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From:   "NeilBrown" <neilb@suse.de>
To:     "Chuck Lever" <chuck.lever@oracle.com>
Cc:     linux-nfs@vger.kernel.org, jlayton@redhat.com
Subject: Re: [PATCH v6 13/14] NFSD: Allocate an rhashtable for nfs4_file objects
In-reply-to: <166689678047.90991.16096403318324605089.stgit@klimt.1015granger.net>
References: <166689625728.90991.15067635142973595248.stgit@klimt.1015granger.net>,
 <166689678047.90991.16096403318324605089.stgit@klimt.1015granger.net>
Date:   Fri, 28 Oct 2022 10:24:33 +1100
Message-id: <166691307319.13915.11000056177725554613@noble.neil.brown.name>
Precedence: bulk

On Fri, 28 Oct 2022, Chuck Lever wrote:
> Introduce the infrastructure for managing nfs4_file objects in an
> rhashtable. This infrastructure will be used by the next patch.
>=20
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> Reviewed-by: NeilBrown <neilb@suse.de>
> ---
>  fs/nfsd/nfs4state.c |   26 +++++++++++++++++++++++++-
>  fs/nfsd/state.h     |    1 +
>  2 files changed, 26 insertions(+), 1 deletion(-)
>=20
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index a07fbbe289cf..3afb73750d2d 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -44,7 +44,9 @@
>  #include <linux/jhash.h>
>  #include <linux/string_helpers.h>
>  #include <linux/fsnotify.h>
> +#include <linux/rhashtable.h>
>  #include <linux/nfs_ssc.h>
> +
>  #include "xdr4.h"
>  #include "xdr4cb.h"
>  #include "vfs.h"
> @@ -721,6 +723,21 @@ static unsigned int file_hashval(const struct svc_fh *=
fh)
> =20
>  static struct hlist_head file_hashtbl[FILE_HASH_SIZE];
> =20
> +static struct rhltable nfs4_file_rhltable ____cacheline_aligned_in_smp;
> +
> +static const struct rhashtable_params nfs4_file_rhash_params =3D {
> +	.key_len		=3D sizeof_field(struct nfs4_file, fi_inode),
> +	.key_offset		=3D offsetof(struct nfs4_file, fi_inode),
> +	.head_offset		=3D offsetof(struct nfs4_file, fi_rlist),
> +
> +	/*
> +	 * Start with a single page hash table to reduce resizing churn
> +	 * on light workloads.
> +	 */

Nice :-)

NeilBrown

> +	.min_size		=3D 256,
> +	.automatic_shrinking	=3D true,
> +};
> +
>  /*
>   * Check if courtesy clients have conflicting access and resolve it if pos=
sible
>   *
> @@ -8025,10 +8042,16 @@ nfs4_state_start(void)
>  {
>  	int ret;
> =20
> -	ret =3D nfsd4_create_callback_queue();
> +	ret =3D rhltable_init(&nfs4_file_rhltable, &nfs4_file_rhash_params);
>  	if (ret)
>  		return ret;
> =20
> +	ret =3D nfsd4_create_callback_queue();
> +	if (ret) {
> +		rhltable_destroy(&nfs4_file_rhltable);
> +		return ret;
> +	}
> +
>  	set_max_delegations();
>  	return 0;
>  }
> @@ -8059,6 +8082,7 @@ nfs4_state_shutdown_net(struct net *net)
> =20
>  	nfsd4_client_tracking_exit(net);
>  	nfs4_state_destroy_net(net);
> +	rhltable_destroy(&nfs4_file_rhltable);
>  #ifdef CONFIG_NFSD_V4_2_INTER_SSC
>  	nfsd4_ssc_shutdown_umount(nn);
>  #endif
> diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
> index e2daef3cc003..190fc7e418a4 100644
> --- a/fs/nfsd/state.h
> +++ b/fs/nfsd/state.h
> @@ -546,6 +546,7 @@ struct nfs4_file {
>  	bool			fi_aliased;
>  	spinlock_t		fi_lock;
>  	struct hlist_node       fi_hash;	/* hash on fi_fhandle */
> +	struct rhlist_head	fi_rlist;
>  	struct list_head        fi_stateids;
>  	union {
>  		struct list_head	fi_delegations;
>=20
>=20
>=20