summaryrefslogtreecommitdiffstats
path: root/fs/btrfs/relocation.c
diff options
context:
space:
mode:
Diffstat (limited to 'fs/btrfs/relocation.c')
-rw-r--r--fs/btrfs/relocation.c4573
1 files changed, 4573 insertions, 0 deletions
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
new file mode 100644
index 0000000000..4eaac3ae5c
--- /dev/null
+++ b/fs/btrfs/relocation.c
@@ -0,0 +1,4573 @@
+// 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"
+#include "subpage.h"
+#include "zoned.h"
+#include "inode-item.h"
+#include "space-info.h"
+#include "fs.h"
+#include "accessors.h"
+#include "extent-tree.h"
+#include "root-tree.h"
+#include "file-item.h"
+#include "relocation.h"
+#include "super.h"
+#include "tree-checker.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_bit(&rc->processed_blocks, node->bytenr,
+ node->bytenr + blocksize - 1, EXTENT_DIRTY, NULL);
+ }
+ 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 = 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 btrfs_trans_handle *trans,
+ 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);
+ 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(trans, 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 read_folio
+ * 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(BTRFS_I(inode));
+ inode = find_next_inode(root, key.objectid);
+ }
+ if (inode && btrfs_ino(BTRFS_I(inode)) == key.objectid) {
+ struct extent_state *cached_state = NULL;
+
+ 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,
+ &cached_state);
+ if (!ret)
+ continue;
+
+ btrfs_drop_extent_map_range(BTRFS_I(inode),
+ key.offset, end, true);
+ unlock_extent(&BTRFS_I(inode)->io_tree,
+ key.offset, end, &cached_state);
+ }
+ }
+
+ 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);
+ btrfs_init_data_ref(&ref, btrfs_header_owner(leaf),
+ key.objectid, key.offset,
+ root->root_key.objectid, false);
+ 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);
+ btrfs_init_data_ref(&ref, btrfs_header_owner(leaf),
+ key.objectid, key.offset,
+ root->root_key.objectid, false);
+ ret = btrfs_free_extent(trans, &ref);
+ if (ret) {
+ btrfs_abort_transaction(trans, ret);
+ break;
+ }
+ }
+ if (dirty)
+ btrfs_mark_buffer_dirty(trans, leaf);
+ if (inode)
+ btrfs_add_delayed_iput(BTRFS_I(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, 0, &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;
+ set_bit(BTRFS_ROOT_RESET_LOCKDEP_CLASS, &src->state);
+ ret = btrfs_search_slot(trans, src, &key, path, 0, 1);
+ clear_bit(BTRFS_ROOT_RESET_LOCKDEP_CLASS, &src->state);
+ 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(trans, 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(trans, path->nodes[level]);
+
+ btrfs_init_generic_ref(&ref, BTRFS_ADD_DELAYED_REF, old_bytenr,
+ blocksize, path->nodes[level]->start);
+ btrfs_init_tree_ref(&ref, level - 1, src->root_key.objectid,
+ 0, true);
+ 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);
+ btrfs_init_tree_ref(&ref, level - 1, dest->root_key.objectid, 0,
+ true);
+ 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,
+ 0, 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,
+ 0, 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) {
+ struct extent_state *cached_state = NULL;
+
+ 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 read_folio to complete */
+ lock_extent(&BTRFS_I(inode)->io_tree, start, end, &cached_state);
+ btrfs_drop_extent_map_range(BTRFS_I(inode), start, end, true);
+ unlock_extent(&BTRFS_I(inode)->io_tree, start, end, &cached_state);
+ }
+ 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(fs_info, 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(fs_info, 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;
+ }
+
+ if (unlikely(root->reloc_root != reloc_root)) {
+ if (root->reloc_root) {
+ btrfs_err(fs_info,
+"reloc tree mismatch, root %lld has reloc root key (%lld %u %llu) gen %llu, expect reloc root key (%lld %u %llu) gen %llu",
+ root->root_key.objectid,
+ root->reloc_root->root_key.objectid,
+ root->reloc_root->root_key.type,
+ root->reloc_root->root_key.offset,
+ btrfs_root_generation(
+ &root->reloc_root->root_item),
+ reloc_root->root_key.objectid,
+ reloc_root->root_key.type,
+ reloc_root->root_key.offset,
+ btrfs_root_generation(
+ &reloc_root->root_item));
+ } else {
+ btrfs_err(fs_info,
+"reloc tree mismatch, root %lld has no reloc root, expect reloc root key (%lld %u %llu) gen %llu",
+ root->root_key.objectid,
+ reloc_root->root_key.objectid,
+ reloc_root->root_key.type,
+ reloc_root->root_key.offset,
+ btrfs_root_generation(
+ &reloc_root->root_item));
+ }
+ list_add(&reloc_root->root_list, &reloc_roots);
+ btrfs_put_root(root);
+ btrfs_abort_transaction(trans, -EUCLEAN);
+ if (!err)
+ err = -EUCLEAN;
+ break;
+ }
+
+ /*
+ * 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 (WARN_ON(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.
