extent-tree.c 18.5 KB
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#include <linux/module.h>
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#include "ctree.h"
#include "disk-io.h"
#include "print-tree.h"
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#include "transaction.h"
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static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
			    *orig_root, u64 num_blocks, u64 search_start, u64
			    search_end, struct btrfs_key *ins);
static int finish_current_insert(struct btrfs_trans_handle *trans, struct
				 btrfs_root *extent_root);
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static int del_pending_extents(struct btrfs_trans_handle *trans, struct
			       btrfs_root *extent_root);
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int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
				struct btrfs_root *root,
				u64 blocknr, u64 num_blocks)
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{
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	struct btrfs_path *path;
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	int ret;
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	struct btrfs_key key;
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	struct btrfs_leaf *l;
	struct btrfs_extent_item *item;
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	struct btrfs_key ins;
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	u32 refs;
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	find_free_extent(trans, root->fs_info->extent_root, 0, 0, (u64)-1,
			 &ins);
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	path = btrfs_alloc_path();
	BUG_ON(!path);
	btrfs_init_path(path);
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	key.objectid = blocknr;
	key.flags = 0;
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	btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
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	key.offset = num_blocks;
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	ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
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				0, 1);
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	if (ret != 0) {
printk("can't find block %Lu %Lu\n", blocknr, num_blocks);
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		BUG();
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	}
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	BUG_ON(ret != 0);
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	l = btrfs_buffer_leaf(path->nodes[0]);
	item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
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	refs = btrfs_extent_refs(item);
	btrfs_set_extent_refs(item, refs + 1);
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	btrfs_mark_buffer_dirty(path->nodes[0]);
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	btrfs_release_path(root->fs_info->extent_root, path);
	btrfs_free_path(path);
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	finish_current_insert(trans, root->fs_info->extent_root);
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	del_pending_extents(trans, root->fs_info->extent_root);
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	return 0;
}

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static int lookup_extent_ref(struct btrfs_trans_handle *trans,
			     struct btrfs_root *root, u64 blocknr,
			     u64 num_blocks, u32 *refs)
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{
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	struct btrfs_path *path;
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	int ret;
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	struct btrfs_key key;
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	struct btrfs_leaf *l;
	struct btrfs_extent_item *item;
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	path = btrfs_alloc_path();
	btrfs_init_path(path);
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	key.objectid = blocknr;
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	key.offset = num_blocks;
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	key.flags = 0;
	btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
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	ret = btrfs_search_slot(trans, root->fs_info->extent_root, &key, path,
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				0, 0);
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	if (ret != 0)
		BUG();
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	l = btrfs_buffer_leaf(path->nodes[0]);
	item = btrfs_item_ptr(l, path->slots[0], struct btrfs_extent_item);
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	*refs = btrfs_extent_refs(item);
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	btrfs_release_path(root->fs_info->extent_root, path);
	btrfs_free_path(path);
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	return 0;
}

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int btrfs_inc_root_ref(struct btrfs_trans_handle *trans,
		       struct btrfs_root *root)
{
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	return btrfs_inc_extent_ref(trans, root, bh_blocknr(root->node), 1);
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}

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int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
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		  struct buffer_head *buf)
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{
	u64 blocknr;
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	struct btrfs_node *buf_node;
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	struct btrfs_leaf *buf_leaf;
	struct btrfs_disk_key *key;
	struct btrfs_file_extent_item *fi;
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	int i;
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	int leaf;
	int ret;
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	if (!root->ref_cows)
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		return 0;
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	buf_node = btrfs_buffer_node(buf);
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	leaf = btrfs_is_leaf(buf_node);
	buf_leaf = btrfs_buffer_leaf(buf);
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	for (i = 0; i < btrfs_header_nritems(&buf_node->header); i++) {
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		if (leaf) {
			key = &buf_leaf->items[i].key;
			if (btrfs_disk_key_type(key) != BTRFS_EXTENT_DATA_KEY)
				continue;
			fi = btrfs_item_ptr(buf_leaf, i,
					    struct btrfs_file_extent_item);
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			if (btrfs_file_extent_type(fi) ==
			    BTRFS_FILE_EXTENT_INLINE)
				continue;
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			ret = btrfs_inc_extent_ref(trans, root,
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				    btrfs_file_extent_disk_blocknr(fi),
				    btrfs_file_extent_disk_num_blocks(fi));
			BUG_ON(ret);
		} else {
			blocknr = btrfs_node_blockptr(buf_node, i);
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			ret = btrfs_inc_extent_ref(trans, root, blocknr, 1);
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			BUG_ON(ret);
		}
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	}
	return 0;
}

