret = btrfs_pin_reserved_extent(trans,
-						next->start, next->len);
-				if (ret)
-					goto out;
-				btrfs_redirty_list_add(trans->transaction, next);
-			} else {
-				unaccount_log_buffer(fs_info, next->start);
-			}
-		}
+		if (wc->free)
+			ret = clean_log_buffer(trans, path->nodes[orig_level]);
 	}
 
 out: