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

#include <stdio.h>
#include <stdlib.h>
#include "kerncompat.h"
#include "radix-tree.h"
#include "ctree.h"
#include "disk-io.h"
#include "print-tree.h"

static int find_free_extent(struct ctree_root *orig_root, u64 num_blocks,
			    u64 search_start, u64 search_end, struct key *ins);
static int finish_current_insert(struct ctree_root *extent_root);
static int run_pending(struct ctree_root *extent_root);

/*
 * pending extents are blocks that we're trying to allocate in the extent
 * map while trying to grow the map because of other allocations.  To avoid
 * recursing, they are tagged in the radix tree and cleaned up after
 * other allocations are done.  The pending tag is also used in the same
 * manner for deletes.
 */
#define CTREE_EXTENT_PENDING_DEL 0

static int inc_block_ref(struct ctree_root *root, u64 blocknr)
{
	struct ctree_path path;
	int ret;
	struct key key;
	struct leaf *l;
	struct extent_item *item;
	struct key ins;

	find_free_extent(root->extent_root, 0, 0, (u64)-1, &ins);
	init_path(&path);
	key.objectid = blocknr;
	key.flags = 0;
	key.offset = 1;
	ret = search_slot(root->extent_root, &key, &path, 0, 1);
	if (ret != 0)
		BUG();
	BUG_ON(ret != 0);
	l = &path.nodes[0]->leaf;
	item = (struct extent_item *)(l->data +
				      l->items[path.slots[0]].offset);
	item->refs++;

	BUG_ON(list_empty(&path.nodes[0]->dirty));
	release_path(root->extent_root, &path);
	finish_current_insert(root->extent_root);
	run_pending(root->extent_root);
	return 0;
}

static int lookup_block_ref(struct ctree_root *root, u64 blocknr, int *refs)
{
	struct ctree_path path;
	int ret;
	struct key key;
	struct leaf *l;
	struct extent_item *item;
	init_path(&path);
	key.objectid = blocknr;
	key.flags = 0;
	key.offset = 1;
	ret = search_slot(root->extent_root, &key, &path, 0, 0);
	if (ret != 0)
		BUG();
	l = &path.nodes[0]->leaf;
	item = (struct extent_item *)(l->data +
				      l->items[path.slots[0]].offset);
	*refs = item->refs;
	release_path(root->extent_root, &path);
	return 0;
}

int btrfs_inc_ref(struct ctree_root *root, struct tree_buffer *buf)
{
	u64 blocknr;
	int i;

	if (root == root->extent_root)
		return 0;
	if (is_leaf(buf->node.header.flags))
		return 0;

	for (i = 0; i < buf->node.header.nritems; i++) {
		blocknr = buf->node.blockptrs[i];
		inc_block_ref(root, blocknr);
	}
	return 0;
}

int btrfs_finish_extent_commit(struct ctree_root *root)
{
	struct ctree_root *extent_root = root->extent_root;
	unsigned long gang[8];
	int ret;
	int i;

	while(1) {
		ret = radix_tree_gang_lookup(&extent_root->pinned_radix,
						 (void **)gang, 0,
						 ARRAY_SIZE(gang));
		if (!ret)
			break;
		for (i = 0; i < ret; i++)
			radix_tree_delete(&extent_root->pinned_radix, gang[i]);
	}
	return 0;
}

static int finish_current_insert(struct ctree_root *extent_root)
{
	struct key ins;
	struct extent_item extent_item;
	int i;
	int ret;

	extent_item.refs = 1;
	extent_item.owner = extent_root->node->node.header.parentid;
	ins.offset = 1;
	ins.flags = 0;

	for (i = 0; i < extent_root->current_insert.flags; i++) {
		ins.objectid = extent_root->current_insert.objectid + i;
		ret = insert_item(extent_root, &ins, &extent_item,
				  sizeof(extent_item));
		BUG_ON(ret);
	}
	extent_root->current_insert.offset = 0;
	return 0;
}

