blob: 008397934778d457f7d90c3fbd03955fab230639 [file] [log] [blame]
/*
* Copyright (C) 2009 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 <linux/sched.h>
#include <linux/pagemap.h>
#include <linux/writeback.h>
#include <linux/blkdev.h>
#include <linux/rbtree.h>
#include "ctree.h"
#include "disk-io.h"
#include "transaction.h"
#include "volumes.h"
#include "locking.h"
#include "btrfs_inode.h"
#include "async-thread.h"
/*
* backref_node, mapping_node and tree_block start with this
*/
struct tree_entry {
struct rb_node rb_node;
u64 bytenr;
};
/*
* present a tree block in the backref cache
*/
struct backref_node {
struct rb_node rb_node;
u64 bytenr;
/* objectid tree block owner */
u64 owner;
/* list of upper level blocks reference this block */
struct list_head upper;
/* list of child blocks in the cache */
struct list_head lower;
/* NULL if this node is not tree root */
struct btrfs_root *root;
/* extent buffer got by COW the block */
struct extent_buffer *eb;
/* level of tree block */
unsigned int level:8;
/* 1 if the block is root of old snapshot */
unsigned int old_root:1;
/* 1 if no child blocks in the cache */
unsigned int lowest:1;
/* is the extent buffer locked */
unsigned int locked:1;
/* has the block been processed */
unsigned int processed:1;
/* have backrefs of this block been checked */
unsigned int checked:1;
};
/*
* present a block pointer in the backref cache
*/
struct backref_edge {
struct list_head list[2];
struct backref_node *node[2];
u64 blockptr;
};
#define LOWER 0
#define UPPER 1
struct backref_cache {
/* red black tree of all backref nodes in the cache */
struct rb_root rb_root;
/* list of backref nodes with no child block in the cache */
struct list_head pending[BTRFS_MAX_LEVEL];
spinlock_t lock;
};
/*
* map address of tree root to tree
*/
struct mapping_node {
struct rb_node rb_node;
u64 bytenr;
void *data;
};
struct mapping_tree {
struct rb_root rb_root;
spinlock_t lock;
};
/*
* present a tree block to process
*/
struct tree_block {
struct rb_node rb_node;
u64 bytenr;
struct btrfs_key key;
unsigned int level:8;
unsigned int key_ready:1;
};
/* inode vector */
#define INODEVEC_SIZE 16
struct inodevec {
struct list_head list;
struct inode *inode[INODEVEC_SIZE];
int nr;
};
struct reloc_control {
/* block group to relocate */
struct btrfs_block_group_cache *block_group;
/* extent tree */
struct btrfs_root *extent_root;
/* inode for moving data */
struct inode *data_inode;
struct btrfs_workers workers;
/* tree blocks have been processed */
struct extent_io_tree processed_blocks;
/* map start of tree root to corresponding reloc tree */
struct mapping_tree reloc_root_tree;
/* list of reloc trees */
struct list_head reloc_roots;
u64 search_start;
u64 extents_found;
u64 extents_skipped;
int stage;
int create_reloc_root;
unsigned int found_file_extent:1;
unsigned int found_old_snapshot:1;
};
/* stages of data relocation */
#define MOVE_DATA_EXTENTS 0
#define UPDATE_DATA_PTRS 1
/*
* merge reloc tree to corresponding fs tree in worker threads
*/
struct async_merge {
struct btrfs_work work;
struct reloc_control *rc;
struct btrfs_root *root;
struct completion *done;
atomic_t *num_pending;
};
static void mapping_tree_init(struct mapping_tree *tree)
{
tree->rb_root.rb_node = NULL;
spin_lock_init(&tree->lock);
}
static void backref_cache_init(struct backref_cache *cache)
{
int i;
cache->rb_root.rb_node = NULL;
for (i = 0; i < BTRFS_MAX_LEVEL; i++)
INIT_LIST_HEAD(&cache->pending[i]);
spin_lock_init(&cache->lock);
}
static void backref_node_init(struct backref_node *node)
{
memset(node, 0, sizeof(*node));
INIT_LIST_HEAD(&node->upper);
INIT_LIST_HEAD(&node->lower);
RB_CLEAR_NODE(&node->rb_node);
}
static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
struct rb_node *node)
{
struct rb_node **p = &root->rb_node;
struct rb_node *parent = NULL;
struct tree_entry *entry;
while (*p) {
parent = *p;
entry = rb_entry(parent, struct tree_entry, rb_node);
if (bytenr < entry->bytenr)
p = &(*p)->rb_left;
else if (bytenr > entry->bytenr)
p = &(*p)->rb_right;
else
return parent;
}
rb_link_node(node, parent, p);
rb_insert_color(node, root);
return NULL;
}
static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
{
struct rb_node *n = root->rb_node;
struct tree_entry *entry;
while (n) {
entry = rb_entry(n, struct tree_entry, rb_node);
if (bytenr < entry->bytenr)
n = n->rb_left;
else if (bytenr > entry->bytenr)
n = n->rb_right;
else
return n;
}
return NULL;
}
/*
* walk up backref nodes until reach node presents tree root
*/
static struct backref_node *walk_up_backref(struct backref_node *node,
struct backref_edge *edges[],
int *index)
{
struct backref_edge *edge;
int idx = *index;
while (!list_empty(&node->upper)) {
edge = list_entry(node->upper.next,
struct backref_edge, list[LOWER]);
edges[idx++] = edge;
node = edge->node[UPPER];
}
*index = idx;
return node;
}
/*
* walk down backref nodes to find start of next reference path
*/
static struct backref_node *walk_down_backref(struct backref_edge *edges[],
int *index)
{
struct backref_edge *edge;
struct backref_node *lower;
int idx = *index;
while (idx > 0) {
edge = edges[idx - 1];
lower = edge->node[LOWER];
if (list_is_last(&edge->list[LOWER], &lower->upper)) {
idx--;
continue;
}
edge = list_entry(edge->list[LOWER].next,
struct backref_edge, list[LOWER]);
edges[idx - 1] = edge;
*index = idx;
return edge->node[UPPER];
}
*index = 0;
return NULL;
}
static void drop_node_buffer(struct backref_node *node)
{
if (node->eb) {
if (node->locked) {
btrfs_tree_unlock(node->eb);
node->locked = 0;
}
free_extent_buffer(node->eb);
node->eb = NULL;
}
}
static void drop_backref_node(struct backref_cache *tree,
struct backref_node *node)
{
BUG_ON(!node->lowest);
BUG_ON(!list_empty(&node->upper));
drop_node_buffer(node);
list_del(&node->lower);
rb_erase(&node->rb_node, &tree->rb_root);
kfree(node);
}
/*
* remove a backref node from the backref cache
*/
static void remove_backref_node(struct backref_cache *cache,
struct backref_node *node)
{
struct backref_node *upper;
struct backref_edge *edge;
if (!node)
return;
BUG_ON(!node->lowest);
while (!list_empty(&node->upper)) {
edge = list_entry(node->upper.next, struct backref_edge,
list[LOWER]);
upper = edge->node[UPPER];
list_del(&edge->list[LOWER]);
list_del(&edge->list[UPPER]);
kfree(edge);
/*
* add the node to pending list if no other
* child block cached.