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int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans, struct
			       btrfs_root *root)
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{
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	unsigned long gang[8];
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	u64 first = 0;
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	int ret;
	int i;
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	struct radix_tree_root *pinned_radix = &root->fs_info->pinned_radix;
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	while(1) {
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		ret = find_first_radix_bit(pinned_radix, gang,
					   ARRAY_SIZE(gang));
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		if (!ret)
			break;
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		if (!first)
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			first = gang[0];
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		for (i = 0; i < ret; i++) {
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			clear_radix_bit(pinned_radix, gang[i]);
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		}
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	}
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	if (root->fs_info->last_insert.objectid > first)
		root->fs_info->last_insert.objectid = first;
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	root->fs_info->last_insert.offset = 0;
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	return 0;
}

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static int finish_current_insert(struct btrfs_trans_handle *trans, struct
				 btrfs_root *extent_root)
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{
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	struct btrfs_key ins;
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	struct btrfs_extent_item extent_item;
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	int i;
	int ret;
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	u64 super_blocks_used;
	struct btrfs_fs_info *info = extent_root->fs_info;
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	btrfs_set_extent_refs(&extent_item, 1);
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	ins.offset = 1;
	ins.flags = 0;
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	btrfs_set_key_type(&ins, BTRFS_EXTENT_ITEM_KEY);
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	for (i = 0; i < extent_root->fs_info->current_insert.flags; i++) {
		ins.objectid = extent_root->fs_info->current_insert.objectid +
				i;
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		super_blocks_used = btrfs_super_blocks_used(info->disk_super);
		btrfs_set_super_blocks_used(info->disk_super,
					    super_blocks_used + 1);
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		ret = btrfs_insert_item(trans, extent_root, &ins, &extent_item,
					sizeof(extent_item));
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		BUG_ON(ret);
	}
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	extent_root->fs_info->current_insert.offset = 0;
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	return 0;
}

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static int pin_down_block(struct btrfs_root *root, u64 blocknr, int pending)
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{
	int err;
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	struct btrfs_header *header;
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	struct buffer_head *bh;

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	if (!pending) {
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		bh = btrfs_find_tree_block(root, blocknr);
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		if (bh) {
			if (buffer_uptodate(bh)) {
				u64 transid =
				    root->fs_info->running_transaction->transid;
				header = btrfs_buffer_header(bh);
				if (btrfs_header_generation(header) ==
				    transid) {
					btrfs_block_release(root, bh);
					return 0;
				}
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			}
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			btrfs_block_release(root, bh);
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		}
		err = set_radix_bit(&root->fs_info->pinned_radix, blocknr);
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	} else {
		err = set_radix_bit(&root->fs_info->pending_del_radix, blocknr);
	}
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	BUG_ON(err);
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	return 0;
}

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/*
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 * remove an extent from the root, returns 0 on success
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 */
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static int __free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
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			 *root, u64 blocknr, u64 num_blocks, int pin)
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{
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	struct btrfs_path *path;
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	struct btrfs_key key;
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	struct btrfs_fs_info *info = root->fs_info;
	struct btrfs_root *extent_root = info->extent_root;
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	int ret;
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	struct btrfs_extent_item *ei;
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	struct btrfs_key ins;
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	u32 refs;
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	key.objectid = blocknr;
	key.flags = 0;
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	btrfs_set_key_type(&key, BTRFS_EXTENT_ITEM_KEY);
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	key.offset = num_blocks;