/*
 * remove an extent from the root, returns 0 on success
 */
int __free_extent(struct ctree_root *root, u64 blocknr, u64 num_blocks)
{
	struct ctree_path path;
	struct key key;
	struct ctree_root *extent_root = root->extent_root;
	int ret;
	struct item *item;
	struct extent_item *ei;
	struct key ins;

	key.objectid = blocknr;
	key.flags = 0;
	key.offset = num_blocks;

	find_free_extent(root, 0, 0, (u64)-1, &ins);
	init_path(&path);
	ret = search_slot(extent_root, &key, &path, -1, 1);
	if (ret) {
		printf("failed to find %Lu\n", key.objectid);
		print_tree(extent_root, extent_root->node);
		printf("failed to find %Lu\n", key.objectid);
		BUG();
	}
	item = path.nodes[0]->leaf.items + path.slots[0];
	ei = (struct extent_item *)(path.nodes[0]->leaf.data + item->offset);
	BUG_ON(ei->refs == 0);
	ei->refs--;
	if (ei->refs == 0) {
		if (root == extent_root) {
			int err;
			radix_tree_preload(GFP_KERNEL);
			err = radix_tree_insert(&extent_root->pinned_radix,
					  blocknr, (void *)blocknr);
			BUG_ON(err);
			radix_tree_preload_end();
		}
		ret = del_item(extent_root, &path);
		if (ret)
			BUG();
	}
	release_path(extent_root, &path);
	finish_current_insert(extent_root);
	return ret;
}

/*
 * find all the blocks marked as pending in the radix tree and remove
 * them from the extent map
 */
static int del_pending_extents(struct ctree_root *extent_root)
{
	int ret;
	struct tree_buffer *gang[4];
	int i;

	while(1) {
		ret = radix_tree_gang_lookup_tag(&extent_root->cache_radix,
						 (void **)gang, 0,
						 ARRAY_SIZE(gang),
						 CTREE_EXTENT_PENDING_DEL);
		if (!ret)
			break;
		for (i = 0; i < ret; i++) {
			ret = __free_extent(extent_root, gang[i]->blocknr, 1);
			radix_tree_tag_clear(&extent_root->cache_radix,
						gang[i]->blocknr,
						CTREE_EXTENT_PENDING_DEL);
			tree_block_release(extent_root, gang[i]);
		}
	}
	return 0;
}

static int run_pending(struct ctree_root *extent_root)
{
	while(radix_tree_tagged(&extent_root->cache_radix,
			        CTREE_EXTENT_PENDING_DEL))
		del_pending_extents(extent_root);
	return 0;
}


/*
 * remove an extent from the root, returns 0 on success
 */
int free_extent(struct ctree_root *root, u64 blocknr, u64 num_blocks)
{
	struct key key;
	struct ctree_root *extent_root = root->extent_root;
	struct tree_buffer *t;
	int pending_ret;
	int ret;

	if (root == extent_root) {
		t = find_tree_block(root, blocknr);
		radix_tree_tag_set(&root->cache_radix, blocknr,
				   CTREE_EXTENT_PENDING_DEL);
		return 0;
	}
	key.objectid = blocknr;
	key.flags = 0;
	key.offset = num_blocks;
	ret = __free_extent(root, blocknr, num_blocks);
	pending_ret = run_pending(root->extent_root);
	return ret ? ret : pending_ret;
}

/*
 * walks the btree of allocated extents and find a hole of a given size.
 * The key ins is changed to record the hole:
 * ins->objectid == block start
 * ins->flags = 0
 * ins->offset == number of blocks
 * Any available blocks before search_start are skipped.
 */
static int find_free_extent(struct ctree_root *orig_root, u64 num_blocks,
			    u64 search_start, u64 search_end, struct key *ins)
{
	struct ctree_path path;
	struct key *key;
	int ret;
	u64 hole_size = 0;
	int slot = 0;
	u64 last_block;
	u64 test_block;
	int start_found;
	struct leaf *l;
	struct ctree_root * root = orig_root->extent_root;
	int total_needed = num_blocks + MAX_LEVEL * 3;

check_failed:
	init_path(&path);
	ins->objectid = search_start;
	ins->offset = 0;
	ins->flags = 0;
	start_found = 0;
	ret = search_slot(root, ins, &path, 0, 0);
	if (ret < 0)
		goto error;

