rhashtable: Introduce max_size/min_size

This patch adds the parameters max_size and min_size which are
meant to replace max_shift and min_shift.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 4 deletions

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 097400362467..c4061bbd0113 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -27,7 +27,7 @@
 #include <linux/err.h>
 
 #define HASH_DEFAULT_SIZE       64UL
-#define HASH_MIN_SIZE           4UL
+#define HASH_MIN_SIZE           4U
 #define BUCKET_LOCKS_PER_CPU   128UL
 
 /* Base bits plus 1 bit for nulls marker */
@@ -188,7 +188,8 @@ static bool rht_grow_above_75(const struct rhashtable *ht,
 {
         /* Expand table when exceeding 75% load */
         return atomic_read(&ht->nelems) > (tbl->size / 4 * 3) &&
-               (!ht->p.max_shift || tbl->size < (1 << ht->p.max_shift));
+               (!ht->p.max_shift || tbl->size < (1 << ht->p.max_shift)) &&
+               (!ht->p.max_size || tbl->size < ht->p.max_size);
 }
 
 /**
@@ -201,7 +202,8 @@ static bool rht_shrink_below_30(const struct rhashtable *ht,
 {
         /* Shrink table beneath 30% load */
         return atomic_read(&ht->nelems) < (tbl->size * 3 / 10) &&
-               tbl->size > (1 << ht->p.min_shift);
+               tbl->size > (1 << ht->p.min_shift) &&
+               tbl->size > ht->p.min_size;
 }
 
 static int rhashtable_rehash_one(struct rhashtable *ht, unsigned old_hash)
@@ -873,7 +875,8 @@ EXPORT_SYMBOL_GPL(rhashtable_walk_stop);
 static size_t rounded_hashtable_size(struct rhashtable_params *params)
 {
         return max(roundup_pow_of_two(params->nelem_hint * 4 / 3),
-                   1UL << params->min_shift);
+                   max(1UL << params->min_shift,
+                       (unsigned long)params->min_size));
 }
 
 /**
@@ -935,6 +938,7 @@ int rhashtable_init(struct rhashtable *ht, struct rhashtable_params *params)
 
         params->min_shift = max_t(size_t, params->min_shift,
                                   ilog2(HASH_MIN_SIZE));
+        params->min_size = max(params->min_size, HASH_MIN_SIZE);
 
         if (params->nelem_hint)
                 size = rounded_hashtable_size(params);