1 files changed, 146 insertions, 0 deletions
diff --git a/fs/btrfs/tree-defrag.c b/fs/btrfs/tree-defrag.c
new file mode 100644
index 000000000000..a6a3956cedfb
--- /dev/null
+++ b/fs/btrfs/tree-defrag.c
@@ -0,0 +1,146 @@
+/*
+ * Copyright (C) 2007 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <linux/sched.h>
+#include "ctree.h"
+#include "disk-io.h"
+#include "print-tree.h"
+#include "transaction.h"
+#include "locking.h"
+
+/* defrag all the leaves in a given btree.  If cache_only == 1, don't read things
+ * from disk, otherwise read all the leaves and try to get key order to
+ * better reflect disk order
+ */
+int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
+			struct btrfs_root *root, int cache_only)
+{
+	struct btrfs_path *path = NULL;
+	struct btrfs_key key;
+	int ret = 0;
+	int wret;
+	int level;
+	int orig_level;
+	int is_extent = 0;
+	int next_key_ret = 0;
+	u64 last_ret = 0;
+	u64 min_trans = 0;
+
+	if (cache_only)
+		goto out;
+
+	if (root->fs_info->extent_root == root) {
+		/*
+		 * there's recursion here right now in the tree locking,
+		 * we can't defrag the extent root without deadlock
+		 */
+		goto out;
+	}
+
+	if (root->ref_cows == 0 && !is_extent)
+		goto out;
+
+	if (btrfs_test_opt(root, SSD))
+		goto out;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	level = btrfs_header_level(root->node);
+	orig_level = level;
+
+	if (level == 0) {
+		goto out;
+	}
+	if (root->defrag_progress.objectid == 0) {
+		struct extent_buffer *root_node;
+		u32 nritems;
+
+		root_node = btrfs_lock_root_node(root);
+		nritems = btrfs_header_nritems(root_node);
+		root->defrag_max.objectid = 0;
+		/* from above we know this is not a leaf */
+		btrfs_node_key_to_cpu(root_node, &root->defrag_max,
+				      nritems - 1);
+		btrfs_tree_unlock(root_node);
+		free_extent_buffer(root_node);
+		memset(&key, 0, sizeof(key));
+	} else {
+		memcpy(&key, &root->defrag_progress, sizeof(key));
+	}
+
+	path->keep_locks = 1;
+	if (cache_only)
+		min_trans = root->defrag_trans_start;
+
+	ret = btrfs_search_forward(root, &key, NULL, path,
+				   cache_only, min_trans);
+	if (ret < 0)
+		goto out;
+	if (ret > 0) {
+		ret = 0;
+		goto out;
+	}
+	btrfs_release_path(root, path);
+	wret = btrfs_search_slot(trans, root, &key, path, 0, 1);
+
+	if (wret < 0) {
+		ret = wret;
+		goto out;
+	}
+	if (!path->nodes[1]) {
+		ret = 0;
+		goto out;
+	}
+	path->slots[1] = btrfs_header_nritems(path->nodes[1]);
+	next_key_ret = btrfs_find_next_key(root, path, &key, 1, cache_only,
+					   min_trans);
+	ret = btrfs_realloc_node(trans, root,
+				 path->nodes[1], 0,
+				 cache_only, &last_ret,
+				 &root->defrag_progress);
+	WARN_ON(ret && ret != -EAGAIN);
+	if (next_key_ret == 0) {
+		memcpy(&root->defrag_progress, &key, sizeof(key));
+		ret = -EAGAIN;
+	}
+
+	btrfs_release_path(root, path);
+	if (is_extent)
+		btrfs_extent_post_op(trans, root);
+out:
+	if (path)
+		btrfs_free_path(path);
+	if (ret == -EAGAIN) {
+		if (root->defrag_max.objectid > root->defrag_progress.objectid)
+			goto done;
+		if (root->defrag_max.type > root->defrag_progress.type)
+			goto done;
+		if (root->defrag_max.offset > root->defrag_progress.offset)
+			goto done;
+		ret = 0;
+	}
+done:
+	if (ret != -EAGAIN) {
+		memset(&root->defrag_progress, 0,
+		       sizeof(root->defrag_progress));
+		root->defrag_trans_start = trans->transid;
+	}
+	return ret;
+}