[linux-2.6-block.git] / fs / btrfs / root-tree.c

/*
 * 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"

/*
 *  search forward for a root, starting with objectid 'search_start'
 *  if a root key is found, the objectid we find is filled into 'found_objectid'
 *  and 0 is returned.  < 0 is returned on error, 1 if there is nothing
 *  left in the tree.
 */
int btrfs_search_root(struct btrfs_root *root, u64 search_start,
		      u64 *found_objectid)
{
	struct btrfs_path *path;
	struct btrfs_key search_key;
	int ret;

	root = root->fs_info->tree_root;
	search_key.objectid = search_start;
	search_key.type = (u8)-1;
	search_key.offset = (u64)-1;

	path = btrfs_alloc_path();
	BUG_ON(!path);
again:
	ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
	if (ret < 0)
		goto out;
	if (ret == 0) {
		ret = 1;
		goto out;
	}
	if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
		ret = btrfs_next_leaf(root, path);
		if (ret)
			goto out;
	}
	btrfs_item_key_to_cpu(path->nodes[0], &search_key, path->slots[0]);
	if (search_key.type != BTRFS_ROOT_ITEM_KEY) {
		search_key.offset++;
		btrfs_release_path(root, path);
		goto again;
	}
	ret = 0;
	*found_objectid = search_key.objectid;

out:
	btrfs_free_path(path);
	return ret;
}

/*
 * 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();
	BUG_ON(!path);
	ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
	if (ret < 0)
		goto out;

	BUG_ON(ret == 0);
	l = path->nodes[0];
	BUG_ON(path->slots[0] == 0);
	slot = path->slots[0] - 1;
	btrfs_item_key_to_cpu(l, &found_key, slot);
	if (found_key.objectid != objectid) {
		ret = 1;
		goto out;
	}
	read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
			   sizeof(*item));
	memcpy(key, &found_key, sizeof(found_key));
	ret = 0;
out:
	btrfs_free_path(path);
	return ret;
}

/*
 * 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\n",
		       (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_release_path(root, path);
	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 *latest)
{
	struct btrfs_root *dead_root;
	struct btrfs_item *item;
	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];
		}
		item = btrfs_item_nr(leaf, slot);
		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(root, 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;
		}

		if (objectid == BTRFS_TREE_RELOC_OBJECTID)
			ret = btrfs_add_dead_reloc_root(dead_root);
		else
			ret = btrfs_add_dead_root(dead_root, latest);
		if (ret)
			goto err;
		goto again;
next:
		slot++;
		path->slots[0]++;
	}
	ret = 0;
err:
	btrfs_free_path(path);
	return ret;
}

/* 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;
	u32 refs;
	struct btrfs_root_item *ri;
	struct extent_buffer *leaf;

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

	refs = btrfs_disk_root_refs(leaf, ri);
	BUG_ON(refs != 0);
	ret = btrfs_del_item(trans, root, path);
out:
	btrfs_release_path(root, path);
	btrfs_free_path(path);
	return ret;
}

#if 0 /* this will get used when snapshot deletion is implemented */
int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
		       struct btrfs_root *tree_root,
		       u64 root_id, u8 type, u64 ref_id)
{
	struct btrfs_key key;
	int ret;
	struct btrfs_path *path;

	path = btrfs_alloc_path();

	key.objectid = root_id;
	key.type = type;
	key.offset = ref_id;

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

	ret = btrfs_del_item(trans, tree_root, path);
	BUG_ON(ret);

	btrfs_free_path(path);
	return ret;
}
#endif

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, u8 type, 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();

	key.objectid = root_id;
	key.type = type;
	key.offset = ref_id;

	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);

