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From:   Chuck Lever III <chuck.lever@oracle.com>
To:     Trond Myklebust <trondmy@hammerspace.com>
CC:     Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        Anna Schumaker <anna.schumaker@netapp.com>
Subject: Re: [PATCH 2/4] SUNRPC: Widen rpc_task::tk_flags
Thread-Topic: [PATCH 2/4] SUNRPC: Widen rpc_task::tk_flags
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Date:   Mon, 25 Jul 2022 13:17:03 +0000
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> On Jul 23, 2022, at 4:10 PM, Trond Myklebust <trondmy@hammerspace.com> wr=
ote:
>=20
> On Fri, 2022-07-22 at 17:55 +0000, Chuck Lever III wrote:
>>=20
>>=20
>>> On Jul 22, 2022, at 1:53 PM, Trond Myklebust
>>> <trondmy@hammerspace.com> wrote:
>>>=20
>>> On Fri, 2022-07-22 at 13:25 -0400, Chuck Lever wrote:
>>>> There is just one unused bit left in rpc_task::tk_flags, and I
>>>> will
>>>> need two in subsequent patches. Double the width of the field to
>>>> accommodate more flag bits.
>>>=20
>>> The values 0x8 and 0x40 are both free, so I'm not seeing why this
>>> patch
>>> is needed at this time.
>>=20
>> It's not needed now, but as recently as last year, there were no free
>> bits (and I needed them for RPC-with-TLS support at that time). We
>> will
>> have to widen this field sooner or later.
>>=20
>> I don't have a problem dropping this one if you'd rather wait.
>>=20
>=20
> I dropped it after applying the other v2 patches.

Thanks for applying the others; I'll drop this one from
my private tree.


> As I said, I don't
> see a need for this expansion yet, and if we do at some point run out
> of bits, I can see other flags we can drop (RPC_TASK_ROOTCREDS and
> RPC_TASK_NULLCREDS being obvious targets) before we need to consider
> actually expanding the size of this field.

Agreed, expanding the flags field is no longer necessary for
RPC-with-TLS, as I've converted it to use the layered connect
mechanism you suggested. The flag it waits on now is
XPRT_CONNECTED.


> In fact, by not expanding it, we can trivially shrink the size of
> struct rpc_task by 8 bytes on x86_64 simply by moving the field
> tk_rpc_status to eliminate the current 4 byte hole. I've added a patch
> to do just that.

--
Chuck Lever