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Re: [PATCH 1/2] vfs: make sure struct filename->iname is word-aligned

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On Tue, Feb 16, 2016 at 11:49:24PM +0100, Rasmus Villemoes wrote:
> I noticed that offsetof(struct filename, iname) is actually 28 on 64
> bit platforms, so we always pass an unaligned pointer to
> strncpy_from_user. This is mostly a problem for those 64 bit platforms
> without HAVE_EFFICIENT_UNALIGNED_ACCESS, but even on x86_64, unaligned
> accesses carry a penalty, especially when done in a loop.
> 
> Let's try to ensure we always pass an aligned destination pointer to
> strncpy_from_user. I considered making refcnt a long instead of doing
> the union thing, and mostly ended up tossing a coin.

Why not swap it with the previous field, then?

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[PATCH 1/2] vfs: make sure struct filename->iname is word-aligned Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2016-02-16 23:50 +0100
  [PATCH 2/2] vfs: don't always include audit-specific members of struct filename Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2016-02-17 00:00 +0100
  Re: [PATCH 1/2] vfs: make sure struct filename->iname is word-aligned Al Viro <viro@ZenIV.linux.org.uk> - 2016-02-17 00:00 +0100
    Re: [PATCH 1/2] vfs: make sure struct filename->iname is word-aligned Rasmus Villemoes <linux@rasmusvillemoes.dk> - 2016-02-18 21:20 +0100
      Re: [PATCH 1/2] vfs: make sure struct filename->iname is word-aligned Theodore Ts'o <tytso@mit.edu> - 2016-02-19 16:10 +0100

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