From: Linus Torvalds <torvalds@linux-foundation.org>
To: David Howells <dhowells@redhat.com>
Cc: Aleksa Sarai <cyphar@cyphar.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Stefan Metzmacher <metze@samba.org>, Ian Kent <raven@themaw.net>,
Miklos Szeredi <mszeredi@redhat.com>,
Christian Brauner <christian@brauner.io>,
Jann Horn <jannh@google.com>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Karel Zak <kzak@redhat.com>,
jlayton@redhat.com, Linux API <linux-api@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
LSM List <linux-security-module@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 01/14] VFS: Add additional RESOLVE_* flags [ver #18]
Date: Wed, 11 Mar 2020 10:59:51 -0700 [thread overview]
Message-ID: <CAHk-=wiaL6zznNtCHKg6+MJuCqDxO=yVfms3qR9A0czjKuSSiA@mail.gmail.com> (raw)
In-Reply-To: <580352.1583825105@warthog.procyon.org.uk>
On Tue, Mar 10, 2020 at 12:25 AM David Howells <dhowells@redhat.com> wrote:
?
> Okay. So what's the equivalent of AT_SYMLINK_NOFOLLOW in RESOLVE_* flag
> terms?
Nothing.
openat2() takes two sets of flags. We'll never get rid of
AT_SYMLINK_NOFOLLOW / O_NOFOLLOW, and we've added RESOLVE_NO_SYMLINKS
to the new set of flags. It's just a separate namespace.
We will _not_ be adding a RESOLVE_XYZ flag for O_NOFOLLOW or
AT_SYMLINK_NOFOLLOW. At least not visible to user space - because as
people already figured out, that just causes problems with consistency
issues.
And yes, the fact that we then have three different user-visible
namespaces (O_xyz flags for open(), AT_xyz flags for linkat(), and now
RESOLVE_xyz flags for openat2()) is sad and messy. But it's an
inherent messiness from just how the world works. We can't get rid of
it.
If we need linkat2() and friends, so be it. Do we?
Could we have a _fourth_ set of flags that are simply for internal use
that is a superset of them all? Sure. But no, it's almost certainly
not worth it. Four is not better than three.
Now, some type-safety in the kernel to make sure that we can't mix
AT_xyz with O_xyz or RESOLVE_xyz - that might be worth it. Although
judging by past experience, not enough people run sparse for it to
really be worth it.
Linus
PS. Yeah, we also have that LOOKUP_xyz namespace, and the access mode
namespace, so we already have those internal format versions too.
next prev parent reply other threads:[~2020-03-11 18:00 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-09 14:00 [PATCH 00/14] VFS: Filesystem information [ver #18] David Howells
2020-03-09 14:00 ` [PATCH 01/14] VFS: Add additional RESOLVE_* flags " David Howells
2020-03-09 20:56 ` Stefan Metzmacher
2020-03-09 21:13 ` David Howells
[not found] ` <20200310005549.adrn3yf4mbljc5f6@yavin>
2020-03-10 1:14 ` Linus Torvalds
2020-03-10 7:25 ` David Howells
2020-03-11 17:59 ` Linus Torvalds [this message]
2020-03-12 9:08 ` Stefan Metzmacher
2020-03-12 16:24 ` Linus Torvalds
2020-03-12 17:11 ` Stefan Metzmacher
2020-03-12 19:37 ` Al Viro
2020-03-12 21:48 ` Jeremy Allison
[not found] ` <20200313095901.tdv4vl7envypgqfz@yavin>
2020-03-13 16:48 ` Jeremy Allison
2020-03-13 18:28 ` Al Viro
2020-03-13 18:35 ` Jeremy Allison
2020-03-16 14:20 ` Aleksa Sarai
2020-03-12 19:25 ` Al Viro
2020-03-12 16:56 ` David Howells
2020-03-12 18:09 ` Linus Torvalds
2020-03-09 14:01 ` [PATCH 02/14] fsinfo: Add fsinfo() syscall to query filesystem information " David Howells
2020-03-10 9:31 ` Christian Brauner
2020-03-10 9:32 ` [PATCH v19 01/14] fsinfo: Add fsinfo() syscall to query filesystem information Christian Brauner
2020-03-10 9:32 ` [PATCH v19 14/14] arch: wire up fsinfo syscall Christian Brauner
2020-03-09 14:01 ` [PATCH 03/14] fsinfo: Provide a bitmap of supported features [ver #18] David Howells
2020-03-09 14:01 ` [PATCH 04/14] fsinfo: Allow retrieval of superblock devname, options and stats " David Howells
2020-03-09 14:01 ` [PATCH 05/14] fsinfo: Allow fsinfo() to look up a mount object by ID " David Howells
2020-03-09 14:01 ` [PATCH 06/14] fsinfo: Add a uniquifier ID to struct mount " David Howells
2020-03-09 14:01 ` [PATCH 07/14] fsinfo: Allow mount information to be queried " David Howells
2020-03-10 9:04 ` Miklos Szeredi
2020-03-09 14:02 ` [PATCH 08/14] fsinfo: Allow the mount topology propogation flags to be retrieved " David Howells
2020-03-10 8:42 ` Christian Brauner
2020-03-09 14:02 ` [PATCH 09/14] fsinfo: Provide notification overrun handling support " David Howells
2020-03-09 14:02 ` [PATCH 10/14] fsinfo: sample: Mount listing program " David Howells
2020-03-09 14:02 ` [PATCH 11/14] fsinfo: Add API documentation " David Howells
2020-03-09 14:02 ` [PATCH 12/14] fsinfo: Add support for AFS " David Howells
2020-03-09 14:02 ` [PATCH 13/14] fsinfo: Example support for Ext4 " David Howells
2020-03-09 14:02 ` [PATCH 14/14] fsinfo: Example support for NFS " David Howells
2020-03-09 17:50 ` [PATCH 00/14] VFS: Filesystem information " Jeff Layton
2020-03-09 19:22 ` Andres Freund
2020-03-09 22:49 ` Jeff Layton
2020-03-10 0:18 ` Andres Freund
2020-03-09 20:02 ` Miklos Szeredi
2020-03-09 22:52 ` David Howells
2020-03-10 9:18 ` Miklos Szeredi
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