From 17d84d611f995d5d33602ff8aed1ae6d2a3ea92c Mon Sep 17 00:00:00 2001
From: Martin Matuska <mm@FreeBSD.org>
Date: Thu, 9 Feb 2012 10:09:12 +0000
Subject: [PATCH] Introduce the "ruleset=number" option for devfs(5) mounts.
 Add support for updating the devfs mount (currently only changing the ruleset
 number is supported). Check mnt_optnew with vfs_filteropt(9).

This new option sets the specified ruleset number as the active ruleset
of the new devfs mount and applies all its rules at mount time. If the
specified ruleset doesn't exist, a new empty ruleset is created.

MFC after:	1 month
---
 share/man/man5/devfs.5      | 25 ++++++++++++++++++++-
 sys/fs/devfs/devfs.h        |  2 ++
 sys/fs/devfs/devfs_rule.c   | 35 ++++++++++++++++++++++++++++++
 sys/fs/devfs/devfs_vfsops.c | 43 ++++++++++++++++++++++++++++++++++++-
 4 files changed, 103 insertions(+), 2 deletions(-)

diff --git a/share/man/man5/devfs.5 b/share/man/man5/devfs.5
index 8c7e598af2ff..7b483fc7a5f1 100644
--- a/share/man/man5/devfs.5
+++ b/share/man/man5/devfs.5
@@ -38,7 +38,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd September 18, 2010
+.Dd February 9, 2012
 .Dt DEVFS 5
 .Os
 .Sh NAME
@@ -90,6 +90,29 @@ and
 .Pa 2 .
 .Xr fdescfs 5
 creates files for all open descriptors.
+.Pp
+The options are as follows:
+.Bl -tag -width indent
+.It Fl o Ar options
+Use the specified mount
+.Ar options ,
+as described in
+.Xr mount 8 .
+The following devfs file system-specific options are available:
+.Bl -tag -width indent
+.It Cm ruleset Ns No = Ns Ar ruleset
+Set ruleset number
+.Ar ruleset
+as the current ruleset for the mount-point and apply all its rules. If the
+ruleset number
+.Ar ruleset
+does not exist, an empty ruleset with the number
+.Ar ruleset
+is created. See
+.Xr devfs 8
+for more information on working with devfs rulesets.
+.El
+.El
 .Sh FILES
 .Bl -tag -width /dev/XXXX -compact
 .It Pa /dev
diff --git a/sys/fs/devfs/devfs.h b/sys/fs/devfs/devfs.h
index d148f8e487cb..d77baa8657bc 100644
--- a/sys/fs/devfs/devfs.h
+++ b/sys/fs/devfs/devfs.h
@@ -182,6 +182,8 @@ void	devfs_rules_apply(struct devfs_mount *, struct devfs_dirent *);
 void	devfs_rules_cleanup(struct devfs_mount *);
 int	devfs_rules_ioctl(struct devfs_mount *, u_long, caddr_t,
 	    struct thread *);
+void	devfs_ruleset_set(devfs_rsnum rsnum, struct devfs_mount *dm);
+void	devfs_ruleset_apply(struct devfs_mount *dm);
 int	devfs_allocv(struct devfs_dirent *, struct mount *, int,
 	    struct vnode **);
 char	*devfs_fqpn(char *, struct devfs_mount *, struct devfs_dirent *,
diff --git a/sys/fs/devfs/devfs_rule.c b/sys/fs/devfs/devfs_rule.c
index ea057977b5f0..f37dd9dbafb5 100644
--- a/sys/fs/devfs/devfs_rule.c
+++ b/sys/fs/devfs/devfs_rule.c
@@ -771,3 +771,38 @@ devfs_rules_cleanup(struct devfs_mount *dm)
 		devfs_ruleset_reap(ds);
 	}
 }
+
+/*
+ * Make rsnum the active ruleset for dm (locked)
+ */
+void
+devfs_ruleset_set(devfs_rsnum rsnum, struct devfs_mount *dm)
+{
+
+	sx_assert(&dm->dm_lock, SX_XLOCKED);
+
+	sx_xlock(&sx_rules);
+	devfs_ruleset_use(rsnum, dm);
+	sx_xunlock(&sx_rules);
+}
+
+/*
+ * Apply the current active ruleset on a mount
+ */
+void
+devfs_ruleset_apply(struct devfs_mount *dm)
+{
+	struct devfs_ruleset *ds;
+
+	sx_assert(&dm->dm_lock, SX_XLOCKED);
+
+	sx_xlock(&sx_rules);
+	if (dm->dm_ruleset == 0) {
+		sx_xunlock(&sx_rules);
+		return;
+	}
+	ds = devfs_ruleset_bynum(dm->dm_ruleset);
+	if (ds != NULL)
+		devfs_ruleset_applydm(ds, dm);
+	sx_xunlock(&sx_rules);
+}
diff --git a/sys/fs/devfs/devfs_vfsops.c b/sys/fs/devfs/devfs_vfsops.c
index 87ec1628851d..bba4bfc544ce 100644
--- a/sys/fs/devfs/devfs_vfsops.c
+++ b/sys/fs/devfs/devfs_vfsops.c
@@ -56,6 +56,10 @@ static vfs_unmount_t	devfs_unmount;
 static vfs_root_t	devfs_root;
 static vfs_statfs_t	devfs_statfs;
 
