hash.o file-item.o inode-item.o inode-map.o disk-io.o \
           transaction.o bit-radix.o inode.o file.o tree-defrag.o \
           extent_map.o sysfs.o struct-funcs.o xattr.o ordered-data.o \
-          extent_io.o volumes.o async-thread.o ioctl.o
+          extent_io.o volumes.o async-thread.o ioctl.o locking.o
 
 btrfs-$(CONFIG_FS_POSIX_ACL)   += acl.o
 else
 
 #include "disk-io.h"
 #include "transaction.h"
 #include "print-tree.h"
+#include "locking.h"
 
 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
                      *root, struct btrfs_path *path, int level);
        int i;
        for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
                if (!p->nodes[i])
-                       break;
+                       continue;
+               if (p->locks[i]) {
+                       btrfs_tree_unlock(p->nodes[i]);
+                       p->locks[i] = 0;
+               }
                free_extent_buffer(p->nodes[i]);
        }
        memset(p, 0, sizeof(*p));
 }
 
+struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
+{
+       struct extent_buffer *eb;
+       spin_lock(&root->node_lock);
+       eb = root->node;
+       extent_buffer_get(eb);
+       spin_unlock(&root->node_lock);
+       return eb;
+}
+
+struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
+{
+       struct extent_buffer *eb;
+
+       while(1) {
+               eb = btrfs_root_node(root);
+               btrfs_tree_lock(eb);
+
+               spin_lock(&root->node_lock);
+               if (eb == root->node) {
+                       spin_unlock(&root->node_lock);
+                       break;
+               }
+               spin_unlock(&root->node_lock);
+
+               btrfs_tree_unlock(eb);
+               free_extent_buffer(eb);
+       }
+       return eb;
+}
+
 static void add_root_to_dirty_list(struct btrfs_root *root)
 {
        if (root->track_dirty && list_empty(&root->dirty_list)) {
        } else {
                first_key.objectid = 0;
        }
-       cow = __btrfs_alloc_free_block(trans, new_root, buf->len,
+       cow = btrfs_alloc_free_block(trans, new_root, buf->len,
                                       new_root_objectid,
                                       trans->transid, first_key.objectid,
                                       level, buf->start, 0);
        int ret = 0;
        int different_trans = 0;
        int level;
+       int unlock_orig = 0;
        struct btrfs_key first_key;
 
+       if (*cow_ret == buf)
+               unlock_orig = 1;
+
+       WARN_ON(!btrfs_tree_locked(buf));
+
        if (root->ref_cows) {
                root_gen = trans->transid;
        } else {
        } else {
                first_key.objectid = 0;
        }
-       cow = __btrfs_alloc_free_block(trans, root, buf->len,
+       cow = btrfs_alloc_free_block(trans, root, buf->len,
                                     root->root_key.objectid,
                                     root_gen, first_key.objectid, level,
                                     search_start, empty_size);
        }
 
        if (buf == root->node) {
+               WARN_ON(parent && parent != buf);
                root_gen = btrfs_header_generation(buf);
+
+               spin_lock(&root->node_lock);
                root->node = cow;
                extent_buffer_get(cow);
+               spin_unlock(&root->node_lock);
+
                if (buf != root->commit_root) {
                        btrfs_free_extent(trans, root, buf->start,
                                          buf->len, root->root_key.objectid,
                                  btrfs_header_owner(parent), root_gen,
                                  0, 0, 1);
        }
+       if (unlock_orig)
+               btrfs_tree_unlock(buf);
        free_extent_buffer(buf);
        btrfs_mark_buffer_dirty(cow);
        *cow_ret = cow;
        int progress_passed = 0;
        struct btrfs_disk_key disk_key;
 
+       /* FIXME this code needs locking */
+       return 0;
+
        parent_level = btrfs_header_level(parent);
        if (cache_only && parent_level != 1)
                return 0;
                return 0;
 
        mid = path->nodes[level];
+       WARN_ON(!path->locks[level]);
        WARN_ON(btrfs_header_generation(mid) != trans->transid);
 
        orig_ptr = btrfs_node_blockptr(mid, orig_slot);
 
                /* promote the child to a root */
                child = read_node_slot(root, mid, 0);
+               btrfs_tree_lock(child);
                BUG_ON(!child);
                ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
                BUG_ON(ret);
 
+               spin_lock(&root->node_lock);
                root->node = child;
+               spin_unlock(&root->node_lock);
+
                add_root_to_dirty_list(root);
+               btrfs_tree_unlock(child);
+               path->locks[level] = 0;
                path->nodes[level] = NULL;
                clean_tree_block(trans, root, mid);
+               btrfs_tree_unlock(mid);
                /* once for the path */
                free_extent_buffer(mid);
                ret = btrfs_free_extent(trans, root, mid->start, mid->len,
 
        left = read_node_slot(root, parent, pslot - 1);
        if (left) {
+               btrfs_tree_lock(left);
                wret = btrfs_cow_block(trans, root, left,
                                       parent, pslot - 1, &left);
                if (wret) {
        }
        right = read_node_slot(root, parent, pslot + 1);
        if (right) {
+               btrfs_tree_lock(right);
                wret = btrfs_cow_block(trans, root, right,
                                       parent, pslot + 1, &right);
                if (wret) {
                        u32 blocksize = right->len;
 
                        clean_tree_block(trans, root, right);
+                       btrfs_tree_unlock(right);
                        free_extent_buffer(right);
                        right = NULL;
                        wret = del_ptr(trans, root, path, level + 1, pslot +
                u64 root_gen = btrfs_header_generation(parent);
                u64 bytenr = mid->start;
                u32 blocksize = mid->len;
+
                clean_tree_block(trans, root, mid);
+               btrfs_tree_unlock(mid);
                free_extent_buffer(mid);
                mid = NULL;
                wret = del_ptr(trans, root, path, level + 1, pslot);
        if (left) {
                if (btrfs_header_nritems(left) > orig_slot) {
                        extent_buffer_get(left);
+                       /* left was locked after cow */
                        path->nodes[level] = left;
                        path->slots[level + 1] -= 1;
                        path->slots[level] = orig_slot;
-                       if (mid)
+                       if (mid) {
+                               btrfs_tree_unlock(mid);
                                free_extent_buffer(mid);
+                       }
                } else {
                        orig_slot -= btrfs_header_nritems(left);
                        path->slots[level] = orig_slot;
            btrfs_node_blockptr(path->nodes[level], path->slots[level]))
                BUG();
 enospc:
-       if (right)
+       if (right) {
+               btrfs_tree_unlock(right);
                free_extent_buffer(right);
-       if (left)
+       }
+       if (left) {
+               if (path->nodes[level] != left)
+                       btrfs_tree_unlock(left);
                free_extent_buffer(left);
+       }
        return ret;
 }
 
        /* first, try to make some room in the middle buffer */
        if (left) {
                u32 left_nr;
+
+               btrfs_tree_lock(left);
                left_nr = btrfs_header_nritems(left);
                if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
                        wret = 1;
                                path->nodes[level] = left;
                                path->slots[level + 1] -= 1;
                                path->slots[level] = orig_slot;
+                               btrfs_tree_unlock(mid);
                                free_extent_buffer(mid);
                        } else {
                                orig_slot -=
                                        btrfs_header_nritems(left);
                                path->slots[level] = orig_slot;
+                               btrfs_tree_unlock(left);
                                free_extent_buffer(left);
                        }
                        return 0;
                }
+               btrfs_tree_unlock(left);
                free_extent_buffer(left);
        }
-       right= read_node_slot(root, parent, pslot + 1);
+       right = read_node_slot(root, parent, pslot + 1);
 
