fs/namei.c: Add hashlen_string() function
We'd like to make more use of the highly-optimized dcache hash functions
throughout the kernel, rather than have every subsystem create its own,
and a function that hashes basic null-terminated strings is required
for that.
(The name is to emphasize that it returns both hash and length.)
It's actually useful in the dcache itself, specifically d_alloc_name().
Other uses in the next patch.
full_name_hash() is also tweaked to make it more generally useful:
1) Take a "char *" rather than "unsigned char *" argument, to
be consistent with hash_name().
2) Handle zero-length inputs. If we want more callers, we don't want
to make them worry about corner cases.
Signed-off-by: George Spelvin <linux@sciencehorizons.net>
diff --git a/include/linux/stringhash.h b/include/linux/stringhash.h
index 2eaaaf6..451771d 100644
--- a/include/linux/stringhash.h
+++ b/include/linux/stringhash.h
@@ -1,7 +1,8 @@
#ifndef __LINUX_STRINGHASH_H
#define __LINUX_STRINGHASH_H
-#include <linux/types.h>
+#include <linux/compiler.h> /* For __pure */
+#include <linux/types.h> /* For u32, u64 */
/*
* Routines for hashing strings of bytes to a 32-bit hash value.
@@ -59,7 +60,7 @@
*
* If not set, this falls back to a wrapper around the preceding.
*/
-extern unsigned int full_name_hash(const unsigned char *, unsigned int);
+extern unsigned int __pure full_name_hash(const char *, unsigned int);
/*
* A hash_len is a u64 with the hash of a string in the low
@@ -69,4 +70,7 @@
#define hashlen_len(hashlen) ((u32)((hashlen) >> 32))
#define hashlen_create(hash, len) ((u64)(len)<<32 | (u32)(hash))
+/* Return the "hash_len" (hash and length) of a null-terminated string */
+extern u64 __pure hashlen_string(const char *name);
+
#endif /* __LINUX_STRINGHASH_H */