[src/trunk]: src/sys/dev/dkwedge No longer access the disk driver directly.

[mlelstv <mlelstv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/a11784801af2
branches:  trunk
changeset: 810230:a11784801af2
user:      mlelstv <mlelstv%NetBSD.org@localhost>
date:      Sat Aug 22 07:48:14 2015 +0000

description:
No longer access the disk driver directly.
If there is an open wedge, temporarily reference its vnode.
Otherwise try to open the block device.

diffstat:

 sys/dev/dkwedge/dk.c |  114 +++++++++++++++++++++++++++++++++++++-------------
 1 files changed, 83 insertions(+), 31 deletions(-)

diffs (182 lines):

diff -r c24243ba5744 -r a11784801af2 sys/dev/dkwedge/dk.c
--- a/sys/dev/dkwedge/dk.c      Sat Aug 22 07:42:46 2015 +0000
+++ b/sys/dev/dkwedge/dk.c      Sat Aug 22 07:48:14 2015 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: dk.c,v 1.81 2015/08/22 07:42:46 mlelstv Exp $  */
+/*     $NetBSD: dk.c,v 1.82 2015/08/22 07:48:14 mlelstv Exp $  */
 
 /*-
  * Copyright (c) 2004, 2005, 2006, 2007 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: dk.c,v 1.81 2015/08/22 07:42:46 mlelstv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: dk.c,v 1.82 2015/08/22 07:48:14 mlelstv Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_dkwedge.h"
@@ -102,6 +102,8 @@
 static int     dkwedge_detach(device_t, int);
 static void    dkwedge_delall1(struct disk *, bool);
 static int     dkwedge_del1(struct dkwedge_info *, int);
+static struct vnode *dk_open_parent(dev_t, int);
+static int     dk_close_parent(struct vnode *, int);
 
 static dev_type_open(dkopen);
 static dev_type_close(dkclose);
@@ -945,34 +947,58 @@
 {
        buf_t *bp;
        int error;
+       bool isopen;
+       dev_t bdev;
+       struct vnode *bdevvp;
 
        /*
         * The kernel cannot read from a character device vnode
         * as physio() only handles user memory.
         *
-        * Determine the corresponding block device and call into
-        * the driver directly.
+        * If the block device has already been opened by a wedge
+        * use that vnode and temporarily bump the open counter.
+        *
+        * Otherwise try to open the block device.
         */
 
-       bp = getiobuf(vp, true);
+       bdev = devsw_chr2blk(vp->v_rdev);
+
+       mutex_enter(&pdk->dk_rawlock);
+       if (pdk->dk_rawopens != 0) {
+               KASSERT(pdk->dk_rawvp != NULL);
+               isopen = true;
+               ++pdk->dk_rawopens;
+               bdevvp = pdk->dk_rawvp;
+       } else {
+               isopen = false;
+               bdevvp = dk_open_parent(bdev, FREAD);
+       }
+       mutex_exit(&pdk->dk_rawlock);
+
+       if (bdevvp == NULL)
+               return EBUSY;
+
+       bp = getiobuf(bdevvp, true);
        bp->b_flags = B_READ;
        bp->b_cflags = BC_BUSY;
-       bp->b_dev = devsw_chr2blk(vp->v_rdev);
+       bp->b_dev = bdev;
        bp->b_data = tbuf;
        bp->b_bufsize = bp->b_bcount = len;
        bp->b_blkno = blkno;
        bp->b_cylinder = 0;
        bp->b_error = 0;
 
-       error = bdev_open(bp->b_dev, FREAD, S_IFBLK, curlwp);
-       if (error)
-               return error;
-
-       bdev_strategy(bp);
+       VOP_STRATEGY(bdevvp, bp);
        error = biowait(bp);
        putiobuf(bp);
 
-       bdev_close(bp->b_dev, FREAD, S_IFBLK, curlwp);
+       mutex_enter(&pdk->dk_rawlock);
+       if (isopen) {
+               --pdk->dk_rawopens;
+       } else {
+               dk_close_parent(bdevvp, FREAD);
+       }
+       mutex_exit(&pdk->dk_rawlock);
 
        return error;
 }
@@ -995,6 +1021,48 @@
        return (dkwedges[unit]);
 }
 
+static struct vnode *
+dk_open_parent(dev_t dev, int mode)
+{
+       struct vnode *vp;
+       int error;
+
+       error = bdevvp(dev, &vp);
+       if (error)
+               return NULL;
+
+       error = vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
+       if (error) {
+               vrele(vp);
+               return NULL;
+       }
+       error = VOP_OPEN(vp, mode, NOCRED);
+       if (error) {
+               vput(vp);
+               return NULL;
+       }
+
+       /* VOP_OPEN() doesn't do this for us. */
+       if (mode & FWRITE) {
+               mutex_enter(vp->v_interlock);
+               vp->v_writecount++;
+               mutex_exit(vp->v_interlock);
+       }
+
+       VOP_UNLOCK(vp);
+
+       return vp;
+}
+
+static int
+dk_close_parent(struct vnode *vp, int mode)
+{
+       int error;
+
+       error = vn_close(vp, mode, NOCRED);
+       return error;
+}
+
 /*
  * dkopen:             [devsw entry point]
  *
@@ -1023,24 +1091,9 @@
        if (sc->sc_dk.dk_openmask == 0) {
                if (sc->sc_parent->dk_rawopens == 0) {
                        KASSERT(sc->sc_parent->dk_rawvp == NULL);
-                       error = bdevvp(sc->sc_pdev, &vp);
-                       if (error)
-                               goto popen_fail;
-                       error = vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
-                       if (error) {
-                               vrele(vp);
+                       vp = dk_open_parent(sc->sc_pdev, FREAD | FWRITE);
+                       if (vp == NULL)
                                goto popen_fail;
-                       }
-                       error = VOP_OPEN(vp, FREAD | FWRITE, NOCRED);
-                       if (error) {
-                               vput(vp);
-                               goto popen_fail;
-                       }
-                       /* VOP_OPEN() doesn't do this for us. */
-                       mutex_enter(vp->v_interlock);
-                       vp->v_writecount++;
-                       mutex_exit(vp->v_interlock);
-                       VOP_UNLOCK(vp);
                        sc->sc_parent->dk_rawvp = vp;
                }
                sc->sc_parent->dk_rawopens++;
@@ -1076,8 +1129,7 @@
 
        if (doclose) {
                KASSERT(sc->sc_parent->dk_rawvp != NULL);
-               error = vn_close(sc->sc_parent->dk_rawvp,
-                   FREAD | FWRITE, NOCRED);
+               dk_close_parent(sc->sc_parent->dk_rawvp, FREAD | FWRITE);
                sc->sc_parent->dk_rawvp = NULL;
        }