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

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;

fs/adfs/dir.c

@@ -207,7 +207,7 @@ adfs_hash(const struct dentry *parent, struct qstr *qstr)
 	 */
 	qstr->len = i = name_len;
 	name = qstr->name;
-	hash = init_name_hash();
+	hash = init_name_hash(parent);
 	while (i--) {
 		char c;
 

fs/affs/namei.c

@@ -61,7 +61,7 @@ affs_get_toupper(struct super_block *sb)
  * Note: the dentry argument is the parent dentry.
  */
 static inline int
-__affs_hash_dentry(struct qstr *qstr, toupper_t toupper, bool notruncate)
+__affs_hash_dentry(const struct dentry *dentry, struct qstr *qstr, toupper_t toupper, bool notruncate)
 {
 	const u8 *name = qstr->name;
 	unsigned long hash;
@@ -72,7 +72,7 @@ __affs_hash_dentry(struct qstr *qstr, toupper_t toupper, bool notruncate)
 	if (retval)
 		return retval;
 
-	hash = init_name_hash();
+	hash = init_name_hash(dentry);
 	len = min(qstr->len, AFFSNAMEMAX);
 	for (; len > 0; name++, len--)
 		hash = partial_name_hash(toupper(*name), hash);
@@ -84,7 +84,7 @@ __affs_hash_dentry(struct qstr *qstr, toupper_t toupper, bool notruncate)
 static int
 affs_hash_dentry(const struct dentry *dentry, struct qstr *qstr)
 {
-	return __affs_hash_dentry(qstr, affs_toupper,
+	return __affs_hash_dentry(dentry, qstr, affs_toupper,
 				  affs_nofilenametruncate(dentry));
 
 }
@@ -92,7 +92,7 @@ affs_hash_dentry(const struct dentry *dentry, struct qstr *qstr)
 static int
 affs_intl_hash_dentry(const struct dentry *dentry, struct qstr *qstr)
 {
-	return __affs_hash_dentry(qstr, affs_intl_toupper,
+	return __affs_hash_dentry(dentry, qstr, affs_intl_toupper,
 				  affs_nofilenametruncate(dentry));
 
 }

fs/autofs4/waitq.c

@@ -398,7 +398,7 @@ int autofs4_wait(struct autofs_sb_info *sbi,
 		}
 	}
 	qstr.name = name;
-	qstr.hash = full_name_hash(name, qstr.len);
+	qstr.hash = full_name_hash(dentry, name, qstr.len);
 
 	if (mutex_lock_interruptible(&sbi->wq_mutex)) {
 		kfree(qstr.name);

fs/ceph/inode.c

@@ -1164,7 +1164,7 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req,
 
 			dname.name = rinfo->dname;
 			dname.len = rinfo->dname_len;
-			dname.hash = full_name_hash(dname.name, dname.len);
+			dname.hash = full_name_hash(parent, dname.name, dname.len);
 			vino.ino = le64_to_cpu(rinfo->targeti.in->ino);
 			vino.snap = le64_to_cpu(rinfo->targeti.in->snapid);
 retry_lookup:
@@ -1508,7 +1508,7 @@ int ceph_readdir_prepopulate(struct ceph_mds_request *req,
 
 		dname.name = rde->name;
 		dname.len = rde->name_len;
-		dname.hash = full_name_hash(dname.name, dname.len);
+		dname.hash = full_name_hash(parent, dname.name, dname.len);
 
 		vino.ino = le64_to_cpu(rde->inode.in->ino);
 		vino.snap = le64_to_cpu(rde->inode.in->snapid);

fs/ceph/mds_client.c

@@ -3204,7 +3204,7 @@ static void handle_lease(struct ceph_mds_client *mdsc,
 		WARN_ON(1);
 		goto release;  /* hrm... */
 	}
-	dname.hash = full_name_hash(dname.name, dname.len);
+	dname.hash = full_name_hash(parent, dname.name, dname.len);
 	dentry = d_lookup(parent, &dname);
 	dput(parent);
 	if (!dentry)

fs/cifs/dir.c

@@ -856,7 +856,7 @@ static int cifs_ci_hash(const struct dentry *dentry, struct qstr *q)
 	wchar_t c;
 	int i, charlen;
 
