[PATCH v5 12/13] NFSD: Allocate an rhashtable for nfs4_file objects

[Chuck Lever <chuck.lever@xxxxxxxxxx>]

Introduce the infrastructure for managing nfs4_file objects in an
rhashtable. This infrastructure will be used by the next patch.

Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
 fs/nfsd/nfs4state.c |   23 ++++++++++++++++++++++-
 fs/nfsd/state.h     |    1 +
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index abed795bb4ec..681cb2daa843 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 +723,18 @@ static unsigned int file_hashval(const struct svc_fh *fh)
 
 static struct hlist_head file_hashtbl[FILE_HASH_SIZE];
 
+static struct rhltable nfs4_file_rhltable ____cacheline_aligned_in_smp;
+
+static const struct rhashtable_params nfs4_file_rhash_params = {
+	.key_len		= sizeof_field(struct nfs4_file, fi_inode),
+	.key_offset		= offsetof(struct nfs4_file, fi_inode),
+	.head_offset		= offsetof(struct nfs4_file, fi_rlist),
+
+	/* Reduce resizing churn on light workloads */
+	.min_size		= 256,		/* buckets */
+	.automatic_shrinking	= true,
+};
+
 /*
  * Check if courtesy clients have conflicting access and resolve it if possible
  *
@@ -8023,10 +8037,16 @@ nfs4_state_start(void)
 {
 	int ret;
 
-	ret = nfsd4_create_callback_queue();
+	ret = rhltable_init(&nfs4_file_rhltable, &nfs4_file_rhash_params);
 	if (ret)
 		return ret;
 
+	ret = nfsd4_create_callback_queue();
+	if (ret) {
+		rhltable_destroy(&nfs4_file_rhltable);
+		return ret;
+	}
+
 	set_max_delegations();
 	return 0;
 }
@@ -8057,6 +8077,7 @@ nfs4_state_shutdown_net(struct net *net)
 
 	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;