Re: >0x7fffffff blocksize filesystem reporting

From: Kirk McKusick (mckusick_at_beastie.mckusick.com)
Date: 11/07/03

  • Next message: Kirk McKusick: "Re: >0x7fffffff blocksize filesystem reporting" 
    To: Tim Robbins <tjr@freebsd.org>
Date: Thu, 06 Nov 2003 16:02:01 -0800

    > Date: Thu, 6 Nov 2003 17:45:28 +1100
    > From: Tim Robbins <tjr@freebsd.org>
    > To: Kirk McKusick <mckusick@mckusick.com>
    > Cc: Peter Wemm <peter@freebsd.org>, Robert Watson <rwatson@nailabs.com>,
    > arch@freebsd.org
    > Subject: Re: >0x7fffffff blocksize filesystem reporting
    > X-ASK-Info: Whitelist match
    >
    > 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

    You make two good points. Here is my revised diff for cvtstatfs:

    + /*
    + * 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 = MIN(nsp->f_bsize, LONG_MAX);
    + osp->f_iosize = MIN(nsp->f_iosize, LONG_MAX);
    + osp->f_blocks = MIN(nsp->f_blocks, LONG_MAX);
    + osp->f_bfree = MIN(nsp->f_bfree, LONG_MAX);
    + osp->f_bavail = MIN(nsp->f_bavail, LONG_MAX);
    + osp->f_files = MIN(nsp->f_files, LONG_MAX);
    + osp->f_ffree = MIN(nsp->f_ffree, LONG_MAX);
    + osp->f_owner = nsp->f_owner;
    + osp->f_type = nsp->f_type;
    + osp->f_flags = nsp->f_flags;
    + osp->f_syncwrites = MIN(nsp->f_syncwrites, LONG_MAX);
    + osp->f_asyncwrites = MIN(nsp->f_asyncwrites, LONG_MAX);
    + osp->f_syncreads = MIN(nsp->f_syncreads, LONG_MAX);
    + osp->f_asyncreads = MIN(nsp->f_asyncreads, LONG_MAX);
    + bcopy(nsp->f_fstypename, osp->f_fstypename,
    + MIN(MFSNAMELEN, OMNAMELEN));
    + bcopy(nsp->f_mntonname, osp->f_mntonname,
    + MIN(MFSNAMELEN, OMNAMELEN));
    + bcopy(nsp->f_mntfromname, osp->f_mntfromname,
    + MIN(MFSNAMELEN, OMNAMELEN));
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