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Date: Thu, 6 Nov 2003 17:45:28 +1100
From: Tim Robbins <tjr@freebsd.org>
To: Kirk McKusick <mckusick@McKusick.COM>
Message-ID: <20031106064528.GA1440@wombat.robbins.dropbear.id.au>
References: <200311060504.hA654feN034044@beastie.mckusick.com>
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cc: Robert Watson <rwatson@nailabs.com>
cc: arch@freebsd.org
cc: Peter Wemm <peter@freebsd.org>
Subject: Re: >0x7fffffff blocksize filesystem reporting
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On Wed, Nov 05, 2003 at 09:04:41PM -0800, Kirk McKusick wrote:

> + /*
> +  * Convert a new format statfs structure to an old format statfs structure.
> +  */
> + static void
> + cvtstatfs(td, nsp, osp)
> + 	struct thread *td;
> + 	struct statfs *nsp;
> + 	struct ostatfs *osp;
> + {
> + 
> + 	bzero(osp, sizeof(*osp));
> + 	osp->f_bsize = nsp->f_bsize;
> + 	osp->f_iosize = nsp->f_iosize;
> + 	osp->f_blocks = nsp->f_blocks;
> + 	osp->f_bfree = nsp->f_bfree;
> + 	osp->f_bavail = nsp->f_bavail;
> + 	osp->f_files = nsp->f_files;
> + 	osp->f_ffree = nsp->f_ffree;
> + 	osp->f_owner = nsp->f_owner;
> + 	osp->f_type = nsp->f_type;
> + 	osp->f_flags = nsp->f_flags;
> + 	osp->f_syncwrites = nsp->f_syncwrites;
> + 	osp->f_asyncwrites = nsp->f_asyncwrites;
> + 	osp->f_syncreads = nsp->f_syncreads;
> + 	osp->f_asyncreads = nsp->f_asyncreads;

It may be better to return LONG_MAX for some of these members than to
truncate the value. Alternatively, the block size could be adjusted
to ensure that f_blocks fits in a "long" even though f_blocks * f_bsize
may overflow it, but this is messy and can't help if f_files or
f_{sync,async}{reads,writes} are too big.

> + 	bcopy(nsp->f_fstypename, osp->f_fstypename, MFSNAMELEN);
> + 	bcopy(nsp->f_mntonname, osp->f_mntonname, MNAMELEN);
> + 	bcopy(nsp->f_mntfromname, osp->f_mntfromname, MNAMELEN);

On architectures where longs are not 32 bits (amd64), OMNAMELEN != MNAMELEN,
so this may do the wrong thing.


Tim