/*
   * Copyright (C) STRATO AG 2013.  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/uuid.h>
  #include <asm/unaligned.h>
  #include "ctree.h"
  #include "transaction.h"
  #include "disk-io.h"
  #include "print-tree.h"
  
  
  static void btrfs_uuid_to_key(u8 *uuid, u8 type, struct btrfs_key *key)
  {
  	key->type = type;
  	key->objectid = get_unaligned_le64(uuid);
  	key->offset = get_unaligned_le64(uuid + sizeof(u64));
  }
  
  /* return -ENOENT for !found, < 0 for errors, or 0 if an item was found */
  static int btrfs_uuid_tree_lookup(struct btrfs_root *uuid_root, u8 *uuid,
  				  u8 type, u64 subid)
  {
  	int ret;
  	struct btrfs_path *path = NULL;
  	struct extent_buffer *eb;
  	int slot;
  	u32 item_size;
  	unsigned long offset;
  	struct btrfs_key key;
  
  	if (WARN_ON_ONCE(!uuid_root)) {
  		ret = -ENOENT;
  		goto out;
  	}
  
  	path = btrfs_alloc_path();
  	if (!path) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	btrfs_uuid_to_key(uuid, type, &key);
  	ret = btrfs_search_slot(NULL, uuid_root, &key, path, 0, 0);
  	if (ret < 0) {
  		goto out;
  	} else if (ret > 0) {
  		ret = -ENOENT;
  		goto out;
  	}
  
  	eb = path->nodes[0];
  	slot = path->slots[0];
  	item_size = btrfs_item_size_nr(eb, slot);
  	offset = btrfs_item_ptr_offset(eb, slot);
  	ret = -ENOENT;
  
  	if (!IS_ALIGNED(item_size, sizeof(u64))) {
  		btrfs_warn(uuid_root->fs_info, "uuid item with illegal size %lu!",
  			(unsigned long)item_size);
  		goto out;
  	}
  	while (item_size) {
  		__le64 data;
  
  		read_extent_buffer(eb, &data, offset, sizeof(data));
  		if (le64_to_cpu(data) == subid) {
  			ret = 0;
  			break;
  		}
  		offset += sizeof(data);
  		item_size -= sizeof(data);
  	}
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  int btrfs_uuid_tree_add(struct btrfs_trans_handle *trans,
  			struct btrfs_root *uuid_root, u8 *uuid, u8 type,
  			u64 subid_cpu)
  {
  	int ret;
  	struct btrfs_path *path = NULL;
  	struct btrfs_key key;
  	struct extent_buffer *eb;
  	int slot;
  	unsigned long offset;
  	__le64 subid_le;
  
  	ret = btrfs_uuid_tree_lookup(uuid_root, uuid, type, subid_cpu);
  	if (ret != -ENOENT)
  		return ret;
  
  	if (WARN_ON_ONCE(!uuid_root)) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	btrfs_uuid_to_key(uuid, type, &key);
  
  	path = btrfs_alloc_path();
  	if (!path) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	ret = btrfs_insert_empty_item(trans, uuid_root, path, &key,
  				      sizeof(subid_le));
  	if (ret >= 0) {
  		/* Add an item for the type for the first time */
  		eb = path->nodes[0];
  		slot = path->slots[0];
  		offset = btrfs_item_ptr_offset(eb, slot);
  	} else if (ret == -EEXIST) {
  		/*
  		 * An item with that type already exists.
  		 * Extend the item and store the new subid at the end.
  		 */
  		btrfs_extend_item(uuid_root, path, sizeof(subid_le));
  		eb = path->nodes[0];
  		slot = path->slots[0];
  		offset = btrfs_item_ptr_offset(eb, slot);
  		offset += btrfs_item_size_nr(eb, slot) - sizeof(subid_le);
  	} else if (ret < 0) {
  		btrfs_warn(uuid_root->fs_info, "insert uuid item failed %d "
  			"(0x%016llx, 0x%016llx) type %u!",
  			ret, (unsigned long long)key.objectid,
  			(unsigned long long)key.offset, type);
  		goto out;
  	}
  
  	ret = 0;
  	subid_le = cpu_to_le64(subid_cpu);
  	write_extent_buffer(eb, &subid_le, offset, sizeof(subid_le));
  	btrfs_mark_buffer_dirty(eb);
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  int btrfs_uuid_tree_rem(struct btrfs_trans_handle *trans,
  			struct btrfs_root *uuid_root, u8 *uuid, u8 type,
  			u64 subid)
  {
  	int ret;
  	struct btrfs_path *path = NULL;
  	struct btrfs_key key;
  	struct extent_buffer *eb;
  	int slot;
  	unsigned long offset;
  	u32 item_size;
  	unsigned long move_dst;
  	unsigned long move_src;
  	unsigned long move_len;
  
  	if (WARN_ON_ONCE(!uuid_root)) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	btrfs_uuid_to_key(uuid, type, &key);
  
  	path = btrfs_alloc_path();
  	if (!path) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	ret = btrfs_search_slot(trans, uuid_root, &key, path, -1, 1);
  	if (ret < 0) {
  		btrfs_warn(uuid_root->fs_info, "error %d while searching for uuid item!",
  			ret);
  		goto out;
  	}
  	if (ret > 0) {
  		ret = -ENOENT;
  		goto out;
  	}
  
