btrfs: abort transaction on generation mismatch when marking eb as dirty

When marking an extent buffer as dirty, at btrfs_mark_buffer_dirty(),
we check if its generation matches the running transaction and if not we
just print a warning. Such mismatch is an indicator that something really
went wrong and only printing a warning message (and stack trace) is not
enough to prevent a corruption. Allowing a transaction to commit with such
an extent buffer will trigger an error if we ever try to read it from disk
due to a generation mismatch with its parent generation.

So abort the current transaction with -EUCLEAN if we notice a generation
mismatch. For this we need to pass a transaction handle to
btrfs_mark_buffer_dirty() which is always available except in test code,
in which case we can pass NULL since it operates on dummy extent buffers
and all test roots have a single node/leaf (root node at level 0).

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 9 insertions, 4 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 43a6ca726879..05282a2f0f5b 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -867,7 +867,7 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
 	}
 
 	root->node = leaf;
-	btrfs_mark_buffer_dirty(leaf);
+	btrfs_mark_buffer_dirty(trans, leaf);
 
 	root->commit_root = btrfs_root_node(root);
 	set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
@@ -942,7 +942,7 @@ int btrfs_alloc_log_tree_node(struct btrfs_trans_handle *trans,
 
 	root->node = leaf;
 
-	btrfs_mark_buffer_dirty(root->node);
+	btrfs_mark_buffer_dirty(trans, root->node);
 	btrfs_tree_unlock(root->node);
 
 	return 0;
@@ -4385,7 +4385,8 @@ void __cold close_ctree(struct btrfs_fs_info *fs_info)
 	btrfs_close_devices(fs_info->fs_devices);
 }
 
-void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
+void btrfs_mark_buffer_dirty(struct btrfs_trans_handle *trans,
+			     struct extent_buffer *buf)
 {
 	struct btrfs_fs_info *fs_info = buf->fs_info;
 	u64 transid = btrfs_header_generation(buf);
@@ -4399,10 +4400,14 @@ void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
 	if (unlikely(test_bit(EXTENT_BUFFER_UNMAPPED, &buf->bflags)))
 		return;
 #endif
+	/* This is an active transaction (its state < TRANS_STATE_UNBLOCKED). */
+	ASSERT(trans->transid == fs_info->generation);
 	btrfs_assert_tree_write_locked(buf);
-	if (transid != fs_info->generation)
+	if (transid != fs_info->generation) {
 		WARN(1, KERN_CRIT "btrfs transid mismatch buffer %llu, found %llu running %llu\n",
 			buf->start, transid, fs_info->generation);
+		btrfs_abort_transaction(trans, -EUCLEAN);
+	}
 	set_extent_buffer_dirty(buf);
 }