Merge tag 'for-5.16/cdrom-2021-10-29' of git://git.kernel.dk/linux-block

Pull CDROM updates from Jens Axboe:
 "On behalf of Phillip, here are the CDROM updates for the 5.16-rc1
  merge window:

   - Add ioctl for improved media change detection (Lukas)

   - Reformat some documentation (Phillip)

   - Redundant variable removal (luo)"

* tag 'for-5.16/cdrom-2021-10-29' of git://git.kernel.dk/linux-block:
  cdrom: Remove redundant variable and its assignment
  cdrom: docs: reformat table in Documentation/userspace-api/ioctl/cdrom.rst
  drivers/cdrom: improved ioctl for media change detection

include/uapi/linux/cdrom.h

@@ -147,6 +147,8 @@
 #define CDROM_NEXT_WRITABLE	0x5394	/* get next writable block */
 #define CDROM_LAST_WRITTEN	0x5395	/* get last block written on disc */
 
+#define CDROM_TIMED_MEDIA_CHANGE   0x5396  /* get the timestamp of the last media change */
+
 /*******************************************************
  * CDROM IOCTL structures
  *******************************************************/
@@ -295,6 +297,23 @@ struct cdrom_generic_command
 	};
 };
 
+/* This struct is used by CDROM_TIMED_MEDIA_CHANGE */
+struct cdrom_timed_media_change_info {
+	__s64	last_media_change;	/* Timestamp of the last detected media
+					 * change in ms. May be set by caller,
+					 * updated upon successful return of
+					 * ioctl.
+					 */
+	__u64	media_flags;		/* Flags returned by ioctl to indicate
+					 * media status.
+					 */
+};
+#define MEDIA_CHANGED_FLAG	0x1	/* Last detected media change was more
+					 * recent than last_media_change set by
+					 * caller.
+					 */
+/* other bits of media_flags available for future use */
+
 /*
  * A CD-ROM physical sector size is 2048, 2052, 2056, 2324, 2332, 2336, 
  * 2340, or 2352 bytes long.