linux-kernel - RE: [PATCH v3 2/2] iov_iter: Don't deal with iter->copy_mc in memcpy_from_iter

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Date:   Wed, 16 Aug 2023 14:19:02 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'David Howells' <dhowells@...hat.com>
CC:     Al Viro <viro@...iv.linux.org.uk>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Jens Axboe <axboe@...nel.dk>,
        "Christoph Hellwig" <hch@...t.de>,
        Christian Brauner <christian@...uner.io>,
        "Matthew Wilcox" <willy@...radead.org>,
        Jeff Layton <jlayton@...nel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v3 2/2] iov_iter: Don't deal with iter->copy_mc in
 memcpy_from_iter_mc()

From: David Howells
> Sent: Wednesday, August 16, 2023 2:01 PM
> 
> David Laight <David.Laight@...LAB.COM> wrote:
> 
> >
> > Couldn't the relevant code directly call __copy_from_iter_mc() ?
> > Or a version then checked iov_is_copy_mc() and then fell
> > back to the standard function.
> 
> No, because the marked iterator is handed by the coredump code to
> __kernel_write_iter() and thence on to who-knows-what driver - which will call
> copy_from_iter() or some such.  $DRIVER shouldn't need to know about
> ->copy_mc.

What about ITER_BVEC_MC ??

	David

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