Btrfs: Add the ability to find and remove dead roots after a crash.

[linux-2.6-block.git] / fs / btrfs / transaction.c

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 321f8852755b53d402c3fa8991a6759d3e28696e..85a2a5e27148ef313917443501ee9e5d74ad21c5 100644 (file)
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -85,11 +85,15 @@ struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 
        if (root != root->fs_info->tree_root && root->last_trans <
            running_trans_id) {
-               radix_tree_tag_set(&root->fs_info->fs_roots_radix,
-                                  (unsigned long)root->root_key.objectid,
-                                  BTRFS_ROOT_TRANS_TAG);
-               root->commit_root = root->node;
-               get_bh(root->node);
+               if (root->root_item.refs != 0) {
+                       radix_tree_tag_set(&root->fs_info->fs_roots_radix,
+                                          (unsigned long)root->root_key.objectid,
+                                          BTRFS_ROOT_TRANS_TAG);
+                       root->commit_root = root->node;
+                       get_bh(root->node);
+               } else {
+                       WARN_ON(1);
+               }
        }
        root->last_trans = running_trans_id;
        h->transid = running_trans_id;
@@ -208,8 +212,24 @@ struct dirty_root {
        struct btrfs_key snap_key;
        struct buffer_head *commit_root;
        struct btrfs_root *root;
+       int free_on_drop;
 };
 
+int btrfs_add_dead_root(struct btrfs_root *root, struct list_head *dead_list)
+{
+       struct dirty_root *dirty;
+
+       dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
+       if (!dirty)
+               return -ENOMEM;
+       memcpy(&dirty->snap_key, &root->root_key, sizeof(root->root_key));
+       dirty->commit_root = root->node;
+       dirty->root = root;
+       dirty->free_on_drop = 1;
+       list_add(&dirty->list, dead_list);
+       return 0;
+}
+
 static int add_dirty_roots(struct btrfs_trans_handle *trans,
                           struct radix_tree_root *radix,
                           struct list_head *list)
@@ -217,9 +237,11 @@ static int add_dirty_roots(struct btrfs_trans_handle *trans,
        struct dirty_root *dirty;
        struct btrfs_root *gang[8];
        struct btrfs_root *root;
+       struct btrfs_root_item tmp_item;
        int i;
        int ret;
        int err = 0;
+       u32 refs;
 
        while(1) {
                ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
@@ -246,6 +268,9 @@ static int add_dirty_roots(struct btrfs_trans_handle *trans,
                        dirty->commit_root = root->commit_root;
                        root->commit_root = NULL;
                        dirty->root = root;
+                       dirty->free_on_drop = 0;
+                       memcpy(&tmp_item, &root->root_item, sizeof(tmp_item));
+
                        root->root_key.offset = root->fs_info->generation;
                        btrfs_set_root_blocknr(&root->root_item,
                                               bh_blocknr(root->node));
@@ -254,7 +279,18 @@ static int add_dirty_roots(struct btrfs_trans_handle *trans,
                                                &root->root_item);
                        if (err)
                                break;
-                       list_add(&dirty->list, list);
+
+                       refs = btrfs_root_refs(&tmp_item);
+                       btrfs_set_root_refs(&tmp_item, refs - 1);
+                       err = btrfs_update_root(trans, root->fs_info->tree_root,
+                                               &dirty->snap_key,
+                                               &tmp_item);
+
+                       BUG_ON(err);
+                       if (refs == 1)
+                               list_add(&dirty->list, list);
+                       else
+                               kfree(dirty);
                }
        }
        return err;
@@ -270,16 +306,20 @@ static int drop_dirty_roots(struct btrfs_root *tree_root,
                mutex_lock(&tree_root->fs_info->fs_mutex);
                dirty = list_entry(list->next, struct dirty_root, list);
                list_del_init(&dirty->list);
+
                trans = btrfs_start_transaction(tree_root, 1);
+printk("deleting root %Lu %u %Lu\n", dirty->snap_key.objectid, dirty->snap_key.flags, dirty->snap_key.offset);
                ret = btrfs_drop_snapshot(trans, dirty->root,
                                          dirty->commit_root);
                BUG_ON(ret);
-
                ret = btrfs_del_root(trans, tree_root, &dirty->snap_key);
                if (ret)
                        break;
                ret = btrfs_end_transaction(trans, tree_root);
                BUG_ON(ret);
+
+               if (dirty->free_on_drop)
+                       kfree(dirty->root);
                kfree(dirty);
                mutex_unlock(&tree_root->fs_info->fs_mutex);
                btrfs_btree_balance_dirty(tree_root);