+ */
+ ret = PTR_ERR(root);
+ goto out;
+ }
+ if (WARN_ON(root->reloc_root != reloc_root)) {
+ /*
+ * This can happen if on-disk metadata has some
+ * corruption, e.g. bad reloc tree key offset.
+ */
+ 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(fs_info, 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, 0, 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, 0, 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(trans, upper->eb);
+
+ btrfs_init_generic_ref(&ref, BTRFS_ADD_DELAYED_REF,
+ node->eb->start, blocksize,
+ upper->eb->start);
+ btrfs_init_tree_ref(&ref, node->level,
+ btrfs_header_owner(upper->eb),
+ root->root_key.objectid, false);
+ 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 btrfs_tree_parent_check check = {
+ .level = block->level,
+ .owner_root = block->owner,
+ .transid = block->key.offset
+ };
+ struct extent_buffer *eb;
+
+ eb = read_tree_block(fs_info, block->bytenr, &check);
+ if (IS_ERR(eb))
+ return PTR_ERR(eb);
+ 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;
+ if (root == root->fs_info->chunk_root)
+ btrfs_reserve_chunk_metadata(trans, false);
+ ret = btrfs_search_slot(trans, root, key, path, 0, 1);
+ btrfs_release_path(path);
+ if (root == root->fs_info->chunk_root)
+ btrfs_trans_release_chunk_metadata(trans);
+ 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(trans, 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 i_size = i_size_read(&inode->vfs_inode);
+ u64 prealloc_start = cluster->start - offset;
+ u64 prealloc_end = cluster->end - offset;
+ u64 cur_offset = prealloc_start;
+
+ /*
+ * For subpage case, previous i_size may not be aligned to PAGE_SIZE.
+ * This means the range [i_size, PAGE_END + 1) is filled with zeros by
+ * btrfs_do_readpage() call of previously relocated file cluster.
+ *
+ * If the current cluster starts in the above range, btrfs_do_readpage()
+ * will skip the read, and relocate_one_page() will later writeback
+ * the padding zeros as new data, causing data corruption.
+ *
+ * Here we have to manually invalidate the range (i_size, PAGE_END + 1).
+ */
+ if (!PAGE_ALIGNED(i_size)) {
+ struct address_space *mapping = inode->vfs_inode.i_mapping;
+ struct btrfs_fs_info *fs_info = inode->root->fs_info;
+ const u32 sectorsize = fs_info->sectorsize;
+ struct page *page;
+
+ ASSERT(sectorsize < PAGE_SIZE);
+ ASSERT(IS_ALIGNED(i_size, sectorsize));
+
+ /*
+ * Subpage can't handle page with DIRTY but without UPTODATE
+ * bit as it can lead to the following deadlock:
+ *
+ * btrfs_read_folio()
+ * | Page already *locked*
+ * |- btrfs_lock_and_flush_ordered_range()
+ * |- btrfs_start_ordered_extent()
+ * |- extent_write_cache_pages()
+ * |- lock_page()
+ * We try to lock the page we already hold.
+ *
+ * Here we just writeback the whole data reloc inode, so that
+ * we will be ensured to have no dirty range in the page, and
+ * are safe to clear the uptodate bits.
+ *
+ * This shouldn't cause too much overhead, as we need to write
+ * the data back anyway.
+ */
+ ret = filemap_write_and_wait(mapping);
+ if (ret < 0)
+ return ret;
+
+ clear_extent_bits(&inode->io_tree, i_size,
+ round_up(i_size, PAGE_SIZE) - 1,
+ EXTENT_UPTODATE);
+ page = find_lock_page(mapping, i_size >> PAGE_SHIFT);
+ /*
+ * If page is freed we don't need to do anything then, as we
+ * will re-read the whole page anyway.