*/
if (list_empty(&upper->lower)) {
list_add_tail(&upper->lower,
&cache->pending[upper->level]);
upper->lowest = 1;
}
}
drop_backref_node(cache, node);
}
/*
* find reloc tree by address of tree root
*/
static struct btrfs_root *find_reloc_root(struct reloc_control *rc,
u64 bytenr)
{
struct rb_node *rb_node;
struct mapping_node *node;
struct btrfs_root *root = NULL;
spin_lock(&rc->reloc_root_tree.lock);
rb_node = tree_search(&rc->reloc_root_tree.rb_root, bytenr);
if (rb_node) {
node = rb_entry(rb_node, struct mapping_node, rb_node);
root = (struct btrfs_root *)node->data;
}
spin_unlock(&rc->reloc_root_tree.lock);
return root;
}
static int is_cowonly_root(u64 root_objectid)
{
if (root_objectid == BTRFS_ROOT_TREE_OBJECTID ||
root_objectid == BTRFS_EXTENT_TREE_OBJECTID ||
root_objectid == BTRFS_CHUNK_TREE_OBJECTID ||
root_objectid == BTRFS_DEV_TREE_OBJECTID ||
root_objectid == BTRFS_TREE_LOG_OBJECTID ||
root_objectid == BTRFS_CSUM_TREE_OBJECTID)
return 1;
return 0;
}
static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
u64 root_objectid)
{
struct btrfs_key key;
key.objectid = root_objectid;
key.type = BTRFS_ROOT_ITEM_KEY;
if (is_cowonly_root(root_objectid))
key.offset = 0;
else
key.offset = (u64)-1;
return btrfs_read_fs_root_no_name(fs_info, &key);
}
#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
static noinline_for_stack
struct btrfs_root *find_tree_root(struct reloc_control *rc,
struct extent_buffer *leaf,
struct btrfs_extent_ref_v0 *ref0)
{
struct btrfs_root *root;
u64 root_objectid = btrfs_ref_root_v0(leaf, ref0);
u64 generation = btrfs_ref_generation_v0(leaf, ref0);
BUG_ON(root_objectid == BTRFS_TREE_RELOC_OBJECTID);
root = read_fs_root(rc->extent_root->fs_info, root_objectid);
BUG_ON(IS_ERR(root));
if (root->ref_cows &&
generation != btrfs_root_generation(&root->root_item))
return NULL;
return root;
}
#endif
static noinline_for_stack
int find_inline_backref(struct extent_buffer *leaf, int slot,
unsigned long *ptr, unsigned long *end)
{
struct btrfs_extent_item *ei;
struct btrfs_tree_block_info *bi;
u32 item_size;
item_size = btrfs_item_size_nr(leaf, slot);
#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
if (item_size < sizeof(*ei)) {
WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
return 1;
}
#endif
ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
WARN_ON(!(btrfs_extent_flags(leaf, ei) &
BTRFS_EXTENT_FLAG_TREE_BLOCK));
if (item_size <= sizeof(*ei) + sizeof(*bi)) {
WARN_ON(item_size < sizeof(*ei) + sizeof(*bi));
return 1;
}
bi = (struct btrfs_tree_block_info *)(ei + 1);
*ptr = (unsigned long)(bi + 1);
*end = (unsigned long)ei + item_size;
return 0;
}
/*
* build backref tree for a given tree block. root of the backref tree
* corresponds the tree block, leaves of the backref tree correspond
* roots of b-trees that reference the tree block.
*
* the basic idea of this function is check backrefs of a given block
* to find upper level blocks that refernece the block, and then check
* bakcrefs of these upper level blocks recursively. the recursion stop
* when tree root is reached or backrefs for the block is cached.
*
* NOTE: if we find backrefs for a block are cached, we know backrefs
* for all upper level blocks that directly/indirectly reference the
* block are also cached.
*/
static struct backref_node *build_backref_tree(struct reloc_control *rc,
struct backref_cache *cache,
struct btrfs_key *node_key,
int level, u64 bytenr)
{
struct btrfs_path *path1;
struct btrfs_path *path2;
struct extent_buffer *eb;
struct btrfs_root *root;
struct backref_node *cur;
struct backref_node *upper;
struct backref_node *lower;
struct backref_node *node = NULL;
struct backref_node *exist = NULL;
struct backref_edge *edge;
struct rb_node *rb_node;
struct btrfs_key key;
unsigned long end;
unsigned long ptr;
LIST_HEAD(list);
int ret;
int err = 0;
path1 = btrfs_alloc_path();
path2 = btrfs_alloc_path();
if (!path1 || !path2) {
err = -ENOMEM;
goto out;
}
node = kmalloc(sizeof(*node), GFP_NOFS);
if (!node) {
err = -ENOMEM;
goto out;
}
backref_node_init(node);
node->bytenr = bytenr;
node->owner = 0;
node->level = level;
node->lowest = 1;
cur = node;
again:
end = 0;
ptr = 0;
key.objectid = cur->bytenr;
key.type = BTRFS_EXTENT_ITEM_KEY;
key.offset = (u64)-1;
path1->search_commit_root = 1;
path1->skip_locking = 1;
ret = btrfs_search_slot(NULL, rc->extent_root, &key, path1,
0, 0);
if (ret < 0) {
err = ret;
goto out;
}
BUG_ON(!ret || !path1->slots[0]);
path1->slots[0]--;
WARN_ON(cur->checked);
if (!list_empty(&cur->upper)) {
/*
* the backref was added previously when processsing
* backref of type BTRFS_TREE_BLOCK_REF_KEY
*/
BUG_ON(!list_is_singular(&cur->upper));
edge = list_entry(cur->upper.next, struct backref_edge,
list[LOWER]);
BUG_ON(!list_empty(&edge->list[UPPER]));
exist = edge->node[UPPER];
/*
* add the upper level block to pending list if we need
* check its backrefs
*/
if (!exist->checked)
list_add_tail(&edge->list[UPPER], &list);
} else {
exist = NULL;
}
while (1) {
cond_resched();
eb = path1->nodes[0];
if (ptr >= end) {
if (path1->slots[0] >= btrfs_header_nritems(eb)) {
ret = btrfs_next_leaf(rc->extent_root, path1);
if (ret < 0) {
err = ret;
goto out;
}
if (ret > 0)
break;
eb = path1->nodes[0];
}
btrfs_item_key_to_cpu(eb, &key, path1->slots[0]);
if (key.objectid != cur->bytenr) {
WARN_ON(exist);
break;
}
if (key.type == BTRFS_EXTENT_ITEM_KEY) {
ret = find_inline_backref(eb, path1->slots[0],
&ptr, &end);
if (ret)
goto next;
}
}
if (ptr < end) {
/* update key for inline back ref */
struct btrfs_extent_inline_ref *iref;
iref = (struct btrfs_extent_inline_ref *)ptr;
key.type = btrfs_extent_inline_ref_type(eb, iref);
key.offset = btrfs_extent_inline_ref_offset(eb, iref);
WARN_ON(key.type != BTRFS_TREE_BLOCK_REF_KEY &&
key.type != BTRFS_SHARED_BLOCK_REF_KEY);
}
if (exist &&
((key.type == BTRFS_TREE_BLOCK_REF_KEY &&
exist->owner == key.offset) ||
(key.type == BTRFS_SHARED_BLOCK_REF_KEY &&
exist->bytenr == key.offset))) {
exist = NULL;
goto next;
}
#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
key.type == BTRFS_EXTENT_REF_V0_KEY) {
if (key.objectid == key.offset &&
key.type == BTRFS_EXTENT_REF_V0_KEY) {
struct btrfs_extent_ref_v0 *ref0;
ref0 = btrfs_item_ptr(eb, path1->slots[0],
struct btrfs_extent_ref_v0);
root = find_tree_root(rc, eb, ref0);
if (root)
cur->root = root;
else
cur->old_root = 1;
break;
}
#else
BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
#endif
if (key.objectid == key.offset) {
/*
* only root blocks of reloc trees use
* backref of this type.
*/
root = find_reloc_root(rc, cur->bytenr);
BUG_ON(!root);
cur->root = root;
break;
}
edge = kzalloc(sizeof(*edge), GFP_NOFS);
if (!edge) {
err = -ENOMEM;
goto out;
}
rb_node = tree_search(&cache->rb_root, key.offset);
if (!rb_node) {
upper = kmalloc(sizeof(*upper), GFP_NOFS);
if (!upper) {
kfree(edge);
err = -ENOMEM;
goto out;
}
backref_node_init(upper);
upper->bytenr = key.offset;
upper->owner = 0;
upper->level = cur->level + 1;
/*
* backrefs for the upper level block isn't
* cached, add the block to pending list
*/
list_add_tail(&edge->list[UPPER], &list);
} else {
upper = rb_entry(rb_node, struct backref_node,
rb_node);
INIT_LIST_HEAD(&edge->list[UPPER]);
}
list_add(&edge->list[LOWER], &cur->upper);
edge->node[UPPER] = upper;
edge->node[LOWER] = cur;
goto next;
} else if (key.type != BTRFS_TREE_BLOCK_REF_KEY) {
goto next;
}
/* key.type == BTRFS_TREE_BLOCK_REF_KEY */
root = read_fs_root(rc->extent_root->fs_info, key.offset);
if (IS_ERR(root)) {
err = PTR_ERR(root);
goto out;
}
if (btrfs_root_level(&root->root_item) == cur->level) {
/* tree root */
BUG_ON(btrfs_root_bytenr(&root->root_item) !=
cur->bytenr);
cur->root = root;
break;
}
level = cur->level + 1;
/*
* searching the tree to find upper level blocks
* reference the block.
*/
path2->search_commit_root = 1;
path2->skip_locking = 1;
path2->lowest_level = level;
ret = btrfs_search_slot(NULL, root, node_key, path2, 0, 0);
path2->lowest_level = 0;
if (ret < 0) {
err = ret;
goto out;
}
eb = path2->nodes[level];
WARN_ON(btrfs_node_blockptr(eb, path2->slots[level]) !=
cur->bytenr);
lower = cur;
for (; level < BTRFS_MAX_LEVEL; level++) {
if (!path2->nodes[level]) {
BUG_ON(btrfs_root_bytenr(&root->root_item) !=
lower->bytenr);
lower->root = root;
break;
}
edge = kzalloc(sizeof(*edge), GFP_NOFS);
if (!edge) {
err = -ENOMEM;
goto out;
}
eb = path2->nodes[level];
rb_node = tree_search(&cache->rb_root, eb->start);
if (!rb_node) {
upper = kmalloc(sizeof(*upper), GFP_NOFS);
if (!upper) {
kfree(edge);
err = -ENOMEM;
goto out;
}
backref_node_init(upper);
upper->bytenr = eb->start;
upper->owner = btrfs_header_owner(eb);
upper->level = lower->level + 1;
/*
* if we know the block isn't shared
* we can void checking its backrefs.
