linux-kernel - Re: [PATCH 5/5] xfs: allow linkat() on O

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Message-ID: <20131214081944.GR31386@dastard>
Date:	Sat, 14 Dec 2013 19:19:44 +1100
From:	Dave Chinner <david@...morbit.com>
To:	Zhi Yong Wu <zwu.kernel@...il.com>
Cc:	Christoph Hellwig <hch@...radead.org>,
	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
	Zhi Yong Wu <wuzhy@...ux.vnet.ibm.com>,
	linux-kernel mlist <linux-kernel@...r.kernel.org>,
	xfstests <xfs@....sgi.com>
Subject: Re: [PATCH 5/5] xfs: allow linkat() on O_TMPFILE files

On Sat, Dec 14, 2013 at 01:36:47AM +0800, Zhi Yong Wu wrote:
> On Sat, Dec 14, 2013 at 12:41 AM, Christoph Hellwig <hch@...radead.org> wrote:
> > On Fri, Dec 13, 2013 at 10:27:53PM +0800, Zhi Yong Wu wrote:
> >> From: Zhi Yong Wu <wuzhy@...ux.vnet.ibm.com>
> >>
> >> Enable O_TMPFILE support in linkat().
> >> For more info, please refer to:
> >>   http://oss.sgi.com/archives/xfs/2013-08/msg00341.html
> >
> > Generall you should provide all reasonable information in the changelog
> > instead of linking to it.
> will apply this, thanks.
> >
> >> +     if (sip->i_d.di_nlink == 0)
> >> +             tres = &M_RES(mp)->tr_link_tmpfile;
> >> +     else
> >> +             tres = &M_RES(mp)->tr_link;
> >
> > As mentioned before I think Dave wanted you to always use the same
> > reservation, but I'll leave that discussion to him.
> If as you said, when some tons of regular files are created, it won't
> waste some disk space? e.g. some files want to reserve some space, but
> get NOSPACE due to other files reserving additional space?

This is a log space reservation, not a disk space reservation. End
either way, what is unused by the transaction is returned to the
free space pool at the end of the transaction. So for simplicity,
we should just use the one reservation for the link transaction -
take whichever is larger at calculation time.

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com
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