+ */
+ if (page) {
+ btrfs_subpage_clear_uptodate(fs_info, page, i_size,
+ round_up(i_size, PAGE_SIZE) - i_size);
+ unlock_page(page);
+ put_page(page);
+ }
+ }
+
+ BUG_ON(cluster->start != cluster->boundary[0]);
+ ret = btrfs_alloc_data_chunk_ondemand(inode,
+ prealloc_end + 1 - prealloc_start);
+ if (ret)
+ return ret;
+
+ btrfs_inode_lock(inode, 0);
+ for (nr = 0; nr < cluster->nr; nr++) {
+ struct extent_state *cached_state = NULL;
+
+ 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, &cached_state);
+ 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, &cached_state);
+ if (ret)
+ break;
+ }
+ btrfs_inode_unlock(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_relocation_extent_mapping(struct inode *inode,
+ u64 start, u64 end, u64 block_start)
+{
+ struct extent_map *em;
+ struct extent_state *cached_state = NULL;
+ 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, &cached_state);
+ ret = btrfs_replace_extent_map_range(BTRFS_I(inode), em, false);
+ unlock_extent(&BTRFS_I(inode)->io_tree, start, end, &cached_state);
+ free_extent_map(em);
+
+ 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 u64 get_cluster_boundary_end(struct file_extent_cluster *cluster,
+ int cluster_nr)
+{
+ /* Last extent, use cluster end directly */
+ if (cluster_nr >= cluster->nr - 1)
+ return cluster->end;
+
+ /* Use next boundary start*/
+ return cluster->boundary[cluster_nr + 1] - 1;
+}
+
+static int relocate_one_page(struct inode *inode, struct file_ra_state *ra,
+ struct file_extent_cluster *cluster,
+ int *cluster_nr, unsigned long page_index)
+{
+ struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+ u64 offset = BTRFS_I(inode)->index_cnt;
+ const unsigned long last_index = (cluster->end - offset) >> PAGE_SHIFT;
+ gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
+ struct page *page;
+ u64 page_start;
+ u64 page_end;
+ u64 cur;
+ int ret;
+
+ ASSERT(page_index <= last_index);
+ page = find_lock_page(inode->i_mapping, page_index);
+ if (!page) {
+ page_cache_sync_readahead(inode->i_mapping, ra, NULL,
+ page_index, last_index + 1 - page_index);
+ page = find_or_create_page(inode->i_mapping, page_index, mask);
+ if (!page)
+ return -ENOMEM;
+ }
+
+ if (PageReadahead(page))
+ page_cache_async_readahead(inode->i_mapping, ra, NULL,
+ page_folio(page), page_index,
+ last_index + 1 - page_index);
+
+ if (!PageUptodate(page)) {
+ btrfs_read_folio(NULL, page_folio(page));
+ lock_page(page);
+ if (!PageUptodate(page)) {
+ ret = -EIO;
+ goto release_page;
+ }
+ }
+
+ /*
+ * We could have lost page private when we dropped the lock to read the
+ * page above, make sure we set_page_extent_mapped here so we have any
+ * of the subpage blocksize stuff we need in place.
+ */
+ ret = set_page_extent_mapped(page);
+ if (ret < 0)
+ goto release_page;
+
+ page_start = page_offset(page);
+ page_end = page_start + PAGE_SIZE - 1;
+
+ /*
+ * Start from the cluster, as for subpage case, the cluster can start
+ * inside the page.
+ */
+ cur = max(page_start, cluster->boundary[*cluster_nr] - offset);
+ while (cur <= page_end) {
+ struct extent_state *cached_state = NULL;
+ u64 extent_start = cluster->boundary[*cluster_nr] - offset;
+ u64 extent_end = get_cluster_boundary_end(cluster,
+ *cluster_nr) - offset;
+ u64 clamped_start = max(page_start, extent_start);
+ u64 clamped_end = min(page_end, extent_end);
+ u32 clamped_len = clamped_end + 1 - clamped_start;
+
+ /* Reserve metadata for this range */
+ ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode),
+ clamped_len, clamped_len,
+ false);
+ if (ret)
+ goto release_page;
+
+ /* Mark the range delalloc and dirty for later writeback */
+ lock_extent(&BTRFS_I(inode)->io_tree, clamped_start, clamped_end,
+ &cached_state);
+ ret = btrfs_set_extent_delalloc(BTRFS_I(inode), clamped_start,
+ clamped_end, 0, &cached_state);
+ if (ret) {
+ clear_extent_bit(&BTRFS_I(inode)->io_tree,
+ clamped_start, clamped_end,
+ EXTENT_LOCKED | EXTENT_BOUNDARY,
+ &cached_state);
+ btrfs_delalloc_release_metadata(BTRFS_I(inode),
+ clamped_len, true);
+ btrfs_delalloc_release_extents(BTRFS_I(inode),
+ clamped_len);
+ goto release_page;
+ }
+ btrfs_page_set_dirty(fs_info, page, clamped_start, clamped_len);
+
+ /*
+ * Set the boundary if it's inside the page.
