Re: [PATCH RFC v16 03/11] NFSD: Add lm_lock_expired call out

["J. Bruce Fields" <bfields@fieldses.org>]

On Fri, Mar 11, 2022 at 06:13:27PM -0800, Dai Ngo wrote:
> Add callout function nfsd4_lm_lock_expired for lm_lock_expired.
> If lock request has conflict with courtesy client then expire the
> courtesy client and return no conflict to caller.
> 
> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> ---
>  fs/nfsd/nfs4state.c | 37 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 37 insertions(+)
> 
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index a65d59510681..583ac807e98d 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -6578,10 +6578,47 @@ nfsd4_lm_notify(struct file_lock *fl)
>  	}
>  }
>  
> +/**
> + * nfsd4_lm_lock_expired - check if lock conflict can be resolved.
> + *
> + * @fl: pointer to file_lock with a potential conflict
> + * Return values:
> + *   %false: real conflict, lock conflict can not be resolved.
> + *   %true: no conflict, lock conflict was resolved.
> + *
> + * Note that this function is called while the flc_lock is held.
> + */
> +static bool
> +nfsd4_lm_lock_expired(struct file_lock *fl)
> +{
> +	struct nfs4_lockowner *lo;
> +	struct nfs4_client *clp;
> +	bool rc = false;
> +
> +	if (!fl)
> +		return false;
> +	lo = (struct nfs4_lockowner *)fl->fl_owner;
> +	clp = lo->lo_owner.so_client;
> +
> +	/* need to sync with courtesy client trying to reconnect */
> +	spin_lock(&clp->cl_cs_lock);
> +	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
> +		rc = true;
> +	else {
> +		if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags)) {
> +			set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
> +			rc =  true;
> +		}
> +	}

I'd prefer:

	if (test_bit(NFSD4_CLIENT_COURTESY, &clp->cl_flags))
		set_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags);
	if (test_bit(NFSD4_CLIENT_EXPIRED, &clp->cl_flags))
		rc = true;

Same result, but more compact and straightforward, I think.

--b.

> +	spin_unlock(&clp->cl_cs_lock);
> +	return rc;
> +}
> +
>  static const struct lock_manager_operations nfsd_posix_mng_ops  = {
>  	.lm_notify = nfsd4_lm_notify,
>  	.lm_get_owner = nfsd4_lm_get_owner,
>  	.lm_put_owner = nfsd4_lm_put_owner,
> +	.lm_lock_expired = nfsd4_lm_lock_expired,
>  };
>  
>  static inline void
> -- 
> 2.9.5