Merge branch 'salted-string-hash'

This changes the vfs dentry hashing to mix in the parent pointer at the
_beginning_ of the hash, rather than at the end.

That actually improves both the hash and the code generation, because we
can move more of the computation to the "static" part of the dcache
setup, and do less at lookup runtime.

It turns out that a lot of other hash users also really wanted to mix in
a base pointer as a 'salt' for the hash, and so the slightly extended
interface ends up working well for other cases too.

Users that want a string hash that is purely about the string pass in a
'salt' pointer of NULL.

* merge branch 'salted-string-hash':
  fs/dcache.c: Save one 32-bit multiply in dcache lookup
  vfs: make the string hashes salt the hash

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/staging/lustre/lustre/llite/statahead.c b/drivers/staging/lustre/lustre/llite/statahead.c
index f77524294c27..8e52722266fe 100644
--- a/drivers/staging/lustre/lustre/llite/statahead.c
+++ b/drivers/staging/lustre/lustre/llite/statahead.c
@@ -170,7 +170,8 @@ static inline int is_omitted_entry(struct ll_statahead_info *sai, __u64 index)
  * Insert it into sai_entries tail when init.
  */
 static struct ll_sa_entry *
-ll_sa_entry_alloc(struct ll_statahead_info *sai, __u64 index,
+ll_sa_entry_alloc(struct dentry *parent,
+		  struct ll_statahead_info *sai, __u64 index,
 		  const char *name, int len)
 {
 	struct ll_inode_info *lli;
@@ -217,7 +218,8 @@ ll_sa_entry_alloc(struct ll_statahead_info *sai, __u64 index,
 	dname = (char *)entry + sizeof(struct ll_sa_entry);
 	memcpy(dname, name, len);
 	dname[len] = 0;
-	entry->se_qstr.hash = full_name_hash(name, len);
+
+	entry->se_qstr.hash = full_name_hash(parent, name, len);
 	entry->se_qstr.len = len;
 	entry->se_qstr.name = dname;
 
@@ -898,7 +900,7 @@ static void ll_statahead_one(struct dentry *parent, const char *entry_name,
 	int		       rc;
 	int		       rc1;
 
-	entry = ll_sa_entry_alloc(sai, sai->sai_index, entry_name,
+	entry = ll_sa_entry_alloc(parent, sai, sai->sai_index, entry_name,
 				  entry_name_len);
 	if (IS_ERR(entry))
 		return;