6 files changed, 71 insertions, 34 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index c683aaa925fa..b9f9f815ed09 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -81,6 +81,10 @@ struct btrfs_ordered_sum;
 #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 btrfs_block_group_cache {
         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 btrfs_fs_info {
         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;
@@ -670,13 +682,6 @@ struct btrfs_fs_info {
         void *bdev_holder;
 };
 
-struct btrfs_leaf_ref_tree {
-        struct rb_root root;
-        struct btrfs_leaf_ref *last;
-        struct list_head list;
-        spinlock_t lock;
-};
-
 /*
  * in ram representation of the tree.  extent_root is used for all allocations
  * and for the extent tree extent_root root.
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 71e81f3a765b..8969fee23318 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1406,6 +1406,8 @@ struct btrfs_root *open_ctree(struct super_block *sb,
                              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 --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 3e2f969de42d..9ab099bc01a4 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1091,16 +1091,26 @@ out:
 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;
+        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 @@ int btrfs_cache_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                         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 @@ int btrfs_cache_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                         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 --git a/fs/btrfs/ref-cache.c b/fs/btrfs/ref-cache.c
index 272b9890c982..c5809988c875 100644
--- a/fs/btrfs/ref-cache.c
+++ b/fs/btrfs/ref-cache.c
@@ -78,7 +78,6 @@ static struct rb_node *tree_insert(struct rb_root *root, u64 bytenr,
         }
 
         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 @@ static struct rb_node *tree_search(struct rb_root *root, u64 bytenr)
         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);
@@ -137,32 +142,43 @@ struct btrfs_leaf_ref *btrfs_lookup_leaf_ref(struct btrfs_root *root,
         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);
         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);
@@ -171,13 +187,15 @@ int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref)
 
 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;
+
+        if (!xchg(&ref->in_tree, 0))
+                return 0;
 
-        BUG_ON(!ref->in_tree);
+        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 --git a/fs/btrfs/ref-cache.h b/fs/btrfs/ref-cache.h
index c361b321c0c3..617564787f52 100644
--- a/fs/btrfs/ref-cache.h
+++ b/fs/btrfs/ref-cache.h
@@ -27,6 +27,7 @@ struct btrfs_extent_info {
 
 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 @@ struct btrfs_leaf_ref *btrfs_alloc_leaf_ref(struct btrfs_root *root,
 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 --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 151b00d52593..656baefa5255 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -650,7 +650,7 @@ static noinline int drop_dirty_roots(struct btrfs_root *tree_root,
                 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);