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linux/fs/btrfs/relocation.c
Josef Bacik fb686c6824 btrfs: check return value of btrfs_commit_transaction in relocation 
There are a few places where we don't check the return value of
btrfs_commit_transaction in relocation.c.  Thankfully all these places
have straightforward error handling, so simply change all of the sites
at once.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2021-04-19 17:25:22 +02:00

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2009 Oracle. All rights reserved.
*/
#include <linux/sched.h>
#include <linux/pagemap.h>
#include <linux/writeback.h>
#include <linux/blkdev.h>
#include <linux/rbtree.h>
#include <linux/slab.h>
#include <linux/error-injection.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"
#include "free-space-cache.h"
#include "qgroup.h"
#include "print-tree.h"
#include "delalloc-space.h"
#include "block-group.h"
#include "backref.h"
#include "misc.h"
/*
* Relocation overview
*
* [What does relocation do]
*
* The objective of relocation is to relocate all extents of the target block
* group to other block groups.
* This is utilized by resize (shrink only), profile converting, compacting
* space, or balance routine to spread chunks over devices.
*
* Before | After
* ------------------------------------------------------------------
* BG A: 10 data extents | BG A: deleted
* BG B: 2 data extents | BG B: 10 data extents (2 old + 8 relocated)
* BG C: 1 extents | BG C: 3 data extents (1 old + 2 relocated)
*
* [How does relocation work]
*
* 1. Mark the target block group read-only
* New extents won't be allocated from the target block group.
*
* 2.1 Record each extent in the target block group
* To build a proper map of extents to be relocated.
*
* 2.2 Build data reloc tree and reloc trees
* Data reloc tree will contain an inode, recording all newly relocated
* data extents.
* There will be only one data reloc tree for one data block group.
*
* Reloc tree will be a special snapshot of its source tree, containing
* relocated tree blocks.
* Each tree referring to a tree block in target block group will get its
* reloc tree built.
*
* 2.3 Swap source tree with its corresponding reloc tree
* Each involved tree only refers to new extents after swap.
*
* 3. Cleanup reloc trees and data reloc tree.
* As old extents in the target block group are still referenced by reloc
* trees, we need to clean them up before really freeing the target block
* group.
*
* The main complexity is in steps 2.2 and 2.3.
*
* The entry point of relocation is relocate_block_group() function.
*/
#define RELOCATION_RESERVED_NODES 256
/*
* map address of tree root to tree
*/
struct mapping_node {
struct {
struct rb_node rb_node;
u64 bytenr;
}; /* Use rb_simle_node for search/insert */
void *data;
};
struct mapping_tree {
struct rb_root rb_root;
spinlock_t lock;
};
/*
* present a tree block to process
*/
struct tree_block {
struct {
struct rb_node rb_node;
u64 bytenr;
}; /* Use rb_simple_node for search/insert */
u64 owner;
struct btrfs_key key;
unsigned int level:8;
unsigned int key_ready:1;
};
#define MAX_EXTENTS 128
struct file_extent_cluster {
u64 start;
u64 end;
u64 boundary[MAX_EXTENTS];
unsigned int nr;
};
struct reloc_control {
/* block group to relocate */
struct btrfs_block_group *block_group;
/* extent tree */
struct btrfs_root *extent_root;
/* inode for moving data */
struct inode *data_inode;
struct btrfs_block_rsv *block_rsv;
struct btrfs_backref_cache backref_cache;
struct file_extent_cluster cluster;
/* 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;
/* list of subvolume trees that get relocated */
struct list_head dirty_subvol_roots;
/* size of metadata reservation for merging reloc trees */
u64 merging_rsv_size;
/* size of relocated tree nodes */
u64 nodes_relocated;
/* reserved size for block group relocation*/
u64 reserved_bytes;
u64 search_start;
u64 extents_found;
unsigned int stage:8;
unsigned int create_reloc_tree:1;
unsigned int merge_reloc_tree:1;
unsigned int found_file_extent:1;
};
/* stages of data relocation */
#define MOVE_DATA_EXTENTS 0
#define UPDATE_DATA_PTRS 1
static void mark_block_processed(struct reloc_control *rc,
struct btrfs_backref_node *node)
{
u32 blocksize;
if (node->level == 0 ||
in_range(node->bytenr, rc->block_group->start,
rc->block_group->length)) {
blocksize = rc->extent_root->fs_info->nodesize;
set_extent_bits(&rc->processed_blocks, node->bytenr,
node->bytenr + blocksize - 1, EXTENT_DIRTY);
}
node->processed = 1;
}
static void mapping_tree_init(struct mapping_tree *tree)
{
tree->rb_root = RB_ROOT;
spin_lock_init(&tree->lock);
}
/*
* walk up backref nodes until reach node presents tree root
*/
static struct btrfs_backref_node *walk_up_backref(
struct btrfs_backref_node *node,
struct btrfs_backref_edge *edges[], int *index)
{
struct btrfs_backref_edge *edge;
int idx = *index;
while (!list_empty(&node->upper)) {
edge = list_entry(node->upper.next,
struct btrfs_backref_edge, list[LOWER]);
edges[idx++] = edge;
node = edge->node[UPPER];
}
BUG_ON(node->detached);
*index = idx;
return node;
}
/*
* walk down backref nodes to find start of next reference path
*/
static struct btrfs_backref_node *walk_down_backref(
struct btrfs_backref_edge *edges[], int *index)
{
struct btrfs_backref_edge *edge;
struct btrfs_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 btrfs_backref_edge, list[LOWER]);
edges[idx - 1] = edge;
*index = idx;
return edge->node[UPPER];
}
*index = 0;
return NULL;
}
static void update_backref_node(struct btrfs_backref_cache *cache,
struct btrfs_backref_node *node, u64 bytenr)
{
struct rb_node *rb_node;
rb_erase(&node->rb_node, &cache->rb_root);
node->bytenr = bytenr;
rb_node = rb_simple_insert(&cache->rb_root, node->bytenr, &node->rb_node);
if (rb_node)
btrfs_backref_panic(cache->fs_info, bytenr, -EEXIST);
}
/*
* update backref cache after a transaction commit
*/
static int update_backref_cache(struct btrfs_trans_handle *trans,
struct btrfs_backref_cache *cache)
{
struct btrfs_backref_node *node;
int level = 0;
if (cache->last_trans == 0) {
cache->last_trans = trans->transid;
return 0;
}
if (cache->last_trans == trans->transid)
return 0;
/*
* detached nodes are used to avoid unnecessary backref
* lookup. transaction commit changes the extent tree.
* so the detached nodes are no longer useful.
*/
while (!list_empty(&cache->detached)) {
node = list_entry(cache->detached.next,
struct btrfs_backref_node, list);
btrfs_backref_cleanup_node(cache, node);
}
while (!list_empty(&cache->changed)) {
node = list_entry(cache->changed.next,
struct btrfs_backref_node, list);
list_del_init(&node->list);
BUG_ON(node->pending);
update_backref_node(cache, node, node->new_bytenr);
}
/*
* some nodes can be left in the pending list if there were
* errors during processing the pending nodes.
*/
for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
list_for_each_entry(node, &cache->pending[level], list) {
BUG_ON(!node->pending);
if (node->bytenr == node->new_bytenr)
continue;
update_backref_node(cache, node, node->new_bytenr);
}
}
cache->last_trans = 0;
return 1;
}
static bool reloc_root_is_dead(struct btrfs_root *root)
{
/*
* Pair with set_bit/clear_bit in clean_dirty_subvols and
* btrfs_update_reloc_root. We need to see the updated bit before
* trying to access reloc_root
*/
smp_rmb();
if (test_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state))
return true;
return false;
}
/*
* Check if this subvolume tree has valid reloc tree.
*
* Reloc tree after swap is considered dead, thus not considered as valid.
* This is enough for most callers, as they don't distinguish dead reloc root
* from no reloc root. But btrfs_should_ignore_reloc_root() below is a
* special case.
*/
static bool have_reloc_root(struct btrfs_root *root)
{
if (reloc_root_is_dead(root))
return false;
if (!root->reloc_root)
return false;
return true;
}
int btrfs_should_ignore_reloc_root(struct btrfs_root *root)
{
struct btrfs_root *reloc_root;
if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
return 0;
/* This root has been merged with its reloc tree, we can ignore it */
if (reloc_root_is_dead(root))
return 1;
reloc_root = root->reloc_root;
if (!reloc_root)
return 0;
if (btrfs_header_generation(reloc_root->commit_root) ==
root->fs_info->running_transaction->transid)
return 0;
/*
* if there is reloc tree and it was created in previous
* transaction backref lookup can find the reloc tree,
* so backref node for the fs tree root is useless for
* relocation.
*/
return 1;
}
/*
* find reloc tree by address of tree root
*/
struct btrfs_root *find_reloc_root(struct btrfs_fs_info *fs_info, u64 bytenr)
{
struct reloc_control *rc = fs_info->reloc_ctl;
struct rb_node *rb_node;
struct mapping_node *node;
struct btrfs_root *root = NULL;
ASSERT(rc);
spin_lock(&rc->reloc_root_tree.lock);
rb_node = rb_simple_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 btrfs_grab_root(root);
}
/*
* For useless nodes, do two major clean ups:
*
* - Cleanup the children edges and nodes
* If child node is also orphan (no parent) during cleanup, then the child
* node will also be cleaned up.
*
* - Freeing up leaves (level 0), keeps nodes detached
* For nodes, the node is still cached as "detached"
*
* Return false if @node is not in the @useless_nodes list.
* Return true if @node is in the @useless_nodes list.
*/
static bool handle_useless_nodes(struct reloc_control *rc,
struct btrfs_backref_node *node)
{
struct btrfs_backref_cache *cache = &rc->backref_cache;
struct list_head *useless_node = &cache->useless_node;
bool ret = false;
while (!list_empty(useless_node)) {
struct btrfs_backref_node *cur;
cur = list_first_entry(useless_node, struct btrfs_backref_node,
list);
list_del_init(&cur->list);
/* Only tree root nodes can be added to @useless_nodes */
ASSERT(list_empty(&cur->upper));
if (cur == node)
ret = true;
/* The node is the lowest node */
if (cur->lowest) {
list_del_init(&cur->lower);
cur->lowest = 0;
}
/* Cleanup the lower edges */
while (!list_empty(&cur->lower)) {
struct btrfs_backref_edge *edge;
struct btrfs_backref_node *lower;
edge = list_entry(cur->lower.next,
struct btrfs_backref_edge, list[UPPER]);
list_del(&edge->list[UPPER]);
list_del(&edge->list[LOWER]);
lower = edge->node[LOWER];
btrfs_backref_free_edge(cache, edge);
/* Child node is also orphan, queue for cleanup */
if (list_empty(&lower->upper))
list_add(&lower->list, useless_node);
}
/* Mark this block processed for relocation */
mark_block_processed(rc, cur);
/*
* Backref nodes for tree leaves are deleted from the cache.
* Backref nodes for upper level tree blocks are left in the
* cache to avoid unnecessary backref lookup.
*/
if (cur->level > 0) {
list_add(&cur->list, &cache->detached);
cur->detached = 1;
} else {
rb_erase(&cur->rb_node, &cache->rb_root);
btrfs_backref_free_node(cache, cur);
}
}
return ret;
}
/*
* 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 reference the block, and then check backrefs of
* these upper level blocks recursively. The recursion stops when tree root is
* reached or backrefs for the block is cached.
*
* NOTE: if we find that backrefs for a block are cached, we know backrefs for
* all upper level blocks that directly/indirectly reference the block are also
* cached.
*/
static noinline_for_stack struct btrfs_backref_node *build_backref_tree(
struct reloc_control *rc, struct btrfs_key *node_key,
int level, u64 bytenr)
{
struct btrfs_backref_iter *iter;
struct btrfs_backref_cache *cache = &rc->backref_cache;
/* For searching parent of TREE_BLOCK_REF */
struct btrfs_path *path;
struct btrfs_backref_node *cur;
struct btrfs_backref_node *node = NULL;
struct btrfs_backref_edge *edge;
int ret;
int err = 0;
iter = btrfs_backref_iter_alloc(rc->extent_root->fs_info, GFP_NOFS);
if (!iter)
return ERR_PTR(-ENOMEM);
path = btrfs_alloc_path();
if (!path) {
err = -ENOMEM;
goto out;
}
node = btrfs_backref_alloc_node(cache, bytenr, level);
if (!node) {
err = -ENOMEM;
goto out;
}
node->lowest = 1;
cur = node;
/* Breadth-first search to build backref cache */
do {
ret = btrfs_backref_add_tree_node(cache, path, iter, node_key,
cur);
if (ret < 0) {
err = ret;
goto out;
}
edge = list_first_entry_or_null(&cache->pending_edge,
struct btrfs_backref_edge, list[UPPER]);
/*
* The pending list isn't empty, take the first block to
* process
*/
if (edge) {
list_del_init(&edge->list[UPPER]);
cur = edge->node[UPPER];
}
} while (edge);
/* Finish the upper linkage of newly added edges/nodes */
ret = btrfs_backref_finish_upper_links(cache, node);
if (ret < 0) {
err = ret;
goto out;
}
if (handle_useless_nodes(rc, node))
node = NULL;
out:
btrfs_backref_iter_free(iter);
btrfs_free_path(path);
if (err) {
btrfs_backref_error_cleanup(cache, node);
return ERR_PTR(err);
}
ASSERT(!node || !node->detached);
ASSERT(list_empty(&cache->useless_node) &&
list_empty(&cache->pending_edge));
return node;
}
/*
* helper to add backref node for the newly created snapshot.