-	hash = init_name_hash();
+	hash = init_name_hash(dentry);
 	for (i = 0; i < q->len; i += charlen) {
 		charlen = codepage->char2uni(&q->name[i], q->len - i, &c);
 		/* error out if we can't convert the character */

fs/dcache.c

@@ -104,11 +104,9 @@ static unsigned int d_hash_shift __read_mostly;
 
 static struct hlist_bl_head *dentry_hashtable __read_mostly;
 
-static inline struct hlist_bl_head *d_hash(const struct dentry *parent,
-					unsigned int hash)
+static inline struct hlist_bl_head *d_hash(unsigned int hash)
 {
-	hash += (unsigned long) parent / L1_CACHE_BYTES;
-	return dentry_hashtable + hash_32(hash, d_hash_shift);
+	return dentry_hashtable + (hash >> (32 - d_hash_shift));
 }
 
 #define IN_LOOKUP_SHIFT 10
@@ -488,7 +486,7 @@ void __d_drop(struct dentry *dentry)
 		if (unlikely(IS_ROOT(dentry)))
 			b = &dentry->d_sb->s_anon;
 		else
-			b = d_hash(dentry->d_parent, dentry->d_name.hash);
+			b = d_hash(dentry->d_name.hash);
 
 		hlist_bl_lock(b);
 		__hlist_bl_del(&dentry->d_hash);
@@ -1716,7 +1714,7 @@ struct dentry *d_alloc_name(struct dentry *parent, const char *name)
 	struct qstr q;
 
 	q.name = name;
-	q.hash_len = hashlen_string(name);
+	q.hash_len = hashlen_string(parent, name);
 	return d_alloc(parent, &q);
 }
 EXPORT_SYMBOL(d_alloc_name);
@@ -2140,7 +2138,7 @@ struct dentry *__d_lookup_rcu(const struct dentry *parent,
 {
 	u64 hashlen = name->hash_len;
 	const unsigned char *str = name->name;
-	struct hlist_bl_head *b = d_hash(parent, hashlen_hash(hashlen));
+	struct hlist_bl_head *b = d_hash(hashlen_hash(hashlen));
 	struct hlist_bl_node *node;
 	struct dentry *dentry;
 
@@ -2257,7 +2255,7 @@ struct dentry *__d_lookup(const struct dentry *parent, const struct qstr *name)
 	unsigned int len = name->len;
 	unsigned int hash = name->hash;
 	const unsigned char *str = name->name;
-	struct hlist_bl_head *b = d_hash(parent, hash);
+	struct hlist_bl_head *b = d_hash(hash);
 	struct hlist_bl_node *node;
 	struct dentry *found = NULL;
 	struct dentry *dentry;
@@ -2337,7 +2335,7 @@ struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name)
 	 * calculate the standard hash first, as the d_op->d_hash()
 	 * routine may choose to leave the hash value unchanged.
 	 */
-	name->hash = full_name_hash(name->name, name->len);
+	name->hash = full_name_hash(dir, name->name, name->len);
 	if (dir->d_flags & DCACHE_OP_HASH) {
 		int err = dir->d_op->d_hash(dir, name);
 		if (unlikely(err < 0))
@@ -2410,7 +2408,7 @@ static void __d_rehash(struct dentry * entry, struct hlist_bl_head *b)
 
 static void _d_rehash(struct dentry * entry)
 {
-	__d_rehash(entry, d_hash(entry->d_parent, entry->d_name.hash));
+	__d_rehash(entry, d_hash(entry->d_name.hash));
 }
 
 /**
@@ -2874,7 +2872,7 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
 	 * for the same hash queue because of how unlikely it is.
 	 */
 	__d_drop(dentry);
-	__d_rehash(dentry, d_hash(target->d_parent, target->d_name.hash));
+	__d_rehash(dentry, d_hash(target->d_name.hash));
 
 	/*
 	 * Unhash the target (d_delete() is not usable here).  If exchanging
@@ -2882,8 +2880,7 @@ static void __d_move(struct dentry *dentry, struct dentry *target,
 	 */
 	__d_drop(target);
 	if (exchange) {
-		__d_rehash(target,
-			   d_hash(dentry->d_parent, dentry->d_name.hash));
+		__d_rehash(target, d_hash(dentry->d_name.hash));
 	}
 
 	/* Switch the names.. */

fs/efivarfs/super.c

@@ -65,7 +65,7 @@ static int efivarfs_d_compare(const struct dentry *parent,
 
 static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr)
 {
-	unsigned long hash = init_name_hash();
+	unsigned long hash = init_name_hash(dentry);
 	const unsigned char *s = qstr->name;
 	unsigned int len = qstr->len;
 