*/
if (btrfs_block_can_be_shared(root, eb))
upper->checked = 0;
else
upper->checked = 1;
/*
* add the block to pending list if we
* need check its backrefs. only block
* at 'cur->level + 1' is added to the
* tail of pending list. this guarantees
* we check backrefs from lower level
* blocks to upper level blocks.
*/
if (!upper->checked &&
level == cur->level + 1) {
list_add_tail(&edge->list[UPPER],
&list);
} else
INIT_LIST_HEAD(&edge->list[UPPER]);
} else {
upper = rb_entry(rb_node, struct backref_node,
rb_node);
BUG_ON(!upper->checked);
INIT_LIST_HEAD(&edge->list[UPPER]);
}
list_add_tail(&edge->list[LOWER], &lower->upper);
edge->node[UPPER] = upper;
edge->node[LOWER] = lower;
if (rb_node)
break;
lower = upper;
upper = NULL;
}
btrfs_release_path(root, path2);
next:
if (ptr < end) {
ptr += btrfs_extent_inline_ref_size(key.type);
if (ptr >= end) {
WARN_ON(ptr > end);
ptr = 0;
end = 0;
}
}
if (ptr >= end)
path1->slots[0]++;
}
btrfs_release_path(rc->extent_root, path1);
cur->checked = 1;
WARN_ON(exist);
/* the pending list isn't empty, take the first block to process */
if (!list_empty(&list)) {
edge = list_entry(list.next, struct backref_edge, list[UPPER]);
list_del_init(&edge->list[UPPER]);
cur = edge->node[UPPER];
goto again;
}
/*
* everything goes well, connect backref nodes and insert backref nodes
* into the cache.
*/
BUG_ON(!node->checked);
rb_node = tree_insert(&cache->rb_root, node->bytenr, &node->rb_node);
BUG_ON(rb_node);
list_for_each_entry(edge, &node->upper, list[LOWER])
list_add_tail(&edge->list[UPPER], &list);
while (!list_empty(&list)) {
edge = list_entry(list.next, struct backref_edge, list[UPPER]);
list_del_init(&edge->list[UPPER]);
upper = edge->node[UPPER];
if (!RB_EMPTY_NODE(&upper->rb_node)) {
if (upper->lowest) {
list_del_init(&upper->lower);
upper->lowest = 0;
}
list_add_tail(&edge->list[UPPER], &upper->lower);
continue;
}
BUG_ON(!upper->checked);
rb_node = tree_insert(&cache->rb_root, upper->bytenr,
&upper->rb_node);
BUG_ON(rb_node);
list_add_tail(&edge->list[UPPER], &upper->lower);
list_for_each_entry(edge, &upper->upper, list[LOWER])
list_add_tail(&edge->list[UPPER], &list);
}
out:
btrfs_free_path(path1);
btrfs_free_path(path2);
if (err) {
INIT_LIST_HEAD(&list);
upper = node;
while (upper) {
if (RB_EMPTY_NODE(&upper->rb_node)) {
list_splice_tail(&upper->upper, &list);
kfree(upper);
}
if (list_empty(&list))
break;
edge = list_entry(list.next, struct backref_edge,
list[LOWER]);
upper = edge->node[UPPER];
kfree(edge);
}
return ERR_PTR(err);
}
return node;
}
/*
* helper to add 'address of tree root -> reloc tree' mapping
*/
static int __add_reloc_root(struct btrfs_root *root)
{
struct rb_node *rb_node;
struct mapping_node *node;
struct reloc_control *rc = root->fs_info->reloc_ctl;
node = kmalloc(sizeof(*node), GFP_NOFS);
BUG_ON(!node);
node->bytenr = root->node->start;
node->data = root;
spin_lock(&rc->reloc_root_tree.lock);
rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
node->bytenr, &node->rb_node);
spin_unlock(&rc->reloc_root_tree.lock);
BUG_ON(rb_node);
list_add_tail(&root->root_list, &rc->reloc_roots);
return 0;
}
/*
* helper to update/delete the 'address of tree root -> reloc tree'
* mapping
*/
static int __update_reloc_root(struct btrfs_root *root, int del)
{
struct rb_node *rb_node;
struct mapping_node *node = NULL;
struct reloc_control *rc = root->fs_info->reloc_ctl;
spin_lock(&rc->reloc_root_tree.lock);
rb_node = tree_search(&rc->reloc_root_tree.rb_root,
root->commit_root->start);
if (rb_node) {
node = rb_entry(rb_node, struct mapping_node, rb_node);
rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
}
spin_unlock(&rc->reloc_root_tree.lock);
BUG_ON((struct btrfs_root *)node->data != root);
if (!del) {
spin_lock(&rc->reloc_root_tree.lock);
node->bytenr = root->node->start;
rb_node = tree_insert(&rc->reloc_root_tree.rb_root,
node->bytenr, &node->rb_node);
spin_unlock(&rc->reloc_root_tree.lock);
BUG_ON(rb_node);
} else {
list_del_init(&root->root_list);
kfree(node);
}
return 0;
}
/*
* create reloc tree for a given fs tree. reloc tree is just a
* snapshot of the fs tree with special root objectid.
*/
int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
struct btrfs_root *reloc_root;
struct extent_buffer *eb;
struct btrfs_root_item *root_item;
struct btrfs_key root_key;
int ret;
if (root->reloc_root) {
reloc_root = root->reloc_root;
reloc_root->last_trans = trans->transid;
return 0;
}
if (!root->fs_info->reloc_ctl ||
!root->fs_info->reloc_ctl->create_reloc_root ||
root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
return 0;
root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
BUG_ON(!root_item);
root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
root_key.type = BTRFS_ROOT_ITEM_KEY;
root_key.offset = root->root_key.objectid;
ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
BTRFS_TREE_RELOC_OBJECTID);
BUG_ON(ret);
btrfs_set_root_last_snapshot(&root->root_item, trans->transid - 1);
memcpy(root_item, &root->root_item, sizeof(*root_item));
btrfs_set_root_refs(root_item, 1);
btrfs_set_root_bytenr(root_item, eb->start);
btrfs_set_root_level(root_item, btrfs_header_level(eb));
btrfs_set_root_generation(root_item, trans->transid);
memset(&root_item->drop_progress, 0, sizeof(struct btrfs_disk_key));
root_item->drop_level = 0;
btrfs_tree_unlock(eb);
free_extent_buffer(eb);
ret = btrfs_insert_root(trans, root->fs_info->tree_root,
&root_key, root_item);
BUG_ON(ret);
kfree(root_item);
reloc_root = btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
&root_key);
BUG_ON(IS_ERR(reloc_root));
reloc_root->last_trans = trans->transid;
__add_reloc_root(reloc_root);
root->reloc_root = reloc_root;
return 0;
}
/*
* update root item of reloc tree
*/
int btrfs_update_reloc_root(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
struct btrfs_root *reloc_root;
struct btrfs_root_item *root_item;
int del = 0;
int ret;
if (!root->reloc_root)
return 0;
reloc_root = root->reloc_root;
root_item = &reloc_root->root_item;
if (btrfs_root_refs(root_item) == 0) {
root->reloc_root = NULL;
del = 1;
}
__update_reloc_root(reloc_root, del);
if (reloc_root->commit_root != reloc_root->node) {
btrfs_set_root_node(root_item, reloc_root->node);
free_extent_buffer(reloc_root->commit_root);
reloc_root->commit_root = btrfs_root_node(reloc_root);
}
ret = btrfs_update_root(trans, root->fs_info->tree_root,
&reloc_root->root_key, root_item);
BUG_ON(ret);
return 0;
}
/*
* helper to find first cached inode with inode number >= objectid
* in a subvolume
*/
static struct inode *find_next_inode(struct btrfs_root *root, u64 objectid)
{
struct rb_node *node;
struct rb_node *prev;
struct btrfs_inode *entry;
struct inode *inode;
spin_lock(&root->inode_lock);
again:
node = root->inode_tree.rb_node;
prev = NULL;
while (node) {
prev = node;
entry = rb_entry(node, struct btrfs_inode, rb_node);
if (objectid < entry->vfs_inode.i_ino)
node = node->rb_left;
else if (objectid > entry->vfs_inode.i_ino)
node = node->rb_right;
else
break;
}
if (!node) {
while (prev) {
entry = rb_entry(prev, struct btrfs_inode, rb_node);
if (objectid <= entry->vfs_inode.i_ino) {
node = prev;
break;
}
prev = rb_next(prev);
}
}
while (node) {
entry = rb_entry(node, struct btrfs_inode, rb_node);
inode = igrab(&entry->vfs_inode);
if (inode) {
spin_unlock(&root->inode_lock);
return inode;
}
objectid = entry->vfs_inode.i_ino + 1;
if (cond_resched_lock(&root->inode_lock))
goto again;
node = rb_next(node);
}
spin_unlock(&root->inode_lock);
return NULL;
}
static int in_block_group(u64 bytenr,
struct btrfs_block_group_cache *block_group)
{
if (bytenr >= block_group->key.objectid &&
bytenr < block_group->key.objectid + block_group->key.offset)
return 1;
return 0;
}
/*
* get new location of data
*/
static int get_new_location(struct inode *reloc_inode, u64 *new_bytenr,
u64 bytenr, u64 num_bytes)
{
struct btrfs_root *root = BTRFS_I(reloc_inode)->root;
struct btrfs_path *path;
struct btrfs_file_extent_item *fi;
struct extent_buffer *leaf;
int ret;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
bytenr -= BTRFS_I(reloc_inode)->index_cnt;
ret = btrfs_lookup_file_extent(NULL, root, path, reloc_inode->i_ino,
bytenr, 0);
if (ret < 0)
goto out;
if (ret > 0) {
ret = -ENOENT;
goto out;
}
leaf = path->nodes[0];
fi = btrfs_item_ptr(leaf, path->slots[0],
struct btrfs_file_extent_item);
BUG_ON(btrfs_file_extent_offset(leaf, fi) ||
btrfs_file_extent_compression(leaf, fi) ||
btrfs_file_extent_encryption(leaf, fi) ||
btrfs_file_extent_other_encoding(leaf, fi));
if (num_bytes != btrfs_file_extent_disk_num_bytes(leaf, fi)) {
ret = 1;
goto out;
}
if (new_bytenr)
*new_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
ret = 0;
out:
btrfs_free_path(path);
return ret;
}
/*
* update file extent items in the tree leaf to point to
* the new locations.
