Hi Jan,

I've tried applying this patch set against 5.4-rc3, and I'm finding a
easily reproducible failure using:

	kvm-xfstests -c ext3conv ext4/039

It is the BUG_ON in fs/jbd2/commit.c, around line 570:

	J_ASSERT(commit_transaction->t_nr_buffers <=
		 atomic_read(&commit_transaction->t_outstanding_credits));

The failure (with the obvious debugging printk added) is:

ext4/039		[15:13:16][    6.747101] run fstests ext4/039 at 2019-10
-19 15:13:16
[    7.018766] Mounted ext4 file system at /vdc supports timestamps until 2038 (
0x7fffffff)
[    8.227631] JBD2: t_nr_buffers 226, t_outstanding_credits=223
[    8.229215] ------------[ cut here ]------------
[    8.230249] kernel BUG at fs/jbd2/commit.c:573!
     	       ...

The full log is attached (although the stack trace isn't terribly
interesting, since this is being run out of kjournald2).

						- Ted