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In-Reply-To: <20190909140104.78818-8-trond.myklebust@hammerspace.com>
From:   Olga Kornievskaia <aglo@umich.edu>
Date:   Wed, 11 Sep 2019 16:13:54 -0400
Message-ID: <CAN-5tyFLWbWR4_2bw_6WKiT71=WPCRZF=gk-vAQ+-tHDtFwrPg@mail.gmail.com>
Subject: Re: [PATCH 8/9] NFSv4: Handle NFS4ERR_OLD_STATEID in CLOSE/OPEN_DOWNGRADE
To:     Trond Myklebust <trondmy@gmail.com>
Cc:     Anna Schumaker <Anna.Schumaker@netapp.com>,
        linux-nfs <linux-nfs@vger.kernel.org>
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Hi Trond,

This patch is causing me "problem" (can be seen using generic/323).
This test creates 100 processes that each want to open the same file,
then close it. Each open gets a stateid with an increasing seqid (the
last received by the client is stateid seqid=100). With the patch,
upon close I see 1st CLOSE use stateid seqid=1 which ends up failing
with ERR_OLD_STATEID and retried until stateid seqid=100 (which was
the current id). Reverting the patch give back sending the CLOSE with
seqid=100. While nothing failing, I don't think the client's behavior
is correct.

On Tue, Sep 10, 2019 at 4:10 AM Trond Myklebust <trondmy@gmail.com> wrote:
>
> If a CLOSE or OPEN_DOWNGRADE operation receives a NFS4ERR_OLD_STATEID
> then bump the seqid before resending. Ensure we only bump the seqid
> by 1.
>
> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
> ---
>  fs/nfs/nfs4_fs.h   |  2 --
>  fs/nfs/nfs4proc.c  | 41 ++++++++++++++++++++++++++++++++++++++---
>  fs/nfs/nfs4state.c | 16 ----------------
>  3 files changed, 38 insertions(+), 21 deletions(-)
>
> diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
> index e8f74ed98e42..16b2e5cc3e94 100644
> --- a/fs/nfs/nfs4_fs.h
> +++ b/fs/nfs/nfs4_fs.h
> @@ -491,8 +491,6 @@ extern int nfs4_set_lock_state(struct nfs4_state *state, struct file_lock *fl);
>  extern int nfs4_select_rw_stateid(struct nfs4_state *, fmode_t,
>                 const struct nfs_lock_context *, nfs4_stateid *,
>                 const struct cred **);
> -extern bool nfs4_refresh_open_stateid(nfs4_stateid *dst,
> -               struct nfs4_state *state);
>  extern bool nfs4_copy_open_stateid(nfs4_stateid *dst,
>                 struct nfs4_state *state);
>
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 025dd5efbf34..49f301198008 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -3308,6 +3308,42 @@ nfs4_wait_on_layoutreturn(struct inode *inode, struct rpc_task *task)
>         return pnfs_wait_on_layoutreturn(inode, task);
>  }
>
> +/*
> + * Update the seqid of an open stateid after receiving
> + * NFS4ERR_OLD_STATEID
> + */
> +static bool nfs4_refresh_open_old_stateid(nfs4_stateid *dst,
> +               struct nfs4_state *state)
> +{
> +       __be32 seqid_open;
> +       u32 dst_seqid;
> +       bool ret;
> +       int seq;
> +
> +       for (;;) {
> +               ret = false;
> +               seq = read_seqbegin(&state->seqlock);
> +               if (!nfs4_state_match_open_stateid_other(state, dst)) {
> +                       if (read_seqretry(&state->seqlock, seq))
> +                               continue;
> +                       break;
> +               }
> +               seqid_open = state->open_stateid.seqid;
> +               dst_seqid = be32_to_cpu(dst->seqid);
> +
> +               if (read_seqretry(&state->seqlock, seq))
> +                       continue;
> +               if ((s32)(dst_seqid - be32_to_cpu(seqid_open)) >= 0)
> +                       dst->seqid = cpu_to_be32(dst_seqid + 1);
> +               else
> +                       dst->seqid = seqid_open;
> +               ret = true;
> +               break;
> +       }
> +
> +       return ret;
> +}
> +
>  struct nfs4_closedata {
>         struct inode *inode;
>         struct nfs4_state *state;
> @@ -3382,7 +3418,7 @@ static void nfs4_close_done(struct rpc_task *task, void *data)
>                         break;
>                 case -NFS4ERR_OLD_STATEID:
>                         /* Did we race with OPEN? */
> -                       if (nfs4_refresh_open_stateid(&calldata->arg.stateid,
> +                       if (nfs4_refresh_open_old_stateid(&calldata->arg.stateid,
>                                                 state))
>                                 goto out_restart;
>                         goto out_release;
> @@ -3451,8 +3487,7 @@ static void nfs4_close_prepare(struct rpc_task *task, void *data)
>         } else if (is_rdwr)
>                 calldata->arg.fmode |= FMODE_READ|FMODE_WRITE;
>
> -       if (!nfs4_valid_open_stateid(state) ||
> -           !nfs4_refresh_open_stateid(&calldata->arg.stateid, state))
> +       if (!nfs4_valid_open_stateid(state))
>                 call_close = 0;
>         spin_unlock(&state->owner->so_lock);
>
> diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
> index cad4e064b328..e23945174da4 100644
> --- a/fs/nfs/nfs4state.c
> +++ b/fs/nfs/nfs4state.c
> @@ -1015,22 +1015,6 @@ static int nfs4_copy_lock_stateid(nfs4_stateid *dst,
>         return ret;
>  }
>
> -bool nfs4_refresh_open_stateid(nfs4_stateid *dst, struct nfs4_state *state)
> -{
> -       bool ret;
> -       int seq;
> -
> -       do {
> -               ret = false;
> -               seq = read_seqbegin(&state->seqlock);
> -               if (nfs4_state_match_open_stateid_other(state, dst)) {
> -                       dst->seqid = state->open_stateid.seqid;
> -                       ret = true;
> -               }
> -       } while (read_seqretry(&state->seqlock, seq));
> -       return ret;
> -}
> -
>  bool nfs4_copy_open_stateid(nfs4_stateid *dst, struct nfs4_state *state)
>  {
>         bool ret;
> --
> 2.21.0
>