Btrfs: tree mod log's old roots could still be part of the tree
authorJan Schmidt <list.btrfs@jan-o-sch.net>
Tue, 23 Oct 2012 09:27:33 +0000 (11:27 +0200)
committerJan Schmidt <list.btrfs@jan-o-sch.net>
Wed, 24 Oct 2012 10:36:37 +0000 (12:36 +0200)
Tree mod log treated old root buffers as always empty buffers when starting
the rewind operations. However, the old root may still be part of the
current tree at a lower level, with still some valid entries.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
fs/btrfs/ctree.c

index e6b75cc..d9308c3 100644 (file)
@@ -1239,6 +1239,7 @@ get_old_root(struct btrfs_root *root, u64 time_seq)
        struct tree_mod_root *old_root = NULL;
        u64 old_generation = 0;
        u64 logical;
+       u32 blocksize;
 
        eb = btrfs_read_lock_root_node(root);
        tm = __tree_mod_log_oldest_root(root->fs_info, root, time_seq);
@@ -1254,12 +1255,28 @@ get_old_root(struct btrfs_root *root, u64 time_seq)
        }
 
        tm = tree_mod_log_search(root->fs_info, logical, time_seq);
-       if (old_root)
+       if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
+               btrfs_tree_read_unlock(root->node);
+               free_extent_buffer(root->node);
+               blocksize = btrfs_level_size(root, old_root->level);
+               eb = read_tree_block(root, logical, blocksize, 0);
+               if (!eb) {
+                       pr_warn("btrfs: failed to read tree block %llu from get_old_root\n",
+                               logical);
+                       WARN_ON(1);
+               } else {
+                       eb = btrfs_clone_extent_buffer(eb);
+               }
+       } else if (old_root) {
+               btrfs_tree_read_unlock(root->node);
+               free_extent_buffer(root->node);
                eb = alloc_dummy_extent_buffer(logical, root->nodesize);
-       else
+       } else {
                eb = btrfs_clone_extent_buffer(root->node);
-       btrfs_tree_read_unlock(root->node);
-       free_extent_buffer(root->node);
+               btrfs_tree_read_unlock(root->node);
+               free_extent_buffer(root->node);
+       }
+
        if (!eb)
                return NULL;
        btrfs_tree_read_lock(eb);