From aa6f5ffbdba45aa8e19e5048648fc6c7b25376d3 Mon Sep 17 00:00:00 2001 From: merge Date: Thu, 22 Jan 2009 13:55:32 +0000 Subject: MERGE-via-pending-tracking-hist-MERGE-via-stable-tracking-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040-1232632141 pending-tracking-hist top was MERGE-via-stable-tracking-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040-1232632141 / fdf777a63bcb59e0dfd78bfe2c6242e01f6d4eb9 ... parent commitmessage: From: merge MERGE-via-stable-tracking-hist-MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040 stable-tracking-hist top was MERGE-via-mokopatches-tracking-fix-stray-endmenu-patch-1232632040 / 90463bfd2d5a3c8b52f6e6d71024a00e052b0ced ... parent commitmessage: From: merge MERGE-via-mokopatches-tracking-hist-fix-stray-endmenu-patch mokopatches-tracking-hist top was fix-stray-endmenu-patch / 3630e0be570de8057e7f8d2fe501ed353cdf34e6 ... parent commitmessage: From: Andy Green fix-stray-endmenu.patch Signed-off-by: Andy Green --- fs/btrfs/ref-cache.c | 230 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 230 insertions(+) create mode 100644 fs/btrfs/ref-cache.c (limited to 'fs/btrfs/ref-cache.c') diff --git a/fs/btrfs/ref-cache.c b/fs/btrfs/ref-cache.c new file mode 100644 index 00000000000..6f0acc4c9ea --- /dev/null +++ b/fs/btrfs/ref-cache.c @@ -0,0 +1,230 @@ +/* + * Copyright (C) 2008 Oracle. All rights reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public + * License v2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public + * License along with this program; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 021110-1307, USA. + */ + +#include +#include "ctree.h" +#include "ref-cache.h" +#include "transaction.h" + +/* + * leaf refs are used to cache the information about which extents + * a given leaf has references on. This allows us to process that leaf + * in btrfs_drop_snapshot without needing to read it back from disk. + */ + +/* + * kmalloc a leaf reference struct and update the counters for the + * total ref cache size + */ +struct btrfs_leaf_ref *btrfs_alloc_leaf_ref(struct btrfs_root *root, + int nr_extents) +{ + struct btrfs_leaf_ref *ref; + size_t size = btrfs_leaf_ref_size(nr_extents); + + ref = kmalloc(size, GFP_NOFS); + if (ref) { + spin_lock(&root->fs_info->ref_cache_lock); + root->fs_info->total_ref_cache_size += size; + spin_unlock(&root->fs_info->ref_cache_lock); + + memset(ref, 0, sizeof(*ref)); + atomic_set(&ref->usage, 1); + INIT_LIST_HEAD(&ref->list); + } + return ref; +} + +/* + * free a leaf reference struct and update the counters for the + * total ref cache size + */ +void btrfs_free_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref) +{ + if (!ref) + return; + WARN_ON(atomic_read(&ref->usage) == 0); + if (atomic_dec_and_test(&ref->usage)) { + size_t size = btrfs_leaf_ref_size(ref->nritems); + + BUG_ON(ref->in_tree); + kfree(ref); + + spin_lock(&root->fs_info->ref_cache_lock); + root->fs_info->total_ref_cache_size -= size; + spin_unlock(&root->fs_info->ref_cache_lock); + } +} + +static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr, + struct rb_node *node) +{ + struct rb_node **p = &root->rb_node; + struct rb_node *parent = NULL; + struct btrfs_leaf_ref *entry; + + while (*p) { + parent = *p; + entry = rb_entry(parent, struct btrfs_leaf_ref, rb_node); + + if (bytenr < entry->bytenr) + p = &(*p)->rb_left; + else if (bytenr > entry->bytenr) + p = &(*p)->rb_right; + else + return parent; + } + + entry = rb_entry(node, struct btrfs_leaf_ref, rb_node); + rb_link_node(node, parent, p); + rb_insert_color(node, root); + return NULL; +} + +static struct rb_node *tree_search(struct rb_root *root, u64 bytenr) +{ + struct rb_node *n = root->rb_node; + struct btrfs_leaf_ref *entry; + + while (n) { + entry = rb_entry(n, struct btrfs_leaf_ref, rb_node); + WARN_ON(!entry->in_tree); + + if (bytenr < entry->bytenr) + n = n->rb_left; + else if (bytenr > entry->bytenr) + n = n->rb_right; + else + return n; + } + return NULL; +} + +int btrfs_remove_leaf_refs(struct btrfs_root *root, u64 max_root_gen, + int shared) +{ + struct btrfs_leaf_ref *ref = NULL; + struct btrfs_leaf_ref_tree *tree = root->ref_tree; + + if (shared) + tree = &root->fs_info->shared_ref_tree; + if (!tree) + return 0; + + spin_lock(&tree->lock); + while (!list_empty(&tree->list)) { + ref = list_entry(tree->list.next, struct btrfs_leaf_ref, list); + BUG_ON(ref->tree != tree); + if (ref->root_gen > max_root_gen) + break; + if (!xchg(&ref->in_tree, 0)) { + cond_resched_lock(&tree->lock); + continue; + } + + rb_erase(&ref->rb_node, &tree->root); + list_del_init(&ref->list); + + spin_unlock(&tree->lock); + btrfs_free_leaf_ref(root, ref); + cond_resched(); + spin_lock(&tree->lock); + } + spin_unlock(&tree->lock); + return 0; +} + +/* + * find the leaf ref for a given extent. This returns the ref struct with + * a usage reference incremented + */ +struct btrfs_leaf_ref *btrfs_lookup_leaf_ref(struct btrfs_root *root, + u64 bytenr) +{ + struct rb_node *rb; + struct btrfs_leaf_ref *ref = NULL; + struct btrfs_leaf_ref_tree *tree = root->ref_tree; +again: + if (tree) { + spin_lock(&tree->lock); + rb = tree_search(&tree->root, bytenr); + if (rb) + ref = rb_entry(rb, struct btrfs_leaf_ref, rb_node); + if (ref) + atomic_inc(&ref->usage); + spin_unlock(&tree->lock); + if (ref) + return ref; + } + if (tree != &root->fs_info->shared_ref_tree) { + tree = &root->fs_info->shared_ref_tree; + goto again; + } + return NULL; +} + +/* + * add a fully filled in leaf ref struct + * remove all the refs older than a given root generation + */ +int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref, + int shared) +{ + int ret = 0; + struct rb_node *rb; + struct btrfs_leaf_ref_tree *tree = root->ref_tree; + + if (shared) + tree = &root->fs_info->shared_ref_tree; + + spin_lock(&tree->lock); + rb = tree_insert(&tree->root, ref->bytenr, &ref->rb_node); + if (rb) { + ret = -EEXIST; + } else { + atomic_inc(&ref->usage); + ref->tree = tree; + ref->in_tree = 1; + list_add_tail(&ref->list, &tree->list); + } + spin_unlock(&tree->lock); + return ret; +} + +/* + * remove a single leaf ref from the tree. This drops the ref held by the tree + * only + */ +int btrfs_remove_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref) +{ + struct btrfs_leaf_ref_tree *tree; + + if (!xchg(&ref->in_tree, 0)) + return 0; + + tree = ref->tree; + spin_lock(&tree->lock); + + rb_erase(&ref->rb_node, &tree->root); + list_del_init(&ref->list); + + spin_unlock(&tree->lock); + + btrfs_free_leaf_ref(root, ref); + return 0; +} -- cgit v1.2.3