/*
   * 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 "ctree.h"

  #include "transaction.h"

  #include "disk-io.h"
  #include "print-tree.h"

  /*

   * lookup the root with the highest offset for a given objectid.  The key we do
   * find is copied into 'key'.  If we find something return 0, otherwise 1, < 0
   * on error.
   */

  int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
  			struct btrfs_root_item *item, struct btrfs_key *key)
  {

  	struct btrfs_path *path;

  	struct btrfs_key search_key;

  	struct btrfs_key found_key;
  	struct extent_buffer *l;

  	int ret;
  	int slot;
  
  	search_key.objectid = objectid;

  	search_key.type = BTRFS_ROOT_ITEM_KEY;

  	search_key.offset = (u64)-1;

  	path = btrfs_alloc_path();

  	if (!path)
  		return -ENOMEM;

  	ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);

  	if (ret < 0)
  		goto out;

  	BUG_ON(ret == 0);

  	if (path->slots[0] == 0) {
  		ret = 1;
  		goto out;
  	}

  	l = path->nodes[0];

  	slot = path->slots[0] - 1;

  	btrfs_item_key_to_cpu(l, &found_key, slot);

  	if (found_key.objectid != objectid ||
  	    found_key.type != BTRFS_ROOT_ITEM_KEY) {

  		ret = 1;
  		goto out;
  	}

  	if (item)
  		read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
  				   sizeof(*item));
  	if (key)
  		memcpy(key, &found_key, sizeof(found_key));

  	ret = 0;
  out:

  	btrfs_free_path(path);

  	return ret;
  }

  void btrfs_set_root_node(struct btrfs_root_item *item,
  			 struct extent_buffer *node)

  {
  	btrfs_set_root_bytenr(item, node->start);
  	btrfs_set_root_level(item, btrfs_header_level(node));
  	btrfs_set_root_generation(item, btrfs_header_generation(node));

  }

  /*
   * copy the data in 'item' into the btree
   */

  int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
  		      *root, struct btrfs_key *key, struct btrfs_root_item
  		      *item)

  {

  	struct btrfs_path *path;

  	struct extent_buffer *l;

  	int ret;
  	int slot;

  	unsigned long ptr;

  	path = btrfs_alloc_path();
  	BUG_ON(!path);

  	ret = btrfs_search_slot(trans, root, key, path, 0, 1);

  	if (ret < 0)
  		goto out;

  
  	if (ret != 0) {
  		btrfs_print_leaf(root, path->nodes[0]);

  		printk(KERN_CRIT "unable to update root key %llu %u %llu
  ",
  		       (unsigned long long)key->objectid, key->type,
  		       (unsigned long long)key->offset);

  		BUG_ON(1);
  	}

  	l = path->nodes[0];

  	slot = path->slots[0];

  	ptr = btrfs_item_ptr_offset(l, slot);
  	write_extent_buffer(l, item, ptr, sizeof(*item));

  	btrfs_mark_buffer_dirty(path->nodes[0]);

  out:

  	btrfs_free_path(path);

  	return ret;
  }

  int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
  		      *root, struct btrfs_key *key, struct btrfs_root_item
  		      *item)

  {
  	int ret;

  	ret = btrfs_insert_item(trans, root, key, item, sizeof(*item));

  	return ret;
  }

  /*
   * at mount time we want to find all the old transaction snapshots that were in

   * the process of being deleted if we crashed.  This is any root item with an
   * offset lower than the latest root.  They need to be queued for deletion to
   * finish what was happening when we crashed.

