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linux/fs/btrfs/relocation.c
Filipe Manana 1cea5cf0e6 btrfs: ensure relocation never runs while we have send operations running 
Relocation and send do not play well together because while send is
running a block group can be relocated, a transaction committed and
the respective disk extents get re-allocated and written to or discarded
while send is about to do something with the extents.

This was explained in commit 9e967495e0 ("Btrfs: prevent send failures
and crashes due to concurrent relocation"), which prevented balance and
send from running in parallel but it did not address one remaining case
where chunk relocation can happen: shrinking a device (and device deletion
which shrinks a device's size to 0 before deleting the device).

We also have now one more case where relocation is triggered: on zoned
filesystems partially used block groups get relocated by a background
thread, introduced in commit 18bb8bbf13 ("btrfs: zoned: automatically
reclaim zones").

So make sure that instead of preventing balance from running when there
are ongoing send operations, we prevent relocation from happening.
This uses the infrastructure recently added by a patch that has the
subject: "btrfs: add cancellable chunk relocation support".

Also it adds a spinlock used exclusively for the exclusivity between
send and relocation, as before fs_info->balance_mutex was used, which
would make an attempt to run send to block waiting for balance to
finish, which can take a lot of time on large filesystems.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2021-06-22 14:11:58 +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/relocation cancellation
*/
noinline int btrfs_should_cancel_balance(struct btrfs_fs_info *fs_info)
{
return atomic_read(&fs_info->balance_cancel_req) ||
atomic_read(&fs_info->reloc_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;
}
/*
* Mark start of chunk relocation that is cancellable. Check if the cancellation
* has been requested meanwhile and don't start in that case.
*
* Return:
* 0 success
* -EINPROGRESS operation is already in progress, that's probably a bug
* -ECANCELED cancellation request was set before the operation started
* -EAGAIN can not start because there are ongoing send operations
*/
static int reloc_chunk_start(struct btrfs_fs_info *fs_info)
{
spin_lock(&fs_info->send_reloc_lock);
if (fs_info->send_in_progress) {
btrfs_warn_rl(fs_info,
"cannot run relocation while send operations are in progress (%d in progress)",
fs_info->send_in_progress);
spin_unlock(&fs_info->send_reloc_lock);
return -EAGAIN;
}
if (test_and_set_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags)) {
/* This should not happen */
spin_unlock(&fs_info->send_reloc_lock);
btrfs_err(fs_info, "reloc already running, cannot start");
return -EINPROGRESS;
}
spin_unlock(&fs_info->send_reloc_lock);
if (atomic_read(&fs_info->reloc_cancel_req) > 0) {
btrfs_info(fs_info, "chunk relocation canceled on start");
/*
* On cancel, clear all requests but let the caller mark
* the end after cleanup operations.
*/
atomic_set(&fs_info->reloc_cancel_req, 0);
return -ECANCELED;
}
return 0;
}
/*
* Mark end of chunk relocation that is cancellable and wake any waiters.
*/
static void reloc_chunk_end(struct btrfs_fs_info *fs_info)
{
/* Requested after start, clear bit first so any waiters can continue */
if (atomic_read(&fs_info->reloc_cancel_req) > 0)
btrfs_info(fs_info, "chunk relocation canceled during operation");
spin_lock(&fs_info->send_reloc_lock);
clear_and_wake_up_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags);
spin_unlock(&fs_info->send_reloc_lock);
atomic_set(&fs_info->reloc_cancel_req, 0);
}
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;
}
ret = reloc_chunk_start(fs_info);
if (ret < 0) {
err = ret;
goto out_put_bg;
}
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);
out_put_bg:
btrfs_put_block_group(bg);
reloc_chunk_end(fs_info);
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;
}
ret = reloc_chunk_start(fs_info);
if (ret < 0) {
err = ret;
goto out_end;
}
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);
out_end:
reloc_chunk_end(fs_info);
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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