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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Wed, 4 Sep 2019 14:36:48 -0700
Message-ID: <CAHk-=wiExfaVhUTvKj7hR6DG4C2+oy6usz0Sa6QbPr5EgDH28w@mail.gmail.com>
Subject: Re: [PATCH v12 10/12] namei: aggressively check for nd->root escape
 on ".." resolution
To:     Aleksa Sarai <cyphar@cyphar.com>
Cc:     Al Viro <viro@zeniv.linux.org.uk>,
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On Wed, Sep 4, 2019 at 2:35 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Wed, Sep 4, 2019 at 2:09 PM Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > So you'd have three stages:
> >
> >  1) ".." always returns -EXDEV
> >
> >  2) ".." returns -EXDEV if there was a concurrent rename/mount
> >
> >  3) ".." returns -EXDEV if there was a concurrent rename/mount and we
> > reset the sequence numbers and check if you escaped.
>
> In fact, I wonder if this should return -EAGAIN instead - to say that
> "retrying may work".

And here "this" was meant to be "case 2" - I was moving the quoted
text around and didn't fix my wording, so now it is ambiguous or
implies #3, which would be crazy.

Sorry for the confusion,

            Linus