1 files changed, 39 insertions, 13 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index a4cb4b642987..da519c1b6ad0 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -682,18 +682,30 @@ noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
 	u64 search_start;
 	int ret;
 
-	if (test_bit(BTRFS_ROOT_DELETING, &root->state))
-		btrfs_err(fs_info,
-			"COW'ing blocks on a fs root that's being dropped");
-
-	if (trans->transaction != fs_info->running_transaction)
-		WARN(1, KERN_CRIT "trans %llu running %llu\n",
-		       trans->transid,
-		       fs_info->running_transaction->transid);
+	if (unlikely(test_bit(BTRFS_ROOT_DELETING, &root->state))) {
+		btrfs_abort_transaction(trans, -EUCLEAN);
+		btrfs_crit(fs_info,
+		   "attempt to COW block %llu on root %llu that is being deleted",
+			   buf->start, btrfs_root_id(root));
+		return -EUCLEAN;
+	}
 
-	if (trans->transid != fs_info->generation)
-		WARN(1, KERN_CRIT "trans %llu running %llu\n",
-		       trans->transid, fs_info->generation);
+	/*
+	 * COWing must happen through a running transaction, which always
+	 * matches the current fs generation (it's a transaction with a state
+	 * less than TRANS_STATE_UNBLOCKED). If it doesn't, then turn the fs
+	 * into error state to prevent the commit of any transaction.
+	 */
+	if (unlikely(trans->transaction != fs_info->running_transaction ||
+		     trans->transid != fs_info->generation)) {
+		btrfs_abort_transaction(trans, -EUCLEAN);
+		btrfs_crit(fs_info,
+"unexpected transaction when attempting to COW block %llu on root %llu, transaction %llu running transaction %llu fs generation %llu",
+			   buf->start, btrfs_root_id(root), trans->transid,
+			   fs_info->running_transaction->transid,
+			   fs_info->generation);
+		return -EUCLEAN;
+	}
 
 	if (!should_cow_block(trans, root, buf)) {
 		*cow_ret = buf;
@@ -805,8 +817,22 @@ int btrfs_realloc_node(struct btrfs_trans_handle *trans,
 	int progress_passed = 0;
 	struct btrfs_disk_key disk_key;
 
-	WARN_ON(trans->transaction != fs_info->running_transaction);
-	WARN_ON(trans->transid != fs_info->generation);
+	/*
+	 * COWing must happen through a running transaction, which always
+	 * matches the current fs generation (it's a transaction with a state
+	 * less than TRANS_STATE_UNBLOCKED). If it doesn't, then turn the fs
+	 * into error state to prevent the commit of any transaction.
+	 */
+	if (unlikely(trans->transaction != fs_info->running_transaction ||
+		     trans->transid != fs_info->generation)) {
+		btrfs_abort_transaction(trans, -EUCLEAN);
+		btrfs_crit(fs_info,
+"unexpected transaction when attempting to reallocate parent %llu for root %llu, transaction %llu running transaction %llu fs generation %llu",
+			   parent->start, btrfs_root_id(root), trans->transid,
+			   fs_info->running_transaction->transid,
+			   fs_info->generation);
+		return -EUCLEAN;
+	}
 
 	parent_nritems = btrfs_header_nritems(parent);
 	blocksize = fs_info->nodesize;