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The memory reclaiming issue happens when snapshot exists. In that case, some cache entries may not be used during old snapshot dropping, so they will remain in the cache until umount. The patch adds a field to struct btrfs_leaf_ref to record create time. Besides, the patch makes all dead roots of a given snapshot linked together in order of create time. After a old snapshot was completely dropped, we check the dead root list and remove all cache entries created before the oldest dead root in the list. Signed-off-by: Chris Mason <chris.mason@oracle.com>
188 lines
4.4 KiB
C
188 lines
4.4 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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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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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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WARN_ON(!entry->in_tree);
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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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entry->in_tree = 1;
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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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{
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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 (!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->in_tree);
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if (ref->root_gen > max_root_gen)
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break;
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rb_erase(&ref->rb_node, &tree->root);
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ref->in_tree = 0;
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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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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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if (!tree)
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return NULL;
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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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return ref;
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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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{
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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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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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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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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 = root->ref_tree;
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BUG_ON(!ref->in_tree);
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spin_lock(&tree->lock);
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rb_erase(&ref->rb_node, &tree->root);
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ref->in_tree = 0;
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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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