[PATCH] dcache: Add helper d_hash_and_lookup

It is very common to hash a dentry and then to call lookup.  If we take fs
specific hash functions into account the full hash logic can get ugly.
Further full_name_hash as an inline function is almost 100 bytes on x86 so
having a non-inline choice in some cases can measurably decrease code size.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index d10bd30..836325e 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -275,6 +275,7 @@
 /* appendix may either be NULL or be used for transname suffixes */
 extern struct dentry * d_lookup(struct dentry *, struct qstr *);
 extern struct dentry * __d_lookup(struct dentry *, struct qstr *);
+extern struct dentry * d_hash_and_lookup(struct dentry *, struct qstr *);
 
 /* validate "insecure" dentry pointer */
 extern int d_validate(struct dentry *, struct dentry *);