[src/trunk]: src/sys/dev Fall back to VOP_READ/VOP_WRITE if the simulated dis...

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

details:   https://anonhg.NetBSD.org/src/rev/ecab369d3c10
branches:  trunk
changeset: 341936:ecab369d3c10
user:      mlelstv <mlelstv%NetBSD.org@localhost>
date:      Mon Nov 30 06:04:47 2015 +0000

description:
Fall back to VOP_READ/VOP_WRITE if the simulated disk has smaller
sectors than the underlying filesystem and VOP_STRATEGY would fail.

diffstat:

 sys/dev/vnd.c |  30 ++++++++++++++++++++++++++++--
 1 files changed, 28 insertions(+), 2 deletions(-)

diffs (65 lines):

diff -r f9a8898ae870 -r ecab369d3c10 sys/dev/vnd.c
--- a/sys/dev/vnd.c     Mon Nov 30 01:31:02 2015 +0000
+++ b/sys/dev/vnd.c     Mon Nov 30 06:04:47 2015 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vnd.c,v 1.254 2015/11/12 15:28:07 christos Exp $       */
+/*     $NetBSD: vnd.c,v 1.255 2015/11/30 06:04:47 mlelstv Exp $        */
 
 /*-
  * Copyright (c) 1996, 1997, 1998, 2008 The NetBSD Foundation, Inc.
@@ -91,7 +91,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vnd.c,v 1.254 2015/11/12 15:28:07 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vnd.c,v 1.255 2015/11/30 06:04:47 mlelstv Exp $");
 
 #if defined(_KERNEL_OPT)
 #include "opt_vnd.h"
@@ -573,6 +573,22 @@
            vnode_has_op(vnd->sc_vp, VOFFSET(vop_strategy));
 }
 
+static bool
+vnode_has_large_blocks(struct vnd_softc *vnd)
+{
+       u_int32_t vnd_secsize, mnt_secsize;
+       uint64_t numsec;
+       unsigned secsize;
+
+       if (getdisksize(vnd->sc_vp, &numsec, &secsize))
+               return true;
+
+       vnd_secsize = vnd->sc_geom.vng_secsize;
+       mnt_secsize = secsize;
+
+       return vnd_secsize % mnt_secsize != 0;
+}
+
 /* XXX this function needs a reliable check to detect
  * sparse files. Otherwise, bmap/strategy may be used
  * and fail on non-allocated blocks. VOP_READ/VOP_WRITE
@@ -588,6 +604,9 @@
        if (!vnode_has_strategy(vnd))
                return false;
 
+       if (vnode_has_large_blocks(vnd))
+               return false;
+
        /* Convert the first logical block number to its
         * physical block number.
         */
@@ -619,6 +638,13 @@
            ! vnode_has_strategy(vnd))
                vnd->sc_flags |= VNF_USE_VN_RDWR;
 
+       /* VOP_STRATEGY can only be used if the backing vnode allows
+        * to access blocks as small as defined by the vnd geometry.
+        */
+       if ((vnd->sc_flags & VNF_USE_VN_RDWR) == 0 &&
+           vnode_has_large_blocks(vnd))
+               vnd->sc_flags |= VNF_USE_VN_RDWR;
+
 #ifdef DEBUG
        if (vnddebug & VDB_INIT)
                printf("vndthread: vp %p, %s\n", vnd->sc_vp,