@@ -98,7 +98,7 @@ static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
 	q.name = name;
 	q.len = strlen(name);
 
-	err = efivarfs_d_hash(NULL, &q);
+	err = efivarfs_d_hash(parent, &q);
 	if (err)
 		return ERR_PTR(err);
 

fs/fat/namei_msdos.c

@@ -154,7 +154,7 @@ static int msdos_hash(const struct dentry *dentry, struct qstr *qstr)
 
 	error = msdos_format_name(qstr->name, qstr->len, msdos_name, options);
 	if (!error)
-		qstr->hash = full_name_hash(msdos_name, MSDOS_NAME);
+		qstr->hash = full_name_hash(dentry, msdos_name, MSDOS_NAME);
 	return 0;
 }
 

fs/fat/namei_vfat.c

@@ -107,7 +107,7 @@ static unsigned int vfat_striptail_len(const struct qstr *qstr)
  */
 static int vfat_hash(const struct dentry *dentry, struct qstr *qstr)
 {
-	qstr->hash = full_name_hash(qstr->name, vfat_striptail_len(qstr));
+	qstr->hash = full_name_hash(dentry, qstr->name, vfat_striptail_len(qstr));
 	return 0;
 }
 
@@ -127,7 +127,7 @@ static int vfat_hashi(const struct dentry *dentry, struct qstr *qstr)
 	name = qstr->name;
 	len = vfat_striptail_len(qstr);
 
-	hash = init_name_hash();
+	hash = init_name_hash(dentry);
 	while (len--)
 		hash = partial_name_hash(nls_tolower(t, *name++), hash);
 	qstr->hash = end_name_hash(hash);

fs/fuse/dev.c

@@ -1525,7 +1525,6 @@ static int fuse_notify_inval_entry(struct fuse_conn *fc, unsigned int size,
 		goto err;
 	fuse_copy_finish(cs);
 	buf[outarg.namelen] = 0;
-	name.hash = full_name_hash(name.name, name.len);
 
 	down_read(&fc->killsb);
 	err = -ENOENT;
@@ -1576,7 +1575,6 @@ static int fuse_notify_delete(struct fuse_conn *fc, unsigned int size,
 		goto err;
 	fuse_copy_finish(cs);
 	buf[outarg.namelen] = 0;
-	name.hash = full_name_hash(name.name, name.len);
 
 	down_read(&fc->killsb);
 	err = -ENOENT;

fs/fuse/dir.c

@@ -955,6 +955,7 @@ int fuse_reverse_inval_entry(struct super_block *sb, u64 parent_nodeid,
 	if (!dir)
 		goto unlock;
 
+	name->hash = full_name_hash(dir, name->name, name->len);
 	entry = d_lookup(dir, name);
 	dput(dir);
 	if (!entry)
@@ -1204,7 +1205,7 @@ static int fuse_direntplus_link(struct file *file,
 
 	fc = get_fuse_conn(dir);
 
-	name.hash = full_name_hash(name.name, name.len);
+	name.hash = full_name_hash(parent, name.name, name.len);
 	dentry = d_lookup(parent, &name);
 	if (!dentry) {
 retry:

fs/hfs/string.c

@@ -59,7 +59,7 @@ int hfs_hash_dentry(const struct dentry *dentry, struct qstr *this)
 	if (len > HFS_NAMELEN)
 		len = HFS_NAMELEN;
 
-	hash = init_name_hash();
+	hash = init_name_hash(dentry);
 	for (; len; len--)
 		hash = partial_name_hash(caseorder[*name++], hash);
 	this->hash = end_name_hash(hash);

fs/hfsplus/unicode.c

@@ -346,7 +346,7 @@ int hfsplus_hash_dentry(const struct dentry *dentry, struct qstr *str)
 
 	casefold = test_bit(HFSPLUS_SB_CASEFOLD, &HFSPLUS_SB(sb)->flags);
 	decompose = !test_bit(HFSPLUS_SB_NODECOMPOSE, &HFSPLUS_SB(sb)->flags);
-	hash = init_name_hash();
+	hash = init_name_hash(dentry);
 	astr = str->name;
 	len = str->len;
 	while (len > 0) {

fs/hpfs/dentry.c

@@ -26,7 +26,7 @@ static int hpfs_hash_dentry(const struct dentry *dentry, struct qstr *qstr)
 		/*return -ENOENT;*/
 	x:
 
