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>

1 files changed, 1 insertions, 2 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index d5ecc6e477da..19b751806789 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1653,8 +1653,7 @@ struct dentry *d_alloc_name(struct dentry *parent, const char *name)
         struct qstr q;
 
         q.name = name;
-        q.len = strlen(name);
-        q.hash = full_name_hash(q.name, q.len);
+        q.hash_len = hashlen_string(name);
         return d_alloc(parent, &q);
 }
 EXPORT_SYMBOL(d_alloc_name);