+ * Data relocation requires the destination extents to have the
+ * same size as the source.
+ * EXTENT_BOUNDARY bit prevents current extent from being merged
+ * with previous extent.
+ */
+ if (in_range(cluster->boundary[*cluster_nr] - offset,
+ page_start, PAGE_SIZE)) {
+ u64 boundary_start = cluster->boundary[*cluster_nr] -
+ offset;
+ u64 boundary_end = boundary_start +
+ fs_info->sectorsize - 1;
+
+ set_extent_bit(&BTRFS_I(inode)->io_tree,
+ boundary_start, boundary_end,
+ EXTENT_BOUNDARY, NULL);
+ }
+ unlock_extent(&BTRFS_I(inode)->io_tree, clamped_start, clamped_end,
+ &cached_state);
+ btrfs_delalloc_release_extents(BTRFS_I(inode), clamped_len);
+ cur += clamped_len;
+
+ /* Crossed extent end, go to next extent */
+ if (cur >= extent_end) {
+ (*cluster_nr)++;
+ /* Just finished the last extent of the cluster, exit. */
+ if (*cluster_nr >= cluster->nr)
+ break;
+ }
+ }
+ unlock_page(page);
+ put_page(page);
+
+ balance_dirty_pages_ratelimited(inode->i_mapping);
+ btrfs_throttle(fs_info);
+ if (btrfs_should_cancel_balance(fs_info))
+ ret = -ECANCELED;
+ return ret;
+
+release_page:
+ unlock_page(page);
+ put_page(page);
+ return ret;
+}
+
+static int relocate_file_extent_cluster(struct inode *inode,
+ struct file_extent_cluster *cluster)
+{
+ u64 offset = BTRFS_I(inode)->index_cnt;
+ unsigned long index;
+ unsigned long last_index;
+ struct file_ra_state *ra;
+ int cluster_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_relocation_extent_mapping(inode, cluster->start - offset,
+ cluster->end - offset, cluster->start);
+ if (ret)
+ goto out;
+
+ last_index = (cluster->end - offset) >> PAGE_SHIFT;
+ for (index = (cluster->start - offset) >> PAGE_SHIFT;
+ index <= last_index && !ret; index++)
+ ret = relocate_one_page(inode, ra, cluster, &cluster_nr, index);
+ if (ret == 0)
+ WARN_ON(cluster_nr != cluster->nr);
+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(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 {
+ btrfs_print_leaf(eb);
+ btrfs_err(rc->block_group->fs_info,
+ "unrecognized tree backref at tree block %llu slot %u",
+ eb->start, path->slots[0]);
+ btrfs_release_path(path);
+ return -EUCLEAN;
+ }
+
+ 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_backref_walk_ctx ctx = { 0 };
+ struct ulist_iterator leaf_uiter;
+ struct ulist_node *ref_node = NULL;
+ const u32 blocksize = rc->extent_root->fs_info->nodesize;
+ int ret = 0;
+
+ btrfs_release_path(path);
+
+ ctx.bytenr = extent_key->objectid;
+ ctx.skip_inode_ref_list = true;
+ ctx.fs_info = rc->extent_root->fs_info;
+
+ ret = btrfs_find_all_leafs(&ctx);
+ if (ret < 0)
+ return ret;
+
+ ULIST_ITER_INIT(&leaf_uiter);
+ while ((ref_node = ulist_next(ctx.refs, &leaf_uiter))) {
+ struct btrfs_tree_parent_check check = { 0 };
+ struct extent_buffer *eb;
+
+ eb = read_tree_block(ctx.fs_info, ref_node->val, &check);
+ 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(ctx.refs);
+ 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) {
+ bool block_found;
+
+ 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;
+ }
+
+ block_found = find_first_extent_bit(&rc->processed_blocks,
+ key.objectid, &start, &end,
+ EXTENT_DIRTY, NULL);
+
+ if (block_found && 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->fs_info,
+ 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);
+ }
+
+ ret = btrfs_commit_transaction(trans);
+ if (ret)
+ unset_reloc_control(rc);
+
+ return ret;
+}
+
+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(fs_info, 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;
+ int ret;
+