	btrfs_free_path(path);
	return ret;
}
Commit	Line	Data
6cbd5570 CM	1	/*
	2	* Copyright (C) 2007 Oracle. All rights reserved.
	3	*
	4	* This program is free software; you can redistribute it and/or
	5	* modify it under the terms of the GNU General Public
	6	* License v2 as published by the Free Software Foundation.
	7	*
	8	* This program is distributed in the hope that it will be useful,
	9	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	10	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	11	* General Public License for more details.
	12	*
	13	* You should have received a copy of the GNU General Public
	14	* License along with this program; if not, write to the
	15	* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	16	* Boston, MA 021110-1307, USA.
	17	*/
	18
3768f368	19	#include "ctree.h"
5eda7b5e	20	#include "transaction.h"
3768f368 CM	21	#include "disk-io.h"
	22	#include "print-tree.h"
	23
bf4ef679	24	/*
d352ac68 CM	25	* search forward for a root, starting with objectid 'search_start'
	26	* if a root key is found, the objectid we find is filled into 'found_objectid'
	27	* and 0 is returned. < 0 is returned on error, 1 if there is nothing
	28	* left in the tree.
bf4ef679 CM	29	*/
	30	int btrfs_search_root(struct btrfs_root *root, u64 search_start,
	31	u64 *found_objectid)
	32	{
	33	struct btrfs_path *path;
	34	struct btrfs_key search_key;
	35	int ret;
	36
	37	root = root->fs_info->tree_root;
	38	search_key.objectid = search_start;
	39	search_key.type = (u8)-1;
	40	search_key.offset = (u64)-1;
	41
	42	path = btrfs_alloc_path();
	43	BUG_ON(!path);
	44	again:
	45	ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
	46	if (ret < 0)
	47	goto out;
	48	if (ret == 0) {
	49	ret = 1;
	50	goto out;
	51	}
	52	if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
	53	ret = btrfs_next_leaf(root, path);
	54	if (ret)
	55	goto out;
	56	}
	57	btrfs_item_key_to_cpu(path->nodes[0], &search_key, path->slots[0]);
	58	if (search_key.type != BTRFS_ROOT_ITEM_KEY) {
	59	search_key.offset++;
	60	btrfs_release_path(root, path);
	61	goto again;
	62	}
	63	ret = 0;
	64	*found_objectid = search_key.objectid;
	65
	66	out:
	67	btrfs_free_path(path);
	68	return ret;
	69	}
	70
d352ac68 CM	71	/*
	72	* lookup the root with the highest offset for a given objectid. The key we do
	73	* find is copied into 'key'. If we find something return 0, otherwise 1, < 0
	74	* on error.
	75	*/
3768f368 CM	76	int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
	77	struct btrfs_root_item item, struct btrfs_key key)
	78	{
5caf2a00	79	struct btrfs_path *path;
3768f368	80	struct btrfs_key search_key;
5f39d397 CM	81	struct btrfs_key found_key;
5f39d397 CM	82	struct extent_buffer *l;
3768f368 CM	83	int ret;
	84	int slot;
	85
	86	search_key.objectid = objectid;
0660b5af	87	search_key.type = BTRFS_ROOT_ITEM_KEY;
5eda7b5e	88	search_key.offset = (u64)-1;
3768f368	89
5caf2a00 CM	90	path = btrfs_alloc_path();
5caf2a00 CM	91	BUG_ON(!path);
5caf2a00	92	ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
3768f368 CM	93	if (ret < 0)
3768f368 CM	94	goto out;
5f39d397	95
3768f368	96	BUG_ON(ret == 0);
5f39d397	97	l = path->nodes[0];
5caf2a00 CM	98	BUG_ON(path->slots[0] == 0);
5caf2a00 CM	99	slot = path->slots[0] - 1;
5f39d397 CM	100	btrfs_item_key_to_cpu(l, &found_key, slot);
5f39d397 CM	101	if (found_key.objectid != objectid) {
3768f368 CM	102	ret = 1;
	103	goto out;
	104	}
5f39d397 CM	105	read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
	106	sizeof(*item));
	107	memcpy(key, &found_key, sizeof(found_key));
3768f368 CM	108	ret = 0;
3768f368 CM	109	out:
5caf2a00	110	btrfs_free_path(path);
3768f368 CM	111	return ret;
	112	}
	113
d352ac68 CM	114	/*
	115	* copy the data in 'item' into the btree
	116	*/
e089f05c CM	117	int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
	118	root, struct btrfs_key key, struct btrfs_root_item
	119	*item)
3768f368	120	{