* the backref node is created by cloning backref node that
* corresponds to root of source tree
*/
static int clone_backref_node(struct btrfs_trans_handle *trans,
struct reloc_control *rc,
struct btrfs_root *src,
struct btrfs_root *dest)
{
struct btrfs_root *reloc_root = src->reloc_root;
struct btrfs_backref_cache *cache = &rc->backref_cache;
struct btrfs_backref_node *node = NULL;
struct btrfs_backref_node *new_node;
struct btrfs_backref_edge *edge;
struct btrfs_backref_edge *new_edge;
struct rb_node *rb_node;
if (cache->last_trans > 0)
update_backref_cache(trans, cache);
rb_node = rb_simple_search(&cache->rb_root, src->commit_root->start);
if (rb_node) {
node = rb_entry(rb_node, struct btrfs_backref_node, rb_node);
if (node->detached)
node = NULL;
else
BUG_ON(node->new_bytenr != reloc_root->node->start);
}
if (!node) {
rb_node = rb_simple_search(&cache->rb_root,
reloc_root->commit_root->start);
if (rb_node) {
node = rb_entry(rb_node, struct btrfs_backref_node,
rb_node);
BUG_ON(node->detached);
}
}
if (!node)
return 0;
new_node = btrfs_backref_alloc_node(cache, dest->node->start,
node->level);
if (!new_node)
return -ENOMEM;
new_node->lowest = node->lowest;
new_node->checked = 1;
new_node->root = btrfs_grab_root(dest);
ASSERT(new_node->root);
if (!node->lowest) {
list_for_each_entry(edge, &node->lower, list[UPPER]) {
new_edge = btrfs_backref_alloc_edge(cache);
if (!new_edge)
goto fail;
btrfs_backref_link_edge(new_edge, edge->node[LOWER],
new_node, LINK_UPPER);
}
} else {
list_add_tail(&new_node->lower, &cache->leaves);
}
rb_node = rb_simple_insert(&cache->rb_root, new_node->bytenr,
&new_node->rb_node);
if (rb_node)
btrfs_backref_panic(trans->fs_info, new_node->bytenr, -EEXIST);
if (!new_node->lowest) {
list_for_each_entry(new_edge, &new_node->lower, list[UPPER]) {
list_add_tail(&new_edge->list[LOWER],
&new_edge->node[LOWER]->upper);
}
}
return 0;
fail:
while (!list_empty(&new_node->lower)) {
new_edge = list_entry(new_node->lower.next,
struct btrfs_backref_edge, list[UPPER]);
list_del(&new_edge->list[UPPER]);
btrfs_backref_free_edge(cache, new_edge);
}
btrfs_backref_free_node(cache, new_node);
return -ENOMEM;
}
/*
* helper to add 'address of tree root -> reloc tree' mapping
*/
static int __must_check __add_reloc_root(struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct rb_node *rb_node;
struct mapping_node *node;
struct reloc_control *rc = fs_info->reloc_ctl;
node = kmalloc(sizeof(*node), GFP_NOFS);
if (!node)
return -ENOMEM;
node->bytenr = root->commit_root->start;
node->data = root;
spin_lock(&rc->reloc_root_tree.lock);
rb_node = rb_simple_insert(&rc->reloc_root_tree.rb_root,
node->bytenr, &node->rb_node);
spin_unlock(&rc->reloc_root_tree.lock);
if (rb_node) {
btrfs_err(fs_info,
"Duplicate root found for start=%llu while inserting into relocation tree",
node->bytenr);
return -EEXIST;
}
list_add_tail(&root->root_list, &rc->reloc_roots);
return 0;
}
/*
* helper to delete the 'address of tree root -> reloc tree'
* mapping
*/
static void __del_reloc_root(struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct rb_node *rb_node;
struct mapping_node *node = NULL;
struct reloc_control *rc = fs_info->reloc_ctl;
bool put_ref = false;
if (rc && root->node) {
spin_lock(&rc->reloc_root_tree.lock);
rb_node = rb_simple_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);
RB_CLEAR_NODE(&node->rb_node);
}
spin_unlock(&rc->reloc_root_tree.lock);
ASSERT(!node || (struct btrfs_root *)node->data == root);
}
/*
* We only put the reloc root here if it's on the list. There's a lot
* of places where the pattern is to splice the rc->reloc_roots, process
* the reloc roots, and then add the reloc root back onto
* rc->reloc_roots. If we call __del_reloc_root while it's off of the
* list we don't want the reference being dropped, because the guy
* messing with the list is in charge of the reference.
*/
spin_lock(&fs_info->trans_lock);
if (!list_empty(&root->root_list)) {
put_ref = true;
list_del_init(&root->root_list);
}
spin_unlock(&fs_info->trans_lock);
if (put_ref)
btrfs_put_root(root);
kfree(node);
}
/*
* helper to update the 'address of tree root -> reloc tree'
* mapping
*/
static int __update_reloc_root(struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct rb_node *rb_node;
struct mapping_node *node = NULL;
struct reloc_control *rc = fs_info->reloc_ctl;
spin_lock(&rc->reloc_root_tree.lock);
rb_node = rb_simple_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);
if (!node)
return 0;
BUG_ON((struct btrfs_root *)node->data != root);
spin_lock(&rc->reloc_root_tree.lock);
node->bytenr = root->node->start;
rb_node = rb_simple_insert(&rc->reloc_root_tree.rb_root,
node->bytenr, &node->rb_node);
spin_unlock(&rc->reloc_root_tree.lock);
if (rb_node)
btrfs_backref_panic(fs_info, node->bytenr, -EEXIST);
return 0;
}
static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
struct btrfs_root *root, u64 objectid)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_root *reloc_root;
struct extent_buffer *eb;
struct btrfs_root_item *root_item;
struct btrfs_key root_key;
int ret = 0;
bool must_abort = false;
root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
if (!root_item)
return ERR_PTR(-ENOMEM);
root_key.objectid = BTRFS_TREE_RELOC_OBJECTID;
root_key.type = BTRFS_ROOT_ITEM_KEY;
root_key.offset = objectid;
if (root->root_key.objectid == objectid) {
u64 commit_root_gen;
/* called by btrfs_init_reloc_root */
ret = btrfs_copy_root(trans, root, root->commit_root, &eb,
BTRFS_TREE_RELOC_OBJECTID);
if (ret)
goto fail;
/*
* Set the last_snapshot field to the generation of the commit
* root - like this ctree.c:btrfs_block_can_be_shared() behaves
* correctly (returns true) when the relocation root is created
* either inside the critical section of a transaction commit
* (through transaction.c:qgroup_account_snapshot()) and when
* it's created before the transaction commit is started.
*/
commit_root_gen = btrfs_header_generation(root->commit_root);
btrfs_set_root_last_snapshot(&root->root_item, commit_root_gen);
} else {
/*
* called by btrfs_reloc_post_snapshot_hook.
* the source tree is a reloc tree, all tree blocks
* modified after it was created have RELOC flag
* set in their headers. so it's OK to not update
* the 'last_snapshot'.
*/
ret = btrfs_copy_root(trans, root, root->node, &eb,
BTRFS_TREE_RELOC_OBJECTID);
if (ret)
goto fail;
}
/*
* We have changed references at this point, we must abort the
* transaction if anything fails.
*/
must_abort = true;
memcpy(root_item, &root->root_item, sizeof(*root_item));
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);
if (root->root_key.objectid == objectid) {
btrfs_set_root_refs(root_item, 0);
memset(&root_item->drop_progress, 0,
sizeof(struct btrfs_disk_key));
btrfs_set_root_drop_level(root_item, 0);
}
btrfs_tree_unlock(eb);
free_extent_buffer(eb);
ret = btrfs_insert_root(trans, fs_info->tree_root,
&root_key, root_item);
if (ret)
goto fail;
kfree(root_item);
reloc_root = btrfs_read_tree_root(fs_info->tree_root, &root_key);
if (IS_ERR(reloc_root)) {
ret = PTR_ERR(reloc_root);
goto abort;
}
set_bit(BTRFS_ROOT_SHAREABLE, &reloc_root->state);
reloc_root->last_trans = trans->transid;
return reloc_root;
fail:
kfree(root_item);
abort:
if (must_abort)
btrfs_abort_transaction(trans, ret);
return ERR_PTR(ret);
}
/*
* create reloc tree for a given fs tree. reloc tree is just a
* snapshot of the fs tree with special root objectid.
*
* The reloc_root comes out of here with two references, one for
* root->reloc_root, and another for being on the rc->reloc_roots list.
*/
int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_root *reloc_root;
struct reloc_control *rc = fs_info->reloc_ctl;
struct btrfs_block_rsv *rsv;
int clear_rsv = 0;
int ret;
if (!rc)
return 0;
/*
* The subvolume has reloc tree but the swap is finished, no need to
* create/update the dead reloc tree
*/
if (reloc_root_is_dead(root))
return 0;
/*
* This is subtle but important. We do not do
* record_root_in_transaction for reloc roots, instead we record their
* corresponding fs root, and then here we update the last trans for the
* reloc root. This means that we have to do this for the entire life
* of the reloc root, regardless of which stage of the relocation we are
* in.
*/
if (root->reloc_root) {
reloc_root = root->reloc_root;
reloc_root->last_trans = trans->transid;
return 0;
}
/*
* We are merging reloc roots, we do not need new reloc trees. Also
* reloc trees never need their own reloc tree.
*/
if (!rc->create_reloc_tree ||
root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
return 0;
if (!trans->reloc_reserved) {
rsv = trans->block_rsv;
trans->block_rsv = rc->block_rsv;
clear_rsv = 1;
}
reloc_root = create_reloc_root(trans, root, root->root_key.objectid);
if (clear_rsv)
trans->block_rsv = rsv;
if (IS_ERR(reloc_root))
return PTR_ERR(reloc_root);
ret = __add_reloc_root(reloc_root);
ASSERT(ret != -EEXIST);
if (ret) {
/* Pairs with create_reloc_root */
btrfs_put_root(reloc_root);
return ret;
}
root->reloc_root = btrfs_grab_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_fs_info *fs_info = root->fs_info;
struct btrfs_root *reloc_root;
struct btrfs_root_item *root_item;
int ret;
if (!have_reloc_root(root))
return 0;
reloc_root = root->reloc_root;
root_item = &reloc_root->root_item;
/*
* We are probably ok here, but __del_reloc_root() will drop its ref of
* the root. We have the ref for root->reloc_root, but just in case
* hold it while we update the reloc root.
*/
btrfs_grab_root(reloc_root);
/* root->reloc_root will stay until current relocation finished */
if (fs_info->reloc_ctl->merge_reloc_tree &&
btrfs_root_refs(root_item) == 0) {
set_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state);
/*
* Mark the tree as dead before we change reloc_root so
* have_reloc_root will not touch it from now on.
*/
smp_wmb();
__del_reloc_root(reloc_root);
}
if (reloc_root->commit_root != reloc_root->node) {
__update_reloc_root(reloc_root);
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, fs_info->tree_root,
&reloc_root->root_key, root_item);
btrfs_put_root(reloc_root);
return ret;
}
/*
* 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 < btrfs_ino(entry))
node = node->rb_left;
else if (objectid > btrfs_ino(entry))
node = node->rb_right;
else
break;
}
if (!node) {
while (prev) {
entry = rb_entry(prev, struct btrfs_inode, rb_node);
if (objectid <= btrfs_ino(entry)) {
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 = btrfs_ino(entry) + 1;
if (cond_resched_lock(&root->inode_lock))
goto again;
node = rb_next(node);
}
spin_unlock(&root->inode_lock);
return NULL;
}
/*
* 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,
btrfs_ino(BTRFS_I(reloc_inode)), 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 = -EINVAL;
goto out;
}
*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 noinline_for_stack
int replace_file_extents(struct btrfs_trans_handle *trans,
struct reloc_control *rc,
struct btrfs_root *root,
struct extent_buffer *leaf)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_key key;
struct btrfs_file_extent_item *fi;
struct inode *inode = NULL;
u64 parent;
u64 bytenr;
u64 new_bytenr = 0;
u64 num_bytes;
u64 end;
u32 nritems;
u32 i;
int ret = 0;
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++) {
struct btrfs_ref ref = { 0 };
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_range(bytenr, rc->block_group->start,
rc->block_group->length))
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 (first) {
inode = find_next_inode(root, key.objectid);
first = 0;
} else if (inode && btrfs_ino(BTRFS_I(inode)) < key.objectid) {
btrfs_add_delayed_iput(inode);
inode = find_next_inode(root, key.objectid);
}
if (inode && btrfs_ino(BTRFS_I(inode)) == key.objectid) {
end = key.offset +
btrfs_file_extent_num_bytes(leaf, fi);
WARN_ON(!IS_ALIGNED(key.offset,
fs_info->sectorsize));
WARN_ON(!IS_ALIGNED(end, fs_info->sectorsize));
end--;
ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
key.offset, end);
if (!ret)
continue;
btrfs_drop_extent_cache(BTRFS_I(inode),
key.offset, end, 1);
unlock_extent(&BTRFS_I(inode)->io_tree,
key.offset, end);
}
}
ret = get_new_location(rc->data_inode, &new_bytenr,
bytenr, num_bytes);
if (ret) {
/*
* Don't have to abort since we've not changed anything
* in the file extent yet.