  	eb = path->nodes[0];
  	slot = path->slots[0];
  	offset = btrfs_item_ptr_offset(eb, slot);
  	item_size = btrfs_item_size_nr(eb, slot);
  	if (!IS_ALIGNED(item_size, sizeof(u64))) {
  		btrfs_warn(uuid_root->fs_info, "uuid item with illegal size %lu!",
  			(unsigned long)item_size);
  		ret = -ENOENT;
  		goto out;
  	}
  	while (item_size) {
  		__le64 read_subid;
  
  		read_extent_buffer(eb, &read_subid, offset, sizeof(read_subid));
  		if (le64_to_cpu(read_subid) == subid)
  			break;
  		offset += sizeof(read_subid);
  		item_size -= sizeof(read_subid);
  	}
  
  	if (!item_size) {
  		ret = -ENOENT;
  		goto out;
  	}
  
  	item_size = btrfs_item_size_nr(eb, slot);
  	if (item_size == sizeof(subid)) {
  		ret = btrfs_del_item(trans, uuid_root, path);
  		goto out;
  	}
  
  	move_dst = offset;
  	move_src = offset + sizeof(subid);
  	move_len = item_size - (move_src - btrfs_item_ptr_offset(eb, slot));
  	memmove_extent_buffer(eb, move_dst, move_src, move_len);
  	btrfs_truncate_item(uuid_root, path, item_size - sizeof(subid), 1);
  
  out:
  	btrfs_free_path(path);
  	return ret;
  }
  
  static int btrfs_uuid_iter_rem(struct btrfs_root *uuid_root, u8 *uuid, u8 type,
  			       u64 subid)
  {
  	struct btrfs_trans_handle *trans;
  	int ret;
  
  	/* 1 - for the uuid item */
  	trans = btrfs_start_transaction(uuid_root, 1);
  	if (IS_ERR(trans)) {
  		ret = PTR_ERR(trans);
  		goto out;
  	}
  
  	ret = btrfs_uuid_tree_rem(trans, uuid_root, uuid, type, subid);
  	btrfs_end_transaction(trans, uuid_root);
  
  out:
  	return ret;
  }
  
  int btrfs_uuid_tree_iterate(struct btrfs_fs_info *fs_info,
  			    int (*check_func)(struct btrfs_fs_info *, u8 *, u8,
  					      u64))
  {
  	struct btrfs_root *root = fs_info->uuid_root;
  	struct btrfs_key key;
  	struct btrfs_path *path;
  	int ret = 0;
  	struct extent_buffer *leaf;
  	int slot;
  	u32 item_size;
  	unsigned long offset;
  
  	path = btrfs_alloc_path();
  	if (!path) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	key.objectid = 0;
  	key.type = 0;
  	key.offset = 0;
  
  again_search_slot:
  	path->keep_locks = 1;
  	ret = btrfs_search_forward(root, &key, path, 0);
  	if (ret) {
  		if (ret > 0)
  			ret = 0;
  		goto out;
  	}
  
  	while (1) {
  		cond_resched();
  		leaf = path->nodes[0];
  		slot = path->slots[0];
  		btrfs_item_key_to_cpu(leaf, &key, slot);
  
  		if (key.type != BTRFS_UUID_KEY_SUBVOL &&
  		    key.type != BTRFS_UUID_KEY_RECEIVED_SUBVOL)
  			goto skip;
  
  		offset = btrfs_item_ptr_offset(leaf, slot);
  		item_size = btrfs_item_size_nr(leaf, slot);
  		if (!IS_ALIGNED(item_size, sizeof(u64))) {
  			btrfs_warn(fs_info, "uuid item with illegal size %lu!",
  				(unsigned long)item_size);
  			goto skip;
  		}
  		while (item_size) {
  			u8 uuid[BTRFS_UUID_SIZE];
  			__le64 subid_le;
  			u64 subid_cpu;
  
  			put_unaligned_le64(key.objectid, uuid);
  			put_unaligned_le64(key.offset, uuid + sizeof(u64));
  			read_extent_buffer(leaf, &subid_le, offset,
  					   sizeof(subid_le));
  			subid_cpu = le64_to_cpu(subid_le);
  			ret = check_func(fs_info, uuid, key.type, subid_cpu);
  			if (ret < 0)
  				goto out;
  			if (ret > 0) {
  				btrfs_release_path(path);
  				ret = btrfs_uuid_iter_rem(root, uuid, key.type,
  							  subid_cpu);
  				if (ret == 0) {
  					/*
  					 * this might look inefficient, but the
  					 * justification is that it is an
  					 * exception that check_func returns 1,
  					 * and that in the regular case only one
  					 * entry per UUID exists.
  					 */
  					goto again_search_slot;
  				}
  				if (ret < 0 && ret != -ENOENT)
  					goto out;
  			}
  			item_size -= sizeof(subid_le);
  			offset += sizeof(subid_le);
  		}
  
  skip:
  		ret = btrfs_next_item(root, path);
  		if (ret == 0)
  			continue;
  		else if (ret > 0)
  			ret = 0;
  		break;
  	}
  
  out:
  	btrfs_free_path(path);
  	if (ret)
  		btrfs_warn(fs_info, "btrfs_uuid_tree_iterate failed %d", ret);
  	return 0;
  }