	while (1) {
		l = &path.nodes[0]->leaf;
		slot = path.slots[0];
		if (slot >= l->header.nritems) {
			ret = next_leaf(root, &path);
			if (ret == 0)
				continue;
			if (ret < 0)
				goto error;
			if (!start_found) {
				ins->objectid = search_start;
				ins->offset = (u64)-1;
				start_found = 1;
				goto check_pending;
			}
			ins->objectid = last_block > search_start ?
					last_block : search_start;
			ins->offset = (u64)-1;
			goto check_pending;
		}
		if (slot == 0) {
			int last_slot = l->header.nritems - 1;
			u64 span = l->items[last_slot].key.objectid;
			span -= l->items[slot].key.objectid;
			if (span + total_needed > last_slot - slot) {
				path.slots[0] = last_slot + 1;
				key = &l->items[last_slot].key;
				last_block = key->objectid + key->offset;
				start_found = 1;
				continue;
			}
		}
		key = &l->items[slot].key;
		if (key->objectid >= search_start) {
			if (start_found) {
				hole_size = key->objectid - last_block;
				if (hole_size > total_needed) {
					ins->objectid = last_block;
					ins->offset = hole_size;
					goto check_pending;
				}
			} else
				start_found = 1;
			last_block = key->objectid + key->offset;
		}
		path.slots[0]++;
	}
	// FIXME -ENOSPC
check_pending:
	/* we have to make sure we didn't find an extent that has already
	 * been allocated by the map tree or the original allocation
	 */
	release_path(root, &path);
	BUG_ON(ins->objectid < search_start);
	for (test_block = ins->objectid;
	     test_block < ins->objectid + total_needed; test_block++) {
		if (radix_tree_lookup(&root->pinned_radix, test_block)) {
			search_start = test_block + 1;
			goto check_failed;
		}
	}
	BUG_ON(root->current_insert.offset);
	root->current_insert.offset = total_needed;
	root->current_insert.objectid = ins->objectid + num_blocks;
	root->current_insert.flags = 0;
	ins->offset = num_blocks;
	return 0;
error:
	release_path(root, &path);
	return ret;
}

/*
 * finds a free extent and does all the dirty work required for allocation
 * returns the key for the extent through ins, and a tree buffer for
 * the first block of the extent through buf.
 *
 * returns 0 if everything worked, non-zero otherwise.
 */
int alloc_extent(struct ctree_root *root, u64 num_blocks, u64 search_start,
			 u64 search_end, u64 owner, struct key *ins)
{
	int ret;
	int pending_ret;
	struct ctree_root *extent_root = root->extent_root;
	struct extent_item extent_item;

	extent_item.refs = 1;
	extent_item.owner = owner;

	if (root == extent_root) {
		BUG_ON(extent_root->current_insert.offset == 0);
		BUG_ON(num_blocks != 1);
		BUG_ON(extent_root->current_insert.flags ==
		       extent_root->current_insert.offset);
		ins->offset = 1;
		ins->objectid = extent_root->current_insert.objectid +
				extent_root->current_insert.flags++;
		return 0;
	}
	ret = find_free_extent(root, num_blocks, search_start,
			       search_end, ins);
	if (ret)
		return ret;

	ret = insert_item(extent_root, ins, &extent_item,
			  sizeof(extent_item));

	finish_current_insert(extent_root);
	pending_ret = run_pending(extent_root);
	if (ret)
		return ret;
	if (pending_ret)
		return pending_ret;
	return 0;
}

/*
 * helper function to allocate a block for a given tree
 * returns the tree buffer or NULL.
 */
struct tree_buffer *alloc_free_block(struct ctree_root *root)
{
	struct key ins;
	int ret;
	struct tree_buffer *buf;

	ret = alloc_extent(root, 1, 0, (unsigned long)-1,
			   root->node->node.header.parentid,
			   &ins);
	if (ret) {
		BUG();
		return NULL;
	}
	buf = find_tree_block(root, ins.objectid);
	dirty_tree_block(root, buf);
	return buf;
}

int btrfs_drop_snapshot(struct ctree_root *root, struct tree_buffer *snap)
{
	int ret;
	int level;
	int refs;
	u64 blocknr = snap->blocknr;