*/
break;
}
btrfs_set_file_extent_disk_bytenr(leaf, fi, new_bytenr);
dirty = 1;
key.offset -= btrfs_file_extent_offset(leaf, fi);
btrfs_init_generic_ref(&ref, BTRFS_ADD_DELAYED_REF, new_bytenr,
num_bytes, parent);
ref.real_root = root->root_key.objectid;
btrfs_init_data_ref(&ref, btrfs_header_owner(leaf),
key.objectid, key.offset);
ret = btrfs_inc_extent_ref(trans, &ref);
if (ret) {
btrfs_abort_transaction(trans, ret);
break;
}
btrfs_init_generic_ref(&ref, BTRFS_DROP_DELAYED_REF, bytenr,
num_bytes, parent);
ref.real_root = root->root_key.objectid;
btrfs_init_data_ref(&ref, btrfs_header_owner(leaf),
key.objectid, key.offset);
ret = btrfs_free_extent(trans, &ref);
if (ret) {
btrfs_abort_transaction(trans, ret);
break;
}
}
if (dirty)
btrfs_mark_buffer_dirty(leaf);
if (inode)
btrfs_add_delayed_iput(inode);
return ret;
}
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 noinline_for_stack
int replace_path(struct btrfs_trans_handle *trans, struct reloc_control *rc,
struct btrfs_root *dest, struct btrfs_root *src,
struct btrfs_path *path, struct btrfs_key *next_key,
int lowest_level, int max_level)
{
struct btrfs_fs_info *fs_info = dest->fs_info;
struct extent_buffer *eb;
struct extent_buffer *parent;
struct btrfs_ref ref = { 0 };
struct btrfs_key key;
u64 old_bytenr;
u64 new_bytenr;
u64 old_ptr_gen;
u64 new_ptr_gen;
u64 last_snapshot;
u32 blocksize;
int cow = 0;
int level;
int ret;
int slot;
ASSERT(src->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID);
ASSERT(dest->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
last_snapshot = btrfs_root_last_snapshot(&src->root_item);
again:
slot = path->slots[lowest_level];
btrfs_node_key_to_cpu(path->nodes[lowest_level], &key, slot);
eb = btrfs_lock_root_node(dest);
level = btrfs_header_level(eb);
if (level < lowest_level) {
btrfs_tree_unlock(eb);
free_extent_buffer(eb);
return 0;
}
if (cow) {
ret = btrfs_cow_block(trans, dest, eb, NULL, 0, &eb,
BTRFS_NESTING_COW);
if (ret) {
btrfs_tree_unlock(eb);
free_extent_buffer(eb);
return ret;
}
}
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);
ASSERT(level >= lowest_level);
ret = btrfs_bin_search(parent, &key, &slot);
if (ret < 0)
break;
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 = fs_info->nodesize;
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 (WARN_ON(new_bytenr > 0 && new_bytenr == old_bytenr)) {
ret = level;
break;
}
if (new_bytenr == 0 || old_ptr_gen > last_snapshot ||
memcmp_node_keys(parent, slot, path, level)) {
if (level <= lowest_level) {
ret = 0;
break;
}
eb = btrfs_read_node_slot(parent, slot);
if (IS_ERR(eb)) {
ret = PTR_ERR(eb);
break;
}
btrfs_tree_lock(eb);
if (cow) {
ret = btrfs_cow_block(trans, dest, eb, parent,
slot, &eb,
BTRFS_NESTING_COW);
if (ret) {
btrfs_tree_unlock(eb);
free_extent_buffer(eb);
break;
}
}
btrfs_tree_unlock(parent);
free_extent_buffer(parent);
parent = eb;
continue;
}
if (!cow) {
btrfs_tree_unlock(parent);
free_extent_buffer(parent);
cow = 1;
goto again;
}
btrfs_node_key_to_cpu(path->nodes[level], &key,
path->slots[level]);
btrfs_release_path(path);
path->lowest_level = level;
ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
path->lowest_level = 0;
if (ret) {
if (ret > 0)
ret = -ENOENT;
break;
}
/*
* Info qgroup to trace both subtrees.
*
* We must trace both trees.
* 1) Tree reloc subtree
* If not traced, we will leak data numbers
* 2) Fs subtree
* If not traced, we will double count old data
*
* We don't scan the subtree right now, but only record
* the swapped tree blocks.
* The real subtree rescan is delayed until we have new
* CoW on the subtree root node before transaction commit.
*/
ret = btrfs_qgroup_add_swapped_blocks(trans, dest,
rc->block_group, parent, slot,
path->nodes[level], path->slots[level],
last_snapshot);
if (ret < 0)
break;
/*
* 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]);
btrfs_init_generic_ref(&ref, BTRFS_ADD_DELAYED_REF, old_bytenr,
blocksize, path->nodes[level]->start);
ref.skip_qgroup = true;
btrfs_init_tree_ref(&ref, level - 1, src->root_key.objectid);
ret = btrfs_inc_extent_ref(trans, &ref);
if (ret) {
btrfs_abort_transaction(trans, ret);
break;
}
btrfs_init_generic_ref(&ref, BTRFS_ADD_DELAYED_REF, new_bytenr,
blocksize, 0);
ref.skip_qgroup = true;
btrfs_init_tree_ref(&ref, level - 1, dest->root_key.objectid);
ret = btrfs_inc_extent_ref(trans, &ref);
if (ret) {
btrfs_abort_transaction(trans, ret);
break;
}
btrfs_init_generic_ref(&ref, BTRFS_DROP_DELAYED_REF, new_bytenr,
blocksize, path->nodes[level]->start);
btrfs_init_tree_ref(&ref, level - 1, src->root_key.objectid);
ref.skip_qgroup = true;
ret = btrfs_free_extent(trans, &ref);
if (ret) {
btrfs_abort_transaction(trans, ret);
break;
}
btrfs_init_generic_ref(&ref, BTRFS_DROP_DELAYED_REF, old_bytenr,
blocksize, 0);
btrfs_init_tree_ref(&ref, level - 1, dest->root_key.objectid);
ref.skip_qgroup = true;
ret = btrfs_free_extent(trans, &ref);
if (ret) {
btrfs_abort_transaction(trans, ret);
break;
}
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 ptr_gen = 0;
u64 last_snapshot;
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;
}
eb = btrfs_read_node_slot(eb, path->slots[i]);
if (IS_ERR(eb))
return PTR_ERR(eb);
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 btrfs_fs_info *fs_info = root->fs_info;
struct inode *inode = NULL;
u64 objectid;
u64 start, end;
u64 ino;
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;
ino = btrfs_ino(BTRFS_I(inode));
if (ino > max_key->objectid) {
iput(inode);
break;
}
objectid = ino + 1;
if (!S_ISREG(inode->i_mode))
continue;
if (unlikely(min_key->objectid == 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, fs_info->sectorsize));
}
} else {
start = 0;
}
if (unlikely(max_key->objectid == 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, fs_info->sectorsize));
end--;
}
} else {
end = (u64)-1;
}
/* the lock_extent waits for readpage to complete */
lock_extent(&BTRFS_I(inode)->io_tree, start, end);
btrfs_drop_extent_cache(BTRFS_I(inode), start, end, 1);
unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
}
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;
}
/*
* Insert current subvolume into reloc_control::dirty_subvol_roots
*/
static int insert_dirty_subvol(struct btrfs_trans_handle *trans,
struct reloc_control *rc,
struct btrfs_root *root)
{
struct btrfs_root *reloc_root = root->reloc_root;
struct btrfs_root_item *reloc_root_item;
int ret;
/* @root must be a subvolume tree root with a valid reloc tree */
ASSERT(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID);
ASSERT(reloc_root);
reloc_root_item = &reloc_root->root_item;
memset(&reloc_root_item->drop_progress, 0,
sizeof(reloc_root_item->drop_progress));
btrfs_set_root_drop_level(reloc_root_item, 0);
btrfs_set_root_refs(reloc_root_item, 0);
ret = btrfs_update_reloc_root(trans, root);
if (ret)
return ret;
if (list_empty(&root->reloc_dirty_list)) {
btrfs_grab_root(root);
list_add_tail(&root->reloc_dirty_list, &rc->dirty_subvol_roots);
}
return 0;
}
static int clean_dirty_subvols(struct reloc_control *rc)
{
struct btrfs_root *root;
struct btrfs_root *next;
int ret = 0;
int ret2;
list_for_each_entry_safe(root, next, &rc->dirty_subvol_roots,
reloc_dirty_list) {
if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
/* Merged subvolume, cleanup its reloc root */
struct btrfs_root *reloc_root = root->reloc_root;
list_del_init(&root->reloc_dirty_list);
root->reloc_root = NULL;
/*
* Need barrier to ensure clear_bit() only happens after
* root->reloc_root = NULL. Pairs with have_reloc_root.
*/
smp_wmb();
clear_bit(BTRFS_ROOT_DEAD_RELOC_TREE, &root->state);
if (reloc_root) {
/*
* btrfs_drop_snapshot drops our ref we hold for
* ->reloc_root. If it fails however we must
* drop the ref ourselves.
*/
ret2 = btrfs_drop_snapshot(reloc_root, 0, 1);
if (ret2 < 0) {
btrfs_put_root(reloc_root);
if (!ret)
ret = ret2;
}
}
btrfs_put_root(root);
} else {
/* Orphan reloc tree, just clean it up */
ret2 = btrfs_drop_snapshot(root, 0, 1);
if (ret2 < 0) {
btrfs_put_root(root);
if (!ret)
ret = ret2;
}
}
}
return ret;
}
/*
* 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)
{
struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
struct btrfs_key key;
struct btrfs_key next_key;
struct btrfs_trans_handle *trans = NULL;
struct btrfs_root *reloc_root;
struct btrfs_root_item *root_item;
struct btrfs_path *path;
struct extent_buffer *leaf;
int reserve_level;
int level;
int max_level;
int replaced = 0;
int ret = 0;
u32 min_reserved;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
path->reada = READA_FORWARD;
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);
atomic_inc(&reloc_root->node->refs);
path->nodes[level] = reloc_root->node;
path->slots[level] = 0;
} else {
btrfs_disk_key_to_cpu(&key, &root_item->drop_progress);
level = btrfs_root_drop_level(root_item);
BUG_ON(level == 0);
path->lowest_level = level;
ret = btrfs_search_slot(NULL, reloc_root, &key, path, 0, 0);
path->lowest_level = 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);
}
/*
* In merge_reloc_root(), we modify the upper level pointer to swap the
* tree blocks between reloc tree and subvolume tree. Thus for tree
* block COW, we COW at most from level 1 to root level for each tree.
*
* Thus the needed metadata size is at most root_level * nodesize,
* and * 2 since we have two trees to COW.
*/
reserve_level = max_t(int, 1, btrfs_root_level(root_item));
min_reserved = fs_info->nodesize * reserve_level * 2;
memset(&next_key, 0, sizeof(next_key));
while (1) {
ret = btrfs_block_rsv_refill(root, rc->block_rsv, min_reserved,
BTRFS_RESERVE_FLUSH_LIMIT);
if (ret)
goto out;
trans = btrfs_start_transaction(root, 0);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
trans = NULL;
goto out;
}
/*
* At this point we no longer have a reloc_control, so we can't
* depend on btrfs_init_reloc_root to update our last_trans.
*
* But that's ok, we started the trans handle on our
* corresponding fs_root, which means it's been added to the
* dirty list. At commit time we'll still call
* btrfs_update_reloc_root() and update our root item
* appropriately.
