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-rw-r--r--fs/btrfs/ctree.h19
-rw-r--r--fs/btrfs/extent-tree.c6
2 files changed, 22 insertions, 3 deletions
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 307dedf95c70..2c341956a01c 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -371,6 +371,25 @@ static inline void btrfs_set_root_last_trans(struct btrfs_root *root, u64 transi
}
/*
+ * Return the generation this root started with.
+ *
+ * Every normal root that is created with root->root_key.offset set to it's
+ * originating generation. If it is a snapshot it is the generation when the
+ * snapshot was created.
+ *
+ * However for TREE_RELOC roots root_key.offset is the objectid of the owning
+ * tree root. Thankfully we copy the root item of the owning tree root, which
+ * has it's last_snapshot set to what we would have root_key.offset set to, so
+ * return that if this is a TREE_RELOC root.
+ */
+static inline u64 btrfs_root_origin_generation(const struct btrfs_root *root)
+{
+ if (btrfs_root_id(root) == BTRFS_TREE_RELOC_OBJECTID)
+ return btrfs_root_last_snapshot(&root->root_item);
+ return root->root_key.offset;
+}
+
+/*
* Structure that conveys information about an extent that is going to replace
* all the extents in a file range.
*/
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 412e318e4a22..43a771f7bd7a 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5285,7 +5285,7 @@ static bool visit_node_for_delete(struct btrfs_root *root, struct walk_control *
* reference to it.
*/
generation = btrfs_node_ptr_generation(eb, slot);
- if (!wc->update_ref || generation <= root->root_key.offset)
+ if (!wc->update_ref || generation <= btrfs_root_origin_generation(root))
return false;
/*
@@ -5340,7 +5340,7 @@ static noinline void reada_walk_down(struct btrfs_trans_handle *trans,
goto reada;
if (wc->stage == UPDATE_BACKREF &&
- generation <= root->root_key.offset)
+ generation <= btrfs_root_origin_generation(root))
continue;
/* We don't lock the tree block, it's OK to be racy here */
@@ -5683,7 +5683,7 @@ static noinline int do_walk_down(struct btrfs_trans_handle *trans,
* for the subtree
*/
if (wc->stage == UPDATE_BACKREF &&
- generation <= root->root_key.offset) {
+ generation <= btrfs_root_origin_generation(root)) {
wc->lookup_info = 1;
return 1;
}