md: superblock changes for PPL

Include information about PPL location and size into mdp_superblock_1
and copy it to/from rdev. Because PPL is mutually exclusive with bitmap,
put it in place of 'bitmap_offset'. Add a new flag MD_FEATURE_PPL for
'feature_map', analogically to MD_FEATURE_BITMAP_OFFSET. Add MD_HAS_PPL
to mddev->flags to indicate that PPL is enabled on an array.

Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Signed-off-by: Shaohua Li <shli@fb.com>

1 files changed, 14 insertions, 4 deletions

diff --git a/include/uapi/linux/raid/md_p.h b/include/uapi/linux/raid/md_p.h
index 9930f3e9040f..fe2112810c43 100644
--- a/include/uapi/linux/raid/md_p.h
+++ b/include/uapi/linux/raid/md_p.h
@@ -242,10 +242,18 @@ struct mdp_superblock_1 {
 
         __le32  chunksize;      /* in 512byte sectors */
         __le32  raid_disks;
-        __le32  bitmap_offset;  /* sectors after start of superblock that bitmap starts
-                                 * NOTE: signed, so bitmap can be before superblock
-                                 * only meaningful of feature_map[0] is set.
-                                 */
+        union {
+                __le32  bitmap_offset;  /* sectors after start of superblock that bitmap starts
+                                         * NOTE: signed, so bitmap can be before superblock
+                                         * only meaningful of feature_map[0] is set.
+                                         */
+
+                /* only meaningful when feature_map[MD_FEATURE_PPL] is set */
+                struct {
+                        __le16 offset; /* sectors from start of superblock that ppl starts (signed) */
+                        __le16 size; /* ppl size in sectors */
+                } ppl;
+        };
 
         /* These are only valid with feature bit '4' */
         __le32  new_level;      /* new level we are reshaping to                */
@@ -318,6 +326,7 @@ struct mdp_superblock_1 {
                                              */
 #define MD_FEATURE_CLUSTERED            256 /* clustered MD */
 #define MD_FEATURE_JOURNAL              512 /* support write cache */
+#define MD_FEATURE_PPL                  1024 /* support PPL */
 #define MD_FEATURE_ALL                  (MD_FEATURE_BITMAP_OFFSET       \
                                         |MD_FEATURE_RECOVERY_OFFSET     \
                                         |MD_FEATURE_RESHAPE_ACTIVE      \
@@ -328,6 +337,7 @@ struct mdp_superblock_1 {
                                         |MD_FEATURE_RECOVERY_BITMAP     \
                                         |MD_FEATURE_CLUSTERED           \
                                         |MD_FEATURE_JOURNAL             \
+                                        |MD_FEATURE_PPL                 \
                                         )
 
 struct r5l_payload_header {