	level = node_level(snap->node.header.flags);
	ret = lookup_block_ref(root, snap->blocknr, &refs);
	BUG_ON(ret);
	if (refs == 1 && level != 0) {
		struct node *n = &snap->node;
		struct tree_buffer *b;
		int i;
		for (i = 0; i < n->header.nritems; i++) {
			b = read_tree_block(root, n->blockptrs[i]);
			/* FIXME, don't recurse here */
			ret = btrfs_drop_snapshot(root, b);
			BUG_ON(ret);
			tree_block_release(root, b);
		}
	}
	ret = free_extent(root, blocknr, 1);
	BUG_ON(ret);
	return 0;
}
Commit	Line	Data
fec577fb CM	1	#include <stdio.h>
	2	#include <stdlib.h>
	3	#include "kerncompat.h"
	4	#include "radix-tree.h"
	5	#include "ctree.h"
	6	#include "disk-io.h"
	7	#include "print-tree.h"
	8
037e6390 CM	9	static int find_free_extent(struct ctree_root *orig_root, u64 num_blocks,
	10	u64 search_start, u64 search_end, struct key *ins);
	11	static int finish_current_insert(struct ctree_root *extent_root);
	12	static int run_pending(struct ctree_root *extent_root);
	13
fec577fb CM	14	/*
	15	* pending extents are blocks that we're trying to allocate in the extent
	16	* map while trying to grow the map because of other allocations. To avoid
	17	* recursing, they are tagged in the radix tree and cleaned up after
	18	* other allocations are done. The pending tag is also used in the same
	19	* manner for deletes.
	20	*/
037e6390	21	#define CTREE_EXTENT_PENDING_DEL 0
fec577fb	22
02217ed2 CM	23	static int inc_block_ref(struct ctree_root *root, u64 blocknr)
	24	{
	25	struct ctree_path path;
	26	int ret;
	27	struct key key;
	28	struct leaf *l;
	29	struct extent_item *item;
037e6390 CM	30	struct key ins;
	31
	32	find_free_extent(root->extent_root, 0, 0, (u64)-1, &ins);
02217ed2 CM	33	init_path(&path);
	34	key.objectid = blocknr;
	35	key.flags = 0;
	36	key.offset = 1;
	37	ret = search_slot(root->extent_root, &key, &path, 0, 1);
a28ec197 CM	38	if (ret != 0)
a28ec197 CM	39	BUG();
02217ed2 CM	40	BUG_ON(ret != 0);
	41	l = &path.nodes[0]->leaf;
	42	item = (struct extent_item *)(l->data +
	43	l->items[path.slots[0]].offset);
	44	item->refs++;
a28ec197	45
02217ed2 CM	46	BUG_ON(list_empty(&path.nodes[0]->dirty));
02217ed2 CM	47	release_path(root->extent_root, &path);
037e6390 CM	48	finish_current_insert(root->extent_root);
037e6390 CM	49	run_pending(root->extent_root);
02217ed2 CM	50	return 0;
	51	}
	52
a28ec197 CM	53	static int lookup_block_ref(struct ctree_root root, u64 blocknr, int refs)
	54	{
	55	struct ctree_path path;
	56	int ret;
	57	struct key key;
	58	struct leaf *l;
	59	struct extent_item *item;
	60	init_path(&path);
	61	key.objectid = blocknr;
	62	key.flags = 0;
	63	key.offset = 1;
	64	ret = search_slot(root->extent_root, &key, &path, 0, 0);
	65	if (ret != 0)
	66	BUG();
	67	l = &path.nodes[0]->leaf;
	68	item = (struct extent_item *)(l->data +
	69	l->items[path.slots[0]].offset);
	70	*refs = item->refs;
	71	release_path(root->extent_root, &path);
	72	return 0;
	73	}
	74
02217ed2 CM	75	int btrfs_inc_ref(struct ctree_root root, struct tree_buffer buf)
	76	{
	77	u64 blocknr;
	78	int i;
a28ec197 CM	79
	80	if (root == root->extent_root)
	81	return 0;
	82	if (is_leaf(buf->node.header.flags))
	83	return 0;
	84
02217ed2 CM	85	for (i = 0; i < buf->node.header.nritems; i++) {
	86	blocknr = buf->node.blockptrs[i];
	87	inc_block_ref(root, blocknr);
	88	}
	89	return 0;
	90	}
	91
a28ec197 CM	92	int btrfs_finish_extent_commit(struct ctree_root *root)
	93	{
	94	struct ctree_root *extent_root = root->extent_root;
	95	unsigned long gang[8];
	96	int ret;
	97	int i;
	98