*/
static int replace_file_extents(struct btrfs_trans_handle *trans,
struct reloc_control *rc,
struct btrfs_root *root,
struct extent_buffer *leaf,
struct list_head *inode_list)
{
struct btrfs_key key;
struct btrfs_file_extent_item *fi;
struct inode *inode = NULL;
struct inodevec *ivec = NULL;
u64 parent;
u64 bytenr;
u64 new_bytenr;
u64 num_bytes;
u64 end;
u32 nritems;
u32 i;
int ret;
int first = 1;
int dirty = 0;
if (rc->stage != UPDATE_DATA_PTRS)
return 0;
/* reloc trees always use full backref */
if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
parent = leaf->start;
else
parent = 0;
nritems = btrfs_header_nritems(leaf);
for (i = 0; i < nritems; i++) {
cond_resched();
btrfs_item_key_to_cpu(leaf, &key, i);
if (key.type != BTRFS_EXTENT_DATA_KEY)
continue;
fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
if (btrfs_file_extent_type(leaf, fi) ==
BTRFS_FILE_EXTENT_INLINE)
continue;
bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
if (bytenr == 0)
continue;
if (!in_block_group(bytenr, rc->block_group))
continue;
/*
* if we are modifying block in fs tree, wait for readpage
* to complete and drop the extent cache
*/
if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
if (!ivec || ivec->nr == INODEVEC_SIZE) {
ivec = kmalloc(sizeof(*ivec), GFP_NOFS);
BUG_ON(!ivec);
ivec->nr = 0;
list_add_tail(&ivec->list, inode_list);
}
if (first) {
inode = find_next_inode(root, key.objectid);
if (inode)
ivec->inode[ivec->nr++] = inode;
first = 0;
} else if (inode && inode->i_ino < key.objectid) {
inode = find_next_inode(root, key.objectid);
if (inode)
ivec->inode[ivec->nr++] = inode;
}
if (inode && inode->i_ino == key.objectid) {
end = key.offset +
btrfs_file_extent_num_bytes(leaf, fi);
WARN_ON(!IS_ALIGNED(key.offset,
root->sectorsize));
WARN_ON(!IS_ALIGNED(end, root->sectorsize));
end--;
ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
key.offset, end,
GFP_NOFS);
if (!ret)
continue;
btrfs_drop_extent_cache(inode, key.offset, end,
1);
unlock_extent(&BTRFS_I(inode)->io_tree,
key.offset, end, GFP_NOFS);
}
}
ret = get_new_location(rc->data_inode, &new_bytenr,
bytenr, num_bytes);
if (ret > 0)
continue;
BUG_ON(ret < 0);
btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
dirty = 1;
key.offset -= btrfs_file_extent_offset(leaf, fi);
ret = btrfs_inc_extent_ref(trans, root, new_bytenr,
num_bytes, parent,
btrfs_header_owner(leaf),
key.objectid, key.offset);
BUG_ON(ret);
ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
parent, btrfs_header_owner(leaf),
key.objectid, key.offset);
BUG_ON(ret);
}
if (dirty)
btrfs_mark_buffer_dirty(leaf);
return 0;
}
static noinline_for_stack
int memcmp_node_keys(struct extent_buffer *eb, int slot,
struct btrfs_path *path, int level)
{
struct btrfs_disk_key key1;
struct btrfs_disk_key key2;
btrfs_node_key(eb, &key1, slot);
btrfs_node_key(path->nodes[level], &key2, path->slots[level]);
return memcmp(&key1, &key2, sizeof(key1));
}
/*
* try to replace tree blocks in fs tree with the new blocks
* in reloc tree. tree blocks haven't been modified since the
* reloc tree was create can be replaced.
*
* if a block was replaced, level of the block + 1 is returned.
* if no block got replaced, 0 is returned. if there are other
* errors, a negative error number is returned.
*/
static int replace_path(struct btrfs_trans_handle *trans,
struct btrfs_root *dest, struct btrfs_root *src,
struct btrfs_path *path, struct btrfs_key *next_key,
struct extent_buffer **leaf,
int lowest_level, int max_level)
{
struct extent_buffer *eb;
struct extent_buffer *parent;
struct btrfs_key key;
u64 old_bytenr;
u64 new_bytenr;
u64 old_ptr_gen;
u64 new_ptr_gen;
u64 last_snapshot;
u32 blocksize;
int level;
int ret;
int slot;
BUG_ON(src->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
BUG_ON(dest->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
BUG_ON(lowest_level > 1 && leaf);
last_snapshot = btrfs_root_last_snapshot(&src->root_item);
slot = path->slots[lowest_level];
btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
eb = btrfs_lock_root_node(dest);
btrfs_set_lock_blocking(eb);
level = btrfs_header_level(eb);
if (level < lowest_level) {
btrfs_tree_unlock(eb);
free_extent_buffer(eb);
return 0;
}
ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb);
BUG_ON(ret);
btrfs_set_lock_blocking(eb);
if (next_key) {
next_key->objectid = (u64)-1;
next_key->type = (u8)-1;
next_key->offset = (u64)-1;
}
parent = eb;
while (1) {
level = btrfs_header_level(parent);
BUG_ON(level < lowest_level);
ret = btrfs_bin_search(parent, &key, level, &slot);
if (ret && slot > 0)
slot--;
if (next_key && slot + 1 < btrfs_header_nritems(parent))
btrfs_node_key_to_cpu(parent, next_key, slot + 1);
old_bytenr = btrfs_node_blockptr(parent, slot);
blocksize = btrfs_level_size(dest, level - 1);
old_ptr_gen = btrfs_node_ptr_generation(parent, slot);
if (level <= max_level) {
eb = path->nodes[level];
new_bytenr = btrfs_node_blockptr(eb,
path->slots[level]);
new_ptr_gen = btrfs_node_ptr_generation(eb,
path->slots[level]);
} else {
new_bytenr = 0;
new_ptr_gen = 0;
}
if (new_bytenr > 0 && new_bytenr == old_bytenr) {
WARN_ON(1);
ret = level;
break;
}
if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
memcmp_node_keys(parent, slot, path, level)) {
if (level <= lowest_level && !leaf) {
ret = 0;
break;
}
eb = read_tree_block(dest, old_bytenr, blocksize,
old_ptr_gen);
btrfs_tree_lock(eb);
ret = btrfs_cow_block(trans, dest, eb, parent,
slot, &eb);
BUG_ON(ret);
btrfs_set_lock_blocking(eb);
if (level <= lowest_level) {
*leaf = eb;
ret = 0;
break;
}
btrfs_tree_unlock(parent);
free_extent_buffer(parent);
parent = eb;
continue;
}
btrfs_node_key_to_cpu(path->nodes[level], &key,
path->slots[level]);
btrfs_release_path(src, path);
path->lowest_level = level;
ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
path->lowest_level = 0;
BUG_ON(ret);
/*
* swap blocks in fs tree and reloc tree.