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	find_free_extent(trans, root, 0, 0, (u64)-1, &ins);
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	path = btrfs_alloc_path();
	BUG_ON(!path);
	btrfs_init_path(path);
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	ret = btrfs_search_slot(trans, extent_root, &key, path, -1, 1);
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	if (ret) {
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		printk("failed to find %Lu\n", key.objectid);
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		btrfs_print_tree(extent_root, extent_root->node);
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		printk("failed to find %Lu\n", key.objectid);
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		BUG();
	}
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	ei = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]), path->slots[0],
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			    struct btrfs_extent_item);
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	BUG_ON(ei->refs == 0);
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	refs = btrfs_extent_refs(ei) - 1;
	btrfs_set_extent_refs(ei, refs);
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	btrfs_mark_buffer_dirty(path->nodes[0]);
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	if (refs == 0) {
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		u64 super_blocks_used;
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		if (pin) {
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			ret = pin_down_block(root, blocknr, 0);
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			BUG_ON(ret);
		}

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		super_blocks_used = btrfs_super_blocks_used(info->disk_super);
		btrfs_set_super_blocks_used(info->disk_super,
					    super_blocks_used - num_blocks);
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		ret = btrfs_del_item(trans, extent_root, path);
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		if (ret)
			BUG();
	}
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	btrfs_release_path(extent_root, path);
	btrfs_free_path(path);
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	finish_current_insert(trans, extent_root);
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	return ret;
}

/*
 * find all the blocks marked as pending in the radix tree and remove
 * them from the extent map
 */
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static int del_pending_extents(struct btrfs_trans_handle *trans, struct
			       btrfs_root *extent_root)
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{
	int ret;
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	int wret;
	int err = 0;
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	unsigned long gang[4];
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	int i;
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	struct radix_tree_root *pending_radix;
	struct radix_tree_root *pinned_radix;

	pending_radix = &extent_root->fs_info->pending_del_radix;
	pinned_radix = &extent_root->fs_info->pinned_radix;
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	while(1) {
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		ret = find_first_radix_bit(pending_radix, gang,
					   ARRAY_SIZE(gang));
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		if (!ret)
			break;
		for (i = 0; i < ret; i++) {
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			wret = set_radix_bit(pinned_radix, gang[i]);
			BUG_ON(wret);
			wret = clear_radix_bit(pending_radix, gang[i]);
			BUG_ON(wret);
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			wret = __free_extent(trans, extent_root,
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					     gang[i], 1, 0);
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			if (wret)
				err = wret;
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		}
	}
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	return err;
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}

/*
 * remove an extent from the root, returns 0 on success
 */
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int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
		      *root, u64 blocknr, u64 num_blocks, int pin)
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{
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	struct btrfs_root *extent_root = root->fs_info->extent_root;
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	int pending_ret;
	int ret;
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	if (root == extent_root) {
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		pin_down_block(root, blocknr, 1);
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		return 0;
	}
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	ret = __free_extent(trans, root, blocknr, num_blocks, pin);
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	pending_ret = del_pending_extents(trans, root->fs_info->extent_root);
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	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
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 * ins->flags = BTRFS_EXTENT_ITEM_KEY
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 * ins->offset == number of blocks
 * Any available blocks before search_start are skipped.
 */
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static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
			    *orig_root, u64 num_blocks, u64 search_start, u64
			    search_end, struct btrfs_key *ins)
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{
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	struct btrfs_path *path;
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	struct btrfs_key key;
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	int ret;
	u64 hole_size = 0;
	int slot = 0;
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	u64 last_block = 0;
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	u64 test_block;
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	int start_found;
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	struct btrfs_leaf *l;
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	struct btrfs_root * root = orig_root->fs_info->extent_root;
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	int total_needed = num_blocks;
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	int level;
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	path = btrfs_alloc_path();
	ins->flags = 0;
	btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);

