From: Peter Maydell <peter.maydell@linaro.org>
To: "Theodore Y. Ts'o" <tytso@mit.edu>
Cc: Linus Walleij <linus.walleij@linaro.org>,
"Suzuki K. Poulose" <suzuki.poulose@arm.com>,
Andreas Dilger <adilger.kernel@dilger.ca>,
Ext4 Developers List <linux-ext4@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
QEMU Developers <qemu-devel@nongnu.org>,
Florian Weimer <fw@deneb.enyo.de>,
Andy Lutomirski <luto@kernel.org>,
stable <stable@vger.kernel.org>
Subject: Re: [PATCH] ext4: Give 32bit personalities 32bit hashes
Date: Tue, 24 Mar 2020 09:29:58 +0000 [thread overview]
Message-ID: <CAFEAcA_6RY1XFVNJCo5=tTkv2GQpXZRqh_Zz4dYadq-8MJZgTQ@mail.gmail.com> (raw)
In-Reply-To: <20200324023431.GD53396@mit.edu>
On Tue, 24 Mar 2020 at 02:34, Theodore Y. Ts'o <tytso@mit.edu> wrote:
> Another possibility, which would be messier for qemu, would be use a
> flag set via fcntl. That would require qemu from noticing when the
> guest is calling open, openat, or openat2, and then inserting a fcntl
> system call to set the 32-bit readdir mode. That's cleaner from the
> kernel interface complexity perspective, but it's messier for qemu.
On the contrary, that would be a much better interface for QEMU.
We always know when we're doing an open-syscall on behalf
of the guest, and it would be trivial to make the fcntl() call then.
That would ensure that we don't accidentally get the
'32-bit semantics' on file descriptors QEMU opens for its own
purposes, and wouldn't leave us open to the risk in future that
setting the PER_LINUX32 flag for all of QEMU causes
unexpected extra behaviour in future kernels that would be correct
for the guest binary but wrong/broken for QEMU's own internals.
thanks
-- PMM
next prev parent reply other threads:[~2020-03-24 9:30 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-17 11:31 [PATCH] ext4: Give 32bit personalities 32bit hashes Linus Walleij
2020-03-17 11:52 ` Florian Weimer
2020-03-17 12:38 ` Linus Walleij
2020-03-17 11:58 ` Peter Maydell
2020-03-19 15:13 ` Linus Walleij
2020-03-19 15:25 ` Peter Maydell
2020-03-19 22:23 ` Linus Walleij
2020-03-24 2:34 ` Theodore Y. Ts'o
2020-03-24 9:29 ` Peter Maydell [this message]
2020-03-24 18:47 ` Theodore Y. Ts'o
2020-03-24 21:17 ` Linus Walleij
2020-03-17 22:28 ` Andreas Dilger
2020-03-19 15:18 ` Linus Walleij
2020-03-17 22:30 ` Sasha Levin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAFEAcA_6RY1XFVNJCo5=tTkv2GQpXZRqh_Zz4dYadq-8MJZgTQ@mail.gmail.com' \
--to=peter.maydell@linaro.org \
--cc=adilger.kernel@dilger.ca \
--cc=fw@deneb.enyo.de \
--cc=linus.walleij@linaro.org \
--cc=linux-api@vger.kernel.org \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=qemu-devel@nongnu.org \
--cc=stable@vger.kernel.org \
--cc=suzuki.poulose@arm.com \
--cc=tytso@mit.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).