        /*
         * then try to empty the right most buffer into the middle
         */
        if (right) {
                u32 right_nr;
+               btrfs_tree_lock(right);
                right_nr = btrfs_header_nritems(right);
                if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
                        wret = 1;
                                path->slots[level + 1] += 1;
                                path->slots[level] = orig_slot -
                                        btrfs_header_nritems(mid);
+                               btrfs_tree_unlock(mid);
                                free_extent_buffer(mid);
                        } else {
+                               btrfs_tree_unlock(right);
                                free_extent_buffer(right);
                        }
                        return 0;
                }
+               btrfs_tree_unlock(right);
                free_extent_buffer(right);
        }
        return 1;
                return;
 
        node = path->nodes[level];
+       WARN_ON(!path->skip_locking && !btrfs_tree_locked(node));
+
        search = btrfs_node_blockptr(node, slot);
        blocksize = btrfs_level_size(root, level - 1);
        eb = btrfs_find_tree_block(root, search, blocksize);
                        highest_read = search;
        }
 }
+
+static void unlock_up(struct btrfs_path *path, int level, int lowest_unlock)
+{
+       int i;
+       int skip_level = level;
+       struct extent_buffer *t;
+
+       for (i = level; i < BTRFS_MAX_LEVEL; i++) {
+               if (!path->nodes[i])
+                       break;
+               if (!path->locks[i])
+                       break;
+               if (path->slots[i] == 0) {
+                       skip_level = i + 1;
+                       continue;
+               }
+               if (path->keep_locks) {
+                       u32 nritems;
+                       t = path->nodes[i];
+                       nritems = btrfs_header_nritems(t);
+                       if (path->slots[i] >= nritems - 1) {
+                               skip_level = i + 1;
+                               continue;
+                       }
+               }
+               t = path->nodes[i];
+               if (i >= lowest_unlock && i > skip_level && path->locks[i]) {
+                       btrfs_tree_unlock(t);
+                       path->locks[i] = 0;
+               }
+       }
+}
+
 /*
  * look for key in the tree.  path is filled in with nodes along the way
  * if key is found, we return zero and you can find the item in the leaf
        int ret;
        int level;
        int should_reada = p->reada;
+       int lowest_unlock = 1;
        u8 lowest_level = 0;
 
        lowest_level = p->lowest_level;
        WARN_ON(lowest_level && ins_len);
        WARN_ON(p->nodes[0] != NULL);
-       WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
+       // WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
+       WARN_ON(root == root->fs_info->extent_root &&
+               !mutex_is_locked(&root->fs_info->alloc_mutex));
+       WARN_ON(root == root->fs_info->chunk_root &&
+               !mutex_is_locked(&root->fs_info->chunk_mutex));
+       WARN_ON(root == root->fs_info->dev_root &&
+               !mutex_is_locked(&root->fs_info->chunk_mutex));
+       if (ins_len < 0)
+               lowest_unlock = 2;
 again:
-       b = root->node;
-       extent_buffer_get(b);
+       if (!p->skip_locking)
+               b = btrfs_lock_root_node(root);
+       else
+               b = btrfs_root_node(root);
+
        while (b) {
                level = btrfs_header_level(b);
                if (cow) {
                        WARN_ON(1);
                level = btrfs_header_level(b);
                p->nodes[level] = b;
+               if (!p->skip_locking)
+                       p->locks[level] = 1;
                ret = check_block(root, p, level);
                if (ret)
                        return -1;
+
                ret = bin_search(b, key, level, &slot);
                if (level != 0) {
                        if (ret && slot > 0)
                                BUG_ON(btrfs_header_nritems(b) == 1);
                        }
                        /* this is only true while dropping a snapshot */
-                       if (level == lowest_level)
+                       if (level == lowest_level) {
+                               unlock_up(p, level, lowest_unlock);
                                break;
+                       }
 
                        if (should_reada)
                                reada_for_search(root, p, level, slot,
                                                 key->objectid);
 
                        b = read_node_slot(root, b, slot);
+                       if (!p->skip_locking)
+                               btrfs_tree_lock(b);
+                       unlock_up(p, level, lowest_unlock);
                } else {
                        p->slots[level] = slot;
                        if (ins_len > 0 && btrfs_leaf_free_space(root, b) <
                                if (sret)
                                        return sret;
                        }
+                       unlock_up(p, level, lowest_unlock);
                        return ret;
                }
        }
                        break;
                t = path->nodes[i];
                btrfs_set_node_key(t, key, tslot);
+               if (!btrfs_tree_locked(path->nodes[i])) {
+                       int ii;
+printk("fixup without lock on level %d\n", btrfs_header_level(path->nodes[i]));
+                       for (ii = 0; ii < BTRFS_MAX_LEVEL; ii++) {
+printk("level %d slot %d\n", ii, path->slots[ii]);
+                       }
+               }
                btrfs_mark_buffer_dirty(path->nodes[i]);
                if (tslot != 0)
                        break;
        u64 lower_gen;
        struct extent_buffer *lower;
        struct extent_buffer *c;
+       struct extent_buffer *old;
        struct btrfs_disk_key lower_key;
 
        BUG_ON(path->nodes[level]);
        else
                btrfs_node_key(lower, &lower_key, 0);
 
-       c = __btrfs_alloc_free_block(trans, root, root->nodesize,
+       c = btrfs_alloc_free_block(trans, root, root->nodesize,
                                   root->root_key.objectid,
                                   root_gen, lower_key.objectid, level,
                                   root->node->start, 0);
        if (IS_ERR(c))
                return PTR_ERR(c);
+
        memset_extent_buffer(c, 0, 0, root->nodesize);
        btrfs_set_header_nritems(c, 1);
        btrfs_set_header_level(c, level);
 
        btrfs_mark_buffer_dirty(c);
 
-       /* the super has an extra ref to root->node */
-       free_extent_buffer(root->node);
+       spin_lock(&root->node_lock);
+       old = root->node;
        root->node = c;
+       spin_unlock(&root->node_lock);
+
+       /* the super has an extra ref to root->node */
+       free_extent_buffer(old);
+
        add_root_to_dirty_list(root);
        extent_buffer_get(c);
        path->nodes[level] = c;
+       path->locks[level] = 1;
        path->slots[level] = 0;
 
        if (root->ref_cows && lower_gen != trans->transid) {
                struct btrfs_path *back_path = btrfs_alloc_path();
                int ret;
+               mutex_lock(&root->fs_info->alloc_mutex);
                ret = btrfs_insert_extent_backref(trans,
                                                  root->fs_info->extent_root,
                                                  path, lower->start,
                                                  root->root_key.objectid,
                                                  trans->transid, 0, 0);
                BUG_ON(ret);
+               mutex_unlock(&root->fs_info->alloc_mutex);
                btrfs_free_path(back_path);
        }
        return 0;
                root_gen = 0;
 
        btrfs_node_key(c, &disk_key, 0);
-       split = __btrfs_alloc_free_block(trans, root, root->nodesize,
+       split = btrfs_alloc_free_block(trans, root, root->nodesize,
                                         root->root_key.objectid,
                                         root_gen,
                                         btrfs_disk_key_objectid(&disk_key),
 
        if (path->slots[level] >= mid) {
                path->slots[level] -= mid;
+               btrfs_tree_unlock(c);
                free_extent_buffer(c);
                path->nodes[level] = split;
                path->slots[level + 1] += 1;
        } else {
+               btrfs_tree_unlock(split);
                free_extent_buffer(split);
        }
        return ret;
                return 1;
 
        right = read_node_slot(root, upper, slot + 1);
+       btrfs_tree_lock(right);
        free_space = btrfs_leaf_free_space(root, right);
-       if (free_space < data_size + sizeof(struct btrfs_item)) {
-               free_extent_buffer(right);
-               return 1;
-       }
+       if (free_space < data_size + sizeof(struct btrfs_item))
+               goto out_unlock;
 
