1 files changed, 29 insertions, 3 deletions

diff --git a/include/linux/raid/md_p.h b/include/linux/raid/md_p.h
index c100fa5d4bfa..774e1acfb8c4 100644
--- a/include/linux/raid/md_p.h
+++ b/include/linux/raid/md_p.h
@@ -102,6 +102,18 @@ typedef struct mdp_device_descriptor_s {
 #define MD_SB_ERRORS            1
 
 #define MD_SB_BITMAP_PRESENT    8 /* bitmap may be present nearby */
+
+/*
+ * Notes:
+ * - if an array is being reshaped (restriped) in order to change the
+ *   the number of active devices in the array, 'raid_disks' will be
+ *   the larger of the old and new numbers.  'delta_disks' will
+ *   be the "new - old".  So if +ve, raid_disks is the new value, and
+ *   "raid_disks-delta_disks" is the old.  If -ve, raid_disks is the
+ *   old value and "raid_disks+delta_disks" is the new (smaller) value.
+ */
+
+
 typedef struct mdp_superblock_s {
         /*
          * Constant generic information
@@ -146,7 +158,13 @@ typedef struct mdp_superblock_s {
         __u32 cp_events_hi;     /* 10 high-order of checkpoint update count   */
 #endif
         __u32 recovery_cp;      /* 11 recovery checkpoint sector count        */
-        __u32 gstate_sreserved[MD_SB_GENERIC_STATE_WORDS - 12];
+        /* There are only valid for minor_version > 90 */
+        __u64 reshape_position; /* 12,13 next address in array-space for reshape */
+        __u32 new_level;        /* 14 new level we are reshaping to           */
+        __u32 delta_disks;      /* 15 change in number of raid_disks          */
+        __u32 new_layout;       /* 16 new layout                              */
+        __u32 new_chunk;        /* 17 new chunk size (bytes)                  */
+        __u32 gstate_sreserved[MD_SB_GENERIC_STATE_WORDS - 18];
 
         /*
          * Personality information
@@ -207,7 +225,14 @@ struct mdp_superblock_1 {
                                  * NOTE: signed, so bitmap can be before superblock
                                  * only meaningful of feature_map[0] is set.
                                  */
-        __u8    pad1[128-100];  /* set to 0 when written */
+
+        /* These are only valid with feature bit '4' */
+        __u64   reshape_position;       /* next address in array-space for reshape */
+        __u32   new_level;      /* new level we are reshaping to                */
+        __u32   delta_disks;    /* change in number of raid_disks               */
+        __u32   new_layout;     /* new layout                                   */
+        __u32   new_chunk;      /* new chunk size (bytes)                       */
+        __u8    pad1[128-124];  /* set to 0 when written */
 
         /* constant this-device information - 64 bytes */
         __u64   data_offset;    /* sector start of data, often 0 */
@@ -240,8 +265,9 @@ struct mdp_superblock_1 {
 
 /* feature_map bits */
 #define MD_FEATURE_BITMAP_OFFSET        1
+#define MD_FEATURE_RESHAPE_ACTIVE       4
 
-#define MD_FEATURE_ALL                  1
+#define MD_FEATURE_ALL                  5
 
 #endif