*/
reloc_root->last_trans = trans->transid;
trans->block_rsv = rc->block_rsv;
replaced = 0;
max_level = level;
ret = walk_down_reloc_tree(reloc_root, path, &level);
if (ret < 0)
goto out;
if (ret > 0)
break;
if (!find_next_key(path, level, &key) &&
btrfs_comp_cpu_keys(&next_key, &key) >= 0) {
ret = 0;
} else {
ret = replace_path(trans, rc, root, reloc_root, path,
&next_key, level, max_level);
}
if (ret < 0)
goto out;
if (ret > 0) {
level = ret;
btrfs_node_key_to_cpu(path->nodes[level], &key,
path->slots[level]);
replaced = 1;
}
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]);
btrfs_set_root_drop_level(root_item, level);
btrfs_end_transaction_throttle(trans);
trans = NULL;
btrfs_btree_balance_dirty(fs_info);
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_NESTING_COW);
btrfs_tree_unlock(leaf);
free_extent_buffer(leaf);
out:
btrfs_free_path(path);
if (ret == 0) {
ret = insert_dirty_subvol(trans, rc, root);
if (ret)
btrfs_abort_transaction(trans, ret);
}
if (trans)
btrfs_end_transaction_throttle(trans);
btrfs_btree_balance_dirty(fs_info);
if (replaced && rc->stage == UPDATE_DATA_PTRS)
invalidate_extent_cache(root, &key, &next_key);
return ret;
}
static noinline_for_stack
int prepare_to_merge(struct reloc_control *rc, int err)
{
struct btrfs_root *root = rc->extent_root;
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_root *reloc_root;
struct btrfs_trans_handle *trans;
LIST_HEAD(reloc_roots);
u64 num_bytes = 0;
int ret;
mutex_lock(&fs_info->reloc_mutex);
rc->merging_rsv_size += fs_info->nodesize * (BTRFS_MAX_LEVEL - 1) * 2;
rc->merging_rsv_size += rc->nodes_relocated * 2;
mutex_unlock(&fs_info->reloc_mutex);
again:
if (!err) {
num_bytes = rc->merging_rsv_size;
ret = btrfs_block_rsv_add(root, rc->block_rsv, num_bytes,
BTRFS_RESERVE_FLUSH_ALL);
if (ret)
err = ret;
}
trans = btrfs_join_transaction(rc->extent_root);
if (IS_ERR(trans)) {
if (!err)
btrfs_block_rsv_release(fs_info, rc->block_rsv,
num_bytes, NULL);
return PTR_ERR(trans);
}
if (!err) {
if (num_bytes != rc->merging_rsv_size) {
btrfs_end_transaction(trans);
btrfs_block_rsv_release(fs_info, rc->block_rsv,
num_bytes, NULL);
goto again;
}
}
rc->merge_reloc_tree = 1;
while (!list_empty(&rc->reloc_roots)) {
reloc_root = list_entry(rc->reloc_roots.next,
struct btrfs_root, root_list);
list_del_init(&reloc_root->root_list);
root = btrfs_get_fs_root(fs_info, reloc_root->root_key.offset,
false);
if (IS_ERR(root)) {
/*
* Even if we have an error we need this reloc root
* back on our list so we can clean up properly.
*/
list_add(&reloc_root->root_list, &reloc_roots);
btrfs_abort_transaction(trans, (int)PTR_ERR(root));
if (!err)
err = PTR_ERR(root);
break;
}
ASSERT(root->reloc_root == reloc_root);
/*
* set reference count to 1, so btrfs_recover_relocation
* knows it should resumes merging
*/
if (!err)
btrfs_set_root_refs(&reloc_root->root_item, 1);
ret = btrfs_update_reloc_root(trans, root);
/*
* Even if we have an error we need this reloc root back on our
* list so we can clean up properly.
*/
list_add(&reloc_root->root_list, &reloc_roots);
btrfs_put_root(root);
if (ret) {
btrfs_abort_transaction(trans, ret);
if (!err)
err = ret;
break;
}
}
list_splice(&reloc_roots, &rc->reloc_roots);
if (!err)
err = btrfs_commit_transaction(trans);
else
btrfs_end_transaction(trans);
return err;
}
static noinline_for_stack
void free_reloc_roots(struct list_head *list)
{
struct btrfs_root *reloc_root, *tmp;
list_for_each_entry_safe(reloc_root, tmp, list, root_list)
__del_reloc_root(reloc_root);
}
static noinline_for_stack
void merge_reloc_roots(struct reloc_control *rc)
{
struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
struct btrfs_root *root;
struct btrfs_root *reloc_root;
LIST_HEAD(reloc_roots);
int found = 0;
int ret = 0;
again:
root = rc->extent_root;
/*
* this serializes us with btrfs_record_root_in_transaction,
* we have to make sure nobody is in the middle of
* adding their roots to the list while we are
* doing this splice
*/
mutex_lock(&fs_info->reloc_mutex);
list_splice_init(&rc->reloc_roots, &reloc_roots);
mutex_unlock(&fs_info->reloc_mutex);
while (!list_empty(&reloc_roots)) {
found = 1;
reloc_root = list_entry(reloc_roots.next,
struct btrfs_root, root_list);
root = btrfs_get_fs_root(fs_info, reloc_root->root_key.offset,
false);
if (btrfs_root_refs(&reloc_root->root_item) > 0) {
if (IS_ERR(root)) {
/*
* For recovery we read the fs roots on mount,
* and if we didn't find the root then we marked
* the reloc root as a garbage root. For normal
* relocation obviously the root should exist in
* memory. However there's no reason we can't
* handle the error properly here just in case.
*/
ASSERT(0);
ret = PTR_ERR(root);
goto out;
}
if (root->reloc_root != reloc_root) {
/*
* This is actually impossible without something
* going really wrong (like weird race condition
* or cosmic rays).
*/
ASSERT(0);
ret = -EINVAL;
goto out;
}
ret = merge_reloc_root(rc, root);
btrfs_put_root(root);
if (ret) {
if (list_empty(&reloc_root->root_list))
list_add_tail(&reloc_root->root_list,
&reloc_roots);
goto out;
}
} else {
if (!IS_ERR(root)) {
if (root->reloc_root == reloc_root) {
root->reloc_root = NULL;
btrfs_put_root(reloc_root);
}
clear_bit(BTRFS_ROOT_DEAD_RELOC_TREE,
&root->state);
btrfs_put_root(root);
}
list_del_init(&reloc_root->root_list);
/* Don't forget to queue this reloc root for cleanup */
list_add_tail(&reloc_root->reloc_dirty_list,
&rc->dirty_subvol_roots);
}
}
if (found) {
found = 0;
goto again;
}
out:
if (ret) {
btrfs_handle_fs_error(fs_info, ret, NULL);
free_reloc_roots(&reloc_roots);
/* new reloc root may be added */
mutex_lock(&fs_info->reloc_mutex);
list_splice_init(&rc->reloc_roots, &reloc_roots);
mutex_unlock(&fs_info->reloc_mutex);
free_reloc_roots(&reloc_roots);
}
/*
* We used to have
*
* BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
*
* here, but it's wrong. If we fail to start the transaction in
* prepare_to_merge() we will have only 0 ref reloc roots, none of which
* have actually been removed from the reloc_root_tree rb tree. This is
* fine because we're bailing here, and we hold a reference on the root
* for the list that holds it, so these roots will be cleaned up when we
* do the reloc_dirty_list afterwards. Meanwhile the root->reloc_root
* will be cleaned up on unmount.
*
* The remaining nodes will be cleaned up by free_reloc_control.
*/
}
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_fs_info *fs_info = reloc_root->fs_info;
struct btrfs_root *root;
int ret;
if (reloc_root->last_trans == trans->transid)
return 0;
root = btrfs_get_fs_root(fs_info, reloc_root->root_key.offset, false);
/*
* This should succeed, since we can't have a reloc root without having
* already looked up the actual root and created the reloc root for this
* root.
*
* However if there's some sort of corruption where we have a ref to a
* reloc root without a corresponding root this could return ENOENT.
*/
if (IS_ERR(root)) {
ASSERT(0);
return PTR_ERR(root);
}
if (root->reloc_root != reloc_root) {
ASSERT(0);
btrfs_err(fs_info,
"root %llu has two reloc roots associated with it",
reloc_root->root_key.offset);
btrfs_put_root(root);
return -EUCLEAN;
}
ret = btrfs_record_root_in_trans(trans, root);
btrfs_put_root(root);
return ret;
}
static noinline_for_stack
struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans,
struct reloc_control *rc,
struct btrfs_backref_node *node,
struct btrfs_backref_edge *edges[])
{
struct btrfs_backref_node *next;
struct btrfs_root *root;
int index = 0;
int ret;
next = node;
while (1) {
cond_resched();
next = walk_up_backref(next, edges, &index);
root = next->root;
/*
* If there is no root, then our references for this block are
* incomplete, as we should be able to walk all the way up to a
* block that is owned by a root.
*
* This path is only for SHAREABLE roots, so if we come upon a
* non-SHAREABLE root then we have backrefs that resolve
* improperly.
*
* Both of these cases indicate file system corruption, or a bug
* in the backref walking code.
*/
if (!root) {
ASSERT(0);
btrfs_err(trans->fs_info,
"bytenr %llu doesn't have a backref path ending in a root",
node->bytenr);
return ERR_PTR(-EUCLEAN);
}
if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) {
ASSERT(0);
btrfs_err(trans->fs_info,
"bytenr %llu has multiple refs with one ending in a non-shareable root",
node->bytenr);
return ERR_PTR(-EUCLEAN);
}
if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
ret = record_reloc_root_in_trans(trans, root);
if (ret)
return ERR_PTR(ret);
break;
}
ret = btrfs_record_root_in_trans(trans, root);
if (ret)
return ERR_PTR(ret);
root = root->reloc_root;
/*
* We could have raced with another thread which failed, so
* root->reloc_root may not be set, return ENOENT in this case.
*/
if (!root)
return ERR_PTR(-ENOENT);
if (next->new_bytenr != root->node->start) {
/*
* We just created the reloc root, so we shouldn't have
* ->new_bytenr set and this shouldn't be in the changed
* list. If it is then we have multiple roots pointing
* at the same bytenr which indicates corruption, or
* we've made a mistake in the backref walking code.
*/
ASSERT(next->new_bytenr == 0);
ASSERT(list_empty(&next->list));
if (next->new_bytenr || !list_empty(&next->list)) {
btrfs_err(trans->fs_info,
"bytenr %llu possibly has multiple roots pointing at the same bytenr %llu",
node->bytenr, next->bytenr);
return ERR_PTR(-EUCLEAN);
}
next->new_bytenr = root->node->start;
btrfs_put_root(next->root);
next->root = btrfs_grab_root(root);
ASSERT(next->root);
list_add_tail(&next->list,
&rc->backref_cache.changed);
mark_block_processed(rc, next);
break;
}
WARN_ON(1);
root = NULL;
next = walk_down_backref(edges, &index);
if (!next || next->level <= node->level)
break;
}
if (!root) {
/*
* This can happen if there's fs corruption or if there's a bug
* in the backref lookup code.
*/
ASSERT(0);
return ERR_PTR(-ENOENT);
}
next = node;
/* setup backref node path for btrfs_reloc_cow_block */
while (1) {
rc->backref_cache.path[next->level] = next;
if (--index < 0)
break;
next = edges[index]->node[UPPER];
}
return root;
}
/*
* Select a tree root for relocation.
*
* Return NULL if the block is not shareable. We should use do_relocation() in
* this case.
*
* Return a tree root pointer if the block is shareable.
* Return -ENOENT if the block is root of reloc tree.
*/
static noinline_for_stack
struct btrfs_root *select_one_root(struct btrfs_backref_node *node)
{
struct btrfs_backref_node *next;
struct btrfs_root *root;
struct btrfs_root *fs_root = NULL;
struct btrfs_backref_edge *edges[BTRFS_MAX_LEVEL - 1];
int index = 0;
next = node;
while (1) {
cond_resched();
next = walk_up_backref(next, edges, &index);
root = next->root;
/*
* This can occur if we have incomplete extent refs leading all
* the way up a particular path, in this case return -EUCLEAN.
*/
if (!root)
return ERR_PTR(-EUCLEAN);
/* No other choice for non-shareable tree */
if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
return root;
if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID)
fs_root = root;
if (next != node)
return NULL;
next = walk_down_backref(edges, &index);
if (!next || next->level <= node->level)
break;
}
if (!fs_root)
return ERR_PTR(-ENOENT);
return fs_root;
}
static noinline_for_stack
u64 calcu_metadata_size(struct reloc_control *rc,
struct btrfs_backref_node *node, int reserve)
{
struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
struct btrfs_backref_node *next = node;
struct btrfs_backref_edge *edge;
struct btrfs_backref_edge *edges[BTRFS_MAX_LEVEL - 1];
u64 num_bytes = 0;
int index = 0;
BUG_ON(reserve && node->processed);
while (next) {
cond_resched();
while (1) {
if (next->processed && (reserve || next != node))
break;
num_bytes += fs_info->nodesize;
if (list_empty(&next->upper))
break;
edge = list_entry(next->upper.next,
struct btrfs_backref_edge, list[LOWER]);
edges[index++] = edge;
next = edge->node[UPPER];
}
next = walk_down_backref(edges, &index);
}
return num_bytes;
}
static int reserve_metadata_space(struct btrfs_trans_handle *trans,
struct reloc_control *rc,
struct btrfs_backref_node *node)
{
struct btrfs_root *root = rc->extent_root;
struct btrfs_fs_info *fs_info = root->fs_info;
u64 num_bytes;
int ret;
u64 tmp;
num_bytes = calcu_metadata_size(rc, node, 1) * 2;
trans->block_rsv = rc->block_rsv;
rc->reserved_bytes += num_bytes;
/*
* We are under a transaction here so we can only do limited flushing.
* If we get an enospc just kick back -EAGAIN so we know to drop the
* transaction and try to refill when we can flush all the things.
*/
ret = btrfs_block_rsv_refill(root, rc->block_rsv, num_bytes,
BTRFS_RESERVE_FLUSH_LIMIT);
if (ret) {
tmp = fs_info->nodesize * RELOCATION_RESERVED_NODES;
while (tmp <= rc->reserved_bytes)
tmp <<= 1;
/*
* only one thread can access block_rsv at this point,
* so we don't need hold lock to protect block_rsv.
* we expand more reservation size here to allow enough
* space for relocation and we will return earlier in
* enospc case.