        /* cow and double check */
        ret = btrfs_cow_block(trans, root, right, upper,
                              slot + 1, &right);
-       if (ret) {
-               free_extent_buffer(right);
-               return 1;
-       }
+       if (ret)
+               goto out_unlock;
+
        free_space = btrfs_leaf_free_space(root, right);
-       if (free_space < data_size + sizeof(struct btrfs_item)) {
-               free_extent_buffer(right);
-               return 1;
-       }
+       if (free_space < data_size + sizeof(struct btrfs_item))
+               goto out_unlock;
 
        left_nritems = btrfs_header_nritems(left);
-       if (left_nritems == 0) {
-               free_extent_buffer(right);
-               return 1;
-       }
+       if (left_nritems == 0)
+               goto out_unlock;
 
        if (empty)
                nr = 0;
                left->map_token = NULL;
        }
 
-       if (push_items == 0) {
-               free_extent_buffer(right);
-               return 1;
-       }
+       if (push_items == 0)
+               goto out_unlock;
 
        if (!empty && push_items == left_nritems)
                WARN_ON(1);
        /* then fixup the leaf pointer in the path */
        if (path->slots[0] >= left_nritems) {
                path->slots[0] -= left_nritems;
+               if (btrfs_header_nritems(path->nodes[0]) == 0)
+                       clean_tree_block(trans, root, path->nodes[0]);
+               btrfs_tree_unlock(path->nodes[0]);
                free_extent_buffer(path->nodes[0]);
                path->nodes[0] = right;
                path->slots[1] += 1;
        } else {
+               btrfs_tree_unlock(right);
                free_extent_buffer(right);
        }
        return 0;
+
+out_unlock:
+       btrfs_tree_unlock(right);
+       free_extent_buffer(right);
+       return 1;
 }
+
 /*
  * push some data in the path leaf to the left, trying to free up at
  * least data_size bytes.  returns zero if the push worked, nonzero otherwise
        }
 
        left = read_node_slot(root, path->nodes[1], slot - 1);
+       btrfs_tree_lock(left);
        free_space = btrfs_leaf_free_space(root, left);
        if (free_space < data_size + sizeof(struct btrfs_item)) {
-               free_extent_buffer(left);
-               return 1;
+               ret = 1;
+               goto out;
        }
 
        /* cow and double check */
                              path->nodes[1], slot - 1, &left);
        if (ret) {
                /* we hit -ENOSPC, but it isn't fatal here */
-               free_extent_buffer(left);
-               return 1;
+               ret = 1;
+               goto out;
        }
 
        free_space = btrfs_leaf_free_space(root, left);
        if (free_space < data_size + sizeof(struct btrfs_item)) {
-               free_extent_buffer(left);
-               return 1;
+               ret = 1;
+               goto out;
        }
 
        if (empty)
        }
 
        if (push_items == 0) {
-               free_extent_buffer(left);
-               return 1;
+               ret = 1;
+               goto out;
        }
        if (!empty && push_items == btrfs_header_nritems(right))
                WARN_ON(1);
        /* then fixup the leaf pointer in the path */
        if (path->slots[0] < push_items) {
                path->slots[0] += old_left_nritems;
+               if (btrfs_header_nritems(path->nodes[0]) == 0)
+                       clean_tree_block(trans, root, path->nodes[0]);
+               btrfs_tree_unlock(path->nodes[0]);
                free_extent_buffer(path->nodes[0]);
                path->nodes[0] = left;
                path->slots[1] -= 1;
        } else {
+               btrfs_tree_unlock(left);
                free_extent_buffer(left);
                path->slots[0] -= push_items;
        }
        BUG_ON(path->slots[0] < 0);
        return ret;
+out:
+       btrfs_tree_unlock(left);
+       free_extent_buffer(left);
+       return ret;
 }
 
 /*
 
        btrfs_item_key(l, &disk_key, 0);
 
-       right = __btrfs_alloc_free_block(trans, root, root->leafsize,
+       right = btrfs_alloc_free_block(trans, root, root->leafsize,
                                         root->root_key.objectid,
                                         root_gen, disk_key.objectid, 0,
                                         l->start, 0);
                                                  path->slots[1] + 1, 1);
                                if (wret)
                                        ret = wret;
+
+                               btrfs_tree_unlock(path->nodes[0]);
                                free_extent_buffer(path->nodes[0]);
                                path->nodes[0] = right;
                                path->slots[0] = 0;
                                                  path->slots[1], 1);
                                if (wret)
                                        ret = wret;
+                               btrfs_tree_unlock(path->nodes[0]);
                                free_extent_buffer(path->nodes[0]);
                                path->nodes[0] = right;
                                path->slots[0] = 0;
        BUG_ON(path->slots[0] != slot);
 
        if (mid <= slot) {
+               btrfs_tree_unlock(path->nodes[0]);
                free_extent_buffer(path->nodes[0]);
                path->nodes[0] = right;
                path->slots[0] -= mid;
                path->slots[1] += 1;
-       } else
+       } else {
+               btrfs_tree_unlock(right);
                free_extent_buffer(right);
+       }
 
        BUG_ON(path->slots[0] < 0);
 
                total_data += data_size[i];
        }
 
-       /* create a root if there isn't one */
-       if (!root->node)
-               BUG();
-
        total_size = total_data + (nr - 1) * sizeof(struct btrfs_item);
        ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
        if (ret == 0) {
                btrfs_print_leaf(root, leaf);
                BUG();
        }
-
 out:
        return ret;
 }
                        btrfs_set_header_level(leaf, 0);
                } else {
                        u64 root_gen = btrfs_header_generation(path->nodes[1]);
-                       clean_tree_block(trans, root, leaf);
                        wret = del_ptr(trans, root, path, 1, path->slots[1]);
                        if (wret)
                                ret = wret;
                                root_gen = btrfs_header_generation(
                                                           path->nodes[1]);
 
-                               clean_tree_block(trans, root, leaf);
-
                                wret = del_ptr(trans, root, path, 1, slot);
                                if (wret)
                                        ret = wret;
                                if (wret)
                                        ret = wret;
                        } else {
-                               btrfs_mark_buffer_dirty(leaf);
+                               /* if we're still in the path, make sure
+                                * we're dirty.  Otherwise, one of the
+                                * push_leaf functions must have already
+                                * dirtied this buffer
+                                */
+                               if (path->nodes[0] == leaf)
+                                       btrfs_mark_buffer_dirty(leaf);
                                free_extent_buffer(leaf);
                        }
                } else {
 }
 