*/
btrfs_set_node_blockptr(parent, slot, new_bytenr);
btrfs_set_node_ptr_generation(parent, slot, new_ptr_gen);
btrfs_mark_buffer_dirty(parent);
btrfs_set_node_blockptr(path->nodes[level],
path->slots[level], old_bytenr);
btrfs_set_node_ptr_generation(path->nodes[level],
path->slots[level], old_ptr_gen);
btrfs_mark_buffer_dirty(path->nodes[level]);
ret = btrfs_inc_extent_ref(trans, src, old_bytenr, blocksize,
path->nodes[level]->start,
src->root_key.objectid, level - 1, 0);
BUG_ON(ret);
ret = btrfs_inc_extent_ref(trans, dest, new_bytenr, blocksize,
0, dest->root_key.objectid, level - 1,
0);
BUG_ON(ret);
ret = btrfs_free_extent(trans, src, new_bytenr, blocksize,
path->nodes[level]->start,
src->root_key.objectid, level - 1, 0);
BUG_ON(ret);
ret = btrfs_free_extent(trans, dest, old_bytenr, blocksize,
0, dest->root_key.objectid, level - 1,
0);
BUG_ON(ret);
btrfs_unlock_up_safe(path, 0);
ret = level;
break;
}
btrfs_tree_unlock(parent);
free_extent_buffer(parent);
return ret;
}
/*
* helper to find next relocated block in reloc tree
*/
static noinline_for_stack
int walk_up_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
int *level)
{
struct extent_buffer *eb;
int i;
u64 last_snapshot;
u32 nritems;
last_snapshot = btrfs_root_last_snapshot(&root->root_item);
for (i = 0; i < *level; i++) {
free_extent_buffer(path->nodes[i]);
path->nodes[i] = NULL;
}
for (i = *level; i < BTRFS_MAX_LEVEL && path->nodes[i]; i++) {
eb = path->nodes[i];
nritems = btrfs_header_nritems(eb);
while (path->slots[i] + 1 < nritems) {
path->slots[i]++;
if (btrfs_node_ptr_generation(eb, path->slots[i]) <=
last_snapshot)
continue;
*level = i;
return 0;
}
free_extent_buffer(path->nodes[i]);
path->nodes[i] = NULL;
}
return 1;
}
/*
* walk down reloc tree to find relocated block of lowest level
*/
static noinline_for_stack
int walk_down_reloc_tree(struct btrfs_root *root, struct btrfs_path *path,
int *level)
{
struct extent_buffer *eb = NULL;
int i;
u64 bytenr;
u64 ptr_gen = 0;
u64 last_snapshot;
u32 blocksize;
u32 nritems;
last_snapshot = btrfs_root_last_snapshot(&root->root_item);
for (i = *level; i > 0; i--) {
eb = path->nodes[i];
nritems = btrfs_header_nritems(eb);
while (path->slots[i] < nritems) {
ptr_gen = btrfs_node_ptr_generation(eb, path->slots[i]);
if (ptr_gen > last_snapshot)
break;
path->slots[i]++;
}
if (path->slots[i] >= nritems) {
if (i == *level)
break;
*level = i + 1;
return 0;
}
if (i == 1) {
*level = i;
return 0;
}
bytenr = btrfs_node_blockptr(eb, path->slots[i]);
blocksize = btrfs_level_size(root, i - 1);
eb = read_tree_block(root, bytenr, blocksize, ptr_gen);
BUG_ON(btrfs_header_level(eb) != i - 1);
path->nodes[i - 1] = eb;
path->slots[i - 1] = 0;
}
return 1;
}
/*
* invalidate extent cache for file extents whose key in range of
* [min_key, max_key)
*/
static int invalidate_extent_cache(struct btrfs_root *root,
struct btrfs_key *min_key,
struct btrfs_key *max_key)
{
struct inode *inode = NULL;
u64 objectid;
u64 start, end;
objectid = min_key->objectid;
while (1) {
cond_resched();
iput(inode);
if (objectid > max_key->objectid)
break;
inode = find_next_inode(root, objectid);
if (!inode)
break;
if (inode->i_ino > max_key->objectid) {
iput(inode);
break;
}
objectid = inode->i_ino + 1;
if (!S_ISREG(inode->i_mode))
continue;
if (unlikely(min_key->objectid == inode->i_ino)) {
if (min_key->type > BTRFS_EXTENT_DATA_KEY)
continue;
if (min_key->type < BTRFS_EXTENT_DATA_KEY)
start = 0;
else {
start = min_key->offset;
WARN_ON(!IS_ALIGNED(start, root->sectorsize));
}
} else {
start = 0;
}
if (unlikely(max_key->objectid == inode->i_ino)) {
if (max_key->type < BTRFS_EXTENT_DATA_KEY)
continue;
if (max_key->type > BTRFS_EXTENT_DATA_KEY) {
end = (u64)-1;
} else {
if (max_key->offset == 0)
continue;
end = max_key->offset;
WARN_ON(!IS_ALIGNED(end, root->sectorsize));
end--;
}
} else {
end = (u64)-1;
}
/* the lock_extent waits for readpage to complete */
lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
btrfs_drop_extent_cache(inode, start, end, 1);
unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
}
return 0;
}
static int find_next_key(struct btrfs_path *path, int level,
struct btrfs_key *key)
{
while (level < BTRFS_MAX_LEVEL) {
if (!path->nodes[level])
break;
if (path->slots[level] + 1 <
btrfs_header_nritems(path->nodes[level])) {
btrfs_node_key_to_cpu(path->nodes[level], key,
path->slots[level] + 1);
return 0;
}
level++;
}
return 1;
}
/*
* merge the relocated tree blocks in reloc tree with corresponding
* fs tree.
*/
static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
struct btrfs_root *root)
{
LIST_HEAD(inode_list);
struct btrfs_key key;
struct btrfs_key next_key;
struct btrfs_trans_handle *trans;
struct btrfs_root *reloc_root;
struct btrfs_root_item *root_item;
struct btrfs_path *path;
struct extent_buffer *leaf = NULL;
unsigned long nr;
int level;
int max_level;
int replaced = 0;
int ret;
int err = 0;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
reloc_root = root->reloc_root;
root_item = &reloc_root->root_item;
if (btrfs_disk_key_objectid(&root_item->drop_progress) == 0) {
level = btrfs_root_level(root_item);
extent_buffer_get(reloc_root->node);
path->nodes[level] = reloc_root->node;
path->slots[level] = 0;
} else {
btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
level = root_item->drop_level;
BUG_ON(level == 0);
path->lowest_level = level;
ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
if (ret < 0) {
btrfs_free_path(path);
return ret;
}
btrfs_node_key_to_cpu(path->nodes[level], &next_key,
path->slots[level]);
WARN_ON(memcmp(&key, &next_key, sizeof(key)));
btrfs_unlock_up_safe(path, 0);
}
if (level == 0 && rc->stage == UPDATE_DATA_PTRS) {
trans = btrfs_start_transaction(root, 1);
leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &key, 0);
btrfs_release_path(reloc_root, path);
ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
if (ret < 0) {
err = ret;
goto out;
}
leaf = path->nodes[0];
btrfs_unlock_up_safe(path, 1);
ret = replace_file_extents(trans, rc, root, leaf,
&inode_list);
if (ret < 0)
err = ret;
goto out;
}
memset(&next_key, 0, sizeof(next_key));
while (1) {
leaf = NULL;
replaced = 0;
trans = btrfs_start_transaction(root, 1);
max_level = level;
ret = walk_down_reloc_tree(reloc_root, path, &level);
if (ret < 0) {
err = ret;
goto out;
}
if (ret > 0)
break;
if (!find_next_key(path, level, &key) &&
btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
ret = 0;
} else if (level == 1 && rc->stage == UPDATE_DATA_PTRS) {
ret = replace_path(trans, root, reloc_root,
path, &next_key, &leaf,
level, max_level);
} else {
ret = replace_path(trans, root, reloc_root,
path, &next_key, NULL,
level, max_level);
}
if (ret < 0) {
err = ret;
goto out;
}
if (ret > 0) {
level = ret;
btrfs_node_key_to_cpu(path->nodes[level], &key,
path->slots[level]);
replaced = 1;
} else if (leaf) {
/*
* no block got replaced, try replacing file extents
*/
btrfs_item_key_to_cpu(leaf, &key, 0);
ret = replace_file_extents(trans, rc, root, leaf,
&inode_list);
btrfs_tree_unlock(leaf);
free_extent_buffer(leaf);
BUG_ON(ret < 0);
}
ret = walk_up_reloc_tree(reloc_root, path, &level);
if (ret > 0)
break;
BUG_ON(level == 0);
/*
* save the merging progress in the drop_progress.
* this is OK since root refs == 1 in this case.