	99	while(1) {
	100	ret = radix_tree_gang_lookup(&extent_root->pinned_radix,
	101	(void **)gang, 0,
	102	ARRAY_SIZE(gang));
	103	if (!ret)
	104	break;
	105	for (i = 0; i < ret; i++)
	106	radix_tree_delete(&extent_root->pinned_radix, gang[i]);
	107	}
	108	return 0;
	109	}
	110
037e6390 CM	111	static int finish_current_insert(struct ctree_root *extent_root)
	112	{
	113	struct key ins;
	114	struct extent_item extent_item;
	115	int i;
	116	int ret;
	117
	118	extent_item.refs = 1;
	119	extent_item.owner = extent_root->node->node.header.parentid;
	120	ins.offset = 1;
	121	ins.flags = 0;
	122
	123	for (i = 0; i < extent_root->current_insert.flags; i++) {
	124	ins.objectid = extent_root->current_insert.objectid + i;
	125	ret = insert_item(extent_root, &ins, &extent_item,
	126	sizeof(extent_item));
	127	BUG_ON(ret);
	128	}
	129	extent_root->current_insert.offset = 0;
	130	return 0;
	131	}
	132
fec577fb	133	/*
a28ec197	134	* remove an extent from the root, returns 0 on success
fec577fb	135	*/
a28ec197 CM	136	int __free_extent(struct ctree_root *root, u64 blocknr, u64 num_blocks)
	137	{
	138	struct ctree_path path;
	139	struct key key;
	140	struct ctree_root *extent_root = root->extent_root;
	141	int ret;
	142	struct item *item;
	143	struct extent_item *ei;
037e6390 CM	144	struct key ins;
037e6390 CM	145
a28ec197 CM	146	key.objectid = blocknr;
	147	key.flags = 0;
	148	key.offset = num_blocks;
	149
037e6390	150	find_free_extent(root, 0, 0, (u64)-1, &ins);
a28ec197 CM	151	init_path(&path);
	152	ret = search_slot(extent_root, &key, &path, -1, 1);
	153	if (ret) {
	154	printf("failed to find %Lu\n", key.objectid);
	155	print_tree(extent_root, extent_root->node);
	156	printf("failed to find %Lu\n", key.objectid);
	157	BUG();
	158	}
	159	item = path.nodes[0]->leaf.items + path.slots[0];
	160	ei = (struct extent_item *)(path.nodes[0]->leaf.data + item->offset);
	161	BUG_ON(ei->refs == 0);
	162	ei->refs--;
	163	if (ei->refs == 0) {
	164	if (root == extent_root) {
	165	int err;
	166	radix_tree_preload(GFP_KERNEL);
	167	err = radix_tree_insert(&extent_root->pinned_radix,
	168	blocknr, (void *)blocknr);
	169	BUG_ON(err);
	170	radix_tree_preload_end();
	171	}
	172	ret = del_item(extent_root, &path);
	173	if (ret)
	174	BUG();
	175	}
	176	release_path(extent_root, &path);
037e6390	177	finish_current_insert(extent_root);
a28ec197 CM	178	return ret;
	179	}
	180
a28ec197 CM	181	/*
	182	* find all the blocks marked as pending in the radix tree and remove
	183	* them from the extent map
	184	*/
	185	static int del_pending_extents(struct ctree_root *extent_root)
	186	{
	187	int ret;
	188	struct tree_buffer *gang[4];
	189	int i;
	190
	191	while(1) {
	192	ret = radix_tree_gang_lookup_tag(&extent_root->cache_radix,
	193	(void **)gang, 0,
	194	ARRAY_SIZE(gang),
	195	CTREE_EXTENT_PENDING_DEL);
	196	if (!ret)
	197	break;
	198	for (i = 0; i < ret; i++) {
	199	ret = __free_extent(extent_root, gang[i]->blocknr, 1);
fec577fb CM	200	radix_tree_tag_clear(&extent_root->cache_radix,
fec577fb CM	201	gang[i]->blocknr,
a28ec197	202	CTREE_EXTENT_PENDING_DEL);
fec577fb CM	203	tree_block_release(extent_root, gang[i]);
	204	}
	205	}
	206	return 0;
	207	}
	208
a28ec197 CM	209	static int run_pending(struct ctree_root *extent_root)
	210	{
	211	while(radix_tree_tagged(&extent_root->cache_radix,
037e6390	212	CTREE_EXTENT_PENDING_DEL))
a28ec197	213	del_pending_extents(extent_root);
a28ec197 CM	214	return 0;
	215	}
	216
	217
fec577fb CM	218	/*
	219	* remove an extent from the root, returns 0 on success
