# HG changeset patch
# Parent 80f7f3b65c446994d672ce8cbfcd540c5df3d674
Add d_discard to struct bdevsw/cdevsw, and the plumbing to access it.

Unfortunately we need d_discard in both since we need to be able to
discard from both the block and character forms of disks. I'm
increasingly thinking it would be better to restructure the ops
dispatching so each type of device (ttys, disks, tapes, etc.) has its
own function table. Then we wouldn't need to change every tty driver
to add a disk op.

diff -r 80f7f3b65c44 sys/kern/subr_devsw.c
--- a/sys/kern/subr_devsw.c	Sun Mar 23 02:03:47 2014 -0400
+++ b/sys/kern/subr_devsw.c	Sun Mar 23 02:14:34 2014 -0400
@@ -817,6 +817,22 @@
 }
 
 int
+bdev_discard(dev_t dev, off_t pos, off_t len)
+{
+	const struct bdevsw *d;
+	int rv, mpflag;
+
+	if ((d = bdevsw_lookup(dev)) == NULL)
+		return ENXIO;
+
+	DEV_LOCK(d);
+	rv = (*d->d_discard)(dev, pos, len);
+	DEV_UNLOCK(d);
+
+	return rv;
+}
+
+int
 cdev_open(dev_t dev, int flag, int devtype, lwp_t *l)
 {
 	const struct cdevsw *d;
@@ -982,6 +998,22 @@
 }
 
 int
+cdev_discard(dev_t dev, off_t pos, off_t len)
+{
+	const struct cdevsw *d;
+	int rv, mpflag;
+
+	if ((d = cdevsw_lookup(dev)) == NULL)
+		return ENXIO;
+
+	DEV_LOCK(d);
+	rv = (*d->d_discard)(dev, pos, len);
+	DEV_UNLOCK(d);
+
+	return rv;
+}
+
+int
 cdev_type(dev_t dev)
 {
 	const struct cdevsw *d;
diff -r 80f7f3b65c44 sys/sys/conf.h
--- a/sys/sys/conf.h	Sun Mar 23 02:03:47 2014 -0400
+++ b/sys/sys/conf.h	Sun Mar 23 02:14:34 2014 -0400
@@ -74,6 +74,7 @@
 	int		(*d_ioctl)(dev_t, u_long, void *, int, struct lwp *);
 	int		(*d_dump)(dev_t, daddr_t, void *, size_t);
 	int		(*d_psize)(dev_t);
+	int		(*d_discard)(dev_t, off_t, off_t);
 	int		d_flag;
 };
 
@@ -91,6 +92,7 @@
 	int		(*d_poll)(dev_t, int, struct lwp *);
 	paddr_t		(*d_mmap)(dev_t, off_t, int);
 	int		(*d_kqfilter)(dev_t, struct knote *);
+	int		(*d_discard)(dev_t, off_t, off_t);
 	int		d_flag;
 };
 
@@ -121,6 +123,7 @@
 #define	dev_type_dump(n)	int n (dev_t, daddr_t, void *, size_t)
 #define	dev_type_size(n)	int n (dev_t)
 #define	dev_type_kqfilter(n)	int n (dev_t, struct knote *)
+#define dev_type_discard(n)	int n (dev_t, off_t, off_t)
 
 #define	noopen		((dev_type_open((*)))enodev)
 #define	noclose		((dev_type_close((*)))enodev)
@@ -134,6 +137,7 @@
 #define	nodump		((dev_type_dump((*)))enodev)
 #define	nosize		NULL
 #define	nokqfilter	seltrue_kqfilter
+#define nodiscard	((dev_type_discard((*)))enodev)
 
 #define	nullopen	((dev_type_open((*)))nullop)
 #define	nullclose	((dev_type_close((*)))nullop)
@@ -145,6 +149,7 @@
 #define	nullmmap	((dev_type_mmap((*)))nullop)
 #define	nulldump	((dev_type_dump((*)))nullop)
 #define	nullkqfilter	((dev_type_kqfilter((*)))eopnotsupp)
+#define nulldiscard	((dev_type_discard((*)))nullop)
 
 /* device access wrappers. */
 
@@ -154,6 +159,7 @@
 dev_type_ioctl(bdev_ioctl);
 dev_type_dump(bdev_dump);
 dev_type_size(bdev_size);
+dev_type_discard(bdev_discard);
 
 dev_type_open(cdev_open);
 dev_type_close(cdev_close);
@@ -165,6 +171,7 @@
 dev_type_poll(cdev_poll);
 dev_type_mmap(cdev_mmap);
 dev_type_kqfilter(cdev_kqfilter);
+dev_type_discard(cdev_discard);
 
 int	cdev_type(dev_t);
 int	bdev_type(dev_t);