*/
btrfs_node_key(path->nodes[level], &root_item->drop_progress,
path->slots[level]);
root_item->drop_level = level;
nr = trans->blocks_used;
btrfs_end_transaction(trans, root);
btrfs_btree_balance_dirty(root, nr);
if (replaced && rc->stage == UPDATE_DATA_PTRS)
invalidate_extent_cache(root, &key, &next_key);
}
/*
* handle the case only one block in the fs tree need to be
* relocated and the block is tree root.
*/
leaf = btrfs_lock_root_node(root);
ret = btrfs_cow_block(trans, root, leaf, NULL, 0, &leaf);
btrfs_tree_unlock(leaf);
free_extent_buffer(leaf);
if (ret < 0)
err = ret;
out:
btrfs_free_path(path);
if (err == 0) {
memset(&root_item->drop_progress, 0,
sizeof(root_item->drop_progress));
root_item->drop_level = 0;
btrfs_set_root_refs(root_item, 0);
}
nr = trans->blocks_used;
btrfs_end_transaction(trans, root);
btrfs_btree_balance_dirty(root, nr);
/*
* put inodes while we aren't holding the tree locks
*/
while (!list_empty(&inode_list)) {
struct inodevec *ivec;
ivec = list_entry(inode_list.next, struct inodevec, list);
list_del(&ivec->list);
while (ivec->nr > 0) {
ivec->nr--;
iput(ivec->inode[ivec->nr]);
}
kfree(ivec);
}
if (replaced && rc->stage == UPDATE_DATA_PTRS)
invalidate_extent_cache(root, &key, &next_key);
return err;
}
/*
* callback for the work threads.
* this function merges reloc tree with corresponding fs tree,
* and then drops the reloc tree.
*/
static void merge_func(struct btrfs_work *work)
{
struct btrfs_trans_handle *trans;
struct btrfs_root *root;
struct btrfs_root *reloc_root;
struct async_merge *async;
async = container_of(work, struct async_merge, work);
reloc_root = async->root;
if (btrfs_root_refs(&reloc_root->root_item) > 0) {
root = read_fs_root(reloc_root->fs_info,
reloc_root->root_key.offset);
BUG_ON(IS_ERR(root));
BUG_ON(root->reloc_root != reloc_root);
merge_reloc_root(async->rc, root);
trans = btrfs_start_transaction(root, 1);
btrfs_update_reloc_root(trans, root);
btrfs_end_transaction(trans, root);
}
btrfs_drop_snapshot(reloc_root, 0);
if (atomic_dec_and_test(async->num_pending))
complete(async->done);
kfree(async);
}
static int merge_reloc_roots(struct reloc_control *rc)
{
struct async_merge *async;
struct btrfs_root *root;
struct completion done;
atomic_t num_pending;
init_completion(&done);
atomic_set(&num_pending, 1);
while (!list_empty(&rc->reloc_roots)) {
root = list_entry(rc->reloc_roots.next,
struct btrfs_root, root_list);
list_del_init(&root->root_list);
async = kmalloc(sizeof(*async), GFP_NOFS);
BUG_ON(!async);
async->work.func = merge_func;
async->work.flags = 0;
async->rc = rc;
async->root = root;
async->done = &done;
async->num_pending = &num_pending;
atomic_inc(&num_pending);
btrfs_queue_worker(&rc->workers, &async->work);
}
if (!atomic_dec_and_test(&num_pending))
wait_for_completion(&done);
BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
return 0;
}
static void free_block_list(struct rb_root *blocks)
{
struct tree_block *block;
struct rb_node *rb_node;
while ((rb_node = rb_first(blocks))) {
block = rb_entry(rb_node, struct tree_block, rb_node);
rb_erase(rb_node, blocks);
kfree(block);
}
}
static int record_reloc_root_in_trans(struct btrfs_trans_handle *trans,
struct btrfs_root *reloc_root)
{
struct btrfs_root *root;
if (reloc_root->last_trans == trans->transid)
return 0;
root = read_fs_root(reloc_root->fs_info, reloc_root->root_key.offset);
BUG_ON(IS_ERR(root));
BUG_ON(root->reloc_root != reloc_root);
return btrfs_record_root_in_trans(trans, root);
}
/*
* select one tree from trees that references the block.
* for blocks in refernce counted trees, we preper reloc tree.
* if no reloc tree found and reloc_only is true, NULL is returned.
*/
static struct btrfs_root *__select_one_root(struct btrfs_trans_handle *trans,
struct backref_node *node,
struct backref_edge *edges[],
int *nr, int reloc_only)
{
struct backref_node *next;
struct btrfs_root *root;
int index;
int loop = 0;
again:
index = 0;
next = node;
while (1) {
cond_resched();
next = walk_up_backref(next, edges, &index);
root = next->root;
if (!root) {
BUG_ON(!node->old_root);
goto skip;
}
/* no other choice for non-refernce counted tree */
if (!root->ref_cows) {
BUG_ON(reloc_only);
break;
}
if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
record_reloc_root_in_trans(trans, root);
break;
}
if (loop) {
btrfs_record_root_in_trans(trans, root);
break;
}
if (reloc_only || next != node) {
if (!root->reloc_root)
btrfs_record_root_in_trans(trans, root);
root = root->reloc_root;
/*
* if the reloc tree was created in current
* transation, there is no node in backref tree
* corresponds to the root of the reloc tree.
*/
if (btrfs_root_last_snapshot(&root->root_item) ==
trans->transid - 1)
break;
}
skip:
root = NULL;
next = walk_down_backref(edges, &index);
if (!next || next->level <= node->level)
break;
}
if (!root && !loop && !reloc_only) {
loop = 1;
goto again;
}
if (root)
*nr = index;
else
*nr = 0;
return root;
}
static noinline_for_stack
struct btrfs_root *select_one_root(struct btrfs_trans_handle *trans,
struct backref_node *node)
{
struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
int nr;
return __select_one_root(trans, node, edges, &nr, 0);
}
static noinline_for_stack
struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
struct backref_node *node,
struct backref_edge *edges[], int *nr)
{
return __select_one_root(trans, node, edges, nr, 1);
}
static void grab_path_buffers(struct btrfs_path *path,
struct backref_node *node,
struct backref_edge *edges[], int nr)
{
int i = 0;
while (1) {
drop_node_buffer(node);
node->eb = path->nodes[node->level];
BUG_ON(!node->eb);
if (path->locks[node->level])
node->locked = 1;
path->nodes[node->level] = NULL;
path->locks[node->level] = 0;
if (i >= nr)
break;
edges[i]->blockptr = node->eb->start;
node = edges[i]->node[UPPER];
i++;
}
}
/*
* relocate a block tree, and then update pointers in upper level
* blocks that reference the block to point to the new location.
*
* if called by link_to_upper, the block has already been relocated.
* in that case this function just updates pointers.
*/
static int do_relocation(struct btrfs_trans_handle *trans,
struct backref_node *node,
struct btrfs_key *key,
struct btrfs_path *path, int lowest)
{
struct backref_node *upper;
struct backref_edge *edge;
struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
struct btrfs_root *root;
struct extent_buffer *eb;
u32 blocksize;
u64 bytenr;
u64 generation;
int nr;
int slot;
int ret;
int err = 0;
BUG_ON(lowest && node->eb);
path->lowest_level = node->level + 1;
list_for_each_entry(edge, &node->upper, list[LOWER]) {
cond_resched();
if (node->eb && node->eb->start == edge->blockptr)
continue;
upper = edge->node[UPPER];
root = select_reloc_root(trans, upper, edges, &nr);
if (!root)
continue;
if (upper->eb && !upper->locked)
drop_node_buffer(upper);
if (!upper->eb) {
ret = btrfs_search_slot(trans, root, key, path, 0, 1);
if (ret < 0) {
err = ret;
break;
}
BUG_ON(ret > 0);
slot = path->slots[upper->level];
btrfs_unlock_up_safe(path, upper->level + 1);
grab_path_buffers(path, upper, edges, nr);
btrfs_release_path(NULL, path);
} else {
ret = btrfs_bin_search(upper->eb, key, upper->level,
&slot);
BUG_ON(ret);
}
bytenr = btrfs_node_blockptr(upper->eb, slot);
if (!lowest) {
if (node->eb->start == bytenr) {
btrfs_tree_unlock(upper->eb);
upper->locked = 0;
continue;
}
} else {
BUG_ON(node->bytenr != bytenr);
}
blocksize = btrfs_level_size(root, node->level);
generation = btrfs_node_ptr_generation(upper->eb, slot);
eb = read_tree_block(root, bytenr, blocksize, generation);
btrfs_tree_lock(eb);
btrfs_set_lock_blocking(eb);
if (!node->eb) {
ret = btrfs_cow_block(trans, root, eb, upper->eb,
slot, &eb);
if (ret < 0) {
err = ret;
break;
}
btrfs_set_lock_blocking(eb);
node->eb = eb;
node->locked = 1;
} else {
btrfs_set_node_blockptr(upper->eb, slot,
node->eb->start);
btrfs_set_node_ptr_generation(upper->eb, slot,
trans->transid);
btrfs_mark_buffer_dirty(upper->eb);
ret = btrfs_inc_extent_ref(trans, root,
node->eb->start, blocksize,
upper->eb->start,
btrfs_header_owner(upper->eb),
node->level, 0);
BUG_ON(ret);
ret = btrfs_drop_subtree(trans, root, eb, upper->eb);
BUG_ON(ret);
}
if (!lowest) {
btrfs_tree_unlock(upper->eb);
upper->locked = 0;
}
}
path->lowest_level = 0;
return err;
}
static int link_to_upper(struct btrfs_trans_handle *trans,
struct backref_node *node,
struct btrfs_path *path)
{
struct btrfs_key key;
if (!node->eb || list_empty(&node->upper))
return 0;
btrfs_node_key_to_cpu(node->eb, &key, 0);
return do_relocation(trans, node, &key, path, 0);
}
static int finish_pending_nodes(struct btrfs_trans_handle *trans,
struct backref_cache *cache,
struct btrfs_path *path)
{
struct backref_node *node;
int level;
int ret;
int err = 0;
for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
while (!list_empty(&cache->pending[level])) {
node = list_entry(cache->pending[level].next,
struct backref_node, lower);
BUG_ON(node->level != level);
ret = link_to_upper(trans, node, path);
if (ret < 0)
err = ret;
/*
* this remove the node from the pending list and
* may add some other nodes to the level + 1
* pending list
*/
remove_backref_node(cache, node);
}
}
BUG_ON(!RB_EMPTY_ROOT(&cache->rb_root));
return err;
}
static void mark_block_processed(struct reloc_control *rc,
struct backref_node *node)
{
u32 blocksize;
if (node->level == 0 ||
in_block_group(node->bytenr, rc->block_group)) {
blocksize = btrfs_level_size(rc->extent_root, node->level);
set_extent_bits(&rc->processed_blocks, node->bytenr,
node->bytenr + blocksize - 1, EXTENT_DIRTY,
GFP_NOFS);
}
node->processed = 1;
}
/*
* mark a block and all blocks directly/indirectly reference the block
* as processed.
