dm: allow targets to require splitting WRITE_ZEROES and SECURE_ERASE

Introduce max_write_zeroes_granularity and
max_secure_erase_granularity flags in the dm_target struct.

If a target sets these then DM core will split IO of these operation
types accordingly (in terms of max_write_zeroes_sectors and
max_secure_erase_sectors respectively).

Signed-off-by: Mike Snitzer <snitzer@kernel.org>

include/linux/device-mapper.h

@@ -359,11 +359,23 @@ struct dm_target {
 	bool discards_supported:1;
 
 	/*
-	 * Set if this target requires that discards be split on both
-	 * 'discard_granularity' and 'max_discard_sectors' boundaries.
+	 * Set if this target requires that discards be split on
+	 * 'max_discard_sectors' boundaries.
 	 */
 	bool max_discard_granularity:1;
 
+	/*
+	 * Set if this target requires that secure_erases be split on
+	 * 'max_secure_erase_sectors' boundaries.
+	 */
+	bool max_secure_erase_granularity:1;
+
+	/*
+	 * Set if this target requires that write_zeroes be split on
+	 * 'max_write_zeroes_sectors' boundaries.
+	 */
+	bool max_write_zeroes_granularity:1;
+
 	/*
 	 * Set if we need to limit the number of in-flight bios when swapping.
 	 */