	220	*/
	221	int free_extent(struct ctree_root *root, u64 blocknr, u64 num_blocks)
	222	{
fec577fb CM	223	struct key key;
	224	struct ctree_root *extent_root = root->extent_root;
	225	struct tree_buffer *t;
	226	int pending_ret;
	227	int ret;
a28ec197	228
fec577fb	229	if (root == extent_root) {
a28ec197	230	t = find_tree_block(root, blocknr);
037e6390	231	radix_tree_tag_set(&root->cache_radix, blocknr,
a28ec197	232	CTREE_EXTENT_PENDING_DEL);
fec577fb CM	233	return 0;
fec577fb CM	234	}
a28ec197 CM	235	key.objectid = blocknr;
	236	key.flags = 0;
	237	key.offset = num_blocks;
	238	ret = __free_extent(root, blocknr, num_blocks);
	239	pending_ret = run_pending(root->extent_root);
fec577fb CM	240	return ret ? ret : pending_ret;
	241	}
	242
	243	/*
	244	* walks the btree of allocated extents and find a hole of a given size.
	245	* The key ins is changed to record the hole:
	246	* ins->objectid == block start
	247	* ins->flags = 0
	248	* ins->offset == number of blocks
	249	* Any available blocks before search_start are skipped.
	250	*/
0f70abe2 CM	251	static int find_free_extent(struct ctree_root *orig_root, u64 num_blocks,
0f70abe2 CM	252	u64 search_start, u64 search_end, struct key *ins)
fec577fb CM	253	{
	254	struct ctree_path path;
	255	struct key *key;
	256	int ret;
	257	u64 hole_size = 0;
	258	int slot = 0;
	259	u64 last_block;
037e6390	260	u64 test_block;
fec577fb CM	261	int start_found;
	262	struct leaf *l;
	263	struct ctree_root * root = orig_root->extent_root;
037e6390	264	int total_needed = num_blocks + MAX_LEVEL * 3;
fec577fb CM	265
	266	check_failed:
	267	init_path(&path);
	268	ins->objectid = search_start;
	269	ins->offset = 0;
	270	ins->flags = 0;
	271	start_found = 0;
02217ed2	272	ret = search_slot(root, ins, &path, 0, 0);
0f70abe2 CM	273	if (ret < 0)
0f70abe2 CM	274	goto error;
aa5d6bed	275
fec577fb CM	276	while (1) {
	277	l = &path.nodes[0]->leaf;
	278	slot = path.slots[0];
	279	if (slot >= l->header.nritems) {
	280	ret = next_leaf(root, &path);
	281	if (ret == 0)
	282	continue;
0f70abe2 CM	283	if (ret < 0)
0f70abe2 CM	284	goto error;
fec577fb CM	285	if (!start_found) {
fec577fb CM	286	ins->objectid = search_start;
037e6390	287	ins->offset = (u64)-1;
fec577fb CM	288	start_found = 1;
	289	goto check_pending;
	290	}
	291	ins->objectid = last_block > search_start ?
	292	last_block : search_start;
037e6390	293	ins->offset = (u64)-1;
fec577fb CM	294	goto check_pending;
fec577fb CM	295	}
037e6390 CM	296	if (slot == 0) {
	297	int last_slot = l->header.nritems - 1;
	298	u64 span = l->items[last_slot].key.objectid;
	299	span -= l->items[slot].key.objectid;
	300	if (span + total_needed > last_slot - slot) {
	301	path.slots[0] = last_slot + 1;
	302	key = &l->items[last_slot].key;
	303	last_block = key->objectid + key->offset;
	304	start_found = 1;
	305	continue;
	306	}
	307	}
fec577fb CM	308	key = &l->items[slot].key;
	309	if (key->objectid >= search_start) {
	310	if (start_found) {
	311	hole_size = key->objectid - last_block;
037e6390	312	if (hole_size > total_needed) {
fec577fb	313	ins->objectid = last_block;
037e6390	314	ins->offset = hole_size;
fec577fb CM	315	goto check_pending;
	316	}
	317	} else
	318	start_found = 1;
	319	last_block = key->objectid + key->offset;
	320	}
	321	path.slots[0]++;
	322	}
	323	// FIXME -ENOSPC
	324	check_pending:
	325	/* we have to make sure we didn't find an extent that has already
	326	* been allocated by the map tree or the original allocation
	327	*/
	328	release_path(root, &path);
	329	BUG_ON(ins->objectid < search_start);
