btrfs: rename root fields in delayed refs structs

Both data and metadata delayed ref structures have fields named
root/ref_root respectively. Those are somewhat cryptic and don't really
convey the real meaning. In fact those roots are really the original
owners of the respective block (i.e in case of a snapshot a data delayed
ref will contain the original root that owns the given block). Rename
those fields accordingly and adjust comments.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/delayed-ref.c

@@ -922,7 +922,7 @@ int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
 
 	if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags) &&
 	    is_fstree(generic_ref->real_root) &&
-	    is_fstree(generic_ref->tree_ref.root) &&
+	    is_fstree(generic_ref->tree_ref.owning_root) &&
 	    !generic_ref->skip_qgroup) {
 		record = kzalloc(sizeof(*record), GFP_NOFS);
 		if (!record) {
@@ -938,14 +938,15 @@ int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
 		ref_type = BTRFS_TREE_BLOCK_REF_KEY;
 
 	init_delayed_ref_common(fs_info, &ref->node, bytenr, num_bytes,
-				generic_ref->tree_ref.root, action, ref_type);
-	ref->root = generic_ref->tree_ref.root;
+				generic_ref->tree_ref.owning_root, action,
+				ref_type);
+	ref->root = generic_ref->tree_ref.owning_root;
 	ref->parent = parent;
 	ref->level = level;
 
 	init_delayed_ref_head(head_ref, record, bytenr, num_bytes,
-			      generic_ref->tree_ref.root, 0, action, false,
-			      is_system);
+			      generic_ref->tree_ref.owning_root, 0, action,
+			      false, is_system);
 	head_ref->extent_op = extent_op;
 
 	delayed_refs = &trans->transaction->delayed_refs;
@@ -997,7 +998,7 @@ int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
 	u64 bytenr = generic_ref->bytenr;
 	u64 num_bytes = generic_ref->len;
 	u64 parent = generic_ref->parent;
-	u64 ref_root = generic_ref->data_ref.ref_root;
+	u64 ref_root = generic_ref->data_ref.owning_root;
 	u64 owner = generic_ref->data_ref.ino;
 	u64 offset = generic_ref->data_ref.offset;
 	u8 ref_type;

fs/btrfs/delayed-ref.h

@@ -186,8 +186,8 @@ enum btrfs_ref_type {
 struct btrfs_data_ref {
 	/* For EXTENT_DATA_REF */
 
-	/* Root which refers to this data extent */
-	u64 ref_root;
+	/* Original root this data extent belongs to */
+	u64 owning_root;
 
 	/* Inode which refers to this data extent */
 	u64 ino;
@@ -210,11 +210,11 @@ struct btrfs_tree_ref {
 	int level;
 
 	/*
-	 * Root which refers to this tree block.
+	 * Root which owns this tree block.
 	 *
 	 * For TREE_BLOCK_REF (skinny metadata, either inline or keyed)
 	 */
-	u64 root;
+	u64 owning_root;
 
 	/* For non-skinny metadata, no special member needed */
 };
@@ -277,7 +277,7 @@ static inline void btrfs_init_tree_ref(struct btrfs_ref *generic_ref,
 	if (!generic_ref->real_root)
 		generic_ref->real_root = root;
 	generic_ref->tree_ref.level = level;
-	generic_ref->tree_ref.root = root;
+	generic_ref->tree_ref.owning_root = root;
 	generic_ref->type = BTRFS_REF_METADATA;
 }
 
@@ -287,7 +287,7 @@ static inline void btrfs_init_data_ref(struct btrfs_ref *generic_ref,
 	/* If @real_root not set, use @root as fallback */
 	if (!generic_ref->real_root)
 		generic_ref->real_root = ref_root;
-	generic_ref->data_ref.ref_root = ref_root;
+	generic_ref->data_ref.owning_root = ref_root;
 	generic_ref->data_ref.ino = ino;
 	generic_ref->data_ref.offset = offset;
 	generic_ref->type = BTRFS_REF_DATA;

fs/btrfs/extent-tree.c

@@ -1396,7 +1396,7 @@ int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
 	ASSERT(generic_ref->type != BTRFS_REF_NOT_SET &&
 	       generic_ref->action);
 	BUG_ON(generic_ref->type == BTRFS_REF_METADATA &&
-	       generic_ref->tree_ref.root == BTRFS_TREE_LOG_OBJECTID);
+	       generic_ref->tree_ref.owning_root == BTRFS_TREE_LOG_OBJECTID);
 
 	if (generic_ref->type == BTRFS_REF_METADATA)
 		ret = btrfs_add_delayed_tree_ref(trans, generic_ref, NULL);
@@ -3372,9 +3372,9 @@ int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_ref *ref)
 	 * tree, just update pinning info and exit early.
 	 */
 	if ((ref->type == BTRFS_REF_METADATA &&
-	     ref->tree_ref.root == BTRFS_TREE_LOG_OBJECTID) ||
+	     ref->tree_ref.owning_root == BTRFS_TREE_LOG_OBJECTID) ||
 	    (ref->type == BTRFS_REF_DATA &&
-	     ref->data_ref.ref_root == BTRFS_TREE_LOG_OBJECTID)) {
+	     ref->data_ref.owning_root == BTRFS_TREE_LOG_OBJECTID)) {
 		/* unlocks the pinned mutex */
 		btrfs_pin_extent(trans, ref->bytenr, ref->len, 1);
 		ret = 0;
@@ -3385,9 +3385,9 @@ int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_ref *ref)
 	}
 
 	if (!((ref->type == BTRFS_REF_METADATA &&
-	       ref->tree_ref.root == BTRFS_TREE_LOG_OBJECTID) ||
+	       ref->tree_ref.owning_root == BTRFS_TREE_LOG_OBJECTID) ||
 	      (ref->type == BTRFS_REF_DATA &&
-	       ref->data_ref.ref_root == BTRFS_TREE_LOG_OBJECTID)))
+	       ref->data_ref.owning_root == BTRFS_TREE_LOG_OBJECTID)))
 		btrfs_ref_tree_mod(fs_info, ref);
 
 	return ret;

fs/btrfs/ref-verify.c

@@ -678,10 +678,10 @@ int btrfs_ref_tree_mod(struct btrfs_fs_info *fs_info,
 
 	if (generic_ref->type == BTRFS_REF_METADATA) {
 		if (!parent)
-			ref_root = generic_ref->tree_ref.root;
+			ref_root = generic_ref->tree_ref.owning_root;
 		owner = generic_ref->tree_ref.level;
 	} else if (!parent) {
-		ref_root = generic_ref->data_ref.ref_root;
+		ref_root = generic_ref->data_ref.owning_root;
 		owner = generic_ref->data_ref.ino;
 		offset = generic_ref->data_ref.offset;
 	}