 /*
- * walk up the tree as far as required to find the previous leaf.
+ * search the tree again to find a leaf with lesser keys
  * returns 0 if it found something or 1 if there are no lesser leaves.
  * returns < 0 on io errors.
  */
 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
 {
-       int slot;
-       int level = 1;
-       struct extent_buffer *c;
-       struct extent_buffer *next = NULL;
+       struct btrfs_key key;
+       struct btrfs_disk_key found_key;
+       int ret;
 
-       while(level < BTRFS_MAX_LEVEL) {
-               if (!path->nodes[level])
-                       return 1;
+       btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
 
-               slot = path->slots[level];
-               c = path->nodes[level];
-               if (slot == 0) {
-                       level++;
-                       if (level == BTRFS_MAX_LEVEL)
-                               return 1;
-                       continue;
-               }
-               slot--;
-
-               if (next)
-                       free_extent_buffer(next);
+       if (key.offset > 0)
+               key.offset--;
+       else if (key.type > 0)
+               key.type--;
+       else if (key.objectid > 0)
+               key.objectid--;
+       else
+               return 1;
 
-               next = read_node_slot(root, c, slot);
-               break;
-       }
-       path->slots[level] = slot;
-       while(1) {
-               level--;
-               c = path->nodes[level];
-               free_extent_buffer(c);
-               slot = btrfs_header_nritems(next);
-               if (slot != 0)
-                       slot--;
-               path->nodes[level] = next;
-               path->slots[level] = slot;
-               if (!level)
-                       break;
-               next = read_node_slot(root, next, slot);
-       }
-       return 0;
+       btrfs_release_path(root, path);
+       ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+       if (ret < 0)
+               return ret;
+       btrfs_item_key(path->nodes[0], &found_key, 0);
+       ret = comp_keys(&found_key, &key);
+       if (ret < 0)
+               return 0;
+       return 1;
 }
 
 /*
- * walk up the tree as far as required to find the next leaf.
+ * search the tree again to find a leaf with greater keys
  * returns 0 if it found something or 1 if there are no greater leaves.
  * returns < 0 on io errors.
  */
        int level = 1;
        struct extent_buffer *c;
        struct extent_buffer *next = NULL;
+       struct btrfs_key key;
+       u32 nritems;
+       int ret;
+
+       nritems = btrfs_header_nritems(path->nodes[0]);
+       if (nritems == 0) {
+               return 1;
+       }
+
+       btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
+
+       path->keep_locks = 1;
+       btrfs_release_path(root, path);
+       ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+       path->keep_locks = 0;
+
+       if (ret < 0)
+               return ret;
+
+       if (path->slots[0] < nritems - 1) {
+               goto done;
+       }
 
        while(level < BTRFS_MAX_LEVEL) {
                if (!path->nodes[level])
                c = path->nodes[level];
                if (slot >= btrfs_header_nritems(c)) {
                        level++;
-                       if (level == BTRFS_MAX_LEVEL)
+                       if (level == BTRFS_MAX_LEVEL) {
                                return 1;
+                       }
                        continue;
                }
 
-               if (next)
+               if (next) {
+                       btrfs_tree_unlock(next);
                        free_extent_buffer(next);
+               }
 
-               if (path->reada)
+               if (level == 1 && path->locks[1] && path->reada)
                        reada_for_search(root, path, level, slot, 0);
 
                next = read_node_slot(root, c, slot);
+               if (!path->skip_locking)
+                       btrfs_tree_lock(next);
                break;
        }
        path->slots[level] = slot;
        while(1) {
                level--;
                c = path->nodes[level];
+               if (path->locks[level])
+                       btrfs_tree_unlock(c);
                free_extent_buffer(c);
                path->nodes[level] = next;
                path->slots[level] = 0;
+               path->locks[level] = 1;
                if (!level)
                        break;
-               if (path->reada)
-                       reada_for_search(root, path, level, 0, 0);
+               if (level == 1 && path->locks[1] && path->reada)
+                       reada_for_search(root, path, level, slot, 0);
                next = read_node_slot(root, next, 0);
+               if (!path->skip_locking)
+                       btrfs_tree_lock(next);
        }
+done:
+       unlock_up(path, 0, 1);
        return 0;
 }
 
 
 struct btrfs_path {
        struct extent_buffer *nodes[BTRFS_MAX_LEVEL];
        int slots[BTRFS_MAX_LEVEL];
+       /* if there is real range locking, this locks field will change */
+       int locks[BTRFS_MAX_LEVEL];
        int reada;
+       /* keep some upper locks as we walk down */
+       int keep_locks;
        int lowest_level;
+       int skip_locking;
 };
 
 /*
        spinlock_t hash_lock;
        struct mutex trans_mutex;
        struct mutex fs_mutex;
+       struct mutex alloc_mutex;
+       struct mutex chunk_mutex;
        struct list_head trans_list;
        struct list_head hashers;
        struct list_head dead_roots;
  */
 struct btrfs_root {
        struct extent_buffer *node;
+
+       /* the node lock is held while changing the node pointer */
+       spinlock_t node_lock;
+
        struct extent_buffer *commit_root;
        struct btrfs_root_item root_item;
        struct btrfs_key root_key;
                                                 struct btrfs_block_group_cache
                                                 *hint, u64 search_start,
                                                 int data, int owner);
-int btrfs_inc_root_ref(struct btrfs_trans_handle *trans,
-                      struct btrfs_root *root, u64 owner_objectid);
 struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
-                                           struct btrfs_root *root, u32 size,
-                                           u64 root_objectid,
-                                           u64 hint, u64 empty_size);
-struct extent_buffer *__btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
                                             struct btrfs_root *root,
                                             u32 blocksize,
                                             u64 root_objectid,
                                             int level,
                                             u64 hint,
                                             u64 empty_size);
-int btrfs_grow_extent_tree(struct btrfs_trans_handle *trans,
-                          struct btrfs_root *root, u64 new_size);
 int btrfs_shrink_extent_tree(struct btrfs_root *root, u64 new_size);
 int btrfs_insert_extent_backref(struct btrfs_trans_handle *trans,
                                 struct btrfs_root *root,
 int btrfs_previous_item(struct btrfs_root *root,
                        struct btrfs_path *path, u64 min_objectid,
                        int type);
+
+struct extent_buffer *btrfs_root_node(struct btrfs_root *root);
+struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root);
+
 int btrfs_cow_block(struct btrfs_trans_handle *trans,
                    struct btrfs_root *root, struct extent_buffer *buf,
                    struct extent_buffer *parent, int parent_slot,
 
 #include "volumes.h"
 #include "print-tree.h"
 #include "async-thread.h"
+#include "locking.h"
 
 #if 0
 static int check_tree_block(struct btrfs_root *root, struct extent_buffer *buf)
 {
        struct inode *btree_inode = root->fs_info->btree_inode;
        if (btrfs_header_generation(buf) ==
-           root->fs_info->running_transaction->transid)
+           root->fs_info->running_transaction->transid) {
+               WARN_ON(!btrfs_tree_locked(buf));
                clear_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree,
                                          buf);
+       }
        return 0;
 }
 
        root->in_sysfs = 0;
 
        INIT_LIST_HEAD(&root->dirty_list);
+       spin_lock_init(&root->node_lock);
        memset(&root->root_key, 0, sizeof(root->root_key));
        memset(&root->root_item, 0, sizeof(root->root_item));
        memset(&root->defrag_progress, 0, sizeof(root->defrag_progress));
 
        mutex_init(&fs_info->trans_mutex);
        mutex_init(&fs_info->fs_mutex);
+       mutex_init(&fs_info->alloc_mutex);
+       mutex_init(&fs_info->chunk_mutex);
 