-	hash = init_name_hash();
+	hash = init_name_hash(dentry);
 	for (i = 0; i < l; i++)
 		hash = partial_name_hash(hpfs_upcase(hpfs_sb(dentry->d_sb)->sb_cp_table,qstr->name[i]), hash);
 	qstr->hash = end_name_hash(hash);

fs/isofs/inode.c

@@ -174,7 +174,7 @@ struct iso9660_options{
  * Compute the hash for the isofs name corresponding to the dentry.
  */
 static int
-isofs_hashi_common(struct qstr *qstr, int ms)
+isofs_hashi_common(const struct dentry *dentry, struct qstr *qstr, int ms)
 {
 	const char *name;
 	int len;
@@ -188,7 +188,7 @@ isofs_hashi_common(struct qstr *qstr, int ms)
 			len--;
 	}
 
-	hash = init_name_hash();
+	hash = init_name_hash(dentry);
 	while (len--) {
 		c = tolower(*name++);
 		hash = partial_name_hash(c, hash);
@@ -231,7 +231,7 @@ static int isofs_dentry_cmp_common(
 static int
 isofs_hashi(const struct dentry *dentry, struct qstr *qstr)
 {
-	return isofs_hashi_common(qstr, 0);
+	return isofs_hashi_common(dentry, qstr, 0);
 }
 
 static int
@@ -246,7 +246,7 @@ isofs_dentry_cmpi(const struct dentry *parent, const struct dentry *dentry,
  * Compute the hash for the isofs name corresponding to the dentry.
  */
 static int
-isofs_hash_common(struct qstr *qstr, int ms)
+isofs_hash_common(const struct dentry *dentry, struct qstr *qstr, int ms)
 {
 	const char *name;
 	int len;
@@ -258,7 +258,7 @@ isofs_hash_common(struct qstr *qstr, int ms)
 			len--;
 	}
 
-	qstr->hash = full_name_hash(name, len);
+	qstr->hash = full_name_hash(dentry, name, len);
 
 	return 0;
 }
@@ -266,13 +266,13 @@ isofs_hash_common(struct qstr *qstr, int ms)
 static int
 isofs_hash_ms(const struct dentry *dentry, struct qstr *qstr)
 {
-	return isofs_hash_common(qstr, 1);
+	return isofs_hash_common(dentry, qstr, 1);
 }
 
 static int
 isofs_hashi_ms(const struct dentry *dentry, struct qstr *qstr)
 {
-	return isofs_hashi_common(qstr, 1);
+	return isofs_hashi_common(dentry, qstr, 1);
 }
 
 static int

fs/jffs2/dir.c

@@ -81,6 +81,7 @@ static struct dentry *jffs2_lookup(struct inode *dir_i, struct dentry *target,
 	struct jffs2_full_dirent *fd = NULL, *fd_list;
 	uint32_t ino = 0;
 	struct inode *inode = NULL;
+	unsigned int nhash;
 
 	jffs2_dbg(1, "jffs2_lookup()\n");
 
@@ -89,11 +90,14 @@ static struct dentry *jffs2_lookup(struct inode *dir_i, struct dentry *target,
 
 	dir_f = JFFS2_INODE_INFO(dir_i);
 
+	/* The 'nhash' on the fd_list is not the same as the dentry hash */
+	nhash = full_name_hash(NULL, target->d_name.name, target->d_name.len);
+
 	mutex_lock(&dir_f->sem);
 
 	/* NB: The 2.2 backport will need to explicitly check for '.' and '..' here */
-	for (fd_list = dir_f->dents; fd_list && fd_list->nhash <= target->d_name.hash; fd_list = fd_list->next) {
-		if (fd_list->nhash == target->d_name.hash &&
+	for (fd_list = dir_f->dents; fd_list && fd_list->nhash <= nhash; fd_list = fd_list->next) {
+		if (fd_list->nhash == nhash &&
 		    (!fd || fd_list->version > fd->version) &&
 		    strlen(fd_list->name) == target->d_name.len &&
 		    !strncmp(fd_list->name, target->d_name.name, target->d_name.len)) {

fs/jffs2/readinode.c

@@ -674,7 +674,7 @@ static inline int read_direntry(struct jffs2_sb_info *c, struct jffs2_raw_node_r
 		}
 	}
 