*/
static void update_processed_blocks(struct reloc_control *rc,
struct backref_node *node)
{
struct backref_node *next = node;
struct backref_edge *edge;
struct backref_edge *edges[BTRFS_MAX_LEVEL - 1];
int index = 0;
while (next) {
cond_resched();
while (1) {
if (next->processed)
break;
mark_block_processed(rc, next);
if (list_empty(&next->upper))
break;
edge = list_entry(next->upper.next,
struct backref_edge, list[LOWER]);
edges[index++] = edge;
next = edge->node[UPPER];
}
next = walk_down_backref(edges, &index);
}
}
static int tree_block_processed(u64 bytenr, u32 blocksize,
struct reloc_control *rc)
{
if (test_range_bit(&rc->processed_blocks, bytenr,
bytenr + blocksize - 1, EXTENT_DIRTY, 1))
return 1;
return 0;
}
/*
* check if there are any file extent pointers in the leaf point to
* data require processing
*/
static int check_file_extents(struct reloc_control *rc,
u64 bytenr, u32 blocksize, u64 ptr_gen)
{
struct btrfs_key found_key;
struct btrfs_file_extent_item *fi;
struct extent_buffer *leaf;
u32 nritems;
int i;
int ret = 0;
leaf = read_tree_block(rc->extent_root, bytenr, blocksize, ptr_gen);
nritems = btrfs_header_nritems(leaf);
for (i = 0; i < nritems; i++) {
cond_resched();
btrfs_item_key_to_cpu(leaf, &found_key, i);
if (found_key.type != BTRFS_EXTENT_DATA_KEY)
continue;
fi = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
if (btrfs_file_extent_type(leaf, fi) ==
BTRFS_FILE_EXTENT_INLINE)
continue;
bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
if (bytenr == 0)
continue;
if (in_block_group(bytenr, rc->block_group)) {
ret = 1;
break;
}
}
free_extent_buffer(leaf);
return ret;
}
/*
* scan child blocks of a given block to find blocks require processing
*/
static int add_child_blocks(struct btrfs_trans_handle *trans,
struct reloc_control *rc,
struct backref_node *node,
struct rb_root *blocks)
{
struct tree_block *block;
struct rb_node *rb_node;
u64 bytenr;
u64 ptr_gen;
u32 blocksize;
u32 nritems;
int i;
int err = 0;
nritems = btrfs_header_nritems(node->eb);
blocksize = btrfs_level_size(rc->extent_root, node->level - 1);
for (i = 0; i < nritems; i++) {
cond_resched();
bytenr = btrfs_node_blockptr(node->eb, i);
ptr_gen = btrfs_node_ptr_generation(node->eb, i);
if (ptr_gen == trans->transid)
continue;
if (!in_block_group(bytenr, rc->block_group) &&
(node->level > 1 || rc->stage == MOVE_DATA_EXTENTS))
continue;
if (tree_block_processed(bytenr, blocksize, rc))
continue;
readahead_tree_block(rc->extent_root,
bytenr, blocksize, ptr_gen);
}
for (i = 0; i < nritems; i++) {
cond_resched();
bytenr = btrfs_node_blockptr(node->eb, i);
ptr_gen = btrfs_node_ptr_generation(node->eb, i);
if (ptr_gen == trans->transid)
continue;
if (!in_block_group(bytenr, rc->block_group) &&
(node->level > 1 || rc->stage == MOVE_DATA_EXTENTS))
continue;
if (tree_block_processed(bytenr, blocksize, rc))
continue;
if (!in_block_group(bytenr, rc->block_group) &&
!check_file_extents(rc, bytenr, blocksize, ptr_gen))
continue;
block = kmalloc(sizeof(*block), GFP_NOFS);
if (!block) {
err = -ENOMEM;
break;
}
block->bytenr = bytenr;
btrfs_node_key_to_cpu(node->eb, &block->key, i);
block->level = node->level - 1;
block->key_ready = 1;
rb_node = tree_insert(blocks, block->bytenr, &block->rb_node);
BUG_ON(rb_node);
}
if (err)
free_block_list(blocks);
return err;
}
/*
* find adjacent blocks require processing
*/
static noinline_for_stack
int add_adjacent_blocks(struct btrfs_trans_handle *trans,
struct reloc_control *rc,
struct backref_cache *cache,
struct rb_root *blocks, int level,
struct backref_node **upper)
{
struct backref_node *node;
int ret = 0;
WARN_ON(!list_empty(&cache->pending[level]));
if (list_empty(&cache->pending[level + 1]))
return 1;
node = list_entry(cache->pending[level + 1].next,
struct backref_node, lower);
if (node->eb)
ret = add_child_blocks(trans, rc, node, blocks);
*upper = node;
return ret;
}
static int get_tree_block_key(struct reloc_control *rc,
struct tree_block *block)
{
struct extent_buffer *eb;
BUG_ON(block->key_ready);
eb = read_tree_block(rc->extent_root, block->bytenr,
block->key.objectid, block->key.offset);
WARN_ON(btrfs_header_level(eb) != block->level);
if (block->level == 0)
btrfs_item_key_to_cpu(eb, &block->key, 0);
else
btrfs_node_key_to_cpu(eb, &block->key, 0);
free_extent_buffer(eb);
block->key_ready = 1;
return 0;
}
static int reada_tree_block(struct reloc_control *rc,
struct tree_block *block)
{
BUG_ON(block->key_ready);
readahead_tree_block(rc->extent_root, block->bytenr,
block->key.objectid, block->key.offset);
return 0;
}
/*
* helper function to relocate a tree block
*/
static int relocate_tree_block(struct btrfs_trans_handle *trans,
struct reloc_control *rc,
struct backref_node *node,
struct btrfs_key *key,
struct btrfs_path *path)
{
struct btrfs_root *root;
int ret;
root = select_one_root(trans, node);
if (unlikely(!root)) {
rc->found_old_snapshot = 1;
update_processed_blocks(rc, node);
return 0;
}
if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
ret = do_relocation(trans, node, key, path, 1);
if (ret < 0)
goto out;
if (node->level == 0 && rc->stage == UPDATE_DATA_PTRS) {
ret = replace_file_extents(trans, rc, root,
node->eb, NULL);
if (ret < 0)
goto out;
}
drop_node_buffer(node);
} else if (!root->ref_cows) {
path->lowest_level = node->level;
ret = btrfs_search_slot(trans, root, key, path, 0, 1);
btrfs_release_path(root, path);
if (ret < 0)
goto out;
} else if (root != node->root) {
WARN_ON(node->level > 0 || rc->stage != UPDATE_DATA_PTRS);
}
update_processed_blocks(rc, node);
ret = 0;
out:
drop_node_buffer(node);
return ret;
}
/*
* relocate a list of blocks
*/
static noinline_for_stack
int relocate_tree_blocks(struct btrfs_trans_handle *trans,
struct reloc_control *rc, struct rb_root *blocks)
{
struct backref_cache *cache;
struct backref_node *node;
struct btrfs_path *path;
struct tree_block *block;
struct rb_node *rb_node;
int level = -1;
int ret;
int err = 0;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
cache = kmalloc(sizeof(*cache), GFP_NOFS);
if (!cache) {
btrfs_free_path(path);
return -ENOMEM;
}
backref_cache_init(cache);
rb_node = rb_first(blocks);
while (rb_node) {
block = rb_entry(rb_node, struct tree_block, rb_node);
if (level == -1)
level = block->level;
else
BUG_ON(level != block->level);
if (!block->key_ready)
reada_tree_block(rc, block);
rb_node = rb_next(rb_node);
}
rb_node = rb_first(blocks);
while (rb_node) {
block = rb_entry(rb_node, struct tree_block, rb_node);
if (!block->key_ready)
get_tree_block_key(rc, block);
rb_node = rb_next(rb_node);
}
rb_node = rb_first(blocks);
while (rb_node) {
block = rb_entry(rb_node, struct tree_block, rb_node);
node = build_backref_tree(rc, cache, &block->key,
block->level, block->bytenr);
if (IS_ERR(node)) {
err = PTR_ERR(node);
goto out;
}
ret = relocate_tree_block(trans, rc, node, &block->key,
path);
if (ret < 0) {
err = ret;
goto out;
}
remove_backref_node(cache, node);
rb_node = rb_next(rb_node);
}
if (level > 0)
goto out;
free_block_list(blocks);
/*
* now backrefs of some upper level tree blocks have been cached,
* try relocating blocks referenced by these upper level blocks.
