Date: Tue, 30 May 2006 13:17:08 -0600
From: Andreas Dilger <adilger@clusterfs.com>
To: sho@tnes.nec.co.jp, "Stephen C. Tweedie" <sct@redhat.com>,
       "Theodore Ts'o" <tytso@mit.edu>
Cc: linux-kernel@vger.kernel.org, ext2-devel@lists.sourceforge.net,
       jitendra@linsyssoft.com, cmm@us.ibm.com
Subject: Re: [UPDATE][13/24]ext3 enlarge file size
Message-ID: <20060530191707.GK5964@schatzie.adilger.int>
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	"Stephen C. Tweedie" <sct@redhat.com>, Theodore Ts'o <tytso@mit.edu>,
	linux-kernel@vger.kernel.org, ext2-devel@lists.sourceforge.net,
	jitendra@linsyssoft.com, cmm@us.ibm.com
References: <20060530212540sho@rifu.tnes.nec.co.jp>
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On May 30, 2006  21:25 +0900, sho@tnes.nec.co.jp wrote:
> > >  	/* This constant is calculated to be the largest file size for a
> > >  	 * dense, 4k-blocksize file such that the total number of
> > >  	 * sectors in the file, including data and all indirect blocks,
> > >  	 * does not exceed 2^32. */
> > > +	if (sizeof(blkcnt_t) < sizeof(u64)) {
> > > +		upper_limit = 0x1ff7fffd000LL;
> > > +	}
> > > +	/* With CONFIG_LSF on, file size is limited to blocksize*(4G-1) */
> > > +	else { 
> > > +		upper_limit = (1LL << (bits + 32)) - (1LL << bits);
> > > +	}
> > 
> > This doesn't take into account that there will be some number of extra
> > blocks on the file for {dt}indirect blocks.  There was some discussion
> > among ext3 developers to use another field in the inode to allow the
> > i_blocks count to grow up to 2^48 bits in conjunction with this
> > patch, which will remove any worry about additional metadata blocks
> > and also allow future growth without yet another COMPAT flag.
> 
> I'm considering using l_i_frag and l_i_fsize as the high bits of
> i_blocks for 48-bits, besides i_blocks in fs blocksize.  Is there any
> comment?

Ted or Stephen, would you care to comment?  These are the same fields
used by the earlier patch "Pushing ext3 file size limits beyond 2TB"
by Goldwyn Rodrigues <Goldwynr@noida.hcltech.com>.  Having this under
the same RO_COMPAT_HUGE_FILE makes a lot of sense.

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

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