-	fd->nhash = full_name_hash(fd->name, rd->nsize);
+	fd->nhash = full_name_hash(NULL, fd->name, rd->nsize);
 	fd->next = NULL;
 	fd->name[rd->nsize] = '\0';
 

fs/jffs2/scan.c

@@ -1100,7 +1100,7 @@ static int jffs2_scan_dirent_node(struct jffs2_sb_info *c, struct jffs2_eraseblo
 	fd->next = NULL;
 	fd->version = je32_to_cpu(rd->version);
 	fd->ino = je32_to_cpu(rd->ino);
-	fd->nhash = full_name_hash(fd->name, checkedlen);
+	fd->nhash = full_name_hash(NULL, fd->name, checkedlen);
 	fd->type = rd->type;
 	jffs2_add_fd_to_list(c, fd, &ic->scan_dents);
 

fs/jffs2/summary.c

@@ -476,7 +476,7 @@ static int jffs2_sum_process_sum_data(struct jffs2_sb_info *c, struct jffs2_eras
 				fd->next = NULL;
 				fd->version = je32_to_cpu(spd->version);
 				fd->ino = je32_to_cpu(spd->ino);
-				fd->nhash = full_name_hash(fd->name, checkedlen);
+				fd->nhash = full_name_hash(NULL, fd->name, checkedlen);
 				fd->type = spd->type;
 
 				jffs2_add_fd_to_list(c, fd, &ic->scan_dents);

fs/jffs2/write.c

@@ -245,7 +245,7 @@ struct jffs2_full_dirent *jffs2_write_dirent(struct jffs2_sb_info *c, struct jff
 
 	fd->version = je32_to_cpu(rd->version);
 	fd->ino = je32_to_cpu(rd->ino);
-	fd->nhash = full_name_hash(name, namelen);
+	fd->nhash = full_name_hash(NULL, name, namelen);
 	fd->type = rd->type;
 	memcpy(fd->name, name, namelen);
 	fd->name[namelen]=0;
@@ -598,7 +598,7 @@ int jffs2_do_unlink(struct jffs2_sb_info *c, struct jffs2_inode_info *dir_f,
 		jffs2_add_fd_to_list(c, fd, &dir_f->dents);
 		mutex_unlock(&dir_f->sem);
 	} else {
-		uint32_t nhash = full_name_hash(name, namelen);
+		uint32_t nhash = full_name_hash(NULL, name, namelen);
 
 		fd = dir_f->dents;
 		/* We don't actually want to reserve any space, but we do

fs/jfs/namei.c

@@ -1564,7 +1564,7 @@ static int jfs_ci_hash(const struct dentry *dir, struct qstr *this)
 	unsigned long hash;
 	int i;
 
-	hash = init_name_hash();
+	hash = init_name_hash(dir);
 	for (i=0; i < this->len; i++)
 		hash = partial_name_hash(tolower(this->name[i]), hash);
 	this->hash = end_name_hash(hash);

fs/kernfs/dir.c

@@ -336,11 +336,11 @@ struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn)
  */
 static unsigned int kernfs_name_hash(const char *name, const void *ns)
 {
-	unsigned long hash = init_name_hash();
+	unsigned long hash = init_name_hash(ns);
 	unsigned int len = strlen(name);
 	while (len--)
 		hash = partial_name_hash(*name++, hash);
-	hash = (end_name_hash(hash) ^ hash_ptr((void *)ns, 31));
+	hash = end_name_hash(hash);
 	hash &= 0x7fffffffU;
 	/* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */
 	if (hash < 2)

fs/logfs/dir.c

@@ -95,7 +95,7 @@ static int beyond_eof(struct inode *inode, loff_t bix)
  * of each character and pick a prime nearby, preferably a bit-sparse
  * one.
  */
-static u32 hash_32(const char *s, int len, u32 seed)
+static u32 logfs_hash_32(const char *s, int len, u32 seed)
 {
 	u32 hash = seed;
 	int i;
@@ -159,7 +159,7 @@ static struct page *logfs_get_dd_page(struct inode *dir, struct dentry *dentry)
 	struct qstr *name = &dentry->d_name;
 	struct page *page;
 	struct logfs_disk_dentry *dd;
-	u32 hash = hash_32(name->name, name->len, 0);
+	u32 hash = logfs_hash_32(name->name, name->len, 0);
 	pgoff_t index;
 	int round;
 