 #if 0
        ret = add_hasher(fs_info, "crc32c");
 
        mutex_lock(&fs_info->fs_mutex);
 
+       mutex_lock(&fs_info->chunk_mutex);
        ret = btrfs_read_sys_array(tree_root);
+       mutex_unlock(&fs_info->chunk_mutex);
        if (ret) {
                printk("btrfs: failed to read the system array on %s\n",
                       sb->s_id);
                 (unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node),
                 BTRFS_UUID_SIZE);
 
+       mutex_lock(&fs_info->chunk_mutex);
        ret = btrfs_read_chunk_tree(chunk_root);
+       mutex_unlock(&fs_info->chunk_mutex);
        BUG_ON(ret);
 
        btrfs_close_extra_devices(fs_devices);
        u64 transid = btrfs_header_generation(buf);
        struct inode *btree_inode = root->fs_info->btree_inode;
 
+       WARN_ON(!btrfs_tree_locked(buf));
        if (transid != root->fs_info->generation) {
                printk(KERN_CRIT "transid mismatch buffer %llu, found %Lu running %Lu\n",
                        (unsigned long long)buf->start,
 
 #include "print-tree.h"
 #include "transaction.h"
 #include "volumes.h"
+#include "locking.h"
 
 #define BLOCK_GROUP_DATA     EXTENT_WRITEBACK
 #define BLOCK_GROUP_METADATA EXTENT_UPTODATE
                                 btrfs_root *extent_root);
 static int del_pending_extents(struct btrfs_trans_handle *trans, struct
                               btrfs_root *extent_root);
+static struct btrfs_block_group_cache *
+__btrfs_find_block_group(struct btrfs_root *root,
+                        struct btrfs_block_group_cache *hint,
+                        u64 search_start, int data, int owner);
 
+void maybe_lock_mutex(struct btrfs_root *root)
+{
+       if (root != root->fs_info->extent_root &&
+           root != root->fs_info->chunk_root &&
+           root != root->fs_info->dev_root) {
+               mutex_lock(&root->fs_info->alloc_mutex);
+       }
+}
+
+void maybe_unlock_mutex(struct btrfs_root *root)
+{
+       if (root != root->fs_info->extent_root &&
+           root != root->fs_info->chunk_root &&
+           root != root->fs_info->dev_root) {
+               mutex_unlock(&root->fs_info->alloc_mutex);
+       }
+}
 
 static int cache_block_group(struct btrfs_root *root,
                             struct btrfs_block_group_cache *block_group)
                return -ENOMEM;
 
        path->reada = 2;
+       path->skip_locking = 1;
        first_free = block_group->key.objectid;
        key.objectid = block_group->key.objectid;
        key.offset = 0;
                cache = btrfs_lookup_first_block_group(root->fs_info, last);
        }
        cache_miss = 0;
-       cache = btrfs_find_block_group(root, cache, last, data, 0);
+       cache = __btrfs_find_block_group(root, cache, last, data, 0);
        if (!cache)
                goto no_cache;
        *cache_ret = cache;
        return bits;
 }
 
-struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
-                                                struct btrfs_block_group_cache
-                                                *hint, u64 search_start,
-                                                int data, int owner)
+static struct btrfs_block_group_cache *
+__btrfs_find_block_group(struct btrfs_root *root,
+                        struct btrfs_block_group_cache *hint,
+                        u64 search_start, int data, int owner)
 {
        struct btrfs_block_group_cache *cache;
        struct extent_io_tree *block_group_cache;
        return found_group;
 }
 
+struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
+                                                struct btrfs_block_group_cache
+                                                *hint, u64 search_start,
+                                                int data, int owner)
+{
+
+       struct btrfs_block_group_cache *ret;
+       mutex_lock(&root->fs_info->alloc_mutex);
+       ret = __btrfs_find_block_group(root, hint, search_start, data, owner);
+       mutex_unlock(&root->fs_info->alloc_mutex);
+       return ret;
+}
 static u64 hash_extent_ref(u64 root_objectid, u64 ref_generation,
                           u64 owner, u64 owner_offset)
 {
        return ret;
 }
 
-int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
+static int __btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
                                struct btrfs_root *root,
                                u64 bytenr, u64 num_bytes,
                                u64 root_objectid, u64 ref_generation,
        return 0;
 }
 
+int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
+                               struct btrfs_root *root,
+                               u64 bytenr, u64 num_bytes,
+                               u64 root_objectid, u64 ref_generation,
+                               u64 owner, u64 owner_offset)
+{
+       int ret;
+
+       mutex_lock(&root->fs_info->alloc_mutex);
+       ret = __btrfs_inc_extent_ref(trans, root, bytenr, num_bytes,
+                                    root_objectid, ref_generation,
+                                    owner, owner_offset);
+       mutex_unlock(&root->fs_info->alloc_mutex);
+       return ret;
+}
+
 int btrfs_extent_post_op(struct btrfs_trans_handle *trans,
                         struct btrfs_root *root)
 {
        struct btrfs_extent_ref *ref_item;
        int level = -1;
 
+       /* FIXME, needs locking */
+       BUG();
+
+       mutex_lock(&root->fs_info->alloc_mutex);
        path = btrfs_alloc_path();
 again:
        if (level == -1)
 
 out:
        btrfs_free_path(path);
+       mutex_unlock(&root->fs_info->alloc_mutex);
        return total_count;
 }
-int btrfs_inc_root_ref(struct btrfs_trans_handle *trans,
-                      struct btrfs_root *root, u64 owner_objectid)
-{
-       u64 generation;
-       u64 key_objectid;
-       u64 level;
-       u32 nritems;
-       struct btrfs_disk_key disk_key;
-
-       level = btrfs_header_level(root->node);
-       generation = trans->transid;
-       nritems = btrfs_header_nritems(root->node);
-       if (nritems > 0) {
-               if (level == 0)
-                       btrfs_item_key(root->node, &disk_key, 0);
-               else
-                       btrfs_node_key(root->node, &disk_key, 0);
-               key_objectid = btrfs_disk_key_objectid(&disk_key);
-       } else {
-               key_objectid = 0;
-       }
-       return btrfs_inc_extent_ref(trans, root, root->node->start,
-                                   root->node->len, owner_objectid,
-                                   generation, level, key_objectid);
-}
 
 int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
                  struct extent_buffer *buf)
        if (!root->ref_cows)
                return 0;
 
+       mutex_lock(&root->fs_info->alloc_mutex);
        level = btrfs_header_level(buf);
        nritems = btrfs_header_nritems(buf);
        for (i = 0; i < nritems; i++) {
                        disk_bytenr = btrfs_file_extent_disk_bytenr(buf, fi);
                        if (disk_bytenr == 0)
                                continue;
-                       ret = btrfs_inc_extent_ref(trans, root, disk_bytenr,
+                       ret = __btrfs_inc_extent_ref(trans, root, disk_bytenr,
                                    btrfs_file_extent_disk_num_bytes(buf, fi),
                                    root->root_key.objectid, trans->transid,
                                    key.objectid, key.offset);
                } else {
                        bytenr = btrfs_node_blockptr(buf, i);
                        btrfs_node_key_to_cpu(buf, &key, i);
-                       ret = btrfs_inc_extent_ref(trans, root, bytenr,
+                       ret = __btrfs_inc_extent_ref(trans, root, bytenr,
                                           btrfs_level_size(root, level - 1),
                                           root->root_key.objectid,
                                           trans->transid,
                        }
                }
        }
+       mutex_unlock(&root->fs_info->alloc_mutex);
        return 0;
 fail:
        WARN_ON(1);
                }
        }
 #endif
+       mutex_unlock(&root->fs_info->alloc_mutex);
        return ret;
 }
 
        if (!path)
                return -ENOMEM;
 
