/*
 * 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 "kerncompat.h"
#include <errno.h>
#include <stddef.h>
#include "kernel-lib/bitops.h"
#include "kernel-shared/accessors.h"
#include "kernel-shared/extent_io.h"
#include "kernel-shared/uapi/btrfs.h"
#include "kernel-shared/uapi/btrfs_tree.h"
#include "kernel-shared/ctree.h"
#include "kernel-shared/disk-io.h"

struct btrfs_trans_handle;

static int find_name_in_backref(struct extent_buffer *leaf, int slot, const char * name,
				int name_len, struct btrfs_inode_ref **ref_ret)
{
	struct btrfs_inode_ref *ref;
	unsigned long ptr;
	unsigned long name_ptr;
	u32 item_size;
	u32 cur_offset = 0;
	int len;

	item_size = btrfs_item_size(leaf, slot);
	ptr = btrfs_item_ptr_offset(leaf, slot);
	while (cur_offset < item_size) {
		ref = (struct btrfs_inode_ref *)(ptr + cur_offset);
		len = btrfs_inode_ref_name_len(leaf, ref);
		name_ptr = (unsigned long)(ref + 1);
		cur_offset += len + sizeof(*ref);
		if (len != name_len)
			continue;
		if (memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0) {
			*ref_ret = ref;
			return 1;
		}
	}
	return 0;
}

int btrfs_insert_inode_ref(struct btrfs_trans_handle *trans,
			   struct btrfs_root *root,
			   const char *name, int name_len,
			   u64 inode_objectid, u64 ref_objectid, u64 index)
{
	struct btrfs_path *path;
	struct btrfs_key key;
	struct btrfs_inode_ref *ref;
	unsigned long ptr;
	int ret;
	int ins_len = name_len + sizeof(*ref);

	key.objectid = inode_objectid;
	key.type = BTRFS_INODE_REF_KEY;
	key.offset = ref_objectid;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	ret = btrfs_insert_empty_item(trans, root, path, &key,
				      ins_len);
	if (ret == -EEXIST) {
		u32 old_size;

		if (find_name_in_backref(path->nodes[0], path->slots[0], name, name_len, &ref))
			goto out;

		old_size = btrfs_item_size(path->nodes[0], path->slots[0]);
		btrfs_extend_item(path, ins_len);
		ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
				     struct btrfs_inode_ref);
		ref = (struct btrfs_inode_ref *)((unsigned long)ref + old_size);
		btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
		btrfs_set_inode_ref_index(path->nodes[0], ref, index);
		ptr = (unsigned long)(ref + 1);
		ret = 0;
	} else if (ret < 0) {
		if (ret == -EOVERFLOW)
			ret = -EMLINK;
		goto out;
	} else {
		ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
				     struct btrfs_inode_ref);
		btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
		btrfs_set_inode_ref_index(path->nodes[0], ref, index);
		ptr = (unsigned long)(ref + 1);
	}
	write_extent_buffer(path->nodes[0], name, ptr, name_len);
	btrfs_mark_buffer_dirty(path->nodes[0]);

out:
	btrfs_free_path(path);

	if (ret == -EMLINK) {
		if (btrfs_fs_incompat(root->fs_info, EXTENDED_IREF))
			ret = btrfs_insert_inode_extref(trans, root, name,
							name_len,
							inode_objectid,
							ref_objectid, index);
	}
	return ret;
}

int btrfs_lookup_inode(struct btrfs_trans_handle *trans, struct btrfs_root
		       *root, struct btrfs_path *path,
		       struct btrfs_key *location, int mod)
{
	int ins_len = mod < 0 ? -1 : 0;
	int cow = mod != 0;
	int ret;
	int slot;
	struct extent_buffer *leaf;
	struct btrfs_key found_key;

	ret = btrfs_search_slot(trans, root, location, path, ins_len, cow);
	if (ret > 0 && location->type == BTRFS_ROOT_ITEM_KEY &&
	    location->offset == (u64)-1 && path->slots[0] != 0) {
		slot = path->slots[0] - 1;
		leaf = path->nodes[0];
		btrfs_item_key_to_cpu(leaf, &found_key, slot);
		if (found_key.objectid == location->objectid &&
		    found_key.type == location->type) {
			path->slots[0]--;
			return 0;
		}
	}
	return ret;
}

int btrfs_insert_inode(struct btrfs_trans_handle *trans, struct btrfs_root
		       *root, u64 objectid, struct btrfs_inode_item
		       *inode_item)
{
	int ret;
	struct btrfs_key key;

	key.objectid = objectid;
	key.type = BTRFS_INODE_ITEM_KEY;
	key.offset = 0;