*/
rc->block_rsv->size = tmp + fs_info->nodesize *
RELOCATION_RESERVED_NODES;
return -EAGAIN;
}
return 0;
}
/*
* 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 reloc_control *rc,
struct btrfs_backref_node *node,
struct btrfs_key *key,
struct btrfs_path *path, int lowest)
{
struct btrfs_backref_node *upper;
struct btrfs_backref_edge *edge;
struct btrfs_backref_edge *edges[BTRFS_MAX_LEVEL - 1];
struct btrfs_root *root;
struct extent_buffer *eb;
u32 blocksize;
u64 bytenr;
int slot;
int ret = 0;
/*
* If we are lowest then this is the first time we're processing this
* block, and thus shouldn't have an eb associated with it yet.
*/
ASSERT(!lowest || !node->eb);
path->lowest_level = node->level + 1;
rc->backref_cache.path[node->level] = node;
list_for_each_entry(edge, &node->upper, list[LOWER]) {
struct btrfs_ref ref = { 0 };
cond_resched();
upper = edge->node[UPPER];
root = select_reloc_root(trans, rc, upper, edges);
if (IS_ERR(root)) {
ret = PTR_ERR(root);
goto next;
}
if (upper->eb && !upper->locked) {
if (!lowest) {
ret = btrfs_bin_search(upper->eb, key, &slot);
if (ret < 0)
goto next;
BUG_ON(ret);
bytenr = btrfs_node_blockptr(upper->eb, slot);
if (node->eb->start == bytenr)
goto next;
}
btrfs_backref_drop_node_buffer(upper);
}
if (!upper->eb) {
ret = btrfs_search_slot(trans, root, key, path, 0, 1);
if (ret) {
if (ret > 0)
ret = -ENOENT;
btrfs_release_path(path);
break;
}
if (!upper->eb) {
upper->eb = path->nodes[upper->level];
path->nodes[upper->level] = NULL;
} else {
BUG_ON(upper->eb != path->nodes[upper->level]);
}
upper->locked = 1;
path->locks[upper->level] = 0;
slot = path->slots[upper->level];
btrfs_release_path(path);
} else {
ret = btrfs_bin_search(upper->eb, key, &slot);
if (ret < 0)
goto next;
BUG_ON(ret);
}
bytenr = btrfs_node_blockptr(upper->eb, slot);
if (lowest) {
if (bytenr != node->bytenr) {
btrfs_err(root->fs_info,
"lowest leaf/node mismatch: bytenr %llu node->bytenr %llu slot %d upper %llu",
bytenr, node->bytenr, slot,
upper->eb->start);
ret = -EIO;
goto next;
}
} else {
if (node->eb->start == bytenr)
goto next;
}
blocksize = root->fs_info->nodesize;
eb = btrfs_read_node_slot(upper->eb, slot);
if (IS_ERR(eb)) {
ret = PTR_ERR(eb);
goto next;
}
btrfs_tree_lock(eb);
if (!node->eb) {
ret = btrfs_cow_block(trans, root, eb, upper->eb,
slot, &eb, BTRFS_NESTING_COW);
btrfs_tree_unlock(eb);
free_extent_buffer(eb);
if (ret < 0)
goto next;
/*
* We've just COWed this block, it should have updated
* the correct backref node entry.
*/
ASSERT(node->eb == eb);
} 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);
btrfs_init_generic_ref(&ref, BTRFS_ADD_DELAYED_REF,
node->eb->start, blocksize,
upper->eb->start);
ref.real_root = root->root_key.objectid;
btrfs_init_tree_ref(&ref, node->level,
btrfs_header_owner(upper->eb));
ret = btrfs_inc_extent_ref(trans, &ref);
if (!ret)
ret = btrfs_drop_subtree(trans, root, eb,
upper->eb);
if (ret)
btrfs_abort_transaction(trans, ret);
}
next:
if (!upper->pending)
btrfs_backref_drop_node_buffer(upper);
else
btrfs_backref_unlock_node_buffer(upper);
if (ret)
break;
}
if (!ret && node->pending) {
btrfs_backref_drop_node_buffer(node);
list_move_tail(&node->list, &rc->backref_cache.changed);
node->pending = 0;
}
path->lowest_level = 0;
/*
* We should have allocated all of our space in the block rsv and thus
* shouldn't ENOSPC.
*/
ASSERT(ret != -ENOSPC);
return ret;
}
static int link_to_upper(struct btrfs_trans_handle *trans,
struct reloc_control *rc,
struct btrfs_backref_node *node,
struct btrfs_path *path)
{
struct btrfs_key key;
btrfs_node_key_to_cpu(node->eb, &key, 0);
return do_relocation(trans, rc, node, &key, path, 0);
}
static int finish_pending_nodes(struct btrfs_trans_handle *trans,
struct reloc_control *rc,
struct btrfs_path *path, int err)
{
LIST_HEAD(list);
struct btrfs_backref_cache *cache = &rc->backref_cache;
struct btrfs_backref_node *node;
int level;
int ret;
for (level = 0; level < BTRFS_MAX_LEVEL; level++) {
while (!list_empty(&cache->pending[level])) {
node = list_entry(cache->pending[level].next,
struct btrfs_backref_node, list);
list_move_tail(&node->list, &list);
BUG_ON(!node->pending);
if (!err) {
ret = link_to_upper(trans, rc, node, path);
if (ret < 0)
err = ret;
}
}
list_splice_init(&list, &cache->pending[level]);
}
return err;
}
/*
* mark a block and all blocks directly/indirectly reference the block
* as processed.
*/
static void update_processed_blocks(struct reloc_control *rc,
struct btrfs_backref_node *node)
{
struct btrfs_backref_node *next = node;
struct btrfs_backref_edge *edge;
struct btrfs_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 btrfs_backref_edge, list[LOWER]);
edges[index++] = edge;
next = edge->node[UPPER];
}
next = walk_down_backref(edges, &index);
}
}
static int tree_block_processed(u64 bytenr, struct reloc_control *rc)
{
u32 blocksize = rc->extent_root->fs_info->nodesize;
if (test_range_bit(&rc->processed_blocks, bytenr,
bytenr + blocksize - 1, EXTENT_DIRTY, 1, NULL))
return 1;
return 0;
}
static int get_tree_block_key(struct btrfs_fs_info *fs_info,
struct tree_block *block)
{
struct extent_buffer *eb;
eb = read_tree_block(fs_info, block->bytenr, block->owner,
block->key.offset, block->level, NULL);
if (IS_ERR(eb)) {
return PTR_ERR(eb);
} else if (!extent_buffer_uptodate(eb)) {
free_extent_buffer(eb);
return -EIO;
}
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;
}
/*
* helper function to relocate a tree block
*/
static int relocate_tree_block(struct btrfs_trans_handle *trans,
struct reloc_control *rc,
struct btrfs_backref_node *node,
struct btrfs_key *key,
struct btrfs_path *path)
{
struct btrfs_root *root;
int ret = 0;
if (!node)
return 0;
/*
* If we fail here we want to drop our backref_node because we are going
* to start over and regenerate the tree for it.
*/
ret = reserve_metadata_space(trans, rc, node);
if (ret)
goto out;
BUG_ON(node->processed);
root = select_one_root(node);
if (IS_ERR(root)) {
ret = PTR_ERR(root);
/* See explanation in select_one_root for the -EUCLEAN case. */
ASSERT(ret == -ENOENT);
if (ret == -ENOENT) {
ret = 0;
update_processed_blocks(rc, node);
}
goto out;
}
if (root) {
if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) {
/*
* This block was the root block of a root, and this is
* the first time we're processing the block and thus it
* should not have had the ->new_bytenr modified and
* should have not been included on the changed list.
*
* However in the case of corruption we could have
* multiple refs pointing to the same block improperly,
* and thus we would trip over these checks. ASSERT()
* for the developer case, because it could indicate a
* bug in the backref code, however error out for a
* normal user in the case of corruption.
*/
ASSERT(node->new_bytenr == 0);
ASSERT(list_empty(&node->list));
if (node->new_bytenr || !list_empty(&node->list)) {
btrfs_err(root->fs_info,
"bytenr %llu has improper references to it",
node->bytenr);
ret = -EUCLEAN;
goto out;
}
ret = btrfs_record_root_in_trans(trans, root);
if (ret)
goto out;
/*
* Another thread could have failed, need to check if we
* have reloc_root actually set.
*/
if (!root->reloc_root) {
ret = -ENOENT;
goto out;
}
root = root->reloc_root;
node->new_bytenr = root->node->start;
btrfs_put_root(node->root);
node->root = btrfs_grab_root(root);
ASSERT(node->root);
list_add_tail(&node->list, &rc->backref_cache.changed);
} else {
path->lowest_level = node->level;
ret = btrfs_search_slot(trans, root, key, path, 0, 1);
btrfs_release_path(path);
if (ret > 0)
ret = 0;
}
if (!ret)
update_processed_blocks(rc, node);
} else {
ret = do_relocation(trans, rc, node, key, path, 1);
}
out:
if (ret || node->level == 0 || node->cowonly)
btrfs_backref_cleanup_node(&rc->backref_cache, 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 btrfs_fs_info *fs_info = rc->extent_root->fs_info;
struct btrfs_backref_node *node;
struct btrfs_path *path;
struct tree_block *block;
struct tree_block *next;
int ret;
int err = 0;
path = btrfs_alloc_path();
if (!path) {
err = -ENOMEM;
goto out_free_blocks;
}
/* Kick in readahead for tree blocks with missing keys */
rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {
if (!block->key_ready)
btrfs_readahead_tree_block(fs_info, block->bytenr,
block->owner, 0,
block->level);
}
/* Get first keys */
rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {
if (!block->key_ready) {
err = get_tree_block_key(fs_info, block);
if (err)
goto out_free_path;
}
}
/* Do tree relocation */
rbtree_postorder_for_each_entry_safe(block, next, blocks, rb_node) {
node = build_backref_tree(rc, &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;
break;
}
}
out:
err = finish_pending_nodes(trans, rc, path, err);
out_free_path:
btrfs_free_path(path);
out_free_blocks:
free_block_list(blocks);
return err;
}
static noinline_for_stack int prealloc_file_extent_cluster(
struct btrfs_inode *inode,
struct file_extent_cluster *cluster)
{
u64 alloc_hint = 0;
u64 start;
u64 end;
u64 offset = inode->index_cnt;
u64 num_bytes;
int nr;
int ret = 0;
u64 prealloc_start = cluster->start - offset;
u64 prealloc_end = cluster->end - offset;
u64 cur_offset = prealloc_start;
BUG_ON(cluster->start != cluster->boundary[0]);
ret = btrfs_alloc_data_chunk_ondemand(inode,
prealloc_end + 1 - prealloc_start);
if (ret)
return ret;
/*
* On a zoned filesystem, we cannot preallocate the file region.
* Instead, we dirty and fiemap_write the region.
