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d397712bcc
There were many, most are fixed now. struct-funcs.c generates some warnings but these are bogus. Signed-off-by: Chris Mason <chris.mason@oracle.com>
231 lines
5.4 KiB
C
231 lines
5.4 KiB
C
/*
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* Copyright (C) 2008 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#include <linux/sched.h>
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#include "ctree.h"
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#include "ref-cache.h"
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#include "transaction.h"
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/*
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* leaf refs are used to cache the information about which extents
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* a given leaf has references on. This allows us to process that leaf
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* in btrfs_drop_snapshot without needing to read it back from disk.
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*/
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/*
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* kmalloc a leaf reference struct and update the counters for the
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* total ref cache size
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*/
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struct btrfs_leaf_ref *btrfs_alloc_leaf_ref(struct btrfs_root *root,
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int nr_extents)
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{
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struct btrfs_leaf_ref *ref;
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size_t size = btrfs_leaf_ref_size(nr_extents);
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ref = kmalloc(size, GFP_NOFS);
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if (ref) {
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spin_lock(&root->fs_info->ref_cache_lock);
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root->fs_info->total_ref_cache_size += size;
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spin_unlock(&root->fs_info->ref_cache_lock);
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memset(ref, 0, sizeof(*ref));
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atomic_set(&ref->usage, 1);
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INIT_LIST_HEAD(&ref->list);
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}
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return ref;
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}
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/*
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* free a leaf reference struct and update the counters for the
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* total ref cache size
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*/
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void btrfs_free_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref)
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{
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if (!ref)
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return;
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WARN_ON(atomic_read(&ref->usage) == 0);
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if (atomic_dec_and_test(&ref->usage)) {
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size_t size = btrfs_leaf_ref_size(ref->nritems);
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BUG_ON(ref->in_tree);
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kfree(ref);
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spin_lock(&root->fs_info->ref_cache_lock);
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root->fs_info->total_ref_cache_size -= size;
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spin_unlock(&root->fs_info->ref_cache_lock);
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}
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}
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static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
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struct rb_node *node)
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{
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struct rb_node **p = &root->rb_node;
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struct rb_node *parent = NULL;
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struct btrfs_leaf_ref *entry;
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while (*p) {
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parent = *p;
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entry = rb_entry(parent, struct btrfs_leaf_ref, rb_node);
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if (bytenr < entry->bytenr)
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p = &(*p)->rb_left;
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else if (bytenr > entry->bytenr)
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p = &(*p)->rb_right;
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else
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return parent;
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}
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entry = rb_entry(node, struct btrfs_leaf_ref, rb_node);
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rb_link_node(node, parent, p);
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rb_insert_color(node, root);
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return NULL;
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}
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static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
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{
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struct rb_node *n = root->rb_node;
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struct btrfs_leaf_ref *entry;
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while (n) {
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entry = rb_entry(n, struct btrfs_leaf_ref, rb_node);
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WARN_ON(!entry->in_tree);
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if (bytenr < entry->bytenr)
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n = n->rb_left;
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else if (bytenr > entry->bytenr)
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n = n->rb_right;
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else
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return n;
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}
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return NULL;
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}
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int btrfs_remove_leaf_refs(struct btrfs_root *root, u64 max_root_gen,
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int shared)
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{
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struct btrfs_leaf_ref *ref = NULL;
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struct btrfs_leaf_ref_tree *tree = root->ref_tree;
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if (shared)
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tree = &root->fs_info->shared_ref_tree;
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if (!tree)
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return 0;
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spin_lock(&tree->lock);
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while (!list_empty(&tree->list)) {
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ref = list_entry(tree->list.next, struct btrfs_leaf_ref, list);
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BUG_ON(ref->tree != tree);
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if (ref->root_gen > max_root_gen)
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break;
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if (!xchg(&ref->in_tree, 0)) {
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cond_resched_lock(&tree->lock);
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continue;
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}
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rb_erase(&ref->rb_node, &tree->root);
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list_del_init(&ref->list);
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spin_unlock(&tree->lock);
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btrfs_free_leaf_ref(root, ref);
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cond_resched();
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spin_lock(&tree->lock);
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}
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spin_unlock(&tree->lock);
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return 0;
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}
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/*
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* find the leaf ref for a given extent. This returns the ref struct with
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* a usage reference incremented
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*/
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struct btrfs_leaf_ref *btrfs_lookup_leaf_ref(struct btrfs_root *root,
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u64 bytenr)
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{
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struct rb_node *rb;
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struct btrfs_leaf_ref *ref = NULL;
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struct btrfs_leaf_ref_tree *tree = root->ref_tree;
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again:
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if (tree) {
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spin_lock(&tree->lock);
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rb = tree_search(&tree->root, bytenr);
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if (rb)
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ref = rb_entry(rb, struct btrfs_leaf_ref, rb_node);
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if (ref)
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atomic_inc(&ref->usage);
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spin_unlock(&tree->lock);
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if (ref)
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return ref;
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}
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if (tree != &root->fs_info->shared_ref_tree) {
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tree = &root->fs_info->shared_ref_tree;
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goto again;
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}
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return NULL;
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}
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/*
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* add a fully filled in leaf ref struct
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* remove all the refs older than a given root generation
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*/
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int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref,
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int shared)
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{
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int ret = 0;
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struct rb_node *rb;
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struct btrfs_leaf_ref_tree *tree = root->ref_tree;
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if (shared)
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tree = &root->fs_info->shared_ref_tree;
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spin_lock(&tree->lock);
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rb = tree_insert(&tree->root, ref->bytenr, &ref->rb_node);
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if (rb) {
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ret = -EEXIST;
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} else {
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atomic_inc(&ref->usage);
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ref->tree = tree;
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ref->in_tree = 1;
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list_add_tail(&ref->list, &tree->list);
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}
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spin_unlock(&tree->lock);
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return ret;
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}
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/*
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* remove a single leaf ref from the tree. This drops the ref held by the tree
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* only
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*/
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int btrfs_remove_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref)
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{
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struct btrfs_leaf_ref_tree *tree;
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if (!xchg(&ref->in_tree, 0))
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return 0;
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tree = ref->tree;
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spin_lock(&tree->lock);
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rb_erase(&ref->rb_node, &tree->root);
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list_del_init(&ref->list);
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spin_unlock(&tree->lock);
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btrfs_free_leaf_ref(root, ref);
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return 0;
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}
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