037e6390 CM	330	for (test_block = ins->objectid;
	331	test_block < ins->objectid + total_needed; test_block++) {
	332	if (radix_tree_lookup(&root->pinned_radix, test_block)) {
	333	search_start = test_block + 1;
fec577fb CM	334	goto check_failed;
	335	}
	336	}
037e6390 CM	337	BUG_ON(root->current_insert.offset);
	338	root->current_insert.offset = total_needed;
	339	root->current_insert.objectid = ins->objectid + num_blocks;
	340	root->current_insert.flags = 0;
	341	ins->offset = num_blocks;
fec577fb	342	return 0;
0f70abe2 CM	343	error:
	344	release_path(root, &path);
	345	return ret;
fec577fb CM	346	}
fec577fb CM	347
fec577fb CM	348	/*
	349	* finds a free extent and does all the dirty work required for allocation
	350	* returns the key for the extent through ins, and a tree buffer for
	351	* the first block of the extent through buf.
	352	*
	353	* returns 0 if everything worked, non-zero otherwise.
	354	*/
	355	int alloc_extent(struct ctree_root *root, u64 num_blocks, u64 search_start,
037e6390	356	u64 search_end, u64 owner, struct key *ins)
fec577fb CM	357	{
	358	int ret;
	359	int pending_ret;
037e6390	360	struct ctree_root *extent_root = root->extent_root;
fec577fb	361	struct extent_item extent_item;
037e6390	362
fec577fb CM	363	extent_item.refs = 1;
	364	extent_item.owner = owner;
	365
037e6390 CM	366	if (root == extent_root) {
	367	BUG_ON(extent_root->current_insert.offset == 0);
	368	BUG_ON(num_blocks != 1);
	369	BUG_ON(extent_root->current_insert.flags ==
	370	extent_root->current_insert.offset);
	371	ins->offset = 1;
	372	ins->objectid = extent_root->current_insert.objectid +
	373	extent_root->current_insert.flags++;
fec577fb CM	374	return 0;
fec577fb CM	375	}
037e6390 CM	376	ret = find_free_extent(root, num_blocks, search_start,
	377	search_end, ins);
	378	if (ret)
	379	return ret;
fec577fb	380
037e6390 CM	381	ret = insert_item(extent_root, ins, &extent_item,
	382	sizeof(extent_item));
	383
	384	finish_current_insert(extent_root);
	385	pending_ret = run_pending(extent_root);
	386	if (ret)
	387	return ret;
	388	if (pending_ret)
	389	return pending_ret;
	390	return 0;
fec577fb CM	391	}
	392
	393	/*
	394	* helper function to allocate a block for a given tree
	395	* returns the tree buffer or NULL.
	396	*/
	397	struct tree_buffer alloc_free_block(struct ctree_root root)
	398	{
	399	struct key ins;
	400	int ret;
037e6390	401	struct tree_buffer *buf;
fec577fb CM	402
	403	ret = alloc_extent(root, 1, 0, (unsigned long)-1,
	404	root->node->node.header.parentid,
037e6390	405	&ins);
fec577fb CM	406	if (ret) {
	407	BUG();
	408	return NULL;
	409	}
037e6390 CM	410	buf = find_tree_block(root, ins.objectid);
037e6390 CM	411	dirty_tree_block(root, buf);
fec577fb CM	412	return buf;
fec577fb CM	413	}
a28ec197 CM	414
	415	int btrfs_drop_snapshot(struct ctree_root root, struct tree_buffer snap)
	416	{
	417	int ret;
	418	int level;
	419	int refs;
	420	u64 blocknr = snap->blocknr;
	421
	422	level = node_level(snap->node.header.flags);
	423	ret = lookup_block_ref(root, snap->blocknr, &refs);
	424	BUG_ON(ret);
	425	if (refs == 1 && level != 0) {
	426	struct node *n = &snap->node;
	427	struct tree_buffer *b;
	428	int i;
	429	for (i = 0; i < n->header.nritems; i++) {
	430	b = read_tree_block(root, n->blockptrs[i]);
	431	/* FIXME, don't recurse here */
	432	ret = btrfs_drop_snapshot(root, b);
	433	BUG_ON(ret);
	434	tree_block_release(root, b);
	435	}
	436	}
	437	ret = free_extent(root, blocknr, 1);
	438	BUG_ON(ret);
	439	return 0;
	440	}
	441