*/
while (1) {
struct backref_node *upper = NULL;
if (trans->transaction->in_commit ||
trans->transaction->delayed_refs.flushing)
break;
ret = add_adjacent_blocks(trans, rc, cache, blocks, level,
&upper);
if (ret < 0)
err = ret;
if (ret != 0)
break;
rb_node = rb_first(blocks);
while (rb_node) {
block = rb_entry(rb_node, struct tree_block, rb_node);
if (trans->transaction->in_commit ||
trans->transaction->delayed_refs.flushing)
goto out;
BUG_ON(!block->key_ready);
node = build_backref_tree(rc, cache, &block->key,
level, block->bytenr);
if (IS_ERR(node)) {
err = PTR_ERR(node);
goto out;
}
ret = relocate_tree_block(trans, rc, node,
&block->key, path);
if (ret < 0) {
err = ret;
goto out;
}
remove_backref_node(cache, node);
rb_node = rb_next(rb_node);
}
free_block_list(blocks);
if (upper) {
ret = link_to_upper(trans, upper, path);
if (ret < 0) {
err = ret;
break;
}
remove_backref_node(cache, upper);
}
}
out:
free_block_list(blocks);
ret = finish_pending_nodes(trans, cache, path);
if (ret < 0)
err = ret;
kfree(cache);
btrfs_free_path(path);
return err;
}
static noinline_for_stack
int relocate_inode_pages(struct inode *inode, u64 start, u64 len)
{
u64 page_start;
u64 page_end;
unsigned long i;
unsigned long first_index;
unsigned long last_index;
unsigned int total_read = 0;
unsigned int total_dirty = 0;
struct page *page;
struct file_ra_state *ra;
struct btrfs_ordered_extent *ordered;
struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
int ret = 0;
ra = kzalloc(sizeof(*ra), GFP_NOFS);
if (!ra)
return -ENOMEM;
mutex_lock(&inode->i_mutex);
first_index = start >> PAGE_CACHE_SHIFT;
last_index = (start + len - 1) >> PAGE_CACHE_SHIFT;
/* make sure the dirty trick played by the caller work */
ret = invalidate_inode_pages2_range(inode->i_mapping,
first_index, last_index);
if (ret)
goto out_unlock;
file_ra_state_init(ra, inode->i_mapping);
for (i = first_index ; i <= last_index; i++) {
if (total_read % ra->ra_pages == 0) {
btrfs_force_ra(inode->i_mapping, ra, NULL, i,
min(last_index, ra->ra_pages + i - 1));
}
total_read++;
again:
if (((u64)i << PAGE_CACHE_SHIFT) > i_size_read(inode))
BUG_ON(1);
page = grab_cache_page(inode->i_mapping, i);
if (!page) {
ret = -ENOMEM;
goto out_unlock;
}
if (!PageUptodate(page)) {
btrfs_readpage(NULL, page);
lock_page(page);
if (!PageUptodate(page)) {
unlock_page(page);
page_cache_release(page);
ret = -EIO;
goto out_unlock;
}
}
wait_on_page_writeback(page);
page_start = (u64)page->index << PAGE_CACHE_SHIFT;
page_end = page_start + PAGE_CACHE_SIZE - 1;
lock_extent(io_tree, page_start, page_end, GFP_NOFS);
ordered = btrfs_lookup_ordered_extent(inode, page_start);
if (ordered) {
unlock_extent(io_tree, page_start, page_end, GFP_NOFS);
unlock_page(page);
page_cache_release(page);
btrfs_start_ordered_extent(inode, ordered, 1);
btrfs_put_ordered_extent(ordered);
goto again;
}
set_page_extent_mapped(page);
if (i == first_index)
set_extent_bits(io_tree, page_start, page_end,
EXTENT_BOUNDARY, GFP_NOFS);
btrfs_set_extent_delalloc(inode, page_start, page_end);
set_page_dirty(page);
total_dirty++;
unlock_extent(io_tree, page_start, page_end, GFP_NOFS);
unlock_page(page);
page_cache_release(page);
}
out_unlock:
mutex_unlock(&inode->i_mutex);
kfree(ra);
balance_dirty_pages_ratelimited_nr(inode->i_mapping, total_dirty);
return ret;
}
static noinline_for_stack
int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key)
{
struct btrfs_root *root = BTRFS_I(inode)->root;
struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
struct extent_map *em;
u64 start = extent_key->objectid - BTRFS_I(inode)->index_cnt;
u64 end = start + extent_key->offset - 1;
em = alloc_extent_map(GFP_NOFS);
em->start = start;
em->len = extent_key->offset;
em->block_len = extent_key->offset;
em->block_start = extent_key->objectid;
em->bdev = root->fs_info->fs_devices->latest_bdev;
set_bit(EXTENT_FLAG_PINNED, &em->flags);
/* setup extent map to cheat btrfs_readpage */
lock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
while (1) {
int ret;
spin_lock(&em_tree->lock);
ret = add_extent_mapping(em_tree, em);
spin_unlock(&em_tree->lock);
if (ret != -EEXIST) {
free_extent_map(em);
break;
}
btrfs_drop_extent_cache(inode, start, end, 0);
}
unlock_extent(&BTRFS_I(inode)->io_tree, start, end, GFP_NOFS);
return relocate_inode_pages(inode, start, extent_key->offset);
}
#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
static int get_ref_objectid_v0(struct reloc_control *rc,
struct btrfs_path *path,
struct btrfs_key *extent_key,
u64 *ref_objectid, int *path_change)
{
struct btrfs_key key;
struct extent_buffer *leaf;
struct btrfs_extent_ref_v0 *ref0;
int ret;
int slot;
leaf = path->nodes[0];
slot = path->slots[0];
while (1) {
if (slot >= btrfs_header_nritems(leaf)) {
ret = btrfs_next_leaf(rc->extent_root, path);
if (ret < 0)
return ret;
BUG_ON(ret > 0);
leaf = path->nodes[0];
slot = path->slots[0];
if (path_change)
*path_change = 1;
}
btrfs_item_key_to_cpu(leaf, &key, slot);
if (key.objectid != extent_key->objectid)
return -ENOENT;
if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
slot++;
continue;
}
ref0 = btrfs_item_ptr(leaf, slot,
struct btrfs_extent_ref_v0);
*ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
break;
}
return 0;
}
#endif
/*
* helper to add a tree block to the list.
* the major work is getting the generation and level of the block
*/
static int add_tree_block(struct reloc_control *rc,
struct btrfs_key *extent_key,
struct btrfs_path *path,
struct rb_root *blocks)
{
struct extent_buffer *eb;
struct btrfs_extent_item *ei;
struct btrfs_tree_block_info *bi;
struct tree_block *block;
struct rb_node *rb_node;
u32 item_size;
int level = -1;
int generation;
eb = path->nodes[0];
item_size = btrfs_item_size_nr(eb, path->slots[0]);
if (item_size >= sizeof(*ei) + sizeof(*bi)) {
ei = btrfs_item_ptr(eb, path->slots[0],
struct btrfs_extent_item);
bi = (struct btrfs_tree_block_info *)(ei + 1);
generation = btrfs_extent_generation(eb, ei);
level = btrfs_tree_block_level(eb, bi);
} else {
#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
u64 ref_owner;