From 5963ffcaf383134985a5a2d8a4baa582d3999e0a Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Thu, 20 May 2021 11:21:31 -0400 Subject: [PATCH] btrfs: always abort the transaction if we abort a trans handle While stress testing our error handling I noticed that sometimes we would still commit the transaction even though we had aborted the transaction. Currently we track if a trans handle has dirtied any metadata, and if it hasn't we mark the filesystem as having an error (so no new transactions can be started), but we will allow the current transaction to complete as we do not mark the transaction itself as having been aborted. This sounds good in theory, but we were not properly tracking IO errors in btrfs_finish_ordered_io, and thus committing the transaction with bogus free space data. This isn't necessarily a problem per-se with the free space cache, as the other guards in place would have kept us from accepting the free space cache as valid, but highlights a real world case where we had a bug and could have corrupted the filesystem because of it. This "skip abort on empty trans handle" is nice in theory, but assumes we have perfect error handling everywhere, which we clearly do not. Also we do not allow further transactions to be started, so all this does is save the last transaction that was happening, which doesn't necessarily gain us anything other than the potential for real corruption. Remove this particular bit of code, if we decide we need to abort the transaction then abort the current one and keep us from doing real harm to the file system, regardless of whether this specific trans handle dirtied anything or not. Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/ctree.c | 5 +---- fs/btrfs/extent-tree.c | 1 - fs/btrfs/super.c | 11 ----------- fs/btrfs/transaction.c | 8 -------- fs/btrfs/transaction.h | 1 - 5 files changed, 1 insertion(+), 25 deletions(-) diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index a484fb7..4bc3ca2 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -596,7 +596,6 @@ noinline int btrfs_cow_block(struct btrfs_trans_handle *trans, trans->transid, fs_info->generation); if (!should_cow_block(trans, root, buf)) { - trans->dirty = true; *cow_ret = buf; return 0; } @@ -1788,10 +1787,8 @@ again: * then we don't want to set the path blocking, * so we test it here */ - if (!should_cow_block(trans, root, b)) { - trans->dirty = true; + if (!should_cow_block(trans, root, b)) goto cow_done; - } /* * must have write locks on this node and the diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 3d5c35e..d2f39a1 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -4784,7 +4784,6 @@ btrfs_init_new_buffer(struct btrfs_trans_handle *trans, struct btrfs_root *root, set_extent_dirty(&trans->transaction->dirty_pages, buf->start, buf->start + buf->len - 1, GFP_NOFS); } - trans->dirty = true; /* this returns a buffer locked for blocking */ return buf; } diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 4a396c1..bc61321 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -299,17 +299,6 @@ void __btrfs_abort_transaction(struct btrfs_trans_handle *trans, struct btrfs_fs_info *fs_info = trans->fs_info; WRITE_ONCE(trans->aborted, errno); - /* Nothing used. The other threads that have joined this - * transaction may be able to continue. */ - if (!trans->dirty && list_empty(&trans->new_bgs)) { - const char *errstr; - - errstr = btrfs_decode_error(errno); - btrfs_warn(fs_info, - "%s:%d: Aborting unused transaction(%s).", - function, line, errstr); - return; - } WRITE_ONCE(trans->transaction->aborted, errno); /* Wake up anybody who may be waiting on this transaction */ wake_up(&fs_info->transaction_wait); diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index f75de9f..e0a82aa 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -2074,14 +2074,6 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) ASSERT(refcount_read(&trans->use_count) == 1); - /* - * Some places just start a transaction to commit it. We need to make - * sure that if this commit fails that the abort code actually marks the - * transaction as failed, so set trans->dirty to make the abort code do - * the right thing. - */ - trans->dirty = true; - /* Stop the commit early if ->aborted is set */ if (TRANS_ABORTED(cur_trans)) { ret = cur_trans->aborted; diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h index 364cfbb..c49e226 100644 --- a/fs/btrfs/transaction.h +++ b/fs/btrfs/transaction.h @@ -143,7 +143,6 @@ struct btrfs_trans_handle { bool allocating_chunk; bool can_flush_pending_bgs; bool reloc_reserved; - bool dirty; bool in_fsync; struct btrfs_root *root; struct btrfs_fs_info *fs_info; -- 2.7.4