Serious problems with HFS+

From: Matt Mackall (mpm_at_selenic.com)
Date: 03/13/05

  • Next message: Trond Myklebust: "Re: [CHECKER] inconsistent NFS stat cache (NFS on ext3, 2.6.11)" 
    Date:	Sun, 13 Mar 2005 12:36:04 -0800
To: zippel@linux-m68k.org, linux-kernel <linux-kernel@vger.kernel.org>

    I've noticed a few problems with HFS+ support in recent kernels on
    another user's machine running Ubuntu (Warty) running
    2.6.8.1-3-powerpc. I'm not in a position to extensively test or fix
    either of these problem because of the fs tools situation so I'm just
    passing this on.

    First, it reports inappropriate blocks to stat(2). It uses 4096 byte
    blocks rather than 512 byte blocks which stat callers are expecting.
    This seriously confuses du(1) (and me, for a bit). Looks like it may
    be forgetting to set s_blocksize_bits.

    Second, if an HFS+ filesystem mounted via Firewire or USB becomes
    detached, the filesystem appears to continue working just fine. I can
    find on the entire tree, despite memory pressure. I can even create
    new files that continue to appear in directory listings! Writes to
    such files succeed (they're async, of course) and the typical app is
    none the wiser. It's only when apps attempt to read later that they
    encounter problems. It turns out that various apps including scp
    ignore IO errors on read and silently copy zero-filled files to the
    destination. So I got this report as "why aren't the pictures I took
    off my camera visible on my website?"

    This is obviously a really nasty failure mode. At the very least, open
    of new files should fail with -EIO. Preferably the fs should force a
    read-only remount on IO errors. Given that the vast majority of HFS+
    filesystems Linux is likely to be used with are on hotpluggable media,
    I think this FS should be marked EXPERIMENTAL until such integrity
    problems are addressed.

    Having the whole directory tree seemingly pinned in memory is probably
    something that wants addressing as well. 

    -- 
Mathematics is the supreme nostalgia of our time.
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  • Next message: Trond Myklebust: "Re: [CHECKER] inconsistent NFS stat cache (NFS on ext3, 2.6.11)"

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