*/
if (btrfs_is_zoned(inode->root->fs_info)) {
struct btrfs_root *root = inode->root;
struct btrfs_trans_handle *trans;
end = cluster->end - offset + 1;
trans = btrfs_start_transaction(root, 1);
if (IS_ERR(trans))
return PTR_ERR(trans);
inode->vfs_inode.i_ctime = current_time(&inode->vfs_inode);
i_size_write(&inode->vfs_inode, end);
ret = btrfs_update_inode(trans, root, inode);
if (ret) {
btrfs_abort_transaction(trans, ret);
btrfs_end_transaction(trans);
return ret;
}
return btrfs_end_transaction(trans);
}
btrfs_inode_lock(&inode->vfs_inode, 0);
for (nr = 0; nr < cluster->nr; nr++) {
start = cluster->boundary[nr] - offset;
if (nr + 1 < cluster->nr)
end = cluster->boundary[nr + 1] - 1 - offset;
else
end = cluster->end - offset;
lock_extent(&inode->io_tree, start, end);
num_bytes = end + 1 - start;
ret = btrfs_prealloc_file_range(&inode->vfs_inode, 0, start,
num_bytes, num_bytes,
end + 1, &alloc_hint);
cur_offset = end + 1;
unlock_extent(&inode->io_tree, start, end);
if (ret)
break;
}
btrfs_inode_unlock(&inode->vfs_inode, 0);
if (cur_offset < prealloc_end)
btrfs_free_reserved_data_space_noquota(inode->root->fs_info,
prealloc_end + 1 - cur_offset);
return ret;
}
static noinline_for_stack
int setup_extent_mapping(struct inode *inode, u64 start, u64 end,
u64 block_start)
{
struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
struct extent_map *em;
int ret = 0;
em = alloc_extent_map();
if (!em)
return -ENOMEM;
em->start = start;
em->len = end + 1 - start;
em->block_len = em->len;
em->block_start = block_start;
set_bit(EXTENT_FLAG_PINNED, &em->flags);
lock_extent(&BTRFS_I(inode)->io_tree, start, end);
while (1) {
write_lock(&em_tree->lock);
ret = add_extent_mapping(em_tree, em, 0);
write_unlock(&em_tree->lock);
if (ret != -EEXIST) {
free_extent_map(em);
break;
}
btrfs_drop_extent_cache(BTRFS_I(inode), start, end, 0);
}
unlock_extent(&BTRFS_I(inode)->io_tree, start, end);
return ret;
}
/*
* Allow error injection to test balance cancellation
*/
noinline int btrfs_should_cancel_balance(struct btrfs_fs_info *fs_info)
{
return atomic_read(&fs_info->balance_cancel_req) ||
fatal_signal_pending(current);
}
ALLOW_ERROR_INJECTION(btrfs_should_cancel_balance, TRUE);
static int relocate_file_extent_cluster(struct inode *inode,
struct file_extent_cluster *cluster)
{
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
u64 page_start;
u64 page_end;
u64 offset = BTRFS_I(inode)->index_cnt;
unsigned long index;
unsigned long last_index;
struct page *page;
struct file_ra_state *ra;
gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
int nr = 0;
int ret = 0;
if (!cluster->nr)
return 0;
ra = kzalloc(sizeof(*ra), GFP_NOFS);
if (!ra)
return -ENOMEM;
ret = prealloc_file_extent_cluster(BTRFS_I(inode), cluster);
if (ret)
goto out;
file_ra_state_init(ra, inode->i_mapping);
ret = setup_extent_mapping(inode, cluster->start - offset,
cluster->end - offset, cluster->start);
if (ret)
goto out;
index = (cluster->start - offset) >> PAGE_SHIFT;
last_index = (cluster->end - offset) >> PAGE_SHIFT;
while (index <= last_index) {
ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode),
PAGE_SIZE);
if (ret)
goto out;
page = find_lock_page(inode->i_mapping, index);
if (!page) {
page_cache_sync_readahead(inode->i_mapping,
ra, NULL, index,
last_index + 1 - index);
page = find_or_create_page(inode->i_mapping, index,
mask);
if (!page) {
btrfs_delalloc_release_metadata(BTRFS_I(inode),
PAGE_SIZE, true);
btrfs_delalloc_release_extents(BTRFS_I(inode),
PAGE_SIZE);
ret = -ENOMEM;
goto out;
}
}
ret = set_page_extent_mapped(page);
if (ret < 0) {
btrfs_delalloc_release_metadata(BTRFS_I(inode),
PAGE_SIZE, true);
btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
unlock_page(page);
put_page(page);
goto out;
}
if (PageReadahead(page)) {
page_cache_async_readahead(inode->i_mapping,
ra, NULL, page, index,
last_index + 1 - index);
}
if (!PageUptodate(page)) {
btrfs_readpage(NULL, page);
lock_page(page);
if (!PageUptodate(page)) {
unlock_page(page);
put_page(page);
btrfs_delalloc_release_metadata(BTRFS_I(inode),
PAGE_SIZE, true);
btrfs_delalloc_release_extents(BTRFS_I(inode),
PAGE_SIZE);
ret = -EIO;
goto out;
}
}
page_start = page_offset(page);
page_end = page_start + PAGE_SIZE - 1;
lock_extent(&BTRFS_I(inode)->io_tree, page_start, page_end);
if (nr < cluster->nr &&
page_start + offset == cluster->boundary[nr]) {
set_extent_bits(&BTRFS_I(inode)->io_tree,
page_start, page_end,
EXTENT_BOUNDARY);
nr++;
}
ret = btrfs_set_extent_delalloc(BTRFS_I(inode), page_start,
page_end, 0, NULL);
if (ret) {
unlock_page(page);
put_page(page);
btrfs_delalloc_release_metadata(BTRFS_I(inode),
PAGE_SIZE, true);
btrfs_delalloc_release_extents(BTRFS_I(inode),
PAGE_SIZE);
clear_extent_bits(&BTRFS_I(inode)->io_tree,
page_start, page_end,
EXTENT_LOCKED | EXTENT_BOUNDARY);
goto out;
}
set_page_dirty(page);
unlock_extent(&BTRFS_I(inode)->io_tree,
page_start, page_end);
unlock_page(page);
put_page(page);
index++;
btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
balance_dirty_pages_ratelimited(inode->i_mapping);
btrfs_throttle(fs_info);
if (btrfs_should_cancel_balance(fs_info)) {
ret = -ECANCELED;
goto out;
}
}
WARN_ON(nr != cluster->nr);
if (btrfs_is_zoned(fs_info) && !ret)
ret = btrfs_wait_ordered_range(inode, 0, (u64)-1);
out:
kfree(ra);
return ret;
}
static noinline_for_stack
int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
struct file_extent_cluster *cluster)
{
int ret;
if (cluster->nr > 0 && extent_key->objectid != cluster->end + 1) {
ret = relocate_file_extent_cluster(inode, cluster);
if (ret)
return ret;
cluster->nr = 0;
}
if (!cluster->nr)
cluster->start = extent_key->objectid;
else
BUG_ON(cluster->nr >= MAX_EXTENTS);
cluster->end = extent_key->objectid + extent_key->offset - 1;
cluster->boundary[cluster->nr] = extent_key->objectid;
cluster->nr++;
if (cluster->nr >= MAX_EXTENTS) {
ret = relocate_file_extent_cluster(inode, cluster);
if (ret)
return ret;
cluster->nr = 0;
}
return 0;
}
/*
* 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;
u64 generation;
u64 owner = 0;
eb = path->nodes[0];
item_size = btrfs_item_size_nr(eb, path->slots[0]);
if (extent_key->type == BTRFS_METADATA_ITEM_KEY ||
item_size >= sizeof(*ei) + sizeof(*bi)) {
unsigned long ptr = 0, end;
ei = btrfs_item_ptr(eb, path->slots[0],
struct btrfs_extent_item);
end = (unsigned long)ei + item_size;
if (extent_key->type == BTRFS_EXTENT_ITEM_KEY) {
bi = (struct btrfs_tree_block_info *)(ei + 1);
level = btrfs_tree_block_level(eb, bi);
ptr = (unsigned long)(bi + 1);
} else {
level = (int)extent_key->offset;
ptr = (unsigned long)(ei + 1);
}
generation = btrfs_extent_generation(eb, ei);
/*
* We're reading random blocks without knowing their owner ahead
* of time. This is ok most of the time, as all reloc roots and
* fs roots have the same lock type. However normal trees do
* not, and the only way to know ahead of time is to read the
* inline ref offset. We know it's an fs root if
*
* 1. There's more than one ref.
* 2. There's a SHARED_DATA_REF_KEY set.
* 3. FULL_BACKREF is set on the flags.
*
* Otherwise it's safe to assume that the ref offset == the
* owner of this block, so we can use that when calling
* read_tree_block.
*/
if (btrfs_extent_refs(eb, ei) == 1 &&
!(btrfs_extent_flags(eb, ei) &
BTRFS_BLOCK_FLAG_FULL_BACKREF) &&
ptr < end) {
struct btrfs_extent_inline_ref *iref;
int type;
iref = (struct btrfs_extent_inline_ref *)ptr;
type = btrfs_get_extent_inline_ref_type(eb, iref,
BTRFS_REF_TYPE_BLOCK);
if (type == BTRFS_REF_TYPE_INVALID)
return -EINVAL;
if (type == BTRFS_TREE_BLOCK_REF_KEY)
owner = btrfs_extent_inline_ref_offset(eb, iref);
}
} else if (unlikely(item_size == sizeof(struct btrfs_extent_item_v0))) {
btrfs_print_v0_err(eb->fs_info);
btrfs_handle_fs_error(eb->fs_info, -EINVAL, NULL);
return -EINVAL;
} else {
BUG();
}
btrfs_release_path(path);
BUG_ON(level == -1);
block = kmalloc(sizeof(*block), GFP_NOFS);
if (!block)
return -ENOMEM;
block->bytenr = extent_key->objectid;
block->key.objectid = rc->extent_root->fs_info->nodesize;
block->key.offset = generation;
block->level = level;
block->key_ready = 0;
block->owner = owner;
rb_node = rb_simple_insert(blocks, block->bytenr, &block->rb_node);
if (rb_node)
btrfs_backref_panic(rc->extent_root->fs_info, block->bytenr,
-EEXIST);
return 0;
}
/*
* helper to add tree blocks for backref of type BTRFS_SHARED_DATA_REF_KEY
*/
static int __add_tree_block(struct reloc_control *rc,
u64 bytenr, u32 blocksize,
struct rb_root *blocks)
{
struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
struct btrfs_path *path;
struct btrfs_key key;
int ret;
bool skinny = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
if (tree_block_processed(bytenr, rc))
return 0;
if (rb_simple_search(blocks, bytenr))
return 0;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
again:
key.objectid = bytenr;
if (skinny) {
key.type = BTRFS_METADATA_ITEM_KEY;
key.offset = (u64)-1;
} else {
key.type = BTRFS_EXTENT_ITEM_KEY;
key.offset = blocksize;
}
path->search_commit_root = 1;
path->skip_locking = 1;
ret = btrfs_search_slot(NULL, rc->extent_root, &key, path, 0, 0);
if (ret < 0)
goto out;
if (ret > 0 && skinny) {
if (path->slots[0]) {
path->slots[0]--;
btrfs_item_key_to_cpu(path->nodes[0], &key,
path->slots[0]);
if (key.objectid == bytenr &&
(key.type == BTRFS_METADATA_ITEM_KEY ||
(key.type == BTRFS_EXTENT_ITEM_KEY &&
key.offset == blocksize)))
ret = 0;
}
if (ret) {
skinny = false;
btrfs_release_path(path);
goto again;
}
}
if (ret) {
ASSERT(ret == 1);
btrfs_print_leaf(path->nodes[0]);
btrfs_err(fs_info,
"tree block extent item (%llu) is not found in extent tree",
bytenr);
WARN_ON(1);
ret = -EINVAL;
goto out;
}
ret = add_tree_block(rc, &key, path, blocks);
out:
btrfs_free_path(path);
return ret;
}
static int delete_block_group_cache(struct btrfs_fs_info *fs_info,
struct btrfs_block_group *block_group,
struct inode *inode,
u64 ino)
{
struct btrfs_root *root = fs_info->tree_root;
struct btrfs_trans_handle *trans;
int ret = 0;
if (inode)
goto truncate;
inode = btrfs_iget(fs_info->sb, ino, root);
if (IS_ERR(inode))
return -ENOENT;
truncate:
ret = btrfs_check_trunc_cache_free_space(fs_info,
&fs_info->global_block_rsv);
if (ret)
goto out;
trans = btrfs_join_transaction(root);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
goto out;
}
ret = btrfs_truncate_free_space_cache(trans, block_group, inode);
btrfs_end_transaction(trans);
btrfs_btree_balance_dirty(fs_info);
out:
iput(inode);
return ret;
}
/*
* Locate the free space cache EXTENT_DATA in root tree leaf and delete the
* cache inode, to avoid free space cache data extent blocking data relocation.
