Btrfs: avoid delayed metadata items during commits
Snapshot creation has two phases. One is the initial snapshot setup,
and the second is done during commit, while nobody is allowed to modify
the root we are snapshotting.
The delayed metadata insertion code can break that rule, it does a
delayed inode update on the inode of the parent of the snapshot,
and delayed directory item insertion.
This makes sure to run the pending delayed operations before we
record the snapshot root, which avoids corruptions.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index fc515b7..f1cbd02 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -1237,6 +1237,13 @@
return 0;
}
+void btrfs_assert_delayed_root_empty(struct btrfs_root *root)
+{
+ struct btrfs_delayed_root *delayed_root;
+ delayed_root = btrfs_get_delayed_root(root);
+ WARN_ON(btrfs_first_delayed_node(delayed_root));
+}
+
void btrfs_balance_delayed_items(struct btrfs_root *root)
{
struct btrfs_delayed_root *delayed_root;
diff --git a/fs/btrfs/delayed-inode.h b/fs/btrfs/delayed-inode.h
index cb79b67..d1a6a29 100644
--- a/fs/btrfs/delayed-inode.h
+++ b/fs/btrfs/delayed-inode.h
@@ -137,4 +137,8 @@
/* for init */
int __init btrfs_delayed_inode_init(void);
void btrfs_delayed_inode_exit(void);
+
+/* for debugging */
+void btrfs_assert_delayed_root_empty(struct btrfs_root *root);
+
#endif
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index c073d85..51dcec8 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -957,6 +957,15 @@
ret = btrfs_update_inode(trans, parent_root, parent_inode);
BUG_ON(ret);
+ /*
+ * pull in the delayed directory update
+ * and the delayed inode item
+ * otherwise we corrupt the FS during
+ * snapshot
+ */
+ ret = btrfs_run_delayed_items(trans, root);
+ BUG_ON(ret);
+
record_root_in_trans(trans, root);
btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
@@ -1018,14 +1027,6 @@
int ret;
list_for_each_entry(pending, head, list) {
- /*
- * We must deal with the delayed items before creating
- * snapshots, or we will create a snapthot with inconsistent
- * information.
- */
- ret = btrfs_run_delayed_items(trans, fs_info->fs_root);
- BUG_ON(ret);
-
ret = create_pending_snapshot(trans, fs_info, pending);
BUG_ON(ret);
}
@@ -1319,15 +1320,21 @@
*/
mutex_lock(&root->fs_info->reloc_mutex);
- ret = create_pending_snapshots(trans, root->fs_info);
+ ret = btrfs_run_delayed_items(trans, root);
BUG_ON(ret);
- ret = btrfs_run_delayed_items(trans, root);
+ ret = create_pending_snapshots(trans, root->fs_info);
BUG_ON(ret);
ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
BUG_ON(ret);
+ /*
+ * make sure none of the code above managed to slip in a
+ * delayed item
+ */
+ btrfs_assert_delayed_root_empty(root);
+
WARN_ON(cur_trans != trans->transaction);
btrfs_scrub_pause(root);