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From: "J. Bruce Fields" <bfields@redhat.com>
To: Olga Kornievskaia <olga.kornievskaia@gmail.com>
Cc: linux-nfs <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH v5 5/9] NFSD add COPY_NOTIFY operation
Date: Mon, 12 Aug 2019 16:00:36 -0400
Message-ID: <20190812200036.GC29812@parsley.fieldses.org> (raw)
In-Reply-To: <20190812200019.GB29812@parsley.fieldses.org>

On Mon, Aug 12, 2019 at 04:00:19PM -0400, J. Bruce Fields wrote:
> On Mon, Aug 12, 2019 at 03:16:47PM -0400, Olga Kornievskaia wrote:
> > On Mon, Aug 12, 2019 at 12:19 PM Olga Kornievskaia
> > <olga.kornievskaia@gmail.com> wrote:
> > > While this passes my testing, in theory this allows for the race that
> > > we get the copy notify size but then offload_cancel arrive and change
> > > the value. Then refcount_sub_and test_check would have an incorrect
> > > value (can subtract larger than an actual reference count). I have no
> > > solution for that as there is no refcount_sub_and_lock() that will
> > > allow to decrement by a multiple under a lock. Thoughts?
> > 
> > I tried not to use the client's cl_lock but instead use a specific
> > lock to protect the copy notifies stateid on the stateid list. But
> > since stateid's reference counter (sc_count) is protected by it, I
> > think by getting rid of the special lock and using cl_lock will solve
> > the problem of coordinating access between the sc_count and the
> > copy_notify stateid list. Are the any problems with using such a big
> > lock?
> 
> Probably not.  But it can be confusing when a single lock is used for
> several different things.  A comment explaining why you need it might
> help.

(By which I mean, a comment in the code.)

--b.

  reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-08 20:18 [PATCH v5 0/9] server-side support for "inter" SSC copy Olga Kornievskaia
2019-08-08 20:18 ` [PATCH v5 1/9] NFSD fill-in netloc4 structure Olga Kornievskaia
2019-08-11  5:48   ` kbuild test robot
2019-08-12 16:12     ` Olga Kornievskaia
2019-08-12 19:58       ` J. Bruce Fields
2019-08-08 20:18 ` [PATCH v5 2/9] NFSD add ca_source_server<> to COPY Olga Kornievskaia
2019-08-11  5:59   ` kbuild test robot
2019-08-11  7:00   ` kbuild test robot
2019-08-08 20:18 ` [PATCH v5 3/9] NFSD return nfs4_stid in nfs4_preprocess_stateid_op Olga Kornievskaia
2019-08-08 20:18 ` [PATCH v5 4/9] NFSD COPY_NOTIFY xdr Olga Kornievskaia
2019-08-11  6:10   ` kbuild test robot
2019-08-08 20:18 ` [PATCH v5 5/9] NFSD add COPY_NOTIFY operation Olga Kornievskaia
2019-08-11  6:17   ` kbuild test robot
2019-08-12 16:19   ` Olga Kornievskaia
2019-08-12 19:16     ` Olga Kornievskaia
2019-08-12 20:00       ` J. Bruce Fields
2019-08-12 20:00         ` J. Bruce Fields [this message]
2019-08-13 17:57         ` Olga Kornievskaia
2019-08-14 15:05           ` Olga Kornievskaia
2019-08-29 19:23             ` Olga Kornievskaia
2019-08-30 17:56               ` bfields
2019-08-08 20:18 ` [PATCH v5 6/9] NFSD check stateids against copy stateids Olga Kornievskaia
2019-08-08 20:18 ` [PATCH v5 7/9] NFSD generalize nfsd4_compound_state flag names Olga Kornievskaia
2019-08-08 20:18 ` [PATCH v5 8/9] NFSD: allow inter server COPY to have a STALE source server fh Olga Kornievskaia
2019-08-08 20:18 ` [PATCH v5 9/9] NFSD add nfs4 inter ssc to nfsd4_copy Olga Kornievskaia
2019-08-11  6:24   ` kbuild test robot
2019-09-04 20:50 ` [PATCH v5 0/9] server-side support for "inter" SSC copy bfields
2019-09-05  0:05   ` Olga Kornievskaia
2019-09-05  0:13     ` Rick Macklem
2019-09-06 14:23       ` Olga Kornievskaia
2019-09-06 15:32         ` Rick Macklem

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