*/
static int delete_v1_space_cache(struct extent_buffer *leaf,
struct btrfs_block_group *block_group,
u64 data_bytenr)
{
u64 space_cache_ino;
struct btrfs_file_extent_item *ei;
struct btrfs_key key;
bool found = false;
int i;
int ret;
if (btrfs_header_owner(leaf) != BTRFS_ROOT_TREE_OBJECTID)
return 0;
for (i = 0; i < btrfs_header_nritems(leaf); i++) {
u8 type;
btrfs_item_key_to_cpu(leaf, &key, i);
if (key.type != BTRFS_EXTENT_DATA_KEY)
continue;
ei = btrfs_item_ptr(leaf, i, struct btrfs_file_extent_item);
type = btrfs_file_extent_type(leaf, ei);
if ((type == BTRFS_FILE_EXTENT_REG ||
type == BTRFS_FILE_EXTENT_PREALLOC) &&
btrfs_file_extent_disk_bytenr(leaf, ei) == data_bytenr) {
found = true;
space_cache_ino = key.objectid;
break;
}
}
if (!found)
return -ENOENT;
ret = delete_block_group_cache(leaf->fs_info, block_group, NULL,
space_cache_ino);
return ret;
}
/*
* helper to find all tree blocks that reference a given data extent
*/
static noinline_for_stack
int add_data_references(struct reloc_control *rc,
struct btrfs_key *extent_key,
struct btrfs_path *path,
struct rb_root *blocks)
{
struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
struct ulist *leaves = NULL;
struct ulist_iterator leaf_uiter;
struct ulist_node *ref_node = NULL;
const u32 blocksize = fs_info->nodesize;
int ret = 0;
btrfs_release_path(path);
ret = btrfs_find_all_leafs(NULL, fs_info, extent_key->objectid,
0, &leaves, NULL, true);
if (ret < 0)
return ret;
ULIST_ITER_INIT(&leaf_uiter);
while ((ref_node = ulist_next(leaves, &leaf_uiter))) {
struct extent_buffer *eb;
eb = read_tree_block(fs_info, ref_node->val, 0, 0, 0, NULL);
if (IS_ERR(eb)) {
ret = PTR_ERR(eb);
break;
}
ret = delete_v1_space_cache(eb, rc->block_group,
extent_key->objectid);
free_extent_buffer(eb);
if (ret < 0)
break;
ret = __add_tree_block(rc, ref_node->val, blocksize, blocks);
if (ret < 0)
break;
}
if (ret < 0)
free_block_list(blocks);
ulist_free(leaves);
return ret;
}
/*
* helper to find next unprocessed extent
*/
static noinline_for_stack
int find_next_extent(struct reloc_control *rc, struct btrfs_path *path,
struct btrfs_key *extent_key)
{
struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
struct btrfs_key key;
struct extent_buffer *leaf;
u64 start, end, last;
int ret;
last = rc->block_group->start + rc->block_group->length;
while (1) {
cond_resched();
if (rc->search_start >= last) {
ret = 1;
break;
}
key.objectid = rc->search_start;
key.type = BTRFS_EXTENT_ITEM_KEY;
key.offset = 0;
path->search_commit_root = 1;
path->skip_locking = 1;
ret = btrfs_search_slot(NULL, rc->extent_root, &key, path,
0, 0);
if (ret < 0)
break;
next:
leaf = path->nodes[0];
if (path->slots[0] >= btrfs_header_nritems(leaf)) {
ret = btrfs_next_leaf(rc->extent_root, path);
if (ret != 0)
break;
leaf = path->nodes[0];
}
btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
if (key.objectid >= last) {
ret = 1;
break;
}
if (key.type != BTRFS_EXTENT_ITEM_KEY &&
key.type != BTRFS_METADATA_ITEM_KEY) {
path->slots[0]++;
goto next;
}
if (key.type == BTRFS_EXTENT_ITEM_KEY &&
key.objectid + key.offset <= rc->search_start) {
path->slots[0]++;
goto next;
}
if (key.type == BTRFS_METADATA_ITEM_KEY &&
key.objectid + fs_info->nodesize <=
rc->search_start) {
path->slots[0]++;
goto next;
}
ret = find_first_extent_bit(&rc->processed_blocks,
key.objectid, &start, &end,
EXTENT_DIRTY, NULL);
if (ret == 0 && start <= key.objectid) {
btrfs_release_path(path);
rc->search_start = end + 1;
} else {
if (key.type == BTRFS_EXTENT_ITEM_KEY)
rc->search_start = key.objectid + key.offset;
else
rc->search_start = key.objectid +
fs_info->nodesize;
memcpy(extent_key, &key, sizeof(key));
return 0;
}
}
btrfs_release_path(path);
return ret;
}
static void set_reloc_control(struct reloc_control *rc)
{
struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
mutex_lock(&fs_info->reloc_mutex);
fs_info->reloc_ctl = rc;
mutex_unlock(&fs_info->reloc_mutex);
}
static void unset_reloc_control(struct reloc_control *rc)
{
struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
mutex_lock(&fs_info->reloc_mutex);
fs_info->reloc_ctl = NULL;
mutex_unlock(&fs_info->reloc_mutex);
}
static noinline_for_stack
int prepare_to_relocate(struct reloc_control *rc)
{
struct btrfs_trans_handle *trans;
int ret;
rc->block_rsv = btrfs_alloc_block_rsv(rc->extent_root->fs_info,
BTRFS_BLOCK_RSV_TEMP);
if (!rc->block_rsv)
return -ENOMEM;
memset(&rc->cluster, 0, sizeof(rc->cluster));
rc->search_start = rc->block_group->start;
rc->extents_found = 0;
rc->nodes_relocated = 0;
rc->merging_rsv_size = 0;
rc->reserved_bytes = 0;
rc->block_rsv->size = rc->extent_root->fs_info->nodesize *
RELOCATION_RESERVED_NODES;
ret = btrfs_block_rsv_refill(rc->extent_root,
rc->block_rsv, rc->block_rsv->size,
BTRFS_RESERVE_FLUSH_ALL);
if (ret)
return ret;
rc->create_reloc_tree = 1;
set_reloc_control(rc);
trans = btrfs_join_transaction(rc->extent_root);
if (IS_ERR(trans)) {
unset_reloc_control(rc);
/*
* extent tree is not a ref_cow tree and has no reloc_root to
* cleanup. And callers are responsible to free the above
* block rsv.
*/
return PTR_ERR(trans);
}
return btrfs_commit_transaction(trans);
}
static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
{
struct btrfs_fs_info *fs_info = rc->extent_root->fs_info;
struct rb_root blocks = RB_ROOT;
struct btrfs_key key;
struct btrfs_trans_handle *trans = NULL;
struct btrfs_path *path;
struct btrfs_extent_item *ei;
u64 flags;
int ret;
int err = 0;
int progress = 0;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
path->reada = READA_FORWARD;
ret = prepare_to_relocate(rc);
if (ret) {
err = ret;
goto out_free;
}
while (1) {
rc->reserved_bytes = 0;
ret = btrfs_block_rsv_refill(rc->extent_root,
rc->block_rsv, rc->block_rsv->size,
BTRFS_RESERVE_FLUSH_ALL);
if (ret) {
err = ret;
break;
}
progress++;
trans = btrfs_start_transaction(rc->extent_root, 0);
if (IS_ERR(trans)) {
err = PTR_ERR(trans);
trans = NULL;
break;
}
restart:
if (update_backref_cache(trans, &rc->backref_cache)) {
btrfs_end_transaction(trans);
trans = NULL;
continue;
}
ret = find_next_extent(rc, path, &key);
if (ret < 0)
err = ret;
if (ret != 0)
break;
rc->extents_found++;
ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
struct btrfs_extent_item);
flags = btrfs_extent_flags(path->nodes[0], ei);
if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
ret = add_tree_block(rc, &key, path, &blocks);
} else if (rc->stage == UPDATE_DATA_PTRS &&
(flags & BTRFS_EXTENT_FLAG_DATA)) {
ret = add_data_references(rc, &key, path, &blocks);
} else {
btrfs_release_path(path);
ret = 0;
}
if (ret < 0) {
err = ret;
break;
}
if (!RB_EMPTY_ROOT(&blocks)) {
ret = relocate_tree_blocks(trans, rc, &blocks);
if (ret < 0) {
if (ret != -EAGAIN) {
err = ret;
break;
}
rc->extents_found--;
rc->search_start = key.objectid;
}
}
btrfs_end_transaction_throttle(trans);
btrfs_btree_balance_dirty(fs_info);
trans = NULL;
if (rc->stage == MOVE_DATA_EXTENTS &&
(flags & BTRFS_EXTENT_FLAG_DATA)) {
rc->found_file_extent = 1;
ret = relocate_data_extent(rc->data_inode,
&key, &rc->cluster);
if (ret < 0) {
err = ret;
break;
}
}
if (btrfs_should_cancel_balance(fs_info)) {
err = -ECANCELED;
break;
}
}
if (trans && progress && err == -ENOSPC) {
ret = btrfs_force_chunk_alloc(trans, rc->block_group->flags);
if (ret == 1) {
err = 0;
progress = 0;
goto restart;
}
}
btrfs_release_path(path);
clear_extent_bits(&rc->processed_blocks, 0, (u64)-1, EXTENT_DIRTY);
if (trans) {
btrfs_end_transaction_throttle(trans);
btrfs_btree_balance_dirty(fs_info);
}
if (!err) {
ret = relocate_file_extent_cluster(rc->data_inode,
&rc->cluster);
if (ret < 0)
err = ret;
}
rc->create_reloc_tree = 0;
set_reloc_control(rc);
btrfs_backref_release_cache(&rc->backref_cache);
btrfs_block_rsv_release(fs_info, rc->block_rsv, (u64)-1, NULL);
/*
* Even in the case when the relocation is cancelled, we should all go
* through prepare_to_merge() and merge_reloc_roots().
*
* For error (including cancelled balance), prepare_to_merge() will
* mark all reloc trees orphan, then queue them for cleanup in
* merge_reloc_roots()
*/
err = prepare_to_merge(rc, err);
merge_reloc_roots(rc);
rc->merge_reloc_tree = 0;
unset_reloc_control(rc);
btrfs_block_rsv_release(fs_info, rc->block_rsv, (u64)-1, NULL);
/* get rid of pinned extents */
trans = btrfs_join_transaction(rc->extent_root);
if (IS_ERR(trans)) {
err = PTR_ERR(trans);
goto out_free;
}
ret = btrfs_commit_transaction(trans);
if (ret && !err)
err = ret;
out_free:
ret = clean_dirty_subvols(rc);
if (ret < 0 && !err)
err = ret;
btrfs_free_block_rsv(fs_info, rc->block_rsv);
btrfs_free_path(path);
return err;
}
static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
struct btrfs_root *root, u64 objectid)
{
struct btrfs_path *path;
struct btrfs_inode_item *item;
struct extent_buffer *leaf;
u64 flags = BTRFS_INODE_NOCOMPRESS | BTRFS_INODE_PREALLOC;
int ret;
if (btrfs_is_zoned(trans->fs_info))
flags &= ~BTRFS_INODE_PREALLOC;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
ret = btrfs_insert_empty_inode(trans, root, path, objectid);
if (ret)
goto out;
leaf = path->nodes[0];
item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
memzero_extent_buffer(leaf, (unsigned long)item, sizeof(*item));
btrfs_set_inode_generation(leaf, item, 1);
btrfs_set_inode_size(leaf, item, 0);
btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
btrfs_set_inode_flags(leaf, item, flags);
btrfs_mark_buffer_dirty(leaf);
out:
btrfs_free_path(path);
return ret;
}
static void delete_orphan_inode(struct btrfs_trans_handle *trans,
struct btrfs_root *root, u64 objectid)
{
struct btrfs_path *path;
struct btrfs_key key;
int ret = 0;
path = btrfs_alloc_path();
if (!path) {
ret = -ENOMEM;
goto out;
}
key.objectid = objectid;
key.type = BTRFS_INODE_ITEM_KEY;
key.offset = 0;
ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
if (ret) {
if (ret > 0)
ret = -ENOENT;
goto out;
}
ret = btrfs_del_item(trans, root, path);
out:
if (ret)
btrfs_abort_transaction(trans, ret);
btrfs_free_path(path);
}
/*
* helper to create inode for data relocation.
* the inode is in data relocation tree and its link count is 0
*/
static noinline_for_stack
struct inode *create_reloc_inode(struct btrfs_fs_info *fs_info,
struct btrfs_block_group *group)
{
struct inode *inode = NULL;
struct btrfs_trans_handle *trans;
struct btrfs_root *root;
u64 objectid;
int err = 0;
root = btrfs_grab_root(fs_info->data_reloc_root);
trans = btrfs_start_transaction(root, 6);
if (IS_ERR(trans)) {
btrfs_put_root(root);
return ERR_CAST(trans);
}
err = btrfs_get_free_objectid(root, &objectid);
if (err)
goto out;
err = __insert_orphan_inode(trans, root, objectid);
if (err)
goto out;
inode = btrfs_iget(fs_info->sb, objectid, root);
if (IS_ERR(inode)) {
delete_orphan_inode(trans, root, objectid);
err = PTR_ERR(inode);
inode = NULL;
goto out;
}
BTRFS_I(inode)->index_cnt = group->start;
err = btrfs_orphan_add(trans, BTRFS_I(inode));
out:
btrfs_put_root(root);
btrfs_end_transaction(trans);
btrfs_btree_balance_dirty(fs_info);
if (err) {
if (inode)
iput(inode);
inode = ERR_PTR(err);
}
return inode;
}
static struct reloc_control *alloc_reloc_control(struct btrfs_fs_info *fs_info)
{
struct reloc_control *rc;
rc = kzalloc(sizeof(*rc), GFP_NOFS);
if (!rc)
return NULL;
INIT_LIST_HEAD(&rc->reloc_roots);
INIT_LIST_HEAD(&rc->dirty_subvol_roots);
btrfs_backref_init_cache(fs_info, &rc->backref_cache, 1);
mapping_tree_init(&rc->reloc_root_tree);
extent_io_tree_init(fs_info, &rc->processed_blocks,
IO_TREE_RELOC_BLOCKS, NULL);
return rc;
}
static void free_reloc_control(struct reloc_control *rc)
{
struct mapping_node *node, *tmp;
free_reloc_roots(&rc->reloc_roots);
rbtree_postorder_for_each_entry_safe(node, tmp,
&rc->reloc_root_tree.rb_root, rb_node)
kfree(node);
kfree(rc);
}
/*
* Print the block group being relocated
*/
static void describe_relocation(struct btrfs_fs_info *fs_info,
struct btrfs_block_group *block_group)
{
char buf[128] = {'\0'};
btrfs_describe_block_groups(block_group->flags, buf, sizeof(buf));
btrfs_info(fs_info,
"relocating block group %llu flags %s",
block_group->start, buf);
}
static const char *stage_to_string(int stage)
{
if (stage == MOVE_DATA_EXTENTS)
return "move data extents";
if (stage == UPDATE_DATA_PTRS)
return "update data pointers";
return "unknown";
}
/*
* function to relocate all extents in a block group.