+       mutex_lock(&root->fs_info->alloc_mutex);
        while(1) {
                ret = find_first_extent_bit(block_group_cache, last,
                                            &start, &end, BLOCK_GROUP_DIRTY);
                                  BLOCK_GROUP_DIRTY, GFP_NOFS);
        }
        btrfs_free_path(path);
+       mutex_unlock(&root->fs_info->alloc_mutex);
        return werr;
 }
 
                space_info->force_alloc = 0;
        }
        if (space_info->full)
-               return 0;
+               goto out;
 
        thresh = div_factor(space_info->total_bytes, 6);
        if (!force &&
           (space_info->bytes_used + space_info->bytes_pinned + alloc_bytes) <
            thresh)
-               return 0;
+               goto out;
 
+       mutex_lock(&extent_root->fs_info->chunk_mutex);
        ret = btrfs_alloc_chunk(trans, extent_root, &start, &num_bytes, flags);
        if (ret == -ENOSPC) {
 printk("space info full %Lu\n", flags);
                space_info->full = 1;
-               return 0;
+               goto out;
        }
        BUG_ON(ret);
 
        ret = btrfs_make_block_group(trans, extent_root, 0, flags,
                     BTRFS_FIRST_CHUNK_TREE_OBJECTID, start, num_bytes);
        BUG_ON(ret);
-
+       mutex_unlock(&extent_root->fs_info->chunk_mutex);
+out:
        return 0;
 }
 
        struct extent_io_tree *free_space_cache;
        free_space_cache = &root->fs_info->free_space_cache;
 
+       mutex_lock(&root->fs_info->alloc_mutex);
        while(1) {
                ret = find_first_extent_bit(unpin, 0, &start, &end,
                                            EXTENT_DIRTY);
                clear_extent_dirty(unpin, start, end, GFP_NOFS);
                set_extent_dirty(free_space_cache, start, end, GFP_NOFS);
        }
+       mutex_unlock(&root->fs_info->alloc_mutex);
        return 0;
 }
 
                                  GFP_NOFS);
                eb = read_tree_block(extent_root, ins.objectid, ins.offset,
                                     trans->transid);
+               btrfs_tree_lock(eb);
                level = btrfs_header_level(eb);
                if (level == 0) {
                        btrfs_item_key(eb, &first, 0);
                } else {
                        btrfs_node_key(eb, &first, 0);
                }
+               btrfs_tree_unlock(eb);
+               free_extent_buffer(eb);
+               /*
+                * the first key is just a hint, so the race we've created
+                * against reading it is fine
+                */
                err = btrfs_insert_extent_backref(trans, extent_root, path,
                                          start, extent_root->root_key.objectid,
                                          0, level,
                                          btrfs_disk_key_objectid(&first));
                BUG_ON(err);
-               free_extent_buffer(eb);
        }
        btrfs_free_path(path);
        return 0;
                          int pending)
 {
        int err = 0;
-       struct extent_buffer *buf;
 
        if (!pending) {
+#if 0
+               struct extent_buffer *buf;
                buf = btrfs_find_tree_block(root, bytenr, num_bytes);
                if (buf) {
-                       if (btrfs_buffer_uptodate(buf, 0)) {
+                       if (!btrfs_try_tree_lock(buf) &&
+                           btrfs_buffer_uptodate(buf, 0)) {
                                u64 transid =
                                    root->fs_info->running_transaction->transid;
                                u64 header_transid =
                                    !btrfs_header_flag(buf,
                                               BTRFS_HEADER_FLAG_WRITTEN)) {
                                        clean_tree_block(NULL, root, buf);
+                                       btrfs_tree_unlock(buf);
                                        free_extent_buffer(buf);
                                        return 1;
                                }
+                               btrfs_tree_unlock(buf);
                        }
                        free_extent_buffer(buf);
                }
+#endif
                update_pinned_extents(root, bytenr, num_bytes, 1);
        } else {
                set_extent_bits(&root->fs_info->pending_del,
 /*
  * remove an extent from the root, returns 0 on success
  */
-int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
-                     *root, u64 bytenr, u64 num_bytes,
-                     u64 root_objectid, u64 ref_generation,
-                     u64 owner_objectid, u64 owner_offset, int pin)
+static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
+                              struct btrfs_root *root, u64 bytenr,
+                              u64 num_bytes, u64 root_objectid,
+                              u64 ref_generation, u64 owner_objectid,
+                              u64 owner_offset, int pin)
 {
        struct btrfs_root *extent_root = root->fs_info->extent_root;
        int pending_ret;
        return ret ? ret : pending_ret;
 }
 
+int btrfs_free_extent(struct btrfs_trans_handle *trans,
+                     struct btrfs_root *root, u64 bytenr,
+                     u64 num_bytes, u64 root_objectid,
+                     u64 ref_generation, u64 owner_objectid,
+                     u64 owner_offset, int pin)
+{
+       int ret;
+
+       maybe_lock_mutex(root);
+       ret = __btrfs_free_extent(trans, root, bytenr, num_bytes,
+                                 root_objectid, ref_generation,
+                                 owner_objectid, owner_offset, pin);
+       maybe_unlock_mutex(root);
+       return ret;
+}
+
 static u64 stripe_align(struct btrfs_root *root, u64 val)
 {
        u64 mask = ((u64)root->stripesize - 1);
                block_group = btrfs_lookup_first_block_group(info, hint_byte);
                if (!block_group)
                        hint_byte = search_start;
-               block_group = btrfs_find_block_group(root, block_group,
+               block_group = __btrfs_find_block_group(root, block_group,
                                                     hint_byte, data, 1);
                if (last_ptr && *last_ptr == 0 && block_group)
                        hint_byte = block_group->key.objectid;
        } else {
-               block_group = btrfs_find_block_group(root,
+               block_group = __btrfs_find_block_group(root,
                                                     trans->block_group,
                                                     search_start, data, 1);
        }
        }
        block_group = btrfs_lookup_first_block_group(info, search_start);
        cond_resched();
-       block_group = btrfs_find_block_group(root, block_group,
+       block_group = __btrfs_find_block_group(root, block_group,
                                             search_start, data, 0);
        goto check_failed;
 
        struct btrfs_path *path;
        struct btrfs_key keys[2];
 
+       maybe_lock_mutex(root);
+
        if (data) {
                alloc_profile = info->avail_data_alloc_bits &
                                info->data_alloc_profile;
        if (ret) {
                printk("allocation failed flags %Lu\n", data);
        }
-       BUG_ON(ret);
-       if (ret)
-               return ret;
+       if (ret) {
+               BUG();
+               goto out;
+       }
 
        /* block accounting for super block */
        super_used = btrfs_super_bytes_used(&info->super_copy);
        finish_current_insert(trans, extent_root);
        pending_ret = del_pending_extents(trans, extent_root);
 
