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Date: Mon, 15 Mar 2010 11:44:35 -0400
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH 9/9] xfs: log ticket reservation underestimates the
	number of iclogs
Message-ID: <20100315154435.GA29024@infradead.org>
References: <1268620506-10799-1-git-send-email-david@fromorbit.com>
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	<20100315154154.GA20155@infradead.org>
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To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com

> > +	iclog_space = log->l_iclog_size - log->l_iclog_hsize;
> > +	num_headers = (unit_bytes + iclog_space - 1) / iclog_space;
> > +
> > +	/* for split-recs - ophdrs added when data split over LRs */
> > +	unit_bytes += sizeof(xlog_op_header_t) * num_headers;
> > +
> > +	/* add extra header reservations if we overrun */
> > +	while (!num_headers ||
> > +	       ((unit_bytes + iclog_space - 1) / iclog_space) > num_headers) {
> > +		unit_bytes += sizeof(xlog_op_header_t);
> > +		num_headers++;
> > +	}
> 
> Looks good, but why do you check for a zero num_headers here?  The only way
> this could happen after the roundup above is if unit_bytes is zero, which
> can't ever happen - one caller has it hardcoded to 1, and the the other
> has a conditional for it beeing bigger than 0 around the call.

BTW: use of the howmany macro might make some of the above easier
to read.

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