btrfs: add set/get accessors for root_item::drop_level

The drop_level member is used directly unlike all the other int types in
root_item. Add the definition and use it everywhere. The type is u8 so
there's no conversion necessary and the helpers are properly inlined,
this is for consistency.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ctree.h

@@ -2089,6 +2089,7 @@ BTRFS_SETGET_FUNCS(disk_root_level, struct btrfs_root_item, level, 8);
 BTRFS_SETGET_STACK_FUNCS(root_generation, struct btrfs_root_item,
 			 generation, 64);
 BTRFS_SETGET_STACK_FUNCS(root_bytenr, struct btrfs_root_item, bytenr, 64);
+BTRFS_SETGET_STACK_FUNCS(root_drop_level, struct btrfs_root_item, drop_level, 8);
 BTRFS_SETGET_STACK_FUNCS(root_level, struct btrfs_root_item, level, 8);
 BTRFS_SETGET_STACK_FUNCS(root_dirid, struct btrfs_root_item, root_dirid, 64);
 BTRFS_SETGET_STACK_FUNCS(root_refs, struct btrfs_root_item, refs, 32);

fs/btrfs/disk-io.c

@@ -1179,7 +1179,7 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
 		generate_random_guid(root->root_item.uuid);
 	else
 		export_guid(root->root_item.uuid, &guid_null);
-	root->root_item.drop_level = 0;
+	btrfs_set_root_drop_level(&root->root_item, 0);
 
 	key.objectid = objectid;
 	key.type = BTRFS_ROOT_ITEM_KEY;

fs/btrfs/extent-tree.c

@@ -5496,7 +5496,7 @@ int btrfs_drop_snapshot(struct btrfs_root *root, int update_ref, int for_reloc)
 		memcpy(&wc->update_progress, &key,
 		       sizeof(wc->update_progress));
 
-		level = root_item->drop_level;
+		level = btrfs_root_drop_level(root_item);
 		BUG_ON(level == 0);
 		path->lowest_level = level;
 		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
@@ -5529,7 +5529,7 @@ int btrfs_drop_snapshot(struct btrfs_root *root, int update_ref, int for_reloc)
 			}
 			BUG_ON(wc->refs[level] == 0);
 
-			if (level == root_item->drop_level)
+			if (level == btrfs_root_drop_level(root_item))
 				break;
 
 			btrfs_tree_unlock(path->nodes[level]);
@@ -5574,7 +5574,7 @@ int btrfs_drop_snapshot(struct btrfs_root *root, int update_ref, int for_reloc)
 		}
 		btrfs_cpu_key_to_disk(&root_item->drop_progress,
 				      &wc->drop_progress);
-		root_item->drop_level = wc->drop_level;
+		btrfs_set_root_drop_level(root_item, wc->drop_level);
 
 		BUG_ON(wc->level == 0);
 		if (btrfs_should_end_transaction(trans) ||

fs/btrfs/inode.c

@@ -4105,7 +4105,7 @@ int btrfs_delete_subvolume(struct inode *dir, struct dentry *dentry)
 
 	memset(&dest->root_item.drop_progress, 0,
 		sizeof(dest->root_item.drop_progress));
-	dest->root_item.drop_level = 0;
+	btrfs_set_root_drop_level(&dest->root_item, 0);
 	btrfs_set_root_refs(&dest->root_item, 0);
 
 	if (!test_and_set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &dest->state)) {

fs/btrfs/relocation.c

@@ -783,7 +783,7 @@ static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
 		btrfs_set_root_refs(root_item, 0);
 		memset(&root_item->drop_progress, 0,
 		       sizeof(struct btrfs_disk_key));
-		root_item->drop_level = 0;
+		btrfs_set_root_drop_level(root_item, 0);
 	}
 
 	btrfs_tree_unlock(eb);
@@ -1575,7 +1575,7 @@ static void insert_dirty_subvol(struct btrfs_trans_handle *trans,
 	reloc_root_item = &reloc_root->root_item;
 	memset(&reloc_root_item->drop_progress, 0,
 		sizeof(reloc_root_item->drop_progress));
-	reloc_root_item->drop_level = 0;
+	btrfs_set_root_drop_level(reloc_root_item, 0);
 	btrfs_set_root_refs(reloc_root_item, 0);
 	btrfs_update_reloc_root(trans, root);
 
@@ -1672,7 +1672,7 @@ static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
 	} else {
 		btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
 
-		level = root_item->drop_level;
+		level = btrfs_root_drop_level(root_item);
 		BUG_ON(level == 0);
 		path->lowest_level = level;
 		ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
@@ -1769,7 +1769,7 @@ static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
 		 */
 		btrfs_node_key(path->nodes[level], &root_item->drop_progress,
 			       path->slots[level]);
-		root_item->drop_level = level;
+		btrfs_set_root_drop_level(root_item, level);
 
 		btrfs_end_transaction_throttle(trans);
 		trans = NULL;
@@ -3694,7 +3694,7 @@ static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
 
 	memset(&root->root_item.drop_progress, 0,
 		sizeof(root->root_item.drop_progress));
-	root->root_item.drop_level = 0;
+	btrfs_set_root_drop_level(&root->root_item, 0);
 	btrfs_set_root_refs(&root->root_item, 0);
 	ret = btrfs_update_root(trans, fs_info->tree_root,
 				&root->root_key, &root->root_item);

fs/btrfs/tree-checker.c

@@ -1118,10 +1118,10 @@ static int check_root_item(struct extent_buffer *leaf, struct btrfs_key *key,
 			    btrfs_root_level(&ri), BTRFS_MAX_LEVEL - 1);
 		return -EUCLEAN;
 	}
-	if (ri.drop_level >= BTRFS_MAX_LEVEL) {
+	if (btrfs_root_drop_level(&ri) >= BTRFS_MAX_LEVEL) {
 		generic_err(leaf, slot,
 			    "invalid root level, have %u expect [0, %u]",
-			    ri.drop_level, BTRFS_MAX_LEVEL - 1);
+			    btrfs_root_drop_level(&ri), BTRFS_MAX_LEVEL - 1);
 		return -EUCLEAN;
 	}