   */

  int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid)

  {
  	struct btrfs_root *dead_root;

  	struct btrfs_root_item *ri;
  	struct btrfs_key key;

  	struct btrfs_key found_key;

  	struct btrfs_path *path;
  	int ret;
  	u32 nritems;

  	struct extent_buffer *leaf;

  	int slot;

  	key.objectid = objectid;

  	btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
  	key.offset = 0;
  	path = btrfs_alloc_path();
  	if (!path)
  		return -ENOMEM;

  
  again:

  	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
  	if (ret < 0)
  		goto err;

  	while (1) {

  		leaf = path->nodes[0];
  		nritems = btrfs_header_nritems(leaf);

  		slot = path->slots[0];
  		if (slot >= nritems) {
  			ret = btrfs_next_leaf(root, path);
  			if (ret)
  				break;

  			leaf = path->nodes[0];
  			nritems = btrfs_header_nritems(leaf);

  			slot = path->slots[0];
  		}

  		btrfs_item_key_to_cpu(leaf, &key, slot);

  		if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
  			goto next;

  
  		if (key.objectid < objectid)
  			goto next;
  
  		if (key.objectid > objectid)
  			break;

  		ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);

  		if (btrfs_disk_root_refs(leaf, ri) != 0)

  			goto next;

  		memcpy(&found_key, &key, sizeof(key));
  		key.offset++;

  		btrfs_release_path(path);

  		dead_root =
  			btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
  						    &found_key);

  		if (IS_ERR(dead_root)) {
  			ret = PTR_ERR(dead_root);

  			goto err;
  		}

  		ret = btrfs_add_dead_root(dead_root);

  		if (ret)
  			goto err;

  		goto again;

  next:
  		slot++;
  		path->slots[0]++;
  	}
  	ret = 0;
  err:
  	btrfs_free_path(path);
  	return ret;
  }

  int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
  {
  	struct extent_buffer *leaf;
  	struct btrfs_path *path;
  	struct btrfs_key key;

  	struct btrfs_key root_key;
  	struct btrfs_root *root;

  	int err = 0;
  	int ret;
  
  	path = btrfs_alloc_path();
  	if (!path)
  		return -ENOMEM;
  
  	key.objectid = BTRFS_ORPHAN_OBJECTID;
  	key.type = BTRFS_ORPHAN_ITEM_KEY;
  	key.offset = 0;

  	root_key.type = BTRFS_ROOT_ITEM_KEY;
  	root_key.offset = (u64)-1;

  	while (1) {
  		ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
  		if (ret < 0) {
  			err = ret;
  			break;
  		}
  
  		leaf = path->nodes[0];
  		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
  			ret = btrfs_next_leaf(tree_root, path);
  			if (ret < 0)
  				err = ret;
  			if (ret != 0)
  				break;
  			leaf = path->nodes[0];
  		}
  
  		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);

  		btrfs_release_path(path);

  
  		if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
  		    key.type != BTRFS_ORPHAN_ITEM_KEY)
  			break;

  		root_key.objectid = key.offset;
  		key.offset++;
  
  		root = btrfs_read_fs_root_no_name(tree_root->fs_info,
  						  &root_key);
  		if (!IS_ERR(root))
  			continue;
  
  		ret = PTR_ERR(root);
  		if (ret != -ENOENT) {

  			err = ret;
  			break;
  		}

  		ret = btrfs_find_dead_roots(tree_root, root_key.objectid);
  		if (ret) {
  			err = ret;
  			break;
  		}

  	}
  
  	btrfs_free_path(path);
  	return err;
  }

  /* drop the root item for 'key' from 'root' */

  int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  		   struct btrfs_key *key)

  {

  	struct btrfs_path *path;

  	int ret;

  	struct btrfs_root_item *ri;

  	struct extent_buffer *leaf;

  	path = btrfs_alloc_path();

  	if (!path)
  		return -ENOMEM;

  	ret = btrfs_search_slot(trans, root, key, path, -1, 1);

  	if (ret < 0)
  		goto out;

  	BUG_ON(ret != 0);

  	leaf = path->nodes[0];
  	ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);

  	ret = btrfs_del_item(trans, root, path);

  out:

  	btrfs_free_path(path);

  	return ret;
  }

  
  int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
  		       struct btrfs_root *tree_root,

  		       u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
  		       const char *name, int name_len)