	ret = btrfs_insert_item(trans, root, &key, inode_item,
				sizeof(*inode_item));
	return ret;
}

struct btrfs_inode_ref *btrfs_lookup_inode_ref(struct btrfs_trans_handle *trans,
		struct btrfs_root *root, struct btrfs_path *path,
		const char *name, int namelen, u64 ino, u64 parent_ino,
		int ins_len)
{
	struct btrfs_key key;
	struct btrfs_inode_ref *ret_inode_ref = NULL;
	int ret = 0;

	key.objectid = ino;
	key.type = BTRFS_INODE_REF_KEY;
	key.offset = parent_ino;

	ret = btrfs_search_slot(trans, root, &key, path, ins_len,
				ins_len ? 1 : 0);
	if (ret)
		goto out;

	find_name_in_backref(path->nodes[0], path->slots[0], name, namelen, &ret_inode_ref);
out:
	if (ret < 0)
		return ERR_PTR(ret);
	else
		return ret_inode_ref;
}

static int btrfs_find_name_in_ext_backref(struct extent_buffer *leaf,
					  int slot, u64 parent_ino,
					  const char *name, int namelen,
					  struct btrfs_inode_extref **extref_ret)
{
	struct btrfs_inode_extref *extref;
	unsigned long ptr;
	unsigned long name_ptr;
	u32 item_size;
	u32 cur_offset = 0;
	int ref_name_len;

	item_size = btrfs_item_size(leaf, slot);
	ptr = btrfs_item_ptr_offset(leaf, slot);

	/*
	 * Search all extended backrefs in this item. We're only looking
	 * through any collisions so most of the time this is just going to
	 * compare against one buffer. If all is well, we'll return success and
	 * the inode ref object.
	 */
	while (cur_offset < item_size) {
		extref = (struct btrfs_inode_extref *) (ptr + cur_offset);
		name_ptr = (unsigned long)(&extref->name);
		ref_name_len = btrfs_inode_extref_name_len(leaf, extref);

		if (ref_name_len == namelen &&
		    btrfs_inode_extref_parent(leaf, extref) == parent_ino &&
		    (memcmp_extent_buffer(leaf, name, name_ptr, namelen) == 0))
		{
			if (extref_ret)
				*extref_ret = extref;
			return 1;
		}

		cur_offset += ref_name_len + sizeof(*extref);
	}

	return 0;
}

struct btrfs_inode_extref *btrfs_lookup_inode_extref(struct btrfs_trans_handle
		*trans, struct btrfs_path *path, struct btrfs_root *root,
		u64 ino, u64 parent_ino, u64 index, const char *name,
		int namelen, int ins_len)
{
	struct btrfs_key key;
	struct btrfs_inode_extref *extref;
	int ret = 0;

	key.objectid = ino;
	key.type = BTRFS_INODE_EXTREF_KEY;
	key.offset = btrfs_extref_hash(parent_ino, name, namelen);

	ret = btrfs_search_slot(trans, root, &key, path, ins_len,
			ins_len ? 1 : 0);
	if (ret < 0)
		return ERR_PTR(ret);
	if (ret > 0)
		return NULL;
	if (!btrfs_find_name_in_ext_backref(path->nodes[0], path->slots[0],
					    parent_ino, name,
					    namelen, &extref))
		return NULL;

	return extref;
}

int btrfs_del_inode_extref(struct btrfs_trans_handle *trans,
			   struct btrfs_root *root,
			   const char *name, int name_len,
			   u64 inode_objectid, u64 ref_objectid,
			   u64 *index)
{
	struct btrfs_path *path;
	struct btrfs_key key;
	struct btrfs_inode_extref *extref;
	struct extent_buffer *leaf;
	int ret;
	int del_len = name_len + sizeof(*extref);
	unsigned long ptr;
	unsigned long item_start;
	u32 item_size;

	key.objectid = inode_objectid;
	key.type = BTRFS_INODE_EXTREF_KEY;
	key.offset = btrfs_extref_hash(ref_objectid, name, name_len);

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
	if (ret > 0)
		ret = -ENOENT;
	if (ret < 0)
		goto out;