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	level = btrfs_header_level(btrfs_buffer_header(root->node));
	total_needed += (level + 1) * 3;
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	if (root->fs_info->last_insert.objectid == 0 && search_end == (u64)-1) {
		struct btrfs_disk_key *last_key;
		btrfs_init_path(path);
		ins->objectid = (u64)-1;
		ins->offset = (u64)-1;
		ret = btrfs_search_slot(trans, root, ins, path, 0, 0);
		if (ret < 0)
			goto error;
		BUG_ON(ret == 0);
		if (path->slots[0] > 0)
			path->slots[0]--;
		l = btrfs_buffer_leaf(path->nodes[0]);
		last_key = &l->items[path->slots[0]].key;
		search_start = btrfs_disk_key_objectid(last_key);
	}
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	if (root->fs_info->last_insert.objectid > search_start)
		search_start = root->fs_info->last_insert.objectid;
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check_failed:
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	btrfs_init_path(path);
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	ins->objectid = search_start;
	ins->offset = 0;
	start_found = 0;
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	ret = btrfs_search_slot(trans, root, ins, path, 0, 0);
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	if (ret < 0)
		goto error;
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	if (path->slots[0] > 0)
		path->slots[0]--;
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	while (1) {
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		l = btrfs_buffer_leaf(path->nodes[0]);
		slot = path->slots[0];
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		if (slot >= btrfs_header_nritems(&l->header)) {
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			ret = btrfs_next_leaf(root, path);
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			if (ret == 0)
				continue;
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			if (ret < 0)
				goto error;
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			if (!start_found) {
				ins->objectid = search_start;
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				ins->offset = (u64)-1;
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				start_found = 1;
				goto check_pending;
			}
			ins->objectid = last_block > search_start ?
					last_block : search_start;
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			ins->offset = (u64)-1;
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			goto check_pending;
		}
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		btrfs_disk_key_to_cpu(&key, &l->items[slot].key);
		if (key.objectid >= search_start) {
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			if (start_found) {
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				if (last_block < search_start)
					last_block = search_start;
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				hole_size = key.objectid - last_block;
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				if (hole_size > total_needed) {
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					ins->objectid = last_block;
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					ins->offset = hole_size;
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					goto check_pending;
				}
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			}
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		}
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		start_found = 1;
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		last_block = key.objectid + key.offset;
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		path->slots[0]++;
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	}
	// 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
	 */
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	btrfs_release_path(root, path);
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	BUG_ON(ins->objectid < search_start);
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	for (test_block = ins->objectid;
	     test_block < ins->objectid + total_needed; test_block++) {
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		if (test_radix_bit(&root->fs_info->pinned_radix,
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				      test_block)) {
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			search_start = test_block + 1;
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			goto check_failed;
		}
	}
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	BUG_ON(root->fs_info->current_insert.offset);
	root->fs_info->current_insert.offset = total_needed - num_blocks;
	root->fs_info->current_insert.objectid = ins->objectid + num_blocks;
	root->fs_info->current_insert.flags = 0;
	root->fs_info->last_insert.objectid = ins->objectid;
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	ins->offset = num_blocks;
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	btrfs_free_path(path);
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	return 0;
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error:
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	btrfs_release_path(root, path);
	btrfs_free_path(path);
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	return ret;
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}

