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From:   NeilBrown <neilb@suse.com>
To:     Oleg Drokin <oleg.drokin@intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        James Simmons <jsimmons@infradead.org>,
        Andreas Dilger <andreas.dilger@intel.com>
Date:   Thu, 12 Apr 2018 07:54:48 +1000
Subject: [PATCH 08/20] staging: lustre: simplify ldlm_ns_hash_defs[]
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Lustre Development List <lustre-devel@lists.lustre.org>
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As the ldlm_ns_types are dense, we can use the type as
the index to the array, rather than searching through
the array for a match.
We can also discard nsd_hops as all hash tables now
use the same hops.
This makes the table smaller and the code simpler.

Signed-off-by: NeilBrown <neilb@suse.com>
---
 drivers/staging/lustre/lustre/ldlm/ldlm_resource.c |   62 ++++++--------------
 1 file changed, 20 insertions(+), 42 deletions(-)

diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_resource.c b/drivers/staging/lustre/lustre/ldlm/ldlm_resource.c
index a14cc12303ab..4288a81fd62b 100644
--- a/drivers/staging/lustre/lustre/ldlm/ldlm_resource.c
+++ b/drivers/staging/lustre/lustre/ldlm/ldlm_resource.c
@@ -545,55 +545,35 @@ static struct cfs_hash_ops ldlm_ns_hash_ops = {
 	.hs_put		= ldlm_res_hop_put
 };
 
-struct ldlm_ns_hash_def {
-	enum ldlm_ns_type nsd_type;
+static struct {
 	/** hash bucket bits */
 	unsigned int	nsd_bkt_bits;
 	/** hash bits */
 	unsigned int	nsd_all_bits;
-	/** hash operations */
-	struct cfs_hash_ops *nsd_hops;
-};
-
-static struct ldlm_ns_hash_def ldlm_ns_hash_defs[] = {
-	{
-		.nsd_type       = LDLM_NS_TYPE_MDC,
+} ldlm_ns_hash_defs[] = {
+	[LDLM_NS_TYPE_MDC] = {
 		.nsd_bkt_bits   = 11,
 		.nsd_all_bits   = 16,
-		.nsd_hops       = &ldlm_ns_hash_ops,
 	},
-	{
-		.nsd_type       = LDLM_NS_TYPE_MDT,
+	[LDLM_NS_TYPE_MDT] = {
 		.nsd_bkt_bits   = 14,
 		.nsd_all_bits   = 21,
-		.nsd_hops       = &ldlm_ns_hash_ops,
 	},
-	{
-		.nsd_type       = LDLM_NS_TYPE_OSC,
+	[LDLM_NS_TYPE_OSC] = {
 		.nsd_bkt_bits   = 8,
 		.nsd_all_bits   = 12,
-		.nsd_hops       = &ldlm_ns_hash_ops,
 	},
-	{
-		.nsd_type       = LDLM_NS_TYPE_OST,
+	[LDLM_NS_TYPE_OST] = {
 		.nsd_bkt_bits   = 11,
 		.nsd_all_bits   = 17,
-		.nsd_hops       = &ldlm_ns_hash_ops,
 	},
-	{
-		.nsd_type       = LDLM_NS_TYPE_MGC,
+	[LDLM_NS_TYPE_MGC] = {
 		.nsd_bkt_bits   = 3,
 		.nsd_all_bits   = 4,
-		.nsd_hops       = &ldlm_ns_hash_ops,
 	},
-	{
-		.nsd_type       = LDLM_NS_TYPE_MGT,
+	[LDLM_NS_TYPE_MGT] = {
 		.nsd_bkt_bits   = 3,
 		.nsd_all_bits   = 4,
-		.nsd_hops       = &ldlm_ns_hash_ops,
-	},
-	{
-		.nsd_type       = LDLM_NS_TYPE_UNKNOWN,
 	},
 };
 
@@ -617,7 +597,6 @@ struct ldlm_namespace *ldlm_namespace_new(struct obd_device *obd, char *name,
 					  enum ldlm_ns_type ns_type)
 {
 	struct ldlm_namespace *ns = NULL;
-	struct ldlm_ns_hash_def    *nsd;
 	int		    idx;
 	int		    rc;
 
@@ -629,15 +608,10 @@ struct ldlm_namespace *ldlm_namespace_new(struct obd_device *obd, char *name,
 		return NULL;
 	}
 
-	for (idx = 0;; idx++) {
-		nsd = &ldlm_ns_hash_defs[idx];
-		if (nsd->nsd_type == LDLM_NS_TYPE_UNKNOWN) {
-			CERROR("Unknown type %d for ns %s\n", ns_type, name);
-			goto out_ref;
-		}
-
-		if (nsd->nsd_type == ns_type)
-			break;
+	if (ns_type >= ARRAY_SIZE(ldlm_ns_hash_defs) ||
+	    ldlm_ns_hash_defs[ns_type].nsd_bkt_bits == 0) {
+		CERROR("Unknown type %d for ns %s\n", ns_type, name);
+		goto out_ref;
 	}
 
 	ns = kzalloc(sizeof(*ns), GFP_NOFS);
@@ -645,18 +619,22 @@ struct ldlm_namespace *ldlm_namespace_new(struct obd_device *obd, char *name,
 		goto out_ref;
 
 	ns->ns_rs_hash = cfs_hash_create(name,
-					 nsd->nsd_all_bits, nsd->nsd_all_bits,
-					 nsd->nsd_bkt_bits, 0,
+					 ldlm_ns_hash_defs[ns_type].nsd_all_bits,
+					 ldlm_ns_hash_defs[ns_type].nsd_all_bits,
+					 ldlm_ns_hash_defs[ns_type].nsd_bkt_bits,
+					 0,
 					 CFS_HASH_MIN_THETA,
 					 CFS_HASH_MAX_THETA,
-					 nsd->nsd_hops,
+					 &ldlm_ns_hash_ops,
 					 CFS_HASH_DEPTH |
 					 CFS_HASH_BIGNAME |
 					 CFS_HASH_SPIN_BKTLOCK |
 					 CFS_HASH_NO_ITEMREF);
 	if (!ns->ns_rs_hash)
 		goto out_ns;
-	ns->ns_bucket_bits = nsd->nsd_all_bits - nsd->nsd_bkt_bits;
+	ns->ns_bucket_bits = ldlm_ns_hash_defs[ns_type].nsd_all_bits -
+			      ldlm_ns_hash_defs[ns_type].nsd_bkt_bits;
+
 	ns->ns_rs_buckets = kvmalloc_array(1 << ns->ns_bucket_bits,
 					   sizeof(ns->ns_rs_buckets[0]),
 					   GFP_KERNEL);