From: "J. Bruce Fields" <bfields@fieldses.org>
To: Chris Down <chris@chrisdown.name>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>,
linux-fsdevel@vger.kernel.org, Al Viro <viro@zeniv.linux.org.uk>,
Jeff Layton <jlayton@kernel.org>,
Johannes Weiner <hannes@cmpxchg.org>, Tejun Heo <tj@kernel.org>,
linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH] fs: inode: Reduce volatile inode wraparound risk when ino_t is 64 bit
Date: Tue, 7 Jan 2020 22:00:15 -0500 [thread overview]
Message-ID: <20200108030015.GB5476@fieldses.org> (raw)
In-Reply-To: <20200107174407.GA666424@chrisdown.name>
On Tue, Jan 07, 2020 at 05:44:07PM +0000, Chris Down wrote:
> J. Bruce Fields writes:
> >I thought that (dev, inum) was supposed to be unique from creation to
> >last unlink (and last close), and (dev, inum, generation) was supposed
> >to be unique for all time.
>
> Sure, but I mean, we don't really protect against even the first case.
>
> >>I didn't mention generation because, even though it's set on tmpfs
> >>(to prandom_u32()), it's not possible to evaluate it from userspace
> >>since `ioctl` returns ENOTTY. We can't ask userspace applications to
> >>introspect on an inode attribute that they can't even access :-)
> >
> >Is there any reason not to add IOC_GETVERSION support to tmpfs?
> >
> >I wonder if statx should return it too?
>
> We can, but that seems like a tangential discussion/patch series.
> For the second case especially, that's something we should do
> separately from this patchset,
Oh, of course, I'm not objecting to this patchset at all, it's a "why
not also do this?" question.
> since this demonstrably fixes issues encountered in production, and
> extending a user-facing APIs is likely to be a much more extensive
> discussion.
Though if it's a question of just a new implementation of an existing
ioctl, I doubt it's such a big deal. (Not that I'm volunteering to
write the patch.)
--b.
prev parent reply other threads:[~2020-01-08 3:00 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-20 2:49 [PATCH] fs: inode: Reduce volatile inode wraparound risk when ino_t is 64 bit Chris Down
2019-12-20 3:05 ` zhengbin (A)
2019-12-20 8:32 ` Amir Goldstein
2019-12-20 12:16 ` Chris Down
2019-12-20 13:41 ` Amir Goldstein
2019-12-20 16:46 ` Matthew Wilcox
2019-12-20 17:35 ` Amir Goldstein
2019-12-20 19:50 ` Matthew Wilcox
2019-12-23 20:45 ` Chris Down
2019-12-24 3:04 ` Amir Goldstein
2019-12-25 12:54 ` Chris Down
2019-12-26 1:40 ` zhengbin (A)
2019-12-20 21:30 ` Darrick J. Wong
2019-12-21 8:43 ` Amir Goldstein
2019-12-21 18:05 ` Darrick J. Wong
2019-12-21 10:16 ` Chris Down
2020-01-07 17:35 ` J. Bruce Fields
2020-01-07 17:44 ` Chris Down
2020-01-08 3:00 ` J. Bruce Fields [this message]
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