-       if (ret) {
-               return ret;
-       }
+       if (ret)
+               goto out;
        if (pending_ret) {
-               return pending_ret;
+               ret = pending_ret;
+               goto out;
        }
 
 update_block:
                       ins->objectid, ins->offset);
                BUG();
        }
-       return 0;
+out:
+       maybe_unlock_mutex(root);
+       return ret;
 }
-
 /*
  * helper function to allocate a block for a given tree
  * returns the tree buffer or NULL.
  */
 struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
-                                            struct btrfs_root *root,
-                                            u32 blocksize,
-                                            u64 root_objectid, u64 hint,
-                                            u64 empty_size)
-{
-       u64 ref_generation;
-
-       if (root->ref_cows)
-               ref_generation = trans->transid;
-       else
-               ref_generation = 0;
-
-
-       return __btrfs_alloc_free_block(trans, root, blocksize, root_objectid,
-                                       ref_generation, 0, 0, hint, empty_size);
-}
-
-/*
- * helper function to allocate a block for a given tree
- * returns the tree buffer or NULL.
- */
-struct extent_buffer *__btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
                                             struct btrfs_root *root,
                                             u32 blocksize,
                                             u64 root_objectid,
                return ERR_PTR(-ENOMEM);
        }
        btrfs_set_header_generation(buf, trans->transid);
+       btrfs_tree_lock(buf);
        clean_tree_block(trans, root, buf);
        btrfs_set_buffer_uptodate(buf);
 
                disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
                if (disk_bytenr == 0)
                        continue;
-               ret = btrfs_free_extent(trans, root, disk_bytenr,
+               ret = __btrfs_free_extent(trans, root, disk_bytenr,
                                btrfs_file_extent_disk_num_bytes(leaf, fi),
                                leaf_owner, leaf_generation,
                                key.objectid, key.offset, 0);
        int ret;
        u32 refs;
 
+       mutex_lock(&root->fs_info->alloc_mutex);
+
        WARN_ON(*level < 0);
        WARN_ON(*level >= BTRFS_MAX_LEVEL);
        ret = lookup_extent_ref(trans, root,
                bytenr = btrfs_node_blockptr(cur, path->slots[*level]);
                ptr_gen = btrfs_node_ptr_generation(cur, path->slots[*level]);
                blocksize = btrfs_level_size(root, *level - 1);
+
                ret = lookup_extent_ref(trans, root, bytenr, blocksize, &refs);
                BUG_ON(ret);
                if (refs != 1) {
                        root_owner = btrfs_header_owner(parent);
                        root_gen = btrfs_header_generation(parent);
                        path->slots[*level]++;
-                       ret = btrfs_free_extent(trans, root, bytenr,
+                       ret = __btrfs_free_extent(trans, root, bytenr,
                                                blocksize, root_owner,
                                                root_gen, 0, 0, 1);
                        BUG_ON(ret);
                        reada_walk_down(root, cur, path->slots[*level]);
 
                        mutex_unlock(&root->fs_info->fs_mutex);
+                       mutex_unlock(&root->fs_info->alloc_mutex);
                        next = read_tree_block(root, bytenr, blocksize,
                                               ptr_gen);
                        mutex_lock(&root->fs_info->fs_mutex);
+                       mutex_lock(&root->fs_info->alloc_mutex);
 
                        /* we've dropped the lock, double check */
                        ret = lookup_extent_ref(trans, root, bytenr,
 
                                path->slots[*level]++;
                                free_extent_buffer(next);
-                               ret = btrfs_free_extent(trans, root, bytenr,
+                               ret = __btrfs_free_extent(trans, root, bytenr,
                                                        blocksize,
                                                        root_owner,
                                                        root_gen, 0, 0, 1);
        }
 
        root_gen = btrfs_header_generation(parent);
-       ret = btrfs_free_extent(trans, root, path->nodes[*level]->start,
+       ret = __btrfs_free_extent(trans, root, path->nodes[*level]->start,
                                path->nodes[*level]->len,
                                root_owner, root_gen, 0, 0, 1);
        free_extent_buffer(path->nodes[*level]);
        path->nodes[*level] = NULL;
        *level += 1;
        BUG_ON(ret);
+       mutex_unlock(&root->fs_info->alloc_mutex);
        return 0;
 }
 
                btrfs_node_key(node, &found_key, path->slots[level]);
                WARN_ON(memcmp(&found_key, &root_item->drop_progress,
                               sizeof(found_key)));
+               for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
+                       if (path->nodes[i] && path->locks[i]) {
+                               path->locks[i] = 0;
+                               btrfs_tree_unlock(path->nodes[i]);
+                       }
+               }
        }
        while(1) {
                wret = walk_down_tree(trans, root, path, &level);
        u64 end;
        u64 ptr;
        int ret;
+
+       mutex_lock(&info->alloc_mutex);
        while(1) {
                ret = find_first_extent_bit(&info->block_group_cache, 0,
                                            &start, &end, (unsigned int)-1);
                clear_extent_dirty(&info->free_space_cache, start,
                                   end, GFP_NOFS);
        }
+       mutex_unlock(&info->alloc_mutex);
        return 0;
 }
 
 
                eb = read_tree_block(found_root, extent_key->objectid,
                                     extent_key->offset, 0);
+               btrfs_tree_lock(eb);
                level = btrfs_header_level(eb);
 
                if (level == 0)
                else
                        btrfs_node_key_to_cpu(eb, &found_key, 0);
 
+               btrfs_tree_unlock(eb);
                free_extent_buffer(eb);
 
                ret = find_root_for_ref(extent_root, path, &found_key,
        int ret;
        int progress;
 
+       mutex_lock(&root->fs_info->alloc_mutex);
        shrink_block_group = btrfs_lookup_block_group(root->fs_info,
                                                      shrink_start);
        BUG_ON(!shrink_block_group);
                           (unsigned int)-1, GFP_NOFS);
 out:
        btrfs_free_path(path);
+       mutex_unlock(&root->fs_info->alloc_mutex);
        return ret;
 }
 
 int find_first_block_group(struct btrfs_root *root, struct btrfs_path *path,
                           struct btrfs_key *key)
 {
-       int ret;
+       int ret = 0;
        struct btrfs_key found_key;
        struct extent_buffer *leaf;
        int slot;
 
        ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
        if (ret < 0)
-               return ret;
+               goto out;
+
        while(1) {
                slot = path->slots[0];
                leaf = path->nodes[0];
                        if (ret == 0)
                                continue;
                        if (ret < 0)
-                               goto error;
+                               goto out;
                        break;
                }
                btrfs_item_key_to_cpu(leaf, &found_key, slot);
 
                if (found_key.objectid >= key->objectid &&
-                   found_key.type == BTRFS_BLOCK_GROUP_ITEM_KEY)
-                       return 0;
+                   found_key.type == BTRFS_BLOCK_GROUP_ITEM_KEY) {
+                       ret = 0;
+                       goto out;
+               }
                path->slots[0]++;
        }
        ret = -ENOENT;
-error:
+out:
        return ret;
 }
 
        if (!path)
                return -ENOMEM;
 
