Btrfs: tree mod log's old roots could still be part of the tree
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>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index e6b75cc..d9308c38 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1239,6 +1239,7 @@
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 @@
}
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);