increase clone bitmap size (again)

[Martin Natano]

Below is the fixed v_specbitmap enlargements diff, including some tweaks
by mikeb@. I have tested this with fuse _and_ drm on amd64 and macppc. I
also tested on macppc with cloning bpf (not in the tree). Can anyone
come up with another interesting test case?

Comments? Ok?

natano


Index: sys/specdev.h
===================================================================
RCS file: /cvs/src/sys/sys/specdev.h,v
retrieving revision 1.36
diff -u -p -r1.36 specdev.h
--- sys/specdev.h       1 Apr 2016 11:51:55 -0000       1.36
+++ sys/specdev.h       1 Apr 2016 20:35:50 -0000
@@ -46,7 +46,7 @@ struct specinfo {
        daddr_t si_lastr;
        union {
                struct vnode *ci_parent; /* pointer back to parent device */
-               u_int8_t ci_bitmap[8]; /* bitmap of devices cloned off us */
+               u_int8_t *ci_bitmap; /* bitmap of devices cloned off us */
        } si_ci;
 };
 
@@ -71,6 +71,7 @@ struct cloneinfo {
  * This gives us 8 bits for encoding the real minor number.
  */
 #define CLONE_SHIFT    8
+#define CLONE_MAPSZ    128
 
 /*
  * Special device management
Index: kern/vfs_subr.c
===================================================================
RCS file: /cvs/src/sys/kern/vfs_subr.c,v
retrieving revision 1.242
diff -u -p -r1.242 vfs_subr.c
--- kern/vfs_subr.c     1 Apr 2016 11:51:55 -0000       1.242
+++ kern/vfs_subr.c     1 Apr 2016 20:35:50 -0000
@@ -555,7 +555,13 @@ loop:
                nvp->v_specnext = *vpp;
                nvp->v_specmountpoint = NULL;
                nvp->v_speclockf = NULL;
-               memset(nvp->v_specbitmap, 0, sizeof(nvp->v_specbitmap));
+               nvp->v_specbitmap = NULL;
+               if (nvp->v_type == VCHR &&
+                   (cdevsw[major(nvp_rdev)].d_flags & D_CLONE) &&
+                   (minor(nvp_rdev) >> CLONE_SHIFT == 0)) {
+                       nvp->v_specbitmap = malloc(CLONE_MAPSZ, M_VNODE,
+                           M_WAITOK | M_ZERO);
+               }
                *vpp = nvp;
                if (vp != NULLVP) {
                        nvp->v_flag |= VALIASED;
@@ -1092,6 +1098,11 @@ vgonel(struct vnode *vp, struct proc *p)
                        if (vq == NULL)
                                vx->v_flag &= ~VALIASED;
                        vp->v_flag &= ~VALIASED;
+               }
+               if (vp->v_type == VCHR &&
+                   (cdevsw[major(vp->v_rdev)].d_flags & D_CLONE) &&
+                   (minor(vp->v_rdev) >> CLONE_SHIFT == 0)) {
+                       free(vp->v_specbitmap, M_VNODE, CLONE_MAPSZ);
                }
                free(vp->v_specinfo, M_VNODE, sizeof(struct specinfo));
                vp->v_specinfo = NULL;
Index: kern/spec_vnops.c
===================================================================
RCS file: /cvs/src/sys/kern/spec_vnops.c,v
retrieving revision 1.88
diff -u -p -r1.88 spec_vnops.c
--- kern/spec_vnops.c   1 Apr 2016 11:51:55 -0000       1.88
+++ kern/spec_vnops.c   1 Apr 2016 20:35:50 -0000
@@ -707,13 +707,13 @@ spec_open_clone(struct vop_open_args *ap
        if (minor(vp->v_rdev) >= (1 << CLONE_SHIFT))
                return (ENXIO);
 
-       for (i = 1; i < sizeof(vp->v_specbitmap) * NBBY; i++)
+       for (i = 1; i < CLONE_MAPSZ * NBBY; i++)
                if (isclr(vp->v_specbitmap, i)) {
                        setbit(vp->v_specbitmap, i);
                        break;
                }
 
-       if (i == sizeof(vp->v_specbitmap) * NBBY)
+       if (i == CLONE_MAPSZ * NBBY)
                return (EBUSY); /* too many open instances */
 
        error = cdevvp(makedev(major(vp->v_rdev),