	/*
	 * Sanity check - did we find the right item for this name?  This
	 * should always succeed so error here will make the FS readonly.
	 */
	if (!btrfs_find_name_in_ext_backref(path->nodes[0], path->slots[0], ref_objectid,
					    name, name_len, &extref)) {
		ret = -ENOENT;
		goto out;
	}

	leaf = path->nodes[0];
	item_size = btrfs_item_size(leaf, path->slots[0]);
	if (index)
		*index = btrfs_inode_extref_index(leaf, extref);

	if (del_len == item_size) {
		/*
		 * Common case only one ref in the item, remove the whole item.
		 */
		ret = btrfs_del_item(trans, root, path);
		goto out;
	}

	ptr = (unsigned long)extref;
	item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);

	memmove_extent_buffer(leaf, ptr, ptr + del_len,
			      item_size - (ptr + del_len - item_start));

	btrfs_truncate_item(path, item_size - del_len, 1);

out:
	btrfs_free_path(path);

	return ret;
}

/*
 * btrfs_insert_inode_extref() - Inserts an extended inode ref into a tree.
 *
 * The caller must have checked against BTRFS_LINK_MAX already.
 */
int btrfs_insert_inode_extref(struct btrfs_trans_handle *trans,
			      struct btrfs_root *root,
			      const char *name, int name_len,
			      u64 inode_objectid, u64 ref_objectid, u64 index)
{
	struct btrfs_inode_extref *extref;
	int ret;
	int ins_len = name_len + sizeof(*extref);
	unsigned long ptr;
	struct btrfs_path *path;
	struct btrfs_key key;
	struct extent_buffer *leaf;

	key.objectid = inode_objectid;
	key.type = BTRFS_INODE_EXTREF_KEY;
	key.offset = btrfs_extref_hash(ref_objectid, name, name_len);

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	ret = btrfs_insert_empty_item(trans, root, path, &key,
				      ins_len);
	if (ret == -EEXIST) {
		if (btrfs_find_name_in_ext_backref(path->nodes[0], path->slots[0],
						   ref_objectid,
						   name, name_len, NULL))
			goto out;

		btrfs_extend_item(path, ins_len);
		ret = 0;
	}
	if (ret < 0)
		goto out;

	leaf = path->nodes[0];
	ptr = (unsigned long)btrfs_item_ptr(leaf, path->slots[0], char);
	ptr += btrfs_item_size(leaf, path->slots[0]) - ins_len;
	extref = (struct btrfs_inode_extref *)ptr;

	btrfs_set_inode_extref_name_len(path->nodes[0], extref, name_len);
	btrfs_set_inode_extref_index(path->nodes[0], extref, index);
	btrfs_set_inode_extref_parent(path->nodes[0], extref, ref_objectid);

	ptr = (unsigned long)&extref->name;
	write_extent_buffer(path->nodes[0], name, ptr, name_len);
	btrfs_mark_buffer_dirty(path->nodes[0]);

out:
	btrfs_free_path(path);
	return ret;
}

int btrfs_del_inode_ref(struct btrfs_trans_handle *trans,
			struct btrfs_root *root, const char *name, int name_len,
			u64 ino, u64 parent_ino, u64 *index)
{
	struct btrfs_path *path;
	struct btrfs_key key;
	struct btrfs_inode_ref *ref;
	struct extent_buffer *leaf;
	unsigned long ptr;
	unsigned long item_start;
	u32 item_size;
	u32 sub_item_len;
	int ret;
	int search_ext_refs = 0;
	int del_len = name_len + sizeof(*ref);

	key.objectid = ino;
	key.type = BTRFS_INODE_REF_KEY;
	key.offset = parent_ino;

	path = btrfs_alloc_path();
	if (!path)
		return -ENOMEM;

	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
	if (ret > 0) {
		ret = -ENOENT;
		search_ext_refs = 1;
		goto out;
	} else if (ret < 0) {
		goto out;
	}
	if (!find_name_in_backref(path->nodes[0], path->slots[0], name, name_len, &ref)) {
		ret = -ENOENT;
		search_ext_refs = 1;
		goto out;
	}
	leaf = path->nodes[0];
	item_size = btrfs_item_size(leaf, path->slots[0]);

	if (index)
		*index = btrfs_inode_ref_index(leaf, ref);

	if (del_len == item_size) {
		ret = btrfs_del_item(trans, root, path);
		goto out;
	}
	ptr = (unsigned long)ref;
	sub_item_len = name_len + sizeof(*ref);
	item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
	memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
			      item_size - (ptr + sub_item_len - item_start));
	btrfs_truncate_item(path, item_size - sub_item_len, 1);
	btrfs_mark_buffer_dirty(path->nodes[0]);
out:
	btrfs_free_path(path);

	if (search_ext_refs &&
	    btrfs_fs_incompat(root->fs_info, EXTENDED_IREF)) {
		/*
		 * No refs were found, or we could not find the name in our ref
		 * array. Find and remove the extended inode ref then.
		 */
		return btrfs_del_inode_extref(trans, root, name, name_len,
					      ino, parent_ino, index);
	}

	return ret;
}