From: Chuck Lever <chuck.lever@oracle.com>
To: Benjamin Coddington <bcodding@redhat.com>
Cc: Jason L Tibbitts III <tibbs@math.uh.edu>,
Bruce Fields <bfields@fieldses.org>,
Wolfgang Walter <linux@stwm.de>,
Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
km@cm4all.com, linux-kernel@vger.kernel.org
Subject: Re: Regression in 5.1.20: Reading long directory fails
Date: Wed, 11 Sep 2019 13:54:14 -0400 [thread overview]
Message-ID: <B8CDE765-7DCE-4257-91E1-CC85CB7F87F7@oracle.com> (raw)
In-Reply-To: <FAA4DD3D-C58A-4628-8FD5-A7E2E203B75A@redhat.com>
> On Sep 11, 2019, at 1:50 PM, Benjamin Coddington <bcodding@redhat.com> wrote:
>
> On 11 Sep 2019, at 13:40, Benjamin Coddington wrote:
>
>> On 11 Sep 2019, at 13:29, Chuck Lever wrote:
>>
>>>> On Sep 11, 2019, at 1:26 PM, Benjamin Coddington <bcodding@redhat.com> wrote:
>>>>
>>>>
>>>> On 11 Sep 2019, at 12:39, Chuck Lever wrote:
>>>>
>>>>>> On Sep 11, 2019, at 12:25 PM, Benjamin Coddington <bcodding@redhat.com> wrote:
>>>>>>
>>>>
>>>>>> Instead, I think we want to make sure the mic falls squarely into the tail
>>>>>> every time.
>>>>>
>>>>> I'm not clear how you could do that. The length of the page data is not
>>>>> known to the client before it parses the reply. Are you suggesting that
>>>>> gss_unwrap should do it somehow?
>>>>
>>>> Is it too niave to always put the mic at the end of the tail?
>>>
>>> The size of the page content is variable.
>>>
>>> The only way the MIC will fall into the tail is if the page content is
>>> exactly the largest expected size. When the page content is smaller than
>>> that, the receive logic will place part or all of the MIC in ->pages.
>>
>> Ok, right. But what I meant is that xdr_buf_read_netobj() should be renamed
>> and repurposed to be "move the mic from wherever it is to the end of
>> xdr_buf's tail".
>>
>> But now I see what you mean, and I also see that it is already trying to do
>> that.. and we don't want to overlap the copy..
>>
>> So, really, we need the tail to be larger than twice the mic.. less 1. That
>> means the fix is probably just increasing rslack for krb5i.
>
> .. or we can keep the tighter tail space, and if we detect the mic straddles
> the page and tail, we can move the mic into the tail with 2 copies, first
> move the bit in the tail back, then move the bit in the pages.
>
> Which is preferred, less allocation, or in the rare case this occurs, doing
> copy twice?
It sounds like the bug is that the current code does not deal correctly
when the MIC crosses the boundary between ->pages and ->tail? I'd like
to see that addressed rather than changing rslack.
--
Chuck Lever
next prev parent reply other threads:[~2019-09-11 17:56 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <ufak1bhyuew.fsf@epithumia.math.uh.edu>
2019-08-22 19:39 ` Regression in 5.1.20: Reading long directory fails Jason L Tibbitts III
2019-08-28 17:46 ` J. Bruce Fields
2019-08-28 18:29 ` Jason L Tibbitts III
2019-08-28 18:33 ` J. Bruce Fields
2019-09-03 15:49 ` Jason L Tibbitts III
2019-09-03 18:02 ` Wolfgang Walter
2019-09-03 19:06 ` Jason L Tibbitts III
2019-09-03 19:08 ` Chuck Lever
2019-09-03 21:37 ` Wolfgang Walter
2019-09-04 1:50 ` Jason L Tibbitts III
2019-09-06 14:48 ` J. Bruce Fields
2019-09-06 20:47 ` Jason L Tibbitts III
2019-09-06 20:50 ` Chuck Lever
2019-09-08 11:39 ` Benjamin Coddington
2019-09-08 15:19 ` Trond Myklebust
2019-09-08 15:48 ` Chuck Lever
2019-09-08 16:47 ` Trond Myklebust
2019-09-08 16:51 ` Chuck Lever
2019-09-11 16:25 ` Benjamin Coddington
2019-09-11 16:39 ` Chuck Lever
2019-09-11 17:26 ` Benjamin Coddington
2019-09-11 17:27 ` Benjamin Coddington
2019-09-11 17:29 ` Chuck Lever
2019-09-11 17:40 ` Benjamin Coddington
2019-09-11 17:43 ` Chuck Lever
2019-09-11 17:59 ` Benjamin Coddington
2019-09-11 17:50 ` Benjamin Coddington
2019-09-11 17:54 ` Chuck Lever [this message]
2019-09-12 12:29 ` Benjamin Coddington
2019-09-12 12:53 ` Trond Myklebust
2019-09-12 13:08 ` Benjamin Coddington
2019-09-12 13:13 ` J. Bruce Fields
2019-09-12 13:25 ` Trond Myklebust
2019-09-12 13:35 ` Benjamin Coddington
2019-09-12 13:14 ` Trond Myklebust
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