@@ -370,7 +370,7 @@ static int logfs_write_dir(struct inode *dir, struct dentry *dentry,
 {
 	struct page *page;
 	struct logfs_disk_dentry *dd;
-	u32 hash = hash_32(dentry->d_name.name, dentry->d_name.len, 0);
+	u32 hash = logfs_hash_32(dentry->d_name.name, dentry->d_name.len, 0);
 	pgoff_t index;
 	int round, err;
 

fs/namei.c

@@ -1890,9 +1890,9 @@ static inline unsigned int fold_hash(unsigned long x, unsigned long y)
  * payload bytes, to match the way that hash_name() iterates until it
  * finds the delimiter after the name.
  */
-unsigned int full_name_hash(const char *name, unsigned int len)
+unsigned int full_name_hash(const void *salt, const char *name, unsigned int len)
 {
-	unsigned long a, x = 0, y = 0;
+	unsigned long a, x = 0, y = (unsigned long)salt;
 
 	for (;;) {
 		if (!len)
@@ -1911,15 +1911,19 @@ unsigned int full_name_hash(const char *name, unsigned int len)
 EXPORT_SYMBOL(full_name_hash);
 
 /* Return the "hash_len" (hash and length) of a null-terminated string */
-u64 hashlen_string(const char *name)
+u64 hashlen_string(const void *salt, const char *name)
 {
-	unsigned long a = 0, x = 0, y = 0, adata, mask, len;
+	unsigned long a = 0, x = 0, y = (unsigned long)salt;
+	unsigned long adata, mask, len;
 	const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
 
-	len = -sizeof(unsigned long);
+	len = 0;
+	goto inside;
+
 	do {
 		HASH_MIX(x, y, a);
 		len += sizeof(unsigned long);
+inside:
 		a = load_unaligned_zeropad(name+len);
 	} while (!has_zero(a, &adata, &constants));
 
@@ -1935,15 +1939,19 @@ EXPORT_SYMBOL(hashlen_string);
  * Calculate the length and hash of the path component, and
  * return the "hash_len" as the result.
  */
-static inline u64 hash_name(const char *name)
+static inline u64 hash_name(const void *salt, const char *name)
 {
-	unsigned long a = 0, b, x = 0, y = 0, adata, bdata, mask, len;
+	unsigned long a = 0, b, x = 0, y = (unsigned long)salt;
+	unsigned long adata, bdata, mask, len;
 	const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
 
-	len = -sizeof(unsigned long);
+	len = 0;
+	goto inside;
+
 	do {
 		HASH_MIX(x, y, a);
 		len += sizeof(unsigned long);
+inside:
 		a = load_unaligned_zeropad(name+len);
 		b = a ^ REPEAT_BYTE('/');
 	} while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants)));
@@ -1959,9 +1967,9 @@ static inline u64 hash_name(const char *name)
 #else	/* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */
 
 /* Return the hash of a string of known length */
-unsigned int full_name_hash(const char *name, unsigned int len)
+unsigned int full_name_hash(const void *salt, const char *name, unsigned int len)
 {
-	unsigned long hash = init_name_hash();
+	unsigned long hash = init_name_hash(salt);
 	while (len--)
 		hash = partial_name_hash((unsigned char)*name++, hash);
 	return end_name_hash(hash);
@@ -1969,9 +1977,9 @@ unsigned int full_name_hash(const char *name, unsigned int len)
 EXPORT_SYMBOL(full_name_hash);
 
 /* Return the "hash_len" (hash and length) of a null-terminated string */
-u64 hashlen_string(const char *name)
+u64 hashlen_string(const void *salt, const char *name)
 {
-	unsigned long hash = init_name_hash();
+	unsigned long hash = init_name_hash(salt);
 	unsigned long len = 0, c;
 
 	c = (unsigned char)*name;
@@ -1988,9 +1996,9 @@ EXPORT_SYMBOL(hashlen_string);
  * We know there's a real path component here of at least
  * one character.
  */
-static inline u64 hash_name(const char *name)
+static inline u64 hash_name(const void *salt, const char *name)
 {
-	unsigned long hash = init_name_hash();
+	unsigned long hash = init_name_hash(salt);
 	unsigned long len = 0, c;
 
 	c = (unsigned char)*name;
@@ -2030,7 +2038,7 @@ static int link_path_walk(const char *name, struct nameidata *nd)
 		if (err)
 			return err;
 
