[src/trunk]: src/sys Add functions to open devices by device number or path.

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

details:   https://anonhg.NetBSD.org/src/rev/7e7bd52134ab
branches:  trunk
changeset: 460917:7e7bd52134ab
user:      mlelstv <mlelstv%NetBSD.org@localhost>
date:      Sun Nov 10 06:47:30 2019 +0000

description:
Add functions to open devices by device number or path.

diffstat:

 sys/kern/vfs_vnops.c |  57 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 sys/sys/vnode.h      |   6 ++++-
 2 files changed, 60 insertions(+), 3 deletions(-)

diffs (102 lines):

diff -r 032590976922 -r 7e7bd52134ab sys/kern/vfs_vnops.c
--- a/sys/kern/vfs_vnops.c      Sun Nov 10 00:54:57 2019 +0000
+++ b/sys/kern/vfs_vnops.c      Sun Nov 10 06:47:30 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_vnops.c,v 1.201 2019/09/15 20:24:25 christos Exp $ */
+/*     $NetBSD: vfs_vnops.c,v 1.202 2019/11/10 06:47:30 mlelstv Exp $  */
 
 /*-
  * Copyright (c) 2009 The NetBSD Foundation, Inc.
@@ -66,7 +66,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_vnops.c,v 1.201 2019/09/15 20:24:25 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_vnops.c,v 1.202 2019/11/10 06:47:30 mlelstv Exp $");
 
 #include "veriexec.h"
 
@@ -1189,3 +1189,56 @@
 
        return VOCALL(fifo_vnodeop_p, ap->a_desc->vdesc_offset, v);
 }
+
+/*
+ * Open block device by device number
+ */
+int
+vn_bdev_open(dev_t dev, struct vnode **vpp, struct lwp *l)
+{
+       int     error;
+
+       if ((error = bdevvp(dev, vpp)) != 0)
+               return error;
+
+       if ((error = VOP_OPEN(*vpp, FREAD | FWRITE, l->l_cred)) != 0) {
+               vrele(*vpp);
+               return error;
+       }
+       mutex_enter((*vpp)->v_interlock);
+       (*vpp)->v_writecount++;
+       mutex_exit((*vpp)->v_interlock);
+
+       return 0;
+}
+
+/*
+ * Lookup the provided name in the filesystem.  If the file exists,
+ * is a valid block device, and isn't being used by anyone else,
+ * set *vpp to the file's vnode.
+ */
+int
+vn_bdev_openpath(struct pathbuf *pb, struct vnode **vpp, struct lwp *l)
+{
+       struct nameidata nd;
+       struct vnode *vp;
+       dev_t dev;
+       enum vtype vt;
+       int     error;
+
+       NDINIT(&nd, LOOKUP, FOLLOW, pb);
+       if ((error = vn_open(&nd, FREAD | FWRITE, 0)) != 0)
+               return error;
+
+       vp = nd.ni_vp;
+       dev = vp->v_rdev;
+       vt = vp->v_type;
+
+       VOP_UNLOCK(vp);
+       (void) vn_close(vp, FREAD | FWRITE, l->l_cred);
+
+       if (vt != VBLK)
+               return ENOTBLK;
+
+       return vn_bdev_open(dev, vpp, l);
+}
diff -r 032590976922 -r 7e7bd52134ab sys/sys/vnode.h
--- a/sys/sys/vnode.h   Sun Nov 10 00:54:57 2019 +0000
+++ b/sys/sys/vnode.h   Sun Nov 10 06:47:30 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vnode.h,v 1.282 2019/09/26 20:57:19 christos Exp $     */
+/*     $NetBSD: vnode.h,v 1.283 2019/11/10 06:47:30 mlelstv Exp $      */
 
 /*-
  * Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -490,6 +490,7 @@
 struct file;
 struct filedesc;
 struct nameidata;
+struct pathbuf;
 struct proc;
 struct stat;
 struct uio;
@@ -550,6 +551,9 @@
 int    vn_extattr_rm(struct vnode *, int, int, const char *, struct lwp *);
 void   vn_ra_allocctx(struct vnode *);
 int    vn_fifo_bypass(void *);
+int    vn_bdev_open(dev_t, struct vnode **, struct lwp *);
+int    vn_bdev_openpath(struct pathbuf *pb, struct vnode **, struct lwp *);
+
 
 #ifdef DIAGNOSTIC
 static __inline bool