report a suspected bug in ubifs

[Adrian Hunter]

홍신 shin hong wrote:
> Thank you for the reply.
> 
> all accesses to 'wbuf->used' is synchronized by 'io_mutex'
> and its updates(writing accesses) are synchronized by 'wbuf_lock'
> like readers/writer lock ?

Yes, it is like a readers/writers lock.

To read from the wbuf, all that is needed is the spin lock.

To append to the wbuf, without otherwise changing it, all that is needed
is the mutex (and then the spin lock to record that the append happened).

To change the wbuf, the mutex *and* the spin lock are needed.