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From:   Al Viro <viro@zeniv.linux.org.uk>
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Subject: Re: [RFC] pgflags_t
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On Wed, Oct 06, 2021 at 05:32:39PM +0200, David Hildenbrand wrote:

> It feels to me like using __bitwise for access checks and then still
> modifying the __bitwise fields randomly via a backdoor. But sure, if it
> works, I'll be happy if we can use that.

__bitwise == "can't do anything other than bitwise operations without
an explicit force-cast".  All there is to it.  Hell, the very first
use had been for things like __le32 et.al., where the primitives
very much do non-bitwise accesses.  They are known to be safe (==
do the same thing regardless of the host endianness).  Internally
they contain force-casts, precisely so that the caller wouldn't
need to.