fs/dcache.c: Save one 32-bit multiply in dcache lookup
Noe that we're mixing in the parent pointer earlier, we
don't need to use hash_32() to mix its bits. Instead, we can
just take the msbits of the hash value directly.
For those applications which use the partial_name_hash(),
move the multiply to end_name_hash.
Signed-off-by: George Spelvin <linux@sciencehorizons.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/stringhash.h b/include/linux/stringhash.h
index eb7debb..7c2d951 100644
--- a/include/linux/stringhash.h
+++ b/include/linux/stringhash.h
@@ -3,6 +3,7 @@
#include <linux/compiler.h> /* For __pure */
#include <linux/types.h> /* For u32, u64 */
+#include <linux/hash.h>
/*
* Routines for hashing strings of bytes to a 32-bit hash value.
@@ -45,11 +46,12 @@
/*
* Finally: cut down the number of bits to a int value (and try to avoid
- * losing bits)
+ * losing bits). This also has the property (wanted by the dcache)
+ * that the msbits make a good hash table index.
*/
static inline unsigned long end_name_hash(unsigned long hash)
{
- return (unsigned int)hash;
+ return __hash_32((unsigned int)hash);
}
/*