Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

===================================================================
RCS file: /ftp/cvs/cvsroot/src/sys/miscfs/specfs/spec_vnops.c,v
rcsdiff: /ftp/cvs/cvsroot/src/sys/miscfs/specfs/spec_vnops.c,v: warning: Unknown phrases like `commitid ...;' are present.
retrieving revision 1.135
retrieving revision 1.135.2.1
diff -u -p -r1.135 -r1.135.2.1
--- src/sys/miscfs/specfs/spec_vnops.c	2012/04/29 22:54:00	1.135
+++ src/sys/miscfs/specfs/spec_vnops.c	2013/02/25 00:29:59	1.135.2.1
@@ -1,4 +1,4 @@
-/*	$NetBSD: spec_vnops.c,v 1.135 2012/04/29 22:54:00 chs Exp $	*/
+/*	$NetBSD: spec_vnops.c,v 1.135.2.1 2013/02/25 00:29:59 tls Exp $	*/
 
 /*-
  * Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -58,7 +58,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: spec_vnops.c,v 1.135 2012/04/29 22:54:00 chs Exp $");
+__KERNEL_RCSID(0, "$NetBSD: spec_vnops.c,v 1.135.2.1 2013/02/25 00:29:59 tls Exp $");
 
 #include <sys/param.h>
 #include <sys/proc.h>
@@ -93,7 +93,14 @@ const char	devout[] = "devout";
 const char	devioc[] = "devioc";
 const char	devcls[] = "devcls";
 
-vnode_t		*specfs_hash[SPECHSZ];
+#define	SPECHSZ	64
+#if	((SPECHSZ&(SPECHSZ-1)) == 0)
+#define	SPECHASH(rdev)	(((rdev>>5)+(rdev))&(SPECHSZ-1))
+#else
+#define	SPECHASH(rdev)	(((unsigned)((rdev>>5)+(rdev)))%SPECHSZ)
+#endif
+
+static vnode_t	*specfs_hash[SPECHSZ];
 
 /*
  * This vnode operations vector is used for special device nodes
@@ -268,6 +275,82 @@ spec_node_init(vnode_t *vp, dev_t rdev)
 }
 
 /*
+ * Lookup a vnode by device number and return it referenced.
+ */
+int
+spec_node_lookup_by_dev(enum vtype type, dev_t dev, vnode_t **vpp)
+{
+	int error;
+	vnode_t *vp;
+
+	mutex_enter(&device_lock);
+	for (vp = specfs_hash[SPECHASH(dev)]; vp; vp = vp->v_specnext) {
+		if (type == vp->v_type && dev == vp->v_rdev) {
+			mutex_enter(vp->v_interlock);
+			/* If clean or being cleaned, then ignore it. */
+			if ((vp->v_iflag & (VI_CLEAN | VI_XLOCK)) == 0)
+				break;
+			mutex_exit(vp->v_interlock);
+		}
+	}
+	KASSERT(vp == NULL || mutex_owned(vp->v_interlock));
+	if (vp == NULL) {
+		mutex_exit(&device_lock);
+		return ENOENT;
+	}
+	/*
+	 * If it is an opened block device return the opened vnode.
+	 */
+	if (type == VBLK && vp->v_specnode->sn_dev->sd_bdevvp != NULL) {
+		mutex_exit(vp->v_interlock);
+		vp = vp->v_specnode->sn_dev->sd_bdevvp;
+		mutex_enter(vp->v_interlock);
+	}
+	mutex_exit(&device_lock);
+	error = vget(vp, 0);
+	if (error != 0)
+		return error;
+	*vpp = vp;
+
+	return 0;
+}
+
+/*
+ * Lookup a vnode by file system mounted on and return it referenced.
+ */
+int
+spec_node_lookup_by_mount(struct mount *mp, vnode_t **vpp)
+{
+	int i, error;
+	vnode_t *vp, *vq;
+
+	mutex_enter(&device_lock);
+	for (i = 0, vq = NULL; i < SPECHSZ && vq == NULL; i++) {
+		for (vp = specfs_hash[i]; vp; vp = vp->v_specnext) {
+			if (vp->v_type != VBLK)
+				continue;
+			vq = vp->v_specnode->sn_dev->sd_bdevvp;
+			if (vq != NULL && vq->v_specmountpoint == mp)
+				break;
+			vq = NULL;
+		}
+	}
+	if (vq == NULL) {
+		mutex_exit(&device_lock);
+		return ENOENT;
+	}
+	mutex_enter(vq->v_interlock);
+	mutex_exit(&device_lock);
+	error = vget(vq, 0);
+	if (error != 0)
+		return error;
+	*vpp = vq;
+
+	return 0;
+
+}
+
+/*
  * A vnode representing a special device is going away.  Close
  * the device if the vnode holds it open.
  */
@@ -612,11 +695,10 @@ spec_read(void *v)
 			on = uio->uio_offset % bsize;
 			n = min((unsigned)(bsize - on), uio->uio_resid);
 			error = bread(vp, bn, bsize, NOCRED, 0, &bp);
-			n = min(n, bsize - bp->b_resid);
 			if (error) {
-				brelse(bp, 0);
 				return (error);
 			}
+			n = min(n, bsize - bp->b_resid);
 			error = uiomove((char *)bp->b_data + on, n, uio);
 			brelse(bp, 0);
 		} while (error == 0 && uio->uio_resid > 0 && n != 0);
@@ -691,7 +773,6 @@ spec_write(void *v)
 				error = bread(vp, bn, bsize, NOCRED,
 				    B_MODIFY, &bp);
 			if (error) {
-				brelse(bp, 0);
 				return (error);
 			}
 			n = min(n, bsize - bp->b_resid);