compat_ioctl: block: handle Persistent Reservations

These were added to blkdev_ioctl() in linux-5.5 but not
blkdev_compat_ioctl, so add them now.

Cc: <stable@vger.kernel.org> # v4.4+
Fixes: bbd3e064 ("block: add an API for Persistent Reservations")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Fold in followup patch from Arnd with missing pr.h header include.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/compat_ioctl.c

@@ -6,6 +6,7 @@
 #include <linux/compat.h>
 #include <linux/elevator.h>
 #include <linux/hdreg.h>
+#include <linux/pr.h>
 #include <linux/slab.h>
 #include <linux/syscalls.h>
 #include <linux/types.h>
@@ -408,6 +409,14 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 	case BLKTRACETEARDOWN: /* compatible */
 		ret = blk_trace_ioctl(bdev, cmd, compat_ptr(arg));
 		return ret;
+	case IOC_PR_REGISTER:
+	case IOC_PR_RESERVE:
+	case IOC_PR_RELEASE:
+	case IOC_PR_PREEMPT:
+	case IOC_PR_PREEMPT_ABORT:
+	case IOC_PR_CLEAR:
+		return blkdev_ioctl(bdev, mode, cmd,
+				(unsigned long)compat_ptr(arg));
 	default:
 		if (disk->fops->compat_ioctl)
 			ret = disk->fops->compat_ioctl(bdev, mode, cmd, arg);