Re: [PATCH] nfsd: Fix build error

From: Chuck Lever <chuck.lever@oracle.com>
To: Bruce Fields <bfields@fieldses.org>
Cc: YueHaibing <yuehaibing@huawei.com>,
	Olga Kornievskaia <kolga@netapp.com>,
	Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] nfsd: Fix build error
Date: Wed, 4 Mar 2020 16:05:03 -0500	[thread overview]
Message-ID: <9592D8FB-C758-4B52-962B-B04A00627A43@oracle.com> (raw)
In-Reply-To: <20200304200609.GA26924@fieldses.org>

> On Mar 4, 2020, at 3:06 PM, Bruce Fields <bfields@fieldses.org> wrote:
> 
> On Wed, Mar 04, 2020 at 01:00:12PM -0500, Chuck Lever wrote:
>> Hi-
>> 
>>> On Mar 4, 2020, at 8:18 AM, YueHaibing <yuehaibing@huawei.com> wrote:
>>> 
>>> fs/nfsd/nfs4proc.o: In function `nfsd4_do_copy':
>>> nfs4proc.c:(.text+0x23b7): undefined reference to `nfs42_ssc_close'
>>> fs/nfsd/nfs4proc.o: In function `nfsd4_copy':
>>> nfs4proc.c:(.text+0x5d2a): undefined reference to `nfs_sb_deactive'
>>> fs/nfsd/nfs4proc.o: In function `nfsd4_do_async_copy':
>>> nfs4proc.c:(.text+0x61d5): undefined reference to `nfs42_ssc_open'
>>> nfs4proc.c:(.text+0x6389): undefined reference to `nfs_sb_deactive'
>>> 
>>> Add dependency to NFSD_V4_2_INTER_SSC to fix this.
>>> 
>>> Fixes: ce0887ac96d3 ("NFSD add nfs4 inter ssc to nfsd4_copy")
>>> Signed-off-by: YueHaibing <yuehaibing@huawei.com>
>>> ---
>>> fs/nfsd/Kconfig | 1 +
>>> 1 file changed, 1 insertion(+)
>>> 
>>> diff --git a/fs/nfsd/Kconfig b/fs/nfsd/Kconfig
>>> index f368f32..fc587a5 100644
>>> --- a/fs/nfsd/Kconfig
>>> +++ b/fs/nfsd/Kconfig
>>> @@ -136,6 +136,7 @@ config NFSD_FLEXFILELAYOUT
>>> 
>>> config NFSD_V4_2_INTER_SSC
>>> 	bool "NFSv4.2 inter server to server COPY"
>>> +	depends on !(NFSD=y && NFS_FS=m)
>> 
>> The new dependency is not especially clear to me; more explanation
>> in the patch description about the cause of the build failure
>> would definitely be helpful.
>> 
>> NFSD_V4 can't be set unless NFSD is also set.
>> 
>> NFS_V4_2 can't be set unless NFS_V4_1 is also set, and that cannot
>> be set unless NFS_FS is also set.
>> 
>> So what's really going on here?
> 
> I don't understand that "depends" either.
> 
> The fundamental problem, though, is that nfsd is calling nfs code
> directly.
> 
> Which I noticed in earlier review and then forgot to follow up on,
> sorry.
> 
> So either we:
> 
> 	- let nfsd depend on nfs, fix up Kconfig to reflect the fact, or
> 	- write some code so nfsd can load nfs and find those symbols at
> 	  runtime if it needs to do a copy.

Another practical option would be to create a copy of these functions in
the server's SSC code. At least nfs_sb_deactive() is not large.

Not clear if nfs42_ssc_open/close are even used on the client. Maybe they
could be moved to the server?

> The latter's certainly doable, but it'd be simplest to do the former.
> Are there actually a lot of people who want nfsd but not nfs?  Does that
> cause a real problem for anyone?
> 
> --b.

--
Chuck Lever