btrfs: remove old unused commented out code

Remove code which has been #if0-ed out for a very long time and does not
seem to be related to current codebase anymore.
Signed-off-by: David Sterba <dsterba@suse.cz>

fs/btrfs/delayed-ref.c

@@ -709,79 +709,3 @@ btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr)
 		return btrfs_delayed_node_to_head(ref);
 	return NULL;
 }
-
-/*
- * add a delayed ref to the tree.  This does all of the accounting required
- * to make sure the delayed ref is eventually processed before this
- * transaction commits.
- *
- * The main point of this call is to add and remove a backreference in a single
- * shot, taking the lock only once, and only searching for the head node once.
- *
- * It is the same as doing a ref add and delete in two separate calls.
- */
-#if 0
-int btrfs_update_delayed_ref(struct btrfs_trans_handle *trans,
-			  u64 bytenr, u64 num_bytes, u64 orig_parent,
-			  u64 parent, u64 orig_ref_root, u64 ref_root,
-			  u64 orig_ref_generation, u64 ref_generation,
-			  u64 owner_objectid, int pin)
-{
-	struct btrfs_delayed_ref *ref;
-	struct btrfs_delayed_ref *old_ref;
-	struct btrfs_delayed_ref_head *head_ref;
-	struct btrfs_delayed_ref_root *delayed_refs;
-	int ret;
-
-	ref = kmalloc(sizeof(*ref), GFP_NOFS);
-	if (!ref)
-		return -ENOMEM;
-
-	old_ref = kmalloc(sizeof(*old_ref), GFP_NOFS);
-	if (!old_ref) {
-		kfree(ref);
-		return -ENOMEM;
-	}
-
-	/*
-	 * the parent = 0 case comes from cases where we don't actually
-	 * know the parent yet.  It will get updated later via a add/drop
-	 * pair.
-	 */
-	if (parent == 0)
-		parent = bytenr;
-	if (orig_parent == 0)
-		orig_parent = bytenr;
-
-	head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS);
-	if (!head_ref) {
-		kfree(ref);
-		kfree(old_ref);
-		return -ENOMEM;
-	}
-	delayed_refs = &trans->transaction->delayed_refs;
-	spin_lock(&delayed_refs->lock);
-
-	/*
-	 * insert both the head node and the new ref without dropping
-	 * the spin lock
-	 */
-	ret = __btrfs_add_delayed_ref(trans, &head_ref->node, bytenr, num_bytes,
-				      (u64)-1, 0, 0, 0,
-				      BTRFS_UPDATE_DELAYED_HEAD, 0);
-	BUG_ON(ret);
-
-	ret = __btrfs_add_delayed_ref(trans, &ref->node, bytenr, num_bytes,
-				      parent, ref_root, ref_generation,
-				      owner_objectid, BTRFS_ADD_DELAYED_REF, 0);
-	BUG_ON(ret);
-
-	ret = __btrfs_add_delayed_ref(trans, &old_ref->node, bytenr, num_bytes,
-				      orig_parent, orig_ref_root,
-				      orig_ref_generation, owner_objectid,
-				      BTRFS_DROP_DELAYED_REF, pin);
-	BUG_ON(ret);
-	spin_unlock(&delayed_refs->lock);
-	return 0;
-}
-#endif

fs/btrfs/disk-io.c

@@ -1348,35 +1348,6 @@ struct btrfs_root *btrfs_read_fs_root_no_name(struct btrfs_fs_info *fs_info,
 	return ERR_PTR(ret);
 }
 
-#if 0
-	struct btrfs_root *root;
-	int ret;
-
-	root = btrfs_read_fs_root_no_name(fs_info, location);
-	if (!root)
-		return NULL;
-
-	if (root->in_sysfs)
-		return root;
-
-	ret = btrfs_set_root_name(root, name, namelen);
-	if (ret) {
-		free_extent_buffer(root->node);
-		kfree(root);
-		return ERR_PTR(ret);
-	}
-
-	ret = btrfs_sysfs_add_root(root);
-	if (ret) {
-		free_extent_buffer(root->node);
-		kfree(root->name);
-		kfree(root);
-		return ERR_PTR(ret);
-	}
-	root->in_sysfs = 1;
-	return root;
-#endif
-
 static int btrfs_congested_fn(void *congested_data, int bdi_bits)
 {
 	struct btrfs_fs_info *info = (struct btrfs_fs_info *)congested_data;

fs/btrfs/inode.c

@@ -3093,178 +3093,6 @@ static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
 	return err;
 }
 
