md: Increment version for clustered bitmaps

Add BITMAP_MAJOR_CLUSTERED as 5, in order to prevent older kernels
to assemble a clustered device.

In order to maximize compatibility, the major version is set to
BITMAP_MAJOR_CLUSTERED *only* if the bitmap is clustered.

Added MD_FEATURE_CLUSTERED in order to return error for older
kernels which would assemble MD even if the bitmap is corrupted.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

4 files changed, 11 insertions, 6 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 48b5890c28e3..e9d3ee703e6d 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -613,12 +613,10 @@ re_read:
         daemon_sleep = le32_to_cpu(sb->daemon_sleep) * HZ;
         write_behind = le32_to_cpu(sb->write_behind);
         sectors_reserved = le32_to_cpu(sb->sectors_reserved);
-        /* XXX: This is a hack to ensure that we don't use clustering
-         *  in case:
-         *      - dm-raid is in use and
-         *      - the nodes written in bitmap_sb is erroneous.
+        /* Setup nodes/clustername only if bitmap version is
+         * cluster-compatible
          */
-        if (!bitmap->mddev->sync_super) {
+        if (sb->version == cpu_to_le32(BITMAP_MAJOR_CLUSTERED)) {
                 nodes = le32_to_cpu(sb->nodes);
                 strlcpy(bitmap->mddev->bitmap_info.cluster_name,
                                 sb->cluster_name, 64);
@@ -628,7 +626,7 @@ re_read:
         if (sb->magic != cpu_to_le32(BITMAP_MAGIC))
                 reason = "bad magic";
         else if (le32_to_cpu(sb->version) < BITMAP_MAJOR_LO ||
-                 le32_to_cpu(sb->version) > BITMAP_MAJOR_HI)
+                 le32_to_cpu(sb->version) > BITMAP_MAJOR_CLUSTERED)
                 reason = "unrecognized superblock version";
         else if (chunksize < 512)
                 reason = "bitmap chunksize too small";
diff --git a/drivers/md/bitmap.h b/drivers/md/bitmap.h
index f1f4dd01090d..8731fa06855f 100644
--- a/drivers/md/bitmap.h
+++ b/drivers/md/bitmap.h
@@ -9,8 +9,10 @@
 #define BITMAP_MAJOR_LO 3
 /* version 4 insists the bitmap is in little-endian order
  * with version 3, it is host-endian which is non-portable
+ * Version 5 is currently set only for clustered devices
  */
 #define BITMAP_MAJOR_HI 4
+#define BITMAP_MAJOR_CLUSTERED 5
 #define BITMAP_MAJOR_HOSTENDIAN 3
 
 /*
diff --git a/drivers/md/md.c b/drivers/md/md.c
index c702de18207a..1e1bdd86f40c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1735,6 +1735,9 @@ static void super_1_sync(struct mddev *mddev, struct md_rdev *rdev)
                 }
         }
 
+        if (mddev_is_clustered(mddev))
+                sb->feature_map |= cpu_to_le32(MD_FEATURE_CLUSTERED);
+
         if (rdev->badblocks.count == 0)
                 /* Nothing to do for bad blocks*/ ;
         else if (sb->bblog_offset == 0)
diff --git a/include/uapi/linux/raid/md_p.h b/include/uapi/linux/raid/md_p.h
index 2ae6131e69a5..867ee874fa80 100644
--- a/include/uapi/linux/raid/md_p.h
+++ b/include/uapi/linux/raid/md_p.h
@@ -302,6 +302,7 @@ struct mdp_superblock_1 {
 #define MD_FEATURE_RECOVERY_BITMAP      128 /* recovery that is happening
                                              * is guided by bitmap.
                                              */
+#define MD_FEATURE_CLUSTERED            256 /* clustered MD */
 #define MD_FEATURE_ALL                  (MD_FEATURE_BITMAP_OFFSET       \
                                         |MD_FEATURE_RECOVERY_OFFSET     \
                                         |MD_FEATURE_RESHAPE_ACTIVE      \
@@ -310,6 +311,7 @@ struct mdp_superblock_1 {
                                         |MD_FEATURE_RESHAPE_BACKWARDS   \
                                         |MD_FEATURE_NEW_OFFSET          \
                                         |MD_FEATURE_RECOVERY_BITMAP     \
+                                        |MD_FEATURE_CLUSTERED           \
                                         )
 
 #endif