5caf2a00	121	struct btrfs_path *path;
5f39d397	122	struct extent_buffer *l;
3768f368 CM	123	int ret;
3768f368 CM	124	int slot;
5f39d397	125	unsigned long ptr;
3768f368	126
5caf2a00 CM	127	path = btrfs_alloc_path();
5caf2a00 CM	128	BUG_ON(!path);
5caf2a00	129	ret = btrfs_search_slot(trans, root, key, path, 0, 1);
3768f368 CM	130	if (ret < 0)
3768f368 CM	131	goto out;
d6667462 CM	132
	133	if (ret != 0) {
	134	btrfs_print_leaf(root, path->nodes[0]);
d397712b CM	135	printk(KERN_CRIT "unable to update root key %llu %u %llu\n",
	136	(unsigned long long)key->objectid, key->type,
	137	(unsigned long long)key->offset);
d6667462 CM	138	BUG_ON(1);
	139	}
	140
5f39d397	141	l = path->nodes[0];
5caf2a00	142	slot = path->slots[0];
5f39d397 CM	143	ptr = btrfs_item_ptr_offset(l, slot);
5f39d397 CM	144	write_extent_buffer(l, item, ptr, sizeof(*item));
5caf2a00	145	btrfs_mark_buffer_dirty(path->nodes[0]);
3768f368	146	out:
5caf2a00 CM	147	btrfs_release_path(root, path);
5caf2a00 CM	148	btrfs_free_path(path);
3768f368 CM	149	return ret;
	150	}
	151
e089f05c CM	152	int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
	153	root, struct btrfs_key key, struct btrfs_root_item
	154	*item)
3768f368 CM	155	{
3768f368 CM	156	int ret;
e089f05c	157	ret = btrfs_insert_item(trans, root, key, item, sizeof(*item));
3768f368 CM	158	return ret;
	159	}
	160
d352ac68 CM	161	/*
d352ac68 CM	162	* at mount time we want to find all the old transaction snapshots that were in
d397712b CM	163	* the process of being deleted if we crashed. This is any root item with an
	164	* offset lower than the latest root. They need to be queued for deletion to
	165	* finish what was happening when we crashed.
d352ac68	166	*/
5ce14bbc CM	167	int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid,
5ce14bbc CM	168	struct btrfs_root *latest)
5eda7b5e CM	169	{
	170	struct btrfs_root *dead_root;
	171	struct btrfs_item *item;
	172	struct btrfs_root_item *ri;
	173	struct btrfs_key key;
a7a16fd7	174	struct btrfs_key found_key;
5eda7b5e CM	175	struct btrfs_path *path;
	176	int ret;
	177	u32 nritems;
5f39d397	178	struct extent_buffer *leaf;
5eda7b5e CM	179	int slot;
5eda7b5e CM	180
5ce14bbc	181	key.objectid = objectid;
5eda7b5e CM	182	btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
	183	key.offset = 0;
	184	path = btrfs_alloc_path();
	185	if (!path)
	186	return -ENOMEM;
a7a16fd7 CM	187
a7a16fd7 CM	188	again:
5eda7b5e CM	189	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
	190	if (ret < 0)
	191	goto err;
d397712b	192	while (1) {
5f39d397 CM	193	leaf = path->nodes[0];
5f39d397 CM	194	nritems = btrfs_header_nritems(leaf);
5eda7b5e CM	195	slot = path->slots[0];
	196	if (slot >= nritems) {
	197	ret = btrfs_next_leaf(root, path);
	198	if (ret)
	199	break;
5f39d397 CM	200	leaf = path->nodes[0];
5f39d397 CM	201	nritems = btrfs_header_nritems(leaf);
5eda7b5e CM	202	slot = path->slots[0];
5eda7b5e CM	203	}
5f39d397 CM	204	item = btrfs_item_nr(leaf, slot);
5f39d397 CM	205	btrfs_item_key_to_cpu(leaf, &key, slot);
5eda7b5e CM	206	if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
5eda7b5e CM	207	goto next;
5ce14bbc CM	208
	209	if (key.objectid < objectid)
	210	goto next;
	211
	212	if (key.objectid > objectid)
	213	break;
	214
5eda7b5e	215	ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
5f39d397	216	if (btrfs_disk_root_refs(leaf, ri) != 0)
5eda7b5e	217	goto next;
5ce14bbc	218
a7a16fd7 CM	219	memcpy(&found_key, &key, sizeof(key));
	220	key.offset++;
	221	btrfs_release_path(root, path);
e02119d5 CM	222	dead_root =
	223	btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
	224	&found_key);
a1f39630 A	225	if (IS_ERR(dead_root)) {
a1f39630 A	226	ret = PTR_ERR(dead_root);
5eda7b5e CM	227	goto err;
5eda7b5e CM	228	}
5ce14bbc	229
1a40e23b ZY	230	if (objectid == BTRFS_TREE_RELOC_OBJECTID)
	231	ret = btrfs_add_dead_reloc_root(dead_root);
	232	else
	233	ret = btrfs_add_dead_root(dead_root, latest);