*/
int btrfs_relocate_block_group(struct btrfs_fs_info *fs_info, u64 group_start)
{
struct btrfs_block_group *bg;
struct btrfs_root *extent_root = fs_info->extent_root;
struct reloc_control *rc;
struct inode *inode;
struct btrfs_path *path;
int ret;
int rw = 0;
int err = 0;
bg = btrfs_lookup_block_group(fs_info, group_start);
if (!bg)
return -ENOENT;
if (btrfs_pinned_by_swapfile(fs_info, bg)) {
btrfs_put_block_group(bg);
return -ETXTBSY;
}
rc = alloc_reloc_control(fs_info);
if (!rc) {
btrfs_put_block_group(bg);
return -ENOMEM;
}
rc->extent_root = extent_root;
rc->block_group = bg;
ret = btrfs_inc_block_group_ro(rc->block_group, true);
if (ret) {
err = ret;
goto out;
}
rw = 1;
path = btrfs_alloc_path();
if (!path) {
err = -ENOMEM;
goto out;
}
inode = lookup_free_space_inode(rc->block_group, path);
btrfs_free_path(path);
if (!IS_ERR(inode))
ret = delete_block_group_cache(fs_info, rc->block_group, inode, 0);
else
ret = PTR_ERR(inode);
if (ret && ret != -ENOENT) {
err = ret;
goto out;
}
rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
if (IS_ERR(rc->data_inode)) {
err = PTR_ERR(rc->data_inode);
rc->data_inode = NULL;
goto out;
}
describe_relocation(fs_info, rc->block_group);
btrfs_wait_block_group_reservations(rc->block_group);
btrfs_wait_nocow_writers(rc->block_group);
btrfs_wait_ordered_roots(fs_info, U64_MAX,
rc->block_group->start,
rc->block_group->length);
while (1) {
int finishes_stage;
mutex_lock(&fs_info->cleaner_mutex);
ret = relocate_block_group(rc);
mutex_unlock(&fs_info->cleaner_mutex);
if (ret < 0)
err = ret;
finishes_stage = rc->stage;
/*
* We may have gotten ENOSPC after we already dirtied some
* extents. If writeout happens while we're relocating a
* different block group we could end up hitting the
* BUG_ON(rc->stage == UPDATE_DATA_PTRS) in
* btrfs_reloc_cow_block. Make sure we write everything out
* properly so we don't trip over this problem, and then break
* out of the loop if we hit an error.
*/
if (rc->stage == MOVE_DATA_EXTENTS && rc->found_file_extent) {
ret = btrfs_wait_ordered_range(rc->data_inode, 0,
(u64)-1);
if (ret)
err = ret;
invalidate_mapping_pages(rc->data_inode->i_mapping,
0, -1);
rc->stage = UPDATE_DATA_PTRS;
}
if (err < 0)
goto out;
if (rc->extents_found == 0)
break;
btrfs_info(fs_info, "found %llu extents, stage: %s",
rc->extents_found, stage_to_string(finishes_stage));
}
WARN_ON(rc->block_group->pinned > 0);
WARN_ON(rc->block_group->reserved > 0);
WARN_ON(rc->block_group->used > 0);
out:
if (err && rw)
btrfs_dec_block_group_ro(rc->block_group);
iput(rc->data_inode);
btrfs_put_block_group(rc->block_group);
free_reloc_control(rc);
return err;
}
static noinline_for_stack int mark_garbage_root(struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct btrfs_trans_handle *trans;
int ret, err;
trans = btrfs_start_transaction(fs_info->tree_root, 0);
if (IS_ERR(trans))
return PTR_ERR(trans);
memset(&root->root_item.drop_progress, 0,
sizeof(root->root_item.drop_progress));
btrfs_set_root_drop_level(&root->root_item, 0);
btrfs_set_root_refs(&root->root_item, 0);
ret = btrfs_update_root(trans, fs_info->tree_root,
&root->root_key, &root->root_item);
err = btrfs_end_transaction(trans);
if (err)
return err;
return ret;
}
/*
* recover relocation interrupted by system crash.
*
* this function resumes merging reloc trees with corresponding fs trees.
* this is important for keeping the sharing of tree blocks
*/
int btrfs_recover_relocation(struct btrfs_root *root)
{
struct btrfs_fs_info *fs_info = root->fs_info;
LIST_HEAD(reloc_roots);
struct btrfs_key key;
struct btrfs_root *fs_root;
struct btrfs_root *reloc_root;
struct btrfs_path *path;
struct extent_buffer *leaf;
struct reloc_control *rc = NULL;
struct btrfs_trans_handle *trans;
int ret;
int err = 0;
path = btrfs_alloc_path();
if (!path)
return -ENOMEM;
path->reada = READA_BACK;
key.objectid = BTRFS_TREE_RELOC_OBJECTID;
key.type = BTRFS_ROOT_ITEM_KEY;
key.offset = (u64)-1;
while (1) {
ret = btrfs_search_slot(NULL, fs_info->tree_root, &key,
path, 0, 0);
if (ret < 0) {
err = ret;
goto out;
}
if (ret > 0) {
if (path->slots[0] == 0)
break;
path->slots[0]--;
}
leaf = path->nodes[0];
btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
btrfs_release_path(path);
if (key.objectid != BTRFS_TREE_RELOC_OBJECTID ||
key.type != BTRFS_ROOT_ITEM_KEY)
break;
reloc_root = btrfs_read_tree_root(root, &key);
if (IS_ERR(reloc_root)) {
err = PTR_ERR(reloc_root);
goto out;
}
set_bit(BTRFS_ROOT_SHAREABLE, &reloc_root->state);
list_add(&reloc_root->root_list, &reloc_roots);
if (btrfs_root_refs(&reloc_root->root_item) > 0) {
fs_root = btrfs_get_fs_root(fs_info,
reloc_root->root_key.offset, false);
if (IS_ERR(fs_root)) {
ret = PTR_ERR(fs_root);
if (ret != -ENOENT) {
err = ret;
goto out;
}
ret = mark_garbage_root(reloc_root);
if (ret < 0) {
err = ret;
goto out;
}
} else {
btrfs_put_root(fs_root);
}
}
if (key.offset == 0)
break;
key.offset--;
}
btrfs_release_path(path);
if (list_empty(&reloc_roots))
goto out;
rc = alloc_reloc_control(fs_info);
if (!rc) {
err = -ENOMEM;
goto out;
}
rc->extent_root = fs_info->extent_root;
set_reloc_control(rc);
trans = btrfs_join_transaction(rc->extent_root);
if (IS_ERR(trans)) {
err = PTR_ERR(trans);
goto out_unset;
}
rc->merge_reloc_tree = 1;
while (!list_empty(&reloc_roots)) {
reloc_root = list_entry(reloc_roots.next,
struct btrfs_root, root_list);
list_del(&reloc_root->root_list);
if (btrfs_root_refs(&reloc_root->root_item) == 0) {
list_add_tail(&reloc_root->root_list,
&rc->reloc_roots);
continue;
}
fs_root = btrfs_get_fs_root(fs_info, reloc_root->root_key.offset,
false);
if (IS_ERR(fs_root)) {
err = PTR_ERR(fs_root);
list_add_tail(&reloc_root->root_list, &reloc_roots);
btrfs_end_transaction(trans);
goto out_unset;
}
err = __add_reloc_root(reloc_root);
ASSERT(err != -EEXIST);
if (err) {
list_add_tail(&reloc_root->root_list, &reloc_roots);
btrfs_put_root(fs_root);
btrfs_end_transaction(trans);
goto out_unset;
}
fs_root->reloc_root = btrfs_grab_root(reloc_root);
btrfs_put_root(fs_root);
}
err = btrfs_commit_transaction(trans);
if (err)
goto out_unset;
merge_reloc_roots(rc);
unset_reloc_control(rc);
trans = btrfs_join_transaction(rc->extent_root);
if (IS_ERR(trans)) {
err = PTR_ERR(trans);
goto out_clean;
}
err = btrfs_commit_transaction(trans);
out_clean:
ret = clean_dirty_subvols(rc);
if (ret < 0 && !err)
err = ret;
out_unset:
unset_reloc_control(rc);
free_reloc_control(rc);
out:
free_reloc_roots(&reloc_roots);
btrfs_free_path(path);
if (err == 0) {
/* cleanup orphan inode in data relocation tree */
fs_root = btrfs_grab_root(fs_info->data_reloc_root);
ASSERT(fs_root);
err = btrfs_orphan_cleanup(fs_root);
btrfs_put_root(fs_root);
}
return err;
}
/*
* helper to add ordered checksum for data relocation.
*
* cloning checksum properly handles the nodatasum extents.
* it also saves CPU time to re-calculate the checksum.
*/
int btrfs_reloc_clone_csums(struct btrfs_inode *inode, u64 file_pos, u64 len)
{
struct btrfs_fs_info *fs_info = inode->root->fs_info;
struct btrfs_ordered_sum *sums;
struct btrfs_ordered_extent *ordered;
int ret;
u64 disk_bytenr;
u64 new_bytenr;
LIST_HEAD(list);
ordered = btrfs_lookup_ordered_extent(inode, file_pos);
BUG_ON(ordered->file_offset != file_pos || ordered->num_bytes != len);
disk_bytenr = file_pos + inode->index_cnt;
ret = btrfs_lookup_csums_range(fs_info->csum_root, disk_bytenr,
disk_bytenr + len - 1, &list, 0);
if (ret)
goto out;
while (!list_empty(&list)) {
sums = list_entry(list.next, struct btrfs_ordered_sum, list);
list_del_init(&sums->list);
/*
* We need to offset the new_bytenr based on where the csum is.
* We need to do this because we will read in entire prealloc
* extents but we may have written to say the middle of the
* prealloc extent, so we need to make sure the csum goes with
* the right disk offset.
*
* We can do this because the data reloc inode refers strictly
* to the on disk bytes, so we don't have to worry about
* disk_len vs real len like with real inodes since it's all
* disk length.
*/
new_bytenr = ordered->disk_bytenr + sums->bytenr - disk_bytenr;
sums->bytenr = new_bytenr;
btrfs_add_ordered_sum(ordered, sums);
}
out:
btrfs_put_ordered_extent(ordered);
return ret;
}
int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root, struct extent_buffer *buf,
struct extent_buffer *cow)
{
struct btrfs_fs_info *fs_info = root->fs_info;
struct reloc_control *rc;
struct btrfs_backref_node *node;
int first_cow = 0;
int level;
int ret = 0;
rc = fs_info->reloc_ctl;
if (!rc)
return 0;
BUG_ON(rc->stage == UPDATE_DATA_PTRS &&
root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID);
level = btrfs_header_level(buf);
if (btrfs_header_generation(buf) <=
btrfs_root_last_snapshot(&root->root_item))
first_cow = 1;
if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID &&
rc->create_reloc_tree) {
WARN_ON(!first_cow && level == 0);
node = rc->backref_cache.path[level];
BUG_ON(node->bytenr != buf->start &&
node->new_bytenr != buf->start);
btrfs_backref_drop_node_buffer(node);
atomic_inc(&cow->refs);
node->eb = cow;
node->new_bytenr = cow->start;
if (!node->pending) {
list_move_tail(&node->list,
&rc->backref_cache.pending[level]);
node->pending = 1;
}
if (first_cow)
mark_block_processed(rc, node);
if (first_cow && level > 0)
rc->nodes_relocated += buf->len;
}
if (level == 0 && first_cow && rc->stage == UPDATE_DATA_PTRS)
ret = replace_file_extents(trans, rc, root, cow);
return ret;
}
/*
* called before creating snapshot. it calculates metadata reservation
* required for relocating tree blocks in the snapshot
*/
void btrfs_reloc_pre_snapshot(struct btrfs_pending_snapshot *pending,
u64 *bytes_to_reserve)
{
struct btrfs_root *root = pending->root;
struct reloc_control *rc = root->fs_info->reloc_ctl;
if (!rc || !have_reloc_root(root))
return;
if (!rc->merge_reloc_tree)
return;
root = root->reloc_root;
BUG_ON(btrfs_root_refs(&root->root_item) == 0);
/*
* relocation is in the stage of merging trees. the space
* used by merging a reloc tree is twice the size of
* relocated tree nodes in the worst case. half for cowing
* the reloc tree, half for cowing the fs tree. the space
* used by cowing the reloc tree will be freed after the
* tree is dropped. if we create snapshot, cowing the fs
* tree may use more space than it frees. so we need
* reserve extra space.
*/
*bytes_to_reserve += rc->nodes_relocated;
}
/*
* called after snapshot is created. migrate block reservation
* and create reloc root for the newly created snapshot
*
* This is similar to btrfs_init_reloc_root(), we come out of here with two
* references held on the reloc_root, one for root->reloc_root and one for
* rc->reloc_roots.
*/
int btrfs_reloc_post_snapshot(struct btrfs_trans_handle *trans,
struct btrfs_pending_snapshot *pending)
{
struct btrfs_root *root = pending->root;
struct btrfs_root *reloc_root;
struct btrfs_root *new_root;
struct reloc_control *rc = root->fs_info->reloc_ctl;
int ret;
if (!rc || !have_reloc_root(root))
return 0;
rc = root->fs_info->reloc_ctl;
rc->merging_rsv_size += rc->nodes_relocated;
if (rc->merge_reloc_tree) {
ret = btrfs_block_rsv_migrate(&pending->block_rsv,
rc->block_rsv,
rc->nodes_relocated, true);
if (ret)
return ret;
}
new_root = pending->snap;
reloc_root = create_reloc_root(trans, root->reloc_root,
new_root->root_key.objectid);
if (IS_ERR(reloc_root))
return PTR_ERR(reloc_root);
ret = __add_reloc_root(reloc_root);
ASSERT(ret != -EEXIST);
if (ret) {
/* Pairs with create_reloc_root */
btrfs_put_root(reloc_root);
return ret;
}
new_root->reloc_root = btrfs_grab_root(reloc_root);
if (rc->create_reloc_tree)
ret = clone_backref_node(trans, rc, root, reloc_root);
return ret;
}
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