btrfs: replace clearing extent buffer dirty bit with btrfs_clean_block

Now that we're passing in the trans into btrfs_clean_tree_block, we can
easily roll in the handling of the !trans case and replace all
occurrences of

	if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags))
		clear_extent_buffer_dirty(eb);

with

	btrfs_tree_lock(eb);
	btrfs_clean_tree_block(eb);
	btrfs_tree_unlock(eb);

We need the lock because if we are actually dirty we need to make sure
we aren't racing with anything that's starting writeout currently.  This
also makes sure that we're accounting fs_info->dirty_metadata_bytes
appropriately.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/disk-io.c

@@ -872,7 +872,7 @@ void btrfs_clean_tree_block(struct btrfs_trans_handle *trans,
 			    struct extent_buffer *buf)
 {
 	struct btrfs_fs_info *fs_info = buf->fs_info;
-	if (btrfs_header_generation(buf) == trans->transid) {
+	if (!trans || btrfs_header_generation(buf) == trans->transid) {
 		btrfs_assert_tree_write_locked(buf);
 
 		if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &buf->bflags)) {
@@ -4995,11 +4995,12 @@ static int btrfs_destroy_marked_extents(struct btrfs_fs_info *fs_info,
 			start += fs_info->nodesize;
 			if (!eb)
 				continue;
+
+			btrfs_tree_lock(eb);
 			wait_on_extent_buffer_writeback(eb);
+			btrfs_clean_tree_block(NULL, eb);
+			btrfs_tree_unlock(eb);
 
-			if (test_and_clear_bit(EXTENT_BUFFER_DIRTY,
-					       &eb->bflags))
-				clear_extent_buffer_dirty(eb);
 			free_extent_buffer_stale(eb);
 		}
 	}

fs/btrfs/tree-log.c

@@ -2623,11 +2623,12 @@ static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans,
 					return ret;
 				}
 
+				btrfs_tree_lock(next);
+				btrfs_clean_tree_block(trans, next);
+				btrfs_wait_tree_block_writeback(next);
+				btrfs_tree_unlock(next);
+
 				if (trans) {
-					btrfs_tree_lock(next);
-					btrfs_clean_tree_block(trans, next);
-					btrfs_wait_tree_block_writeback(next);
-					btrfs_tree_unlock(next);
 					ret = btrfs_pin_reserved_extent(trans,
 							bytenr, blocksize);
 					if (ret) {
@@ -2637,8 +2638,6 @@ static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans,
 					btrfs_redirty_list_add(
 						trans->transaction, next);
 				} else {
-					if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &next->bflags))
-						clear_extent_buffer_dirty(next);
 					unaccount_log_buffer(fs_info, bytenr);
 				}
 			}
@@ -2693,11 +2692,12 @@ static noinline int walk_up_log_tree(struct btrfs_trans_handle *trans,
 
 				next = path->nodes[*level];
 
+				btrfs_tree_lock(next);
+				btrfs_clean_tree_block(trans, next);
+				btrfs_wait_tree_block_writeback(next);
+				btrfs_tree_unlock(next);
+
 				if (trans) {
-					btrfs_tree_lock(next);
-					btrfs_clean_tree_block(trans, next);
-					btrfs_wait_tree_block_writeback(next);
-					btrfs_tree_unlock(next);
 					ret = btrfs_pin_reserved_extent(trans,
 						     path->nodes[*level]->start,
 						     path->nodes[*level]->len);
@@ -2706,9 +2706,6 @@ static noinline int walk_up_log_tree(struct btrfs_trans_handle *trans,
 					btrfs_redirty_list_add(trans->transaction,
 							       next);
 				} else {
-					if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &next->bflags))
-						clear_extent_buffer_dirty(next);
-
 					unaccount_log_buffer(fs_info,
 						path->nodes[*level]->start);
 				}
@@ -2776,19 +2773,18 @@ static int walk_log_tree(struct btrfs_trans_handle *trans,
 
 			next = path->nodes[orig_level];
 
+			btrfs_tree_lock(next);
+			btrfs_clean_tree_block(trans, next);
+			btrfs_wait_tree_block_writeback(next);
+			btrfs_tree_unlock(next);
+
 			if (trans) {
-				btrfs_tree_lock(next);
-				btrfs_clean_tree_block(trans, next);
-				btrfs_wait_tree_block_writeback(next);
-				btrfs_tree_unlock(next);
 				ret = btrfs_pin_reserved_extent(trans,
 						next->start, next->len);
 				if (ret)
 					goto out;
 				btrfs_redirty_list_add(trans->transaction, next);
 			} else {
-				if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &next->bflags))
-					clear_extent_buffer_dirty(next);
 				unaccount_log_buffer(fs_info, next->start);
 			}
 		}