5eda7b5e CM	234	if (ret)
5eda7b5e CM	235	goto err;
a7a16fd7	236	goto again;
5eda7b5e CM	237	next:
	238	slot++;
	239	path->slots[0]++;
	240	}
	241	ret = 0;
	242	err:
	243	btrfs_free_path(path);
	244	return ret;
	245	}
	246
d352ac68	247	/* drop the root item for 'key' from 'root' */
e089f05c CM	248	int btrfs_del_root(struct btrfs_trans_handle trans, struct btrfs_root root,
e089f05c CM	249	struct btrfs_key *key)
3768f368	250	{
5caf2a00	251	struct btrfs_path *path;
3768f368	252	int ret;
c5739bba CM	253	u32 refs;
c5739bba CM	254	struct btrfs_root_item *ri;
5f39d397	255	struct extent_buffer *leaf;
3768f368	256
5caf2a00 CM	257	path = btrfs_alloc_path();
5caf2a00 CM	258	BUG_ON(!path);
5caf2a00	259	ret = btrfs_search_slot(trans, root, key, path, -1, 1);
3768f368 CM	260	if (ret < 0)
3768f368 CM	261	goto out;
edbd8d4e	262
3768f368	263	BUG_ON(ret != 0);
5f39d397 CM	264	leaf = path->nodes[0];
5f39d397 CM	265	ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);
c5739bba	266
5f39d397	267	refs = btrfs_disk_root_refs(leaf, ri);
5eda7b5e CM	268	BUG_ON(refs != 0);
5eda7b5e CM	269	ret = btrfs_del_item(trans, root, path);
3768f368	270	out:
5caf2a00 CM	271	btrfs_release_path(root, path);
5caf2a00 CM	272	btrfs_free_path(path);
3768f368 CM	273	return ret;
3768f368 CM	274	}
0660b5af	275
b2950863	276	#if 0 /* this will get used when snapshot deletion is implemented */
0660b5af CM	277	int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
	278	struct btrfs_root *tree_root,
	279	u64 root_id, u8 type, u64 ref_id)
	280	{
	281	struct btrfs_key key;
	282	int ret;
	283	struct btrfs_path *path;
	284
	285	path = btrfs_alloc_path();
	286
	287	key.objectid = root_id;
	288	key.type = type;
	289	key.offset = ref_id;
	290
	291	ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
	292	BUG_ON(ret);
	293
	294	ret = btrfs_del_item(trans, tree_root, path);
	295	BUG_ON(ret);
	296
	297	btrfs_free_path(path);
	298	return ret;
	299	}
b2950863	300	#endif
0660b5af	301
ea9e8b11 CM	302	int btrfs_find_root_ref(struct btrfs_root *tree_root,
	303	struct btrfs_path *path,
	304	u64 root_id, u64 ref_id)
	305	{
	306	struct btrfs_key key;
	307	int ret;
	308
	309	key.objectid = root_id;
	310	key.type = BTRFS_ROOT_REF_KEY;
	311	key.offset = ref_id;
	312
	313	ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
	314	return ret;
	315	}
	316
	317
0660b5af CM	318	/*
	319	* add a btrfs_root_ref item. type is either BTRFS_ROOT_REF_KEY
	320	* or BTRFS_ROOT_BACKREF_KEY.
	321	*
	322	* The dirid, sequence, name and name_len refer to the directory entry
	323	* that is referencing the root.
	324	*
	325	* For a forward ref, the root_id is the id of the tree referencing
	326	* the root and ref_id is the id of the subvol or snapshot.
	327	*
	328	* For a back ref the root_id is the id of the subvol or snapshot and
	329	* ref_id is the id of the tree referencing it.
	330	*/
	331	int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
	332	struct btrfs_root *tree_root,
	333	u64 root_id, u8 type, u64 ref_id,
	334	u64 dirid, u64 sequence,
	335	const char *name, int name_len)
	336	{
	337	struct btrfs_key key;
	338	int ret;
	339	struct btrfs_path *path;
	340	struct btrfs_root_ref *ref;
	341	struct extent_buffer *leaf;
	342	unsigned long ptr;
	343
	344
	345	path = btrfs_alloc_path();
	346
	347	key.objectid = root_id;
	348	key.type = type;
	349	key.offset = ref_id;
	350
	351	ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
	352	sizeof(*ref) + name_len);
	353	BUG_ON(ret);
	354
	355	leaf = path->nodes[0];
	356	ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
	357	btrfs_set_root_ref_dirid(leaf, ref, dirid);
	358	btrfs_set_root_ref_sequence(leaf, ref, sequence);
	359	btrfs_set_root_ref_name_len(leaf, ref, name_len);
	360	ptr = (unsigned long)(ref + 1);
	361	write_extent_buffer(leaf, name, ptr, name_len);
	362	btrfs_mark_buffer_dirty(leaf);
	363
	364	btrfs_free_path(path);
	365	return ret;
	366	}