+       mutex_lock(&root->fs_info->alloc_mutex);
        while(1) {
                ret = find_first_block_group(root, path, &key);
                if (ret > 0) {
        ret = 0;
 error:
        btrfs_free_path(path);
+       mutex_unlock(&root->fs_info->alloc_mutex);
        return ret;
 }
 
        ret = del_pending_extents(trans, extent_root);
        BUG_ON(ret);
        set_avail_alloc_bits(extent_root->fs_info, type);
+
        return 0;
 }
 
 
        for (i = 0; i < num_pages; i++) {
                page = extent_buffer_page(eb, i);
-               lock_page(page);
                if (i == 0)
                        set_page_extent_head(page, eb->len);
                else
                        end  = start + PAGE_CACHE_SIZE - 1;
                        if (test_range_bit(tree, start, end,
                                           EXTENT_DIRTY, 0)) {
-                               unlock_page(page);
                                continue;
                        }
                }
                                                PAGECACHE_TAG_DIRTY);
                }
                read_unlock_irq(&page->mapping->tree_lock);
-               unlock_page(page);
        }
        return 0;
 }
                 * on us if the page isn't already dirty.
                 */
                if (i == 0) {
-                       lock_page(page);
                        set_page_extent_head(page, eb->len);
                } else if (PagePrivate(page) &&
                           page->private != EXTENT_PAGE_PRIVATE) {
-                       lock_page(page);
                        set_page_extent_mapped(page);
-                       unlock_page(page);
                }
                __set_page_dirty_nobuffers(extent_buffer_page(eb, i));
-               if (i == 0)
-                       unlock_page(page);
        }
        return set_extent_dirty(tree, eb->start,
                                eb->start + eb->len - 1, GFP_NOFS);
 
        trans = btrfs_start_transaction(root, 1);
        BUG_ON(!trans);
        btrfs_set_trans_block_group(trans, inode);
+       mutex_unlock(&root->fs_info->fs_mutex);
 
        num_bytes = (end - start + blocksize) & ~(blocksize - 1);
        num_bytes = max(blocksize,  num_bytes);
        btrfs_add_ordered_inode(inode);
        btrfs_update_inode(trans, root, inode);
 out:
+       mutex_lock(&root->fs_info->fs_mutex);
        btrfs_end_transaction(trans, root);
        return ret;
 }
 
        mutex_lock(&root->fs_info->fs_mutex);
        trans = btrfs_start_transaction(root, 1);
+       mutex_unlock(&root->fs_info->fs_mutex);
 
        btrfs_set_trans_block_group(trans, inode);
        btrfs_csum_file_blocks(trans, root, inode, bio, sums);
 
+       mutex_lock(&root->fs_info->fs_mutex);
        ret = btrfs_end_transaction(trans, root);
        BUG_ON(ret);
        mutex_unlock(&root->fs_info->fs_mutex);
                goto err;
        }
        ret = btrfs_delete_one_dir_name(trans, root, path, di);
+       btrfs_release_path(root, path);
 
        dentry->d_inode->i_ctime = dir->i_ctime;
        ret = btrfs_del_inode_ref(trans, root, name, name_len,
        struct btrfs_trans_handle *trans;
        unsigned long nr = 0;
 
-       if (inode->i_size > BTRFS_EMPTY_DIR_SIZE)
+       if (inode->i_size > BTRFS_EMPTY_DIR_SIZE) {
                return -ENOTEMPTY;
+       }
 
        mutex_lock(&root->fs_info->fs_mutex);
        ret = btrfs_check_free_space(root, 1, 1);
 
 #include "ioctl.h"
 #include "print-tree.h"
 #include "volumes.h"
+#include "locking.h"
 
 
 
        if (ret)
                goto fail;
 
-       leaf = __btrfs_alloc_free_block(trans, root, root->leafsize,
-                                       objectid, trans->transid, 0, 0,
-                                       0, 0);
+       leaf = btrfs_alloc_free_block(trans, root, root->leafsize,
+                                     objectid, trans->transid, 0, 0,
+                                     0, 0);
        if (IS_ERR(leaf))
                return PTR_ERR(leaf);
 
        memset(&root_item.drop_progress, 0, sizeof(root_item.drop_progress));
        root_item.drop_level = 0;
 
+       btrfs_tree_unlock(leaf);
        free_extent_buffer(leaf);
        leaf = NULL;
 
 
--- /dev/null
+/*
+ * 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 <linux/sched.h>
+#include <linux/gfp.h>
+#include <linux/pagemap.h>
+#include <linux/spinlock.h>
+#include <linux/page-flags.h>
+#include <linux/bug.h>
+#include "ctree.h"
+#include "extent_io.h"
+#include "locking.h"
+
+int btrfs_tree_lock(struct extent_buffer *eb)
+{
+       lock_page(eb->first_page);
+       return 0;
+}
+
+int btrfs_try_tree_lock(struct extent_buffer *eb)
+{
+       return TestSetPageLocked(eb->first_page);
+}
+
+int btrfs_tree_unlock(struct extent_buffer *eb)
+{
+       WARN_ON(!PageLocked(eb->first_page));
+       unlock_page(eb->first_page);
+       return 0;
+}
+
+int btrfs_tree_locked(struct extent_buffer *eb)
+{
+       return PageLocked(eb->first_page);
+}
+
 
--- /dev/null
+/*
+ * 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.
+ */
+
+#ifndef __BTRFS_LOCKING_
+#define __BTRFS_LOCKING_
+
+int btrfs_tree_lock(struct extent_buffer *eb);
+int btrfs_tree_unlock(struct extent_buffer *eb);
+int btrfs_tree_locked(struct extent_buffer *eb);
+int btrfs_try_tree_lock(struct extent_buffer *eb);
+#endif
 
 #include "ctree.h"
 #include "disk-io.h"
 #include "transaction.h"
+#include "locking.h"
 
 static int total_trans = 0;
 extern struct kmem_cache *btrfs_trans_handle_cachep;
                        radix_tree_tag_set(&root->fs_info->fs_roots_radix,
                                   (unsigned long)root->root_key.objectid,
                                   BTRFS_ROOT_DEFRAG_TAG);
-                       root->commit_root = root->node;
-                       extent_buffer_get(root->node);
+                       root->commit_root = btrfs_root_node(root);
                } else {
                        WARN_ON(1);
                }
        struct btrfs_root *tree_root = fs_info->tree_root;
        struct btrfs_root *root = pending->root;
        struct extent_buffer *tmp;
+       struct extent_buffer *old;
        int ret;
        int namelen;
        u64 objectid;
        key.offset = 1;
        btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 
-       extent_buffer_get(root->node);
-       btrfs_cow_block(trans, root, root->node, NULL, 0, &tmp);
-       free_extent_buffer(tmp);
+       old = btrfs_lock_root_node(root);
+       btrfs_cow_block(trans, root, old, NULL, 0, &old);
 
-       btrfs_copy_root(trans, root, root->node, &tmp, objectid);
+       btrfs_copy_root(trans, root, old, &tmp, objectid);
+       btrfs_tree_unlock(old);
+       free_extent_buffer(old);
 
        btrfs_set_root_bytenr(new_root_item, tmp->start);
        btrfs_set_root_level(new_root_item, btrfs_header_level(tmp));
        ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
                                new_root_item);
+       btrfs_tree_unlock(tmp);
        free_extent_buffer(tmp);
        if (ret)
                goto fail;
 
        if (root->fs_info->extent_root == root)
                is_extent = 1;
 
+       goto out;
+
        if (root->ref_cows == 0 && !is_extent)
                goto out;