/*
 * 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.
 */
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int btrfs_alloc_extent(struct btrfs_trans_handle *trans, struct btrfs_root
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			*root, u64 num_blocks, u64 search_start, u64
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			search_end, struct btrfs_key *ins)
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{
	int ret;
	int pending_ret;
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	u64 super_blocks_used;
	struct btrfs_fs_info *info = root->fs_info;
	struct btrfs_root *extent_root = info->extent_root;
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	struct btrfs_extent_item extent_item;
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	btrfs_set_extent_refs(&extent_item, 1);
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	if (root == extent_root) {
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		BUG_ON(extent_root->fs_info->current_insert.offset == 0);
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		BUG_ON(num_blocks != 1);
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		BUG_ON(extent_root->fs_info->current_insert.flags ==
		       extent_root->fs_info->current_insert.offset);
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		ins->offset = 1;
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		ins->objectid = extent_root->fs_info->current_insert.objectid +
				extent_root->fs_info->current_insert.flags++;
484 485
		return 0;
	}
486
	ret = find_free_extent(trans, root, num_blocks, search_start,
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			       search_end, ins);
	if (ret)
		return ret;
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	super_blocks_used = btrfs_super_blocks_used(info->disk_super);
	btrfs_set_super_blocks_used(info->disk_super, super_blocks_used +
				    num_blocks);
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	ret = btrfs_insert_item(trans, extent_root, ins, &extent_item,
				sizeof(extent_item));
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	finish_current_insert(trans, extent_root);
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	pending_ret = del_pending_extents(trans, extent_root);
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	if (ret)
		return ret;
	if (pending_ret)
		return pending_ret;
	return 0;
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}

/*
 * helper function to allocate a block for a given tree
 * returns the tree buffer or NULL.
 */
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struct buffer_head *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
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					    struct btrfs_root *root)
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{
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	struct btrfs_key ins;
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	int ret;
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	struct buffer_head *buf;
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	ret = btrfs_alloc_extent(trans, root, 1, 0, (unsigned long)-1, &ins);
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	if (ret) {
		BUG();
		return NULL;
	}
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	buf = btrfs_find_create_tree_block(root, ins.objectid);
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	set_buffer_uptodate(buf);
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	return buf;
}
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static int drop_leaf_ref(struct btrfs_trans_handle *trans,
			 struct btrfs_root *root, struct buffer_head *cur)
{
	struct btrfs_disk_key *key;
	struct btrfs_leaf *leaf;
	struct btrfs_file_extent_item *fi;
	int i;
	int nritems;
	int ret;

	BUG_ON(!btrfs_is_leaf(btrfs_buffer_node(cur)));
	leaf = btrfs_buffer_leaf(cur);
	nritems = btrfs_header_nritems(&leaf->header);
	for (i = 0; i < nritems; i++) {
		key = &leaf->items[i].key;
		if (btrfs_disk_key_type(key) != BTRFS_EXTENT_DATA_KEY)
			continue;
		fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
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		if (btrfs_file_extent_type(fi) == BTRFS_FILE_EXTENT_INLINE)
			continue;
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		/*
		 * FIXME make sure to insert a trans record that
		 * repeats the snapshot del on crash
		 */
		ret = btrfs_free_extent(trans, root,
					btrfs_file_extent_disk_blocknr(fi),
					btrfs_file_extent_disk_num_blocks(fi),
					0);
		BUG_ON(ret);
	}
	return 0;
}

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/*
 * helper function for drop_snapshot, this walks down the tree dropping ref
 * counts as it goes.
 */
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static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
			  *root, struct btrfs_path *path, int *level)
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{
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	struct buffer_head *next;
	struct buffer_head *cur;
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	u64 blocknr;
	int ret;
	u32 refs;

