From: Al Viro <viro@ZenIV.linux.org.uk>
To: Mark Fasheh <email@example.com>
Cc: firstname.lastname@example.org, email@example.com,
Andrew Morton <firstname.lastname@example.org>,
Amir Goldstein <email@example.com>,
firstname.lastname@example.org, Jeff Mahoney <email@example.com>,
Subject: Re: [PATCH 2/4] nfs: check for NULL vfsmount in nfs_getattr
Date: Thu, 2 Aug 2018 01:43:48 +0100 [thread overview]
Message-ID: <20180802004347.GV30522@ZenIV.linux.org.uk> (raw)
On Tue, Jul 31, 2018 at 10:51:57PM +0000, Mark Fasheh wrote:
> Hi Al,
> On Tue, Jul 31, 2018 at 11:16:05PM +0100, Al Viro wrote:
> > On Tue, Jul 31, 2018 at 02:10:43PM -0700, Mark Fasheh wrote:
> > > ->getattr from inside the kernel won't always have a vfsmount, check for
> > > this.
> > Really? Where would that happen?
> It happens in my first patch. FWIW, I'm not tied to that particular bit of
> code, or even this (latest) approach. I would actually very much appreciate
> your input into how we might fix the problem we have where we are sometimes
> not exporting a correct ino/dev pair to user space.
Which callers would those be? I don't see anything in your series that
wouldn't have vfsmount at hand...
> I have a good break-down of the problem and possible solutions here:
btrfs pulling odd crap with device numbers is a problem, but this is far from
the most obvious unpleasantness caused by that - e.g. userland code expecting
that unequal st_dev for directory and subdirectory means that we have
a mountpoint there. Or assuming it can compare that to st_dev of mountpoints
(or, indeed, the values in /proc/self/mountinfo) to find which fs it's on...
/proc/*/maps is unfortunate, but it does contain the pathnames, doesn't it?
What _real_ problems are there - the ones where we don't have a saner solution?
Note that /proc/locks is (a) FPOS interface and (b) unsuitable for your
next prev parent reply other threads:[~2018-08-02 2:32 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-31 21:10 [RFC PATCH 0/4] vfs: map unique ino/dev pairs for user space Mark Fasheh
2018-07-31 21:10 ` [PATCH 1/4] vfs: introduce function to map unique ino/dev pairs Mark Fasheh
2018-07-31 23:21 ` Mark Fasheh
2018-08-01 5:41 ` Amir Goldstein
2018-08-01 15:59 ` Mark Fasheh
2018-07-31 21:10 ` [PATCH 2/4] nfs: check for NULL vfsmount in nfs_getattr Mark Fasheh
2018-07-31 22:16 ` Al Viro
2018-07-31 22:51 ` Mark Fasheh
2018-08-02 0:43 ` Al Viro [this message]
2018-08-03 2:04 ` Mark Fasheh
2018-07-31 21:10 ` [PATCH 3/4] proc: use vfs helper to get ino/dev pairs for maps file Mark Fasheh
2018-07-31 21:10 ` [PATCH 4/4] locks: map correct ino/dev pairs when exporting to userspace Mark Fasheh
2018-08-01 5:37 ` Amir Goldstein
2018-08-01 17:45 ` Mark Fasheh
2018-08-01 11:03 ` Jeff Layton
2018-08-01 20:38 ` Mark Fasheh
2018-08-02 0:24 ` [RFC PATCH 0/4] vfs: map unique ino/dev pairs for user space J. R. Okajima
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