+ 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, BTRFS_INODE_NOCOMPRESS |
+ BTRFS_INODE_PREALLOC);
+ btrfs_mark_buffer_dirty(trans, 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) {
+ 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
+ */
+static int reloc_chunk_start(struct btrfs_fs_info *fs_info)
+{
+ if (test_and_set_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags)) {
+ /* This should not happen */
+ btrfs_err(fs_info, "reloc already running, cannot start");
+ return -EINPROGRESS;
+ }
+
+ 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");
+ clear_and_wake_up_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags);
+ 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);
+ 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 = btrfs_extent_root(fs_info, group_start);
+ struct reloc_control *rc;
+ struct inode *inode;
+ struct btrfs_path *path;
+ int ret;
+ int rw = 0;
+ int err = 0;
+
+ /*
+ * This only gets set if we had a half-deleted snapshot on mount. We
+ * cannot allow relocation to start while we're still trying to clean up
+ * these pending deletions.
+ */
+ ret = wait_on_bit(&fs_info->flags, BTRFS_FS_UNFINISHED_DROPS, TASK_INTERRUPTIBLE);
+ if (ret)
+ return ret;
+
+ /* We may have been woken up by close_ctree, so bail if we're closing. */
+ if (btrfs_fs_closing(fs_info))
+ return -EINTR;
+
+ bg = btrfs_lookup_block_group(fs_info, group_start);
+ if (!bg)
+ return -ENOENT;
+
+ /*
+ * Relocation of a data block group creates ordered extents. Without
+ * sb_start_write(), we can freeze the filesystem while unfinished
+ * ordered extents are left. Such ordered extents can cause a deadlock
+ * e.g. when syncfs() is waiting for their completion but they can't
+ * finish because they block when joining a transaction, due to the
+ * fact that the freeze locks are being held in write mode.
+ */
+ if (bg->flags & BTRFS_BLOCK_GROUP_DATA)
+ ASSERT(sb_write_started(fs_info->sb));
+
+ 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);
+
+ ret = btrfs_zone_finish(rc->block_group);
+ WARN_ON(ret && ret != -EAGAIN);
+
+ 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_fs_info *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(fs_info->tree_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 = btrfs_extent_root(fs_info, 0);
+
+ 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_ordered_extent *ordered)
+{
+ struct btrfs_inode *inode = BTRFS_I(ordered->inode);
+ struct btrfs_fs_info *fs_info = inode->root->fs_info;
+ u64 disk_bytenr = ordered->file_offset + inode->index_cnt;
+ struct btrfs_root *csum_root = btrfs_csum_root(fs_info, disk_bytenr);
+ LIST_HEAD(list);
+ int ret;
+
+ ret = btrfs_lookup_csums_list(csum_root, disk_bytenr,
+ disk_bytenr + ordered->num_bytes - 1,
+ &list, 0, false);
+ if (ret)
+ return ret;
+
+ while (!list_empty(&list)) {
+ struct btrfs_ordered_sum *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.
+ */
+ sums->logical = ordered->disk_bytenr + sums->logical - disk_bytenr;
+ btrfs_add_ordered_sum(ordered, sums);
+ }
+
+ return 0;
+}
+
+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 && btrfs_is_data_reloc_root(root));
+
+ 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;
+}
+
+/*
+ * Get the current bytenr for the block group which is being relocated.
+ *
+ * Return U64_MAX if no running relocation.
+ */
+u64 btrfs_get_reloc_bg_bytenr(struct btrfs_fs_info *fs_info)
+{
+ u64 logical = U64_MAX;
+
+ lockdep_assert_held(&fs_info->reloc_mutex);
+
+ if (fs_info->reloc_ctl && fs_info->reloc_ctl->block_group)
+ logical = fs_info->reloc_ctl->block_group->start;
+ return logical;
+}