svn commit: r245406 - in head/sys: kern sys

[Konstantin Belousov]

Author: kib
Date: Mon Jan 14 05:41:40 2013
New Revision: 245406
URL: http://svnweb.freebsd.org/changeset/base/245406

Log:
  Add exported vfs_hash_index() function, which calculates the canonical
  pre-masked hash for the given vnode.  The function assumes that
  vp->v_hash is initialized by the filesystem vnode instantiation
  function.  At the moment, it is only done if filesystem uses
  vfs_hash_insert().
  
  Reviewed by:	peter
  Tested by:	peter, pho (previous version)
  Sponsored by:	The FreeBSD Foundation
  MFC after:	5 days

Modified:
  head/sys/kern/vfs_hash.c
  head/sys/sys/vnode.h

Modified: head/sys/kern/vfs_hash.c
==============================================================================
--- head/sys/kern/vfs_hash.c	Mon Jan 14 05:40:21 2013	(r245405)
+++ head/sys/kern/vfs_hash.c	Mon Jan 14 05:41:40 2013	(r245406)
@@ -54,6 +54,13 @@ vfs_hashinit(void *dummy __unused)
 /* Must be SI_ORDER_SECOND so desiredvnodes is available */
 SYSINIT(vfs_hash, SI_SUB_VFS, SI_ORDER_SECOND, vfs_hashinit, NULL);
 
+u_int
+vfs_hash_index(struct vnode *vp)
+{
+
+	return (vp->v_hash + vp->v_mount->mnt_hashseed);
+}
+
 static struct vfs_hash_head *
 vfs_hash_bucket(const struct mount *mp, u_int hash)
 {

Modified: head/sys/sys/vnode.h
==============================================================================
--- head/sys/sys/vnode.h	Mon Jan 14 05:40:21 2013	(r245405)
+++ head/sys/sys/vnode.h	Mon Jan 14 05:41:40 2013	(r245406)
@@ -812,6 +812,7 @@ int	fifo_printinfo(struct vnode *);
 typedef int vfs_hash_cmp_t(struct vnode *vp, void *arg);
 
 int vfs_hash_get(const struct mount *mp, u_int hash, int flags, struct thread *td, struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg);
+u_int vfs_hash_index(struct vnode *vp);
 int vfs_hash_insert(struct vnode *vp, u_int hash, int flags, struct thread *td, struct vnode **vpp, vfs_hash_cmp_t *fn, void *arg);
 void vfs_hash_rehash(struct vnode *vp, u_int hash);
 void vfs_hash_remove(struct vnode *vp);