Clustered read and write are switched at mount-option level.

1. Clustered I/O is switched by the MNT_NOCLUSTERR and MNT_NOCLUSTERW
   bits of the mnt_flag.  The sysctl variables, vfs.foo.doclusterread
   and vfs.foo.doclusterwrite are deleted.  Only mount option can
   control clustered I/O from userland.
2. When foofs_mount mounts block device, foofs_mount checks D_CLUSTERR
   and D_CLUSTERW bits of the d_flags member in the block device switch
   table.  If D_NOCLUSTERR / D_NOCLUSTERW are set, MNT_NOCLUSTERR /
   MNT_NOCLUSTERW bits will be set.  In this case, MNT_NOCLUSTERR and
   MNT_NOCLUSTERW cannot be cleared from userland.
3. Vnode driver disables both clustered read and write.
4. Union filesystem disables clutered write.

Reviewed by:	bde

2 files changed, 15 insertions, 23 deletions

diff --git a/sys/fs/cd9660/cd9660_vfsops.c b/sys/fs/cd9660/cd9660_vfsops.c
index c652ab1..b29a042 100644
--- a/sys/fs/cd9660/cd9660_vfsops.c
+++ b/sys/fs/cd9660/cd9660_vfsops.c
@@ -36,7 +36,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)cd9660_vfsops.c	8.18 (Berkeley) 5/22/95
- * $Id: cd9660_vfsops.c,v 1.27 1997/08/16 19:15:00 wollman Exp $
+ * $Id: cd9660_vfsops.c,v 1.28 1997/09/07 16:20:42 bde Exp $
  */
 
 #include <sys/param.h>
@@ -183,9 +183,11 @@ cd9660_mount(mp, path, data, ndp, p)
 	int error;
 	struct iso_mnt *imp = 0;
 
-	if ((mp->mnt_flag & MNT_ROOTFS) != 0)
+	if ((mp->mnt_flag & MNT_ROOTFS) != 0) {
+		if (bdevsw[major(rootdev)]->d_flags & D_NOCLUSTERR)
+			mp->mnt_flag |= MNT_NOCLUSTERR;
 		return (iso_mountroot(mp, p));
-
+	}
 	if ((error = copyin(data, (caddr_t)&args, sizeof (struct iso_args))))
 		return (error);
 
@@ -195,9 +197,13 @@ cd9660_mount(mp, path, data, ndp, p)
 	/*
 	 * If updating, check whether changing from read-only to
 	 * read/write; if there is no device name, that's all we do.
+	 * Disallow clearing MNT_NOCLUSTERR flag, if block device requests.
 	 */
 	if (mp->mnt_flag & MNT_UPDATE) {
 		imp = VFSTOISOFS(mp);
+		if (bdevsw[major(imp->im_devvp->v_rdev)]->d_flags &
+		    D_NOCLUSTERR)
+			mp->mnt_flag |= MNT_NOCLUSTERR;
 		if (args.fspec == 0)
 			return (vfs_export(mp, &imp->im_export, &args.export));
 	}
@@ -218,9 +224,11 @@ cd9660_mount(mp, path, data, ndp, p)
 		vrele(devvp);
 		return ENXIO;
 	}
-	if ((mp->mnt_flag & MNT_UPDATE) == 0)
+	if ((mp->mnt_flag & MNT_UPDATE) == 0) {
+		if (bdevsw[major(devvp->v_rdev)]->d_flags & D_NOCLUSTERR)
+			mp->mnt_flag |= MNT_NOCLUSTERR;
 		error = iso_mountfs(devvp, mp, p, &args);
-	else {
+	} else {
 		if (devvp != imp->im_devvp)
 			error = EINVAL;	/* needs translation */
 		else
diff --git a/sys/fs/cd9660/cd9660_vnops.c b/sys/fs/cd9660/cd9660_vnops.c
index e518e89..cddb6fd 100644
--- a/sys/fs/cd9660/cd9660_vnops.c
+++ b/sys/fs/cd9660/cd9660_vnops.c
@@ -36,7 +36,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)cd9660_vnops.c	8.19 (Berkeley) 5/27/95
- * $Id: cd9660_vnops.c,v 1.38 1997/09/14 02:57:43 peter Exp $
+ * $Id: cd9660_vnops.c,v 1.39 1997/09/21 04:22:40 dyson Exp $
  */
 
 #include <sys/param.h>
@@ -81,17 +81,6 @@ static int cd9660_print __P((struct vop_print_args *));
 static int cd9660_islocked __P((struct vop_islocked_args *));
 
 /*
- * Sysctl values for the cd9660 filesystem.
- */
-#define	CD9660_CLUSTERREAD	1	/* cluster reading enabled */
-#define	CD9660_MAXID		2	/* number of valid cd9660 ids */
-
-#define	CD9660_NAMES { \
-	{0, 0}, \
-	{ "doclusterread", CTLTYPE_INT}, \
-}
-
-/*
  * Setattr call. Only allowed for block and character special devices.
  */
 int
@@ -299,11 +288,6 @@ cd9660_getattr(ap)
 	return (0);
 }
 
-static int	cd9660_doclusterread = 1;
-SYSCTL_NODE(_vfs, MOUNT_CD9660, cd9660, CTLFLAG_RW, 0, "CD9660 filesystem");
-SYSCTL_INT(_vfs_cd9660, CD9660_CLUSTERREAD, doclusterread,
-		   CTLFLAG_RW, &cd9660_doclusterread, 0, "");
-
 /*
  * Vnode op for reading.
  */
@@ -344,7 +328,7 @@ cd9660_read(ap)
 			n = diff;
 		size = blksize(imp, ip, lbn);
 		rablock = lbn + 1;
-		if (cd9660_doclusterread) {
+		if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERR) == 0) {
 			if (lblktosize(imp, rablock) <= ip->i_size)
 				error = cluster_read(vp, (off_t)ip->i_size,
 				         lbn, size, NOCRED, uio->uio_resid,