Support new raid6 layouts needed for DDF

[thirdparty/mdadm.git] / mdadm.h

diff --git a/mdadm.h b/mdadm.h
index f8f3685963ecc980967457213ee795b15a434709..f580e3e807388ead74966e25ffc20f0ff8577252 100644 (file)
--- a/mdadm.h
+++ b/mdadm.h
@@ -394,7 +394,7 @@ extern int restore_stripes(int *dest, unsigned long long *offsets,
 
 extern char *map_num(mapping_t *map, int num);
 extern int map_name(mapping_t *map, char *name);
-extern mapping_t r5layout[], pers[], modes[], faultylayout[];
+extern mapping_t r5layout[], r6layout[], pers[], modes[], faultylayout[];
 
 extern char *map_dev(int major, int minor, int create);
 
@@ -937,8 +937,44 @@ static inline int xasprintf(char **strp, const char *fmt, ...) {
 #define makedev(M,m) (((M)<<8) | (m))
 #endif
 
-/* for raid5 */
+/* for raid4/5/6 */
 #define ALGORITHM_LEFT_ASYMMETRIC      0
 #define ALGORITHM_RIGHT_ASYMMETRIC     1
 #define ALGORITHM_LEFT_SYMMETRIC       2
 #define ALGORITHM_RIGHT_SYMMETRIC      3
+
+/* Define non-rotating (raid4) algorithms.  These allow
+ * conversion of raid4 to raid5.
+ */
+#define ALGORITHM_PARITY_0             4 /* P or P,Q are initial devices */
+#define ALGORITHM_PARITY_N             5 /* P or P,Q are final devices. */
+
+/* DDF RAID6 layouts differ from md/raid6 layouts in two ways.
+ * Firstly, the exact positioning of the parity block is slightly
+ * different between the 'LEFT_*' modes of md and the "_N_*" modes
+ * of DDF.
+ * Secondly, or order of datablocks over which the Q syndrome is computed
+ * is different.
+ * Consequently we have different layouts for DDF/raid6 than md/raid6.
+ * These layouts are from the DDFv1.2 spec.
+ * Interestingly DDFv1.2-Errata-A does not specify N_CONTINUE but
+ * leaves RLQ=3 as 'Vendor Specific'
+ */
+
+#define ALGORITHM_ROTATING_ZERO_RESTART        8 /* DDF PRL=6 RLQ=1 */
+#define ALGORITHM_ROTATING_N_RESTART   9 /* DDF PRL=6 RLQ=2 */
+#define ALGORITHM_ROTATING_N_CONTINUE  10 /*DDF PRL=6 RLQ=3 */
+
+
+/* For every RAID5 algorithm we define a RAID6 algorithm
+ * with exactly the same layout for data and parity, and
+ * with the Q block always on the last device (N-1).
+ * This allows trivial conversion from RAID5 to RAID6
+ */
+#define ALGORITHM_LEFT_ASYMMETRIC_6    16
+#define ALGORITHM_RIGHT_ASYMMETRIC_6   17
+#define ALGORITHM_LEFT_SYMMETRIC_6     18
+#define ALGORITHM_RIGHT_SYMMETRIC_6    19
+#define ALGORITHM_PARITY_0_6           20
+#define ALGORITHM_PARITY_N_6           ALGORITHM_PARITY_N
+