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	WARN_ON(*level < 0);
	WARN_ON(*level >= BTRFS_MAX_LEVEL);
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	ret = lookup_extent_ref(trans, root, bh_blocknr(path->nodes[*level]),
576
			       1, &refs);
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	BUG_ON(ret);
	if (refs > 1)
		goto out;
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	/*
	 * walk down to the last node level and free all the leaves
	 */
583
	while(*level >= 0) {
584 585
		WARN_ON(*level < 0);
		WARN_ON(*level >= BTRFS_MAX_LEVEL);
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		cur = path->nodes[*level];
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		if (btrfs_header_level(btrfs_buffer_header(cur)) != *level)
			WARN_ON(1);
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		if (path->slots[*level] >=
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		    btrfs_header_nritems(btrfs_buffer_header(cur)))
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			break;
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		if (*level == 0) {
			ret = drop_leaf_ref(trans, root, cur);
			BUG_ON(ret);
			break;
		}
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		blocknr = btrfs_node_blockptr(btrfs_buffer_node(cur),
					      path->slots[*level]);
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		ret = lookup_extent_ref(trans, root, blocknr, 1, &refs);
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		BUG_ON(ret);
		if (refs != 1) {
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			path->slots[*level]++;
603
			ret = btrfs_free_extent(trans, root, blocknr, 1, 1);
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			BUG_ON(ret);
			continue;
		}
		next = read_tree_block(root, blocknr);
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		WARN_ON(*level <= 0);
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		if (path->nodes[*level-1])
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			btrfs_block_release(root, path->nodes[*level-1]);
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		path->nodes[*level-1] = next;
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		*level = btrfs_header_level(btrfs_buffer_header(next));
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		path->slots[*level] = 0;
	}
out:
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	WARN_ON(*level < 0);
	WARN_ON(*level >= BTRFS_MAX_LEVEL);
618
	ret = btrfs_free_extent(trans, root,
619
				bh_blocknr(path->nodes[*level]), 1, 1);
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	btrfs_block_release(root, path->nodes[*level]);
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	path->nodes[*level] = NULL;
	*level += 1;
	BUG_ON(ret);
	return 0;
}

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/*
 * helper for dropping snapshots.  This walks back up the tree in the path
 * to find the first node higher up where we haven't yet gone through
 * all the slots
 */
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static int walk_up_tree(struct btrfs_trans_handle *trans, struct btrfs_root
			*root, struct btrfs_path *path, int *level)
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{
	int i;
	int slot;
	int ret;
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	for(i = *level; i < BTRFS_MAX_LEVEL - 1 && path->nodes[i]; i++) {
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		slot = path->slots[i];
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		if (slot < btrfs_header_nritems(
		    btrfs_buffer_header(path->nodes[i])) - 1) {
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			path->slots[i]++;
			*level = i;
			return 0;
		} else {
646
			ret = btrfs_free_extent(trans, root,
647
						bh_blocknr(path->nodes[*level]),
648
						1, 1);
649
			BUG_ON(ret);
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			btrfs_block_release(root, path->nodes[*level]);
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			path->nodes[*level] = NULL;
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			*level = i + 1;
		}
	}
	return 1;
}

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/*
 * drop the reference count on the tree rooted at 'snap'.  This traverses
 * the tree freeing any blocks that have a ref count of zero after being
 * decremented.
 */
663
int btrfs_drop_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root
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			*root, struct buffer_head *snap)
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{
666
	int ret = 0;
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	int wret;
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	int level;
669
	struct btrfs_path *path;
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	int i;
	int orig_level;

673 674 675
	path = btrfs_alloc_path();
	BUG_ON(!path);
	btrfs_init_path(path);
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	level = btrfs_header_level(btrfs_buffer_header(snap));
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	orig_level = level;
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	path->nodes[level] = snap;
	path->slots[level] = 0;
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	while(1) {
682
		wret = walk_down_tree(trans, root, path, &level);
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		if (wret > 0)
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			break;
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		if (wret < 0)
			ret = wret;

688
		wret = walk_up_tree(trans, root, path, &level);
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		if (wret > 0)
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			break;
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		if (wret < 0)
			ret = wret;
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	}
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	for (i = 0; i <= orig_level; i++) {
695 696
		if (path->nodes[i]) {
			btrfs_block_release(root, path->nodes[i]);
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		}
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	}
699
	btrfs_free_path(path);
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	return ret;
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}