-#if 0
-/*
- * when truncating bytes in a file, it is possible to avoid reading
- * the leaves that contain only checksum items.  This can be the
- * majority of the IO required to delete a large file, but it must
- * be done carefully.
- *
- * The keys in the level just above the leaves are checked to make sure
- * the lowest key in a given leaf is a csum key, and starts at an offset
- * after the new  size.
- *
- * Then the key for the next leaf is checked to make sure it also has
- * a checksum item for the same file.  If it does, we know our target leaf
- * contains only checksum items, and it can be safely freed without reading
- * it.
- *
- * This is just an optimization targeted at large files.  It may do
- * nothing.  It will return 0 unless things went badly.
- */
-static noinline int drop_csum_leaves(struct btrfs_trans_handle *trans,
-				     struct btrfs_root *root,
-				     struct btrfs_path *path,
-				     struct inode *inode, u64 new_size)
-{
-	struct btrfs_key key;
-	int ret;
-	int nritems;
-	struct btrfs_key found_key;
-	struct btrfs_key other_key;
-	struct btrfs_leaf_ref *ref;
-	u64 leaf_gen;
-	u64 leaf_start;
-
-	path->lowest_level = 1;
-	key.objectid = inode->i_ino;
-	key.type = BTRFS_CSUM_ITEM_KEY;
-	key.offset = new_size;
-again:
-	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
-	if (ret < 0)
-		goto out;
-
-	if (path->nodes[1] == NULL) {
-		ret = 0;
-		goto out;
-	}
-	ret = 0;
-	btrfs_node_key_to_cpu(path->nodes[1], &found_key, path->slots[1]);
-	nritems = btrfs_header_nritems(path->nodes[1]);
-
-	if (!nritems)
-		goto out;
-
-	if (path->slots[1] >= nritems)
-		goto next_node;
-
-	/* did we find a key greater than anything we want to delete? */
-	if (found_key.objectid > inode->i_ino ||
-	   (found_key.objectid == inode->i_ino && found_key.type > key.type))
-		goto out;
-
-	/* we check the next key in the node to make sure the leave contains
-	 * only checksum items.  This comparison doesn't work if our
-	 * leaf is the last one in the node
-	 */
-	if (path->slots[1] + 1 >= nritems) {
-next_node:
-		/* search forward from the last key in the node, this
-		 * will bring us into the next node in the tree
-		 */
-		btrfs_node_key_to_cpu(path->nodes[1], &found_key, nritems - 1);
-
-		/* unlikely, but we inc below, so check to be safe */
-		if (found_key.offset == (u64)-1)
-			goto out;
-
-		/* search_forward needs a path with locks held, do the
-		 * search again for the original key.  It is possible
-		 * this will race with a balance and return a path that
-		 * we could modify, but this drop is just an optimization
-		 * and is allowed to miss some leaves.
-		 */
-		btrfs_release_path(root, path);
-		found_key.offset++;
-
-		/* setup a max key for search_forward */
-		other_key.offset = (u64)-1;
-		other_key.type = key.type;
-		other_key.objectid = key.objectid;
-
-		path->keep_locks = 1;
-		ret = btrfs_search_forward(root, &found_key, &other_key,
-					   path, 0, 0);
-		path->keep_locks = 0;
-		if (ret || found_key.objectid != key.objectid ||
-		    found_key.type != key.type) {
-			ret = 0;
-			goto out;
-		}
-
-		key.offset = found_key.offset;
-		btrfs_release_path(root, path);
-		cond_resched();
-		goto again;
-	}
-
-	/* we know there's one more slot after us in the tree,
-	 * read that key so we can verify it is also a checksum item
-	 */
-	btrfs_node_key_to_cpu(path->nodes[1], &other_key, path->slots[1] + 1);
-
-	if (found_key.objectid < inode->i_ino)
-		goto next_key;
-
-	if (found_key.type != key.type || found_key.offset < new_size)
-		goto next_key;
-
-	/*
-	 * if the key for the next leaf isn't a csum key from this objectid,
-	 * we can't be sure there aren't good items inside this leaf.
-	 * Bail out
-	 */
-	if (other_key.objectid != inode->i_ino || other_key.type != key.type)
-		goto out;
-
-	leaf_start = btrfs_node_blockptr(path->nodes[1], path->slots[1]);
-	leaf_gen = btrfs_node_ptr_generation(path->nodes[1], path->slots[1]);
-	/*
-	 * it is safe to delete this leaf, it contains only
-	 * csum items from this inode at an offset >= new_size
-	 */
-	ret = btrfs_del_leaf(trans, root, path, leaf_start);
-	BUG_ON(ret);
-
-	if (root->ref_cows && leaf_gen < trans->transid) {
-		ref = btrfs_alloc_leaf_ref(root, 0);
-		if (ref) {
-			ref->root_gen = root->root_key.offset;
-			ref->bytenr = leaf_start;
-			ref->owner = 0;
-			ref->generation = leaf_gen;
-			ref->nritems = 0;
-
-			btrfs_sort_leaf_ref(ref);
-
-			ret = btrfs_add_leaf_ref(root, ref, 0);
-			WARN_ON(ret);
-			btrfs_free_leaf_ref(root, ref);
-		} else {
-			WARN_ON(1);
-		}
-	}
-next_key:
-	btrfs_release_path(root, path);
-
-	if (other_key.objectid == inode->i_ino &&
-	    other_key.type == key.type && other_key.offset > key.offset) {
-		key.offset = other_key.offset;
-		cond_resched();
-		goto again;
-	}
-	ret = 0;
-out:
-	/* fixup any changes we've made to the path */
-	path->lowest_level = 0;
-	path->keep_locks = 0;
-	btrfs_release_path(root, path);
-	return ret;
-}
-
-#endif
-
 /*
  * this can truncate away extent items, csum items and directory items.
  * It starts at a high offset and removes keys until it can't find

fs/btrfs/transaction.c

@@ -346,49 +346,6 @@ int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 	return ret;
 }
 
