From: Jeff Layton <jlayton@kernel.org>
To: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Trond Myklebust <trondmy@hammerspace.com>,
"zohar@linux.ibm.com" <zohar@linux.ibm.com>,
"djwong@kernel.org" <djwong@kernel.org>,
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"walters@verbum.org" <walters@verbum.org>
Subject: Re: [PATCH v3 1/7] iversion: update comments with info about atime updates
Date: Tue, 30 Aug 2022 15:30:13 -0400 [thread overview]
Message-ID: <b3c0e3ae74a6f30547bd5c49c32c17f1e7a13b0c.camel@kernel.org> (raw)
In-Reply-To: <20220830183244.GG26330@fieldses.org>
On Tue, 2022-08-30 at 14:32 -0400, J. Bruce Fields wrote:
> On Tue, Aug 30, 2022 at 01:02:50PM -0400, Jeff Layton wrote:
> > The fact that NFS kept this more loosely-defined is what allowed us to
> > elide some of the i_version bumps and regain a fair bit of performance
> > for local filesystems [1]. If the change attribute had been more
> > strictly defined like you mention, then that particular optimization
> > would not have been possible.
> >
> > This sort of thing is why I'm a fan of not defining this any more
> > strictly than we require. Later on, maybe we'll come up with a way for
> > filesystems to advertise that they can offer stronger guarantees.
>
> Yeah, the afs change-attribute-as-counter thing seems ambitious--I
> wouldn't even know how to define what exactly you're counting.
>
> My one question is whether it'd be worth just defining the thing as
> *increasing*. That's a lower bar.
>
That's a very good question.
One could argue that NFSv4 sort of requires that for write delegations
anyway. All of the existing implementations that I know of do this, so
that wouldn't rule any of them out.
I'm not opposed to adding that constraint. Let me think on it a bit
more.
> (Though admittedly we don't quite manage it now--see again 1631087ba872
> "Revert "nfsd4: support change_attr_type attribute"".)
>
Factoring the ctime into the change attr seems wrong, since a clock jump
could make it go backward. Do you remember what drove that change (see
630458e730b8) ?
It seems like if the i_version were to go backward, then the ctime
probably would too, and you'd still see a duplicate change attr.
--
Jeff Layton <jlayton@kernel.org>
next prev parent reply other threads:[~2022-08-30 19:30 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-26 21:46 [PATCH v3 0/7] vfs: clean up i_version behavior and expose it via statx Jeff Layton
2022-08-26 21:46 ` [PATCH v3 1/7] iversion: update comments with info about atime updates Jeff Layton
2022-08-29 7:56 ` Dave Chinner
2022-08-29 10:39 ` Jeff Layton
2022-08-29 22:58 ` NeilBrown
2022-08-30 11:40 ` Jeff Layton
2022-08-30 13:24 ` J. Bruce Fields
2022-08-30 13:50 ` Jeff Layton
2022-08-30 14:44 ` J. Bruce Fields
2022-08-30 14:58 ` Trond Myklebust
2022-08-30 15:17 ` J. Bruce Fields
2022-08-30 15:43 ` Trond Myklebust
2022-08-30 17:02 ` Jeff Layton
2022-08-30 17:47 ` Trond Myklebust
2022-08-30 17:53 ` Jeff Layton
2022-08-30 18:25 ` Trond Myklebust
2022-08-30 19:11 ` Jeff Layton
2022-08-30 18:32 ` J. Bruce Fields
2022-08-30 19:30 ` Jeff Layton [this message]
2022-08-30 19:46 ` J. Bruce Fields
2022-08-30 19:57 ` Jeff Layton
2022-08-30 20:08 ` J. Bruce Fields
2022-08-30 1:04 ` Dave Chinner
2022-08-30 12:38 ` Jeff Layton
2022-08-26 21:46 ` [PATCH v3 2/7] ext4: fix i_version handling in ext4 Jeff Layton
2022-08-26 21:46 ` [PATCH v3 3/7] ext4: unconditionally enable the i_version counter Jeff Layton
2022-08-29 14:51 ` Jan Kara
2022-08-26 21:47 ` [PATCH v3 4/7] xfs: don't bump the i_version on an atime update in xfs_vn_update_time Jeff Layton
2022-08-27 7:26 ` Amir Goldstein
2022-08-27 8:01 ` Amir Goldstein
2022-08-27 13:14 ` Jeff Layton
2022-08-27 15:46 ` Darrick J. Wong
2022-08-27 16:03 ` Trond Myklebust
2022-08-27 16:10 ` Jeff Layton
2022-08-27 17:06 ` Trond Myklebust
2022-08-28 13:25 ` Amir Goldstein
2022-08-28 14:37 ` Jeff Layton
2022-08-28 16:53 ` Amir Goldstein
2022-08-29 5:48 ` Dave Chinner
2022-08-29 10:33 ` Jeff Layton
2022-08-30 0:08 ` Dave Chinner
2022-08-30 11:20 ` Jeff Layton
2022-08-28 17:30 ` Amir Goldstein
2022-08-26 21:47 ` [PATCH v3 5/7] vfs: report an inode version in statx for IS_I_VERSION inodes Jeff Layton
2022-08-26 21:47 ` [PATCH v3 6/7] nfs: report the inode version in statx if requested Jeff Layton
2022-08-26 21:47 ` [PATCH v3 7/7] ceph: fill in the change attribute in statx requests Jeff Layton
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