-		hash_len = hash_name(name);
+		hash_len = hash_name(nd->path.dentry, name);
 
 		type = LAST_NORM;
 		if (name[0] == '.') switch (hashlen_len(hash_len)) {
@@ -2436,7 +2444,7 @@ struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
 
 	this.name = name;
 	this.len = len;
-	this.hash = full_name_hash(name, len);
+	this.hash = full_name_hash(base, name, len);
 	if (!len)
 		return ERR_PTR(-EACCES);
 
@@ -2489,7 +2497,7 @@ struct dentry *lookup_one_len_unlocked(const char *name,
 
 	this.name = name;
 	this.len = len;
-	this.hash = full_name_hash(name, len);
+	this.hash = full_name_hash(base, name, len);
 	if (!len)
 		return ERR_PTR(-EACCES);
 

fs/ncpfs/dir.c

@@ -139,7 +139,7 @@ ncp_hash_dentry(const struct dentry *dentry, struct qstr *this)
 		int i;
 
 		t = NCP_IO_TABLE(sb);
-		hash = init_name_hash();
+		hash = init_name_hash(dentry);
 		for (i=0; i<this->len ; i++)
 			hash = partial_name_hash(ncp_tolower(t, this->name[i]),
 									hash);

fs/nfs/dir.c

@@ -232,7 +232,7 @@ int nfs_readdir_make_qstr(struct qstr *string, const char *name, unsigned int le
 	 * in a page cache page which kmemleak does not scan.
 	 */
 	kmemleak_not_leak(string->name);
-	string->hash = full_name_hash(name, len);
+	string->hash = full_name_hash(NULL, name, len);
 	return 0;
 }
 
@@ -502,7 +502,7 @@ void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry)
 		if (filename.len == 2 && filename.name[1] == '.')
 			return;
 	}
-	filename.hash = full_name_hash(filename.name, filename.len);
+	filename.hash = full_name_hash(parent, filename.name, filename.len);
 
 	dentry = d_lookup(parent, &filename);
 again:

fs/ntfs/namei.c

@@ -253,7 +253,7 @@ static struct dentry *ntfs_lookup(struct inode *dir_ino, struct dentry *dent,
 		err = (signed)nls_name.len;
 		goto err_out;
 	}
-	nls_name.hash = full_name_hash(nls_name.name, nls_name.len);
+	nls_name.hash = full_name_hash(dent, nls_name.name, nls_name.len);
 
 	dent = d_add_ci(dent, dent_inode, &nls_name);
 	kfree(nls_name.name);

fs/ocfs2/dlm/dlmcommon.h

@@ -47,7 +47,7 @@
 #define DLM_HASH_BUCKETS	(DLM_HASH_PAGES * DLM_BUCKETS_PER_PAGE)
 
 /* Intended to make it easier for us to switch out hash functions */
-#define dlm_lockid_hash(_n, _l) full_name_hash(_n, _l)
+#define dlm_lockid_hash(_n, _l) full_name_hash(NULL, _n, _l)
 
 enum dlm_mle_type {
 	DLM_MLE_BLOCK = 0,

fs/proc/proc_sysctl.c

@@ -623,7 +623,7 @@ static bool proc_sys_fill_cache(struct file *file,
 
 	qname.name = table->procname;
 	qname.len  = strlen(table->procname);
-	qname.hash = full_name_hash(qname.name, qname.len);
+	qname.hash = full_name_hash(dir, qname.name, qname.len);
 
 	child = d_lookup(dir, &qname);
 	if (!child) {

fs/sysv/namei.c

@@ -33,7 +33,7 @@ static int sysv_hash(const struct dentry *dentry, struct qstr *qstr)
 	   function. */
 	if (qstr->len > SYSV_NAMELEN) {
 		qstr->len = SYSV_NAMELEN;
-		qstr->hash = full_name_hash(qstr->name, qstr->len);
+		qstr->hash = full_name_hash(dentry, qstr->name, qstr->len);
 	}
 	return 0;
 }

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.
@@ -34,7 +35,7 @@
  */
 
 /* Hash courtesy of the R5 hash in reiserfs modulo sign bits */
-#define init_name_hash()		0
+#define init_name_hash(salt)		(unsigned long)(salt)
 
 /* partial hash update function. Assume roughly 4 bits per character */
 static inline unsigned long
@@ -45,11 +46,12 @@ partial_name_hash(unsigned long c, unsigned long prevhash)
 