  {

  	struct btrfs_path *path;
  	struct btrfs_root_ref *ref;
  	struct extent_buffer *leaf;

  	struct btrfs_key key;

  	unsigned long ptr;
  	int err = 0;

  	int ret;

  
  	path = btrfs_alloc_path();

  	if (!path)
  		return -ENOMEM;

  
  	key.objectid = root_id;

  	key.type = BTRFS_ROOT_BACKREF_KEY;

  	key.offset = ref_id;

  again:

  	ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);

  	BUG_ON(ret < 0);
  	if (ret == 0) {
  		leaf = path->nodes[0];
  		ref = btrfs_item_ptr(leaf, path->slots[0],
  				     struct btrfs_root_ref);
  
  		WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
  		WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
  		ptr = (unsigned long)(ref + 1);
  		WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
  		*sequence = btrfs_root_ref_sequence(leaf, ref);
  
  		ret = btrfs_del_item(trans, tree_root, path);

  		if (ret) {
  			err = ret;
  			goto out;
  		}

  	} else
  		err = -ENOENT;
  
  	if (key.type == BTRFS_ROOT_BACKREF_KEY) {

  		btrfs_release_path(path);

  		key.objectid = ref_id;
  		key.type = BTRFS_ROOT_REF_KEY;
  		key.offset = root_id;
  		goto again;
  	}

  out:

  	btrfs_free_path(path);

  	return err;

  }

  int btrfs_find_root_ref(struct btrfs_root *tree_root,
  		   struct btrfs_path *path,
  		   u64 root_id, u64 ref_id)
  {
  	struct btrfs_key key;
  	int ret;
  
  	key.objectid = root_id;
  	key.type = BTRFS_ROOT_REF_KEY;
  	key.offset = ref_id;
  
  	ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
  	return ret;
  }

  /*
   * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
   * or BTRFS_ROOT_BACKREF_KEY.
   *
   * The dirid, sequence, name and name_len refer to the directory entry
   * that is referencing the root.
   *
   * For a forward ref, the root_id is the id of the tree referencing
   * the root and ref_id is the id of the subvol  or snapshot.
   *
   * For a back ref the root_id is the id of the subvol or snapshot and
   * ref_id is the id of the tree referencing it.
   */
  int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
  		       struct btrfs_root *tree_root,

  		       u64 root_id, u64 ref_id, u64 dirid, u64 sequence,

  		       const char *name, int name_len)
  {
  	struct btrfs_key key;
  	int ret;
  	struct btrfs_path *path;
  	struct btrfs_root_ref *ref;
  	struct extent_buffer *leaf;
  	unsigned long ptr;

  	path = btrfs_alloc_path();

  	if (!path)
  		return -ENOMEM;

  
  	key.objectid = root_id;

  	key.type = BTRFS_ROOT_BACKREF_KEY;

  	key.offset = ref_id;

  again:

  	ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
  				      sizeof(*ref) + name_len);
  	BUG_ON(ret);
  
  	leaf = path->nodes[0];
  	ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
  	btrfs_set_root_ref_dirid(leaf, ref, dirid);
  	btrfs_set_root_ref_sequence(leaf, ref, sequence);
  	btrfs_set_root_ref_name_len(leaf, ref, name_len);
  	ptr = (unsigned long)(ref + 1);
  	write_extent_buffer(leaf, name, ptr, name_len);
  	btrfs_mark_buffer_dirty(leaf);

  	if (key.type == BTRFS_ROOT_BACKREF_KEY) {

  		btrfs_release_path(path);

  		key.objectid = ref_id;
  		key.type = BTRFS_ROOT_REF_KEY;
  		key.offset = root_id;
  		goto again;
  	}

  	btrfs_free_path(path);

  	return 0;

  }

  
  /*
   * Old btrfs forgets to init root_item->flags and root_item->byte_limit
   * for subvolumes. To work around this problem, we steal a bit from
   * root_item->inode_item->flags, and use it to indicate if those fields
   * have been properly initialized.
   */
  void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
  {
  	u64 inode_flags = le64_to_cpu(root_item->inode.flags);
  
  	if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
  		inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
  		root_item->inode.flags = cpu_to_le64(inode_flags);
  		root_item->flags = 0;
  		root_item->byte_limit = 0;
  	}
  }