-#if 0
-/*
- * rate limit against the drop_snapshot code.  This helps to slow down new
- * operations if the drop_snapshot code isn't able to keep up.
- */
-static void throttle_on_drops(struct btrfs_root *root)
-{
-	struct btrfs_fs_info *info = root->fs_info;
-	int harder_count = 0;
-
-harder:
-	if (atomic_read(&info->throttles)) {
-		DEFINE_WAIT(wait);
-		int thr;
-		thr = atomic_read(&info->throttle_gen);
-
-		do {
-			prepare_to_wait(&info->transaction_throttle,
-					&wait, TASK_UNINTERRUPTIBLE);
-			if (!atomic_read(&info->throttles)) {
-				finish_wait(&info->transaction_throttle, &wait);
-				break;
-			}
-			schedule();
-			finish_wait(&info->transaction_throttle, &wait);
-		} while (thr == atomic_read(&info->throttle_gen));
-		harder_count++;
-
-		if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&
-		    harder_count < 2)
-			goto harder;
-
-		if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&
-		    harder_count < 10)
-			goto harder;
-
-		if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&
-		    harder_count < 20)
-			goto harder;
-	}
-}
-#endif
-
 void btrfs_throttle(struct btrfs_root *root)
 {
 	mutex_lock(&root->fs_info->trans_mutex);
@@ -808,97 +765,6 @@ int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 	return ret;
 }
 
-#if 0
-/*
- * when dropping snapshots, we generate a ton of delayed refs, and it makes
- * sense not to join the transaction while it is trying to flush the current
- * queue of delayed refs out.
- *
- * This is used by the drop snapshot code only
- */
-static noinline int wait_transaction_pre_flush(struct btrfs_fs_info *info)
-{
-	DEFINE_WAIT(wait);
-
-	mutex_lock(&info->trans_mutex);
-	while (info->running_transaction &&
-	       info->running_transaction->delayed_refs.flushing) {
-		prepare_to_wait(&info->transaction_wait, &wait,
-				TASK_UNINTERRUPTIBLE);
-		mutex_unlock(&info->trans_mutex);
-
-		schedule();
-
-		mutex_lock(&info->trans_mutex);
-		finish_wait(&info->transaction_wait, &wait);
-	}
-	mutex_unlock(&info->trans_mutex);
-	return 0;
-}
-
-/*
- * Given a list of roots that need to be deleted, call btrfs_drop_snapshot on
- * all of them
- */
-int btrfs_drop_dead_root(struct btrfs_root *root)
-{
-	struct btrfs_trans_handle *trans;
-	struct btrfs_root *tree_root = root->fs_info->tree_root;
-	unsigned long nr;
-	int ret;
-
-	while (1) {
-		/*
-		 * we don't want to jump in and create a bunch of
-		 * delayed refs if the transaction is starting to close
-		 */
-		wait_transaction_pre_flush(tree_root->fs_info);
-		trans = btrfs_start_transaction(tree_root, 1);
-
-		/*
-		 * we've joined a transaction, make sure it isn't
-		 * closing right now
-		 */
-		if (trans->transaction->delayed_refs.flushing) {
-			btrfs_end_transaction(trans, tree_root);
-			continue;
-		}
-
-		ret = btrfs_drop_snapshot(trans, root);
-		if (ret != -EAGAIN)
-			break;
-
-		ret = btrfs_update_root(trans, tree_root,
-					&root->root_key,
-					&root->root_item);
-		if (ret)
-			break;
-
-		nr = trans->blocks_used;
-		ret = btrfs_end_transaction(trans, tree_root);
-		BUG_ON(ret);
-
-		btrfs_btree_balance_dirty(tree_root, nr);
-		cond_resched();
-	}
-	BUG_ON(ret);
-
-	ret = btrfs_del_root(trans, tree_root, &root->root_key);
-	BUG_ON(ret);
-
-	nr = trans->blocks_used;
-	ret = btrfs_end_transaction(trans, tree_root);
-	BUG_ON(ret);
-
-	free_extent_buffer(root->node);
-	free_extent_buffer(root->commit_root);
-	kfree(root);
-
-	btrfs_btree_balance_dirty(tree_root, nr);
-	return ret;
-}
-#endif
-
 /*
  * new snapshots need to be created at a very specific time in the
  * transaction commit.  This does the actual creation