Consolidate min_not_zero

We have several users of min_not_zero, each of them using their own
definition.  Move the define to kernel.h.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@carl.home.kernel.dk>

block/blk-settings.c

@@ -455,11 +455,6 @@ void blk_queue_io_opt(struct request_queue *q, unsigned int opt)
 }
 EXPORT_SYMBOL(blk_queue_io_opt);
 
-/*
- * Returns the minimum that is _not_ zero, unless both are zero.
- */
-#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
-
 /**
  * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
  * @t:	the stacking driver (top)

drivers/block/drbd/drbd_receiver.c

@@ -2972,7 +2972,6 @@ static int receive_sizes(struct drbd_conf *mdev, struct p_header *h)
 	 * we still need to figure out whether we accept that. */
 	mdev->p_size = p_size;
 
-#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
 	if (get_ldev(mdev)) {
 		warn_if_differ_considerably(mdev, "lower level device sizes",
 			   p_size, drbd_get_max_capacity(mdev->ldev));

drivers/md/dm-snap.c

@@ -706,8 +706,6 @@ static int dm_add_exception(void *context, chunk_t old, chunk_t new)
 	return 0;
 }
 
-#define min_not_zero(l, r) (((l) == 0) ? (r) : (((r) == 0) ? (l) : min(l, r)))
-
 /*
  * Return a minimum chunk size of all snapshots that have the specified origin.
  * Return zero if the origin has no snapshots.

drivers/md/dm-table.c

@@ -486,11 +486,6 @@ static int __table_get_device(struct dm_table *t, struct dm_target *ti,
 	return 0;
 }
 
-/*
- * Returns the minimum that is _not_ zero, unless both are zero.
- */
-#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
-
 int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
 			 sector_t start, sector_t len, void *data)
 {

include/linux/kernel.h

@@ -640,6 +640,16 @@ static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
 	(void) (&_max1 == &_max2);		\
 	_max1 > _max2 ? _max1 : _max2; })
 
+/**
+ * min_not_zero - return the minimum that is _not_ zero, unless both are zero
+ * @x: value1
+ * @y: value2
+ */
+#define min_not_zero(x, y) ({			\
+	typeof(x) __x = (x);			\
+	typeof(y) __y = (y);			\
+	__x == 0 ? __y : ((__y == 0) ? __x : min(__x, __y)); })
+
 /**
  * clamp - return a value clamped to a given range with strict typechecking
  * @val: current value