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);
@@ -84,15 +84,15 @@ __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));
 
 }
 
 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));
 }
 
 /**
@@ -2874,16 +2872,15 @@ 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
 	 * the two dentries, then rehash onto the other's hash queue.
 	 */
 	__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;
@@ -258,21 +258,21 @@ 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;
 }
 
 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)) {