 /*
  * 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);
 }
 
 /*
@@ -60,7 +62,7 @@ static inline unsigned long end_name_hash(unsigned long hash)
  *
  * If not set, this falls back to a wrapper around the preceding.
  */
-extern unsigned int __pure full_name_hash(const char *, unsigned int);
+extern unsigned int __pure full_name_hash(const void *salt, const char *, unsigned int);
 
 /*
  * A hash_len is a u64 with the hash of a string in the low
@@ -71,6 +73,6 @@ extern unsigned int __pure full_name_hash(const char *, unsigned int);
 #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);
+extern u64 __pure hashlen_string(const void *salt, const char *name);
 
 #endif	/* __LINUX_STRINGHASH_H */

include/linux/sunrpc/svcauth.h

@@ -172,12 +172,12 @@ extern void unix_gid_cache_destroy(struct net *net);
  */
 static inline unsigned long hash_str(char const *name, int bits)
 {
-	return hashlen_hash(hashlen_string(name)) >> (32 - bits);
+	return hashlen_hash(hashlen_string(NULL, name)) >> (32 - bits);
 }
 
 static inline unsigned long hash_mem(char const *buf, int length, int bits)
 {
-	return full_name_hash(buf, length) >> (32 - bits);
+	return full_name_hash(NULL, buf, length) >> (32 - bits);
 }
 
 #endif /* __KERNEL__ */

lib/test_hash.c

@@ -155,8 +155,8 @@ test_hash_init(void)
 		buf[j] = '\0';
 
 		for (i = 0; i <= j; i++) {
-			u64 hashlen = hashlen_string(buf+i);
-			u32 h0 = full_name_hash(buf+i, j-i);
+			u64 hashlen = hashlen_string(buf+i, buf+i);
+			u32 h0 = full_name_hash(buf+i, buf+i, j-i);
 
 			/* Check that hashlen_string gets the length right */
 			if (hashlen_len(hashlen) != j-i) {

net/core/dev.c

@@ -198,7 +198,7 @@ static inline void dev_base_seq_inc(struct net *net)
 
 static inline struct hlist_head *dev_name_hash(struct net *net, const char *name)
 {
-	unsigned int hash = full_name_hash(name, strnlen(name, IFNAMSIZ));
+	unsigned int hash = full_name_hash(net, name, strnlen(name, IFNAMSIZ));
 
 	return &net->dev_name_head[hash_32(hash, NETDEV_HASHBITS)];
 }

security/smack/smack_access.c

@@ -413,7 +413,7 @@ void smk_insert_entry(struct smack_known *skp)
 	unsigned int hash;
 	struct hlist_head *head;
 
-	hash = full_name_hash(skp->smk_known, strlen(skp->smk_known));
+	hash = full_name_hash(NULL, skp->smk_known, strlen(skp->smk_known));
 	head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];
 
 	hlist_add_head_rcu(&skp->smk_hashed, head);
@@ -433,7 +433,7 @@ struct smack_known *smk_find_entry(const char *string)
 	struct hlist_head *head;
 	struct smack_known *skp;
 
-	hash = full_name_hash(string, strlen(string));
+	hash = full_name_hash(NULL, string, strlen(string));
 	head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];
 
 	hlist_for_each_entry_rcu(skp, head, smk_hashed)

security/tomoyo/memory.c

@@ -154,7 +154,7 @@ const struct tomoyo_path_info *tomoyo_get_name(const char *name)
 	if (!name)
 		return NULL;
 	len = strlen(name) + 1;
-	hash = full_name_hash((const unsigned char *) name, len - 1);
+	hash = full_name_hash(NULL, (const unsigned char *) name, len - 1);
 	head = &tomoyo_name_list[hash_long(hash, TOMOYO_HASH_BITS)];
 	if (mutex_lock_interruptible(&tomoyo_policy_lock))
 		return NULL;

security/tomoyo/util.c

@@ -666,7 +666,7 @@ void tomoyo_fill_path_info(struct tomoyo_path_info *ptr)
 	ptr->const_len = tomoyo_const_part_length(name);
 	ptr->is_dir = len && (name[len - 1] == '/');
 	ptr->is_patterned = (ptr->const_len < len);
-	ptr->hash = full_name_hash(name, len);
+	ptr->hash = full_name_hash(NULL, name, len);
 }
 
 /**