+static const char *devfs_opts[] = {
+	"from", "ruleset", NULL
+};
+
 /*
  * Mount the filesystem
  */
@@ -65,15 +69,46 @@ devfs_mount(struct mount *mp)
 	int error;
 	struct devfs_mount *fmp;
 	struct vnode *rvp;
+	int rsnum;
 
 	if (devfs_unr == NULL)
 		devfs_unr = new_unrhdr(0, INT_MAX, NULL);
 
 	error = 0;
 
-	if (mp->mnt_flag & (MNT_UPDATE | MNT_ROOTFS))
+	if (mp->mnt_flag & MNT_ROOTFS)
 		return (EOPNOTSUPP);
 
+	rsnum = 0;
+
+	if (mp->mnt_optnew != NULL) {
+		if (vfs_filteropt(mp->mnt_optnew, devfs_opts))
+			return (EINVAL);
+
+		if (vfs_getopt(mp->mnt_optnew, "ruleset", NULL, NULL) == 0 &&
+		    (vfs_scanopt(mp->mnt_optnew, "ruleset", "%d",
+		    &rsnum) != 1 || rsnum < 0 || rsnum > 65535))
+			error = EINVAL;
+	}
+
+	if (error) {
+		vfs_mount_error(mp, "%s", "invalid ruleset specification");
+		return (error);
+	}
+
+	if (mp->mnt_flag & MNT_UPDATE) {
+		if (rsnum != 0) {
+			fmp = mp->mnt_data;
+			if (fmp != NULL) {
+				sx_xlock(&fmp->dm_lock);
+				devfs_ruleset_set((devfs_rsnum)rsnum, fmp);
+				devfs_ruleset_apply(fmp);
+				sx_xunlock(&fmp->dm_lock);
+			}
+		}
+		return (0);
+	}
+
 	fmp = malloc(sizeof *fmp, M_DEVFS, M_WAITOK | M_ZERO);
 	fmp->dm_idx = alloc_unr(devfs_unr);
 	sx_init(&fmp->dm_lock, "devfsmount");
@@ -101,6 +136,12 @@ devfs_mount(struct mount *mp)
 		return (error);
 	}
 
+	if (rsnum != 0) {
+		sx_xlock(&fmp->dm_lock);
+		devfs_ruleset_set((devfs_rsnum)rsnum, fmp);
+		sx_xunlock(&fmp->dm_lock);
+	}
+
 	VOP_UNLOCK(rvp, 0);
 
 	vfs_mountedfrom(mp, "devfs");