On Mon, May 06, 2013 at 02:49:39PM +0200, Jan Kara wrote:
...
> > > +/*
> > > * start_this_handle: Given a handle, deal with any locking or stalling
> > > * needed to make sure that there is enough journal space for the handle
> > > * to begin. Attach the handle to a transaction and set up the
> > > @@ -151,12 +237,14 @@ static int start_this_handle(journal_t *journal, handle_t *handle,
> > > gfp_t gfp_mask)
> > > {
> > > transaction_t *transaction, *new_transaction = NULL;
> > > - tid_t tid;
> > > - int needed, need_to_start;
> > > int nblocks = handle->h_buffer_credits;
> > > unsigned long ts = jiffies;
> > >
> > > - if (nblocks > journal->j_max_transaction_buffers) {
> > > + /*
> > > + * 1/2 of transaction can be reserved so we can practically handle
> > > + * only 1/2 of maximum transaction size per operation
> > > + */
> >
> > Sorry, but I don't understand here why we only reserve 1/2 of maximum
> > transaction size.
> Well, we allow 1/2 of maximum transaction size to be allocated in already
> reserved handles. So if someone submitted a request for a handle with
> more than 1/2 of maximum transaction size, then we might have to wait for
> reserved handles to be freed. That would be a slight complication in the
> code and it would also possibly introduce livelocking issues - after a
> reserved transaction is freed, someone can reserve a new one before the
> large handle creation request is satisfied. Again this can be solved but
> the complications simply doesn't seem to be worth it.
Fair enough. Thanks for your explanation.
Regards,
- Zheng
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