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Date:   Fri, 27 Aug 2021 18:49:55 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Andreas Gruenbacher <agruenba@redhat.com>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Christoph Hellwig <hch@infradead.org>,
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        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
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Subject: Re: [PATCH v7 05/19] iov_iter: Introduce fault_in_iov_iter_writeable
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 <20210827164926.1726765-6-agruenba@redhat.com>
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On Fri, Aug 27, 2021 at 06:49:12PM +0200, Andreas Gruenbacher wrote:
> Introduce a new fault_in_iov_iter_writeable helper for safely faulting
> in an iterator for writing.  Uses get_user_pages() to fault in the pages
> without actually writing to them, which would be destructive.
> 
> We'll use fault_in_iov_iter_writeable in gfs2 once we've determined that
> the iterator passed to .read_iter isn't in memory.

Again, the calling conventions are wrong.  Make it success/failure or
0/-EFAULT.  And it's inconsistent for iovec and non-iovec cases as it is.