Comment # 21 on bug 1222429 from David Sterba

(In reply to Stefan Hundhammer from comment #17)
> That's a good hint. I assume this affects only the currently running kernel
> and processes, and nothing is written to the device, correct?

I'm not sure I understand the question. Mount is done by currently running
kernel, the log replay can do changes to the underlying device. For example
there's pending change to file permissions in the log, this is found and the
inode updated on device (transaction commit), then mount finishes and the
filesystem does not allow any writes.