Hello,
This patch adds shared reference cache support. The new space
balancing code plays with multiple subvols at the same time, So
the old per-subvol reference cache isn't fit for it.
Regards
Yan Zheng
---
diff -r 47aa0c51998a ctree.h
--- a/ctree.h Thu Sep 25 16:00:36 2008 +0800
+++ b/ctree.h Thu Sep 25 16:02:11 2008 +0800
@@ -80,6 +80,10 @@
/* does write ahead logging to speed up fsyncs */
#define BTRFS_TREE_LOG_OBJECTID -6ULL
#define BTRFS_TREE_LOG_FIXUP_OBJECTID -7ULL
+
+/* for space balancing */
+#define BTRFS_TREE_RELOC_OBJECTID -8ULL
+#define BTRFS_DATA_RELOC_TREE_OBJECTID -9ULL
/* dummy objectid represents multiple objectids */
#define BTRFS_MULTIPLE_OBJECTIDS -255ULL
@@ -539,6 +543,12 @@
struct list_head list;
};
+struct btrfs_leaf_ref_tree {
+ struct rb_root root;
+ struct list_head list;
+ spinlock_t lock;
+};
+
struct btrfs_device;
struct btrfs_fs_devices;
struct btrfs_fs_info {
@@ -637,6 +647,8 @@
struct task_struct *cleaner_kthread;
int thread_pool_size;
+ struct btrfs_leaf_ref_tree shared_ref_tree;
+
struct kobject super_kobj;
struct completion kobj_unregister;
int do_barriers;
@@ -668,13 +680,6 @@
u64 system_alloc_profile;
void *bdev_holder;
-};
-
-struct btrfs_leaf_ref_tree {
- struct rb_root root;
- struct btrfs_leaf_ref *last;
- struct list_head list;
- spinlock_t lock;
};
/*
diff -r 47aa0c51998a disk-io.c
--- a/disk-io.c Thu Sep 25 16:00:36 2008 +0800
+++ b/disk-io.c Thu Sep 25 16:02:11 2008 +0800
@@ -1430,6 +1430,8 @@
fs_info->btree_inode->i_mapping, GFP_NOFS);
fs_info->do_barriers = 1;
+ btrfs_leaf_ref_tree_init(&fs_info->shared_ref_tree);
+
BTRFS_I(fs_info->btree_inode)->root = tree_root;
memset(&BTRFS_I(fs_info->btree_inode)->location, 0,
sizeof(struct btrfs_key));
diff -r 47aa0c51998a extent-tree.c
--- a/extent-tree.c Thu Sep 25 16:00:36 2008 +0800
+++ b/extent-tree.c Thu Sep 25 16:02:11 2008 +0800
@@ -1091,15 +1091,25 @@
int btrfs_cache_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
struct extent_buffer *buf, u32 nr_extents)
{
- u32 nritems;
struct btrfs_key key;
struct btrfs_file_extent_item *fi;
- int i;
- int level;
- int ret = 0;
+ u64 root_gen;
+ u32 nritems;
+ int i;
+ int level;
+ int ret = 0;
+ int shared = 0;
if (!root->ref_cows)
return 0;
+
+ if (root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID) {
+ shared = 0;
+ root_gen = root->root_key.offset;
+ } else {
+ shared = 1;
+ root_gen = trans->transid - 1;
+ }
level = btrfs_header_level(buf);
nritems = btrfs_header_nritems(buf);
@@ -1114,7 +1124,7 @@
goto out;
}
- ref->root_gen = root->root_key.offset;
+ ref->root_gen = root_gen;
ref->bytenr = buf->start;
ref->owner = btrfs_header_owner(buf);
ref->generation = btrfs_header_generation(buf);
@@ -1143,8 +1153,7 @@
info++;
}
- BUG_ON(!root->ref_tree);
- ret = btrfs_add_leaf_ref(root, ref);
+ ret = btrfs_add_leaf_ref(root, ref, shared);
WARN_ON(ret);
btrfs_free_leaf_ref(root, ref);
}
diff -r 47aa0c51998a ref-cache.c
--- a/ref-cache.c Thu Sep 25 16:00:36 2008 +0800
+++ b/ref-cache.c Thu Sep 25 16:02:11 2008 +0800
@@ -78,7 +78,6 @@
}
entry = rb_entry(node, struct btrfs_leaf_ref, rb_node);
- entry->in_tree = 1;
rb_link_node(node, parent, p);
rb_insert_color(node, root);
return NULL;
@@ -103,23 +102,29 @@
return NULL;
}
-int btrfs_remove_leaf_refs(struct btrfs_root *root, u64 max_root_gen)
+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->in_tree);
+ 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);
- ref->in_tree = 0;
list_del_init(&ref->list);
spin_unlock(&tree->lock);
@@ -137,25 +142,34 @@
struct rb_node *rb;
struct btrfs_leaf_ref *ref = NULL;
struct btrfs_leaf_ref_tree *tree = root->ref_tree;
-
- if (!tree)
- return NULL;
-
- 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);
- return ref;
+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;
}
-int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref)
+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);
@@ -163,6 +177,8 @@
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);
@@ -171,13 +187,15 @@
int btrfs_remove_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref)
{
- struct btrfs_leaf_ref_tree *tree = root->ref_tree;
+ struct btrfs_leaf_ref_tree *tree;
- BUG_ON(!ref->in_tree);
+ if (!xchg(&ref->in_tree, 0))
+ return 0;
+
+ tree = ref->tree;
spin_lock(&tree->lock);
rb_erase(&ref->rb_node, &tree->root);
- ref->in_tree = 0;
list_del_init(&ref->list);
spin_unlock(&tree->lock);
diff -r 47aa0c51998a ref-cache.h
--- a/ref-cache.h Thu Sep 25 16:00:36 2008 +0800
+++ b/ref-cache.h Thu Sep 25 16:02:11 2008 +0800
@@ -27,6 +27,7 @@
struct btrfs_leaf_ref {
struct rb_node rb_node;
+ struct btrfs_leaf_ref_tree *tree;
int in_tree;
atomic_t usage;
@@ -64,8 +65,10 @@
void btrfs_free_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref);
struct btrfs_leaf_ref *btrfs_lookup_leaf_ref(struct btrfs_root *root,
u64 bytenr);
-int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref);
-int btrfs_remove_leaf_refs(struct btrfs_root *root, u64 max_root_gen);
+int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref,
+ int shared);
+int btrfs_remove_leaf_refs(struct btrfs_root *root, u64 max_root_gen,
+ int shared);
int btrfs_remove_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref);
#endif
diff -r 47aa0c51998a transaction.c
--- a/transaction.c Thu Sep 25 16:00:36 2008 +0800
+++ b/transaction.c Thu Sep 25 16:02:11 2008 +0800
@@ -650,7 +650,7 @@
ret = btrfs_end_transaction(trans, tree_root);
BUG_ON(ret);
- ret = btrfs_remove_leaf_refs(root, max_useless);
+ ret = btrfs_remove_leaf_refs(root, max_useless, 0);
BUG_ON(ret);
free_extent_buffer(dirty->root->node);
--
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