linux-kernel - Re: [PATCH v3 01/13] nfsd: fix nfsd4_deleg_getattr_conflict in presence of third party lease

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Message-ID: <278CB444-BBAE-411D-9B8A-A6C68FE29567@oracle.com>
Date: Fri, 30 Aug 2024 13:54:44 +0000
From: Chuck Lever III <chuck.lever@...cle.com>
To: Neil Brown <neilb@...e.de>
CC: Jeff Layton <jlayton@...nel.org>, Dai Ngo <dai.ngo@...cle.com>,
        Tom Talpey
	<tom@...pey.com>, Trond Myklebust <trondmy@...nel.org>,
        Anna Schumaker
	<anna@...nel.org>,
        Olga Kornievskaia <okorniev@...hat.com>,
        Al Viro
	<viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>, Jan Kara
	<jack@...e.cz>,
        Jonathan Corbet <corbet@....net>, Tom Haynes
	<loghyr@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux NFS Mailing List <linux-nfs@...r.kernel.org>,
        Linux FS Devel
	<linux-fsdevel@...r.kernel.org>,
        "linux-doc@...r.kernel.org"
	<linux-doc@...r.kernel.org>
Subject: Re: [PATCH v3 01/13] nfsd: fix nfsd4_deleg_getattr_conflict in
 presence of third party lease



> On Aug 30, 2024, at 2:01 AM, NeilBrown <neilb@...e.de> wrote:
> 
> On Fri, 30 Aug 2024, Chuck Lever wrote:
>> On Thu, Aug 29, 2024 at 09:26:39AM -0400, Jeff Layton wrote:
>>> From: NeilBrown <neilb@...e.de>
>>> 
>>> It is not safe to dereference fl->c.flc_owner without first confirming
>>> fl->fl_lmops is the expected manager.  nfsd4_deleg_getattr_conflict()
>>> tests fl_lmops but largely ignores the result and assumes that flc_owner
>>> is an nfs4_delegation anyway.  This is wrong.
>>> 
>>> With this patch we restore the "!= &nfsd_lease_mng_ops" case to behave
>>> as it did before the changed mentioned below.  This the same as the
>>> current code, but without any reference to a possible delegation.
>>> 
>>> Fixes: c5967721e106 ("NFSD: handle GETATTR conflict with write delegation")
>>> Signed-off-by: NeilBrown <neilb@...e.de>
>>> Signed-off-by: Jeff Layton <jlayton@...nel.org>
>> 
>> I've already applied this to nfsd-fixes.
>> 
>> If I include this commit in both nfsd-fixes and nfsd-next then the
>> linux-next merge whines about duplicate patches. Stephen Rothwell
>> suggested git-merging nfsd-fixes and nfsd-next but I'm not quite
>> confident enough to try that.
>> 
>> Barring another solution, merging this series will have to wait a
>> few days before the two trees can sync up.
> 
> Hmmm....  I would probably always rebase nfsd-next on nfsd-fixes, which
> I would rebase on the most recent of rc0, rc1, or the latest rc to
> receive nfsd patches.

That straightforward strategy leaves NFSD fixes scattered
throughout the merge history.


> nfsd-fixes is currently based on 6.10-rc7, while -next is based on
> 6.11-rc5.
> 
> Why the 6.10 base??

nfsd-fixes extends the branch I initially submitted to Linus
for the last merge window. That makes it easy to locate the
full set of NFSD commits that go into each kernel release
in the order they were submitted and keeps the merge
topology simpler.

      B - C - D - E       <<< nfsd
     /         \   \
  - A - X - Y - Z - AA -  <<< master

Or, that's the theory anyway. And generally it's not an
irritant except for right near the end of the development
cycle.

I'm not 100% wedded to this approach, and I am interested
in discussion and improvement.

Stephen Rothwell suggested that I provide a single merged
branch for development and for linux-next to pull. I almost
understand how to do that, but it's still a bit beyond my
current everyday tooling (stgit).


--
Chuck Lever