md: Remove the AllReserved flag for component devices.

This flag is not needed and is used badly.

Devices that are included in a native-metadata array are reserved
exclusively for that array - and currently have AllReserved set.
They all are bd_claimed for the rdev and so cannot be shared.

Devices that are included in external-metadata arrays can be shared
among multiple arrays - providing there is no overlap.
These are bd_claimed for md in general - not for a particular rdev.

When changing the amount of a device that is used in an array we need
to check for overlap.  This currently includes a check on AllReserved
So even without overlap, sharing with an AllReserved device is not
allowed.
However the bd_claim usage already precludes sharing with these
devices, so the test on AllReserved is not needed.  And in fact it is
wrong.

As this is the only use of AllReserved, simply remove all usage and
definition of AllReserved.

Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/md.c

@@ -1947,8 +1947,6 @@ static int lock_rdev(mdk_rdev_t *rdev, dev_t dev, int shared)
 			__bdevname(dev, b));
 		return PTR_ERR(bdev);
 	}
-	if (!shared)
-		set_bit(AllReserved, &rdev->flags);
 	rdev->bdev = bdev;
 	return err;
 }
@@ -2610,12 +2608,11 @@ rdev_size_store(mdk_rdev_t *rdev, const char *buf, size_t len)
 
 			mddev_lock(mddev);
 			list_for_each_entry(rdev2, &mddev->disks, same_set)
-				if (test_bit(AllReserved, &rdev2->flags) ||
-				    (rdev->bdev == rdev2->bdev &&
-				     rdev != rdev2 &&
-				     overlaps(rdev->data_offset, rdev->sectors,
-					      rdev2->data_offset,
-					      rdev2->sectors))) {
+				if (rdev->bdev == rdev2->bdev &&
+				    rdev != rdev2 &&
+				    overlaps(rdev->data_offset, rdev->sectors,
+					     rdev2->data_offset,
+					     rdev2->sectors)) {
 					overlap = 1;
 					break;
 				}

drivers/md/md.h

@@ -93,8 +93,6 @@ struct mdk_rdev_s
 #define	Faulty		1		/* device is known to have a fault */
 #define	In_sync		2		/* device is in_sync with rest of array */
 #define	WriteMostly	4		/* Avoid reading if at all possible */
-#define	AllReserved	6		/* If whole device is reserved for
-					 * one array */
 #define	AutoDetected	7		/* added by auto-detect */
 #define Blocked		8		/* An error occured on an externally
 					 * managed array, don't allow writes