md: load/store badblock list from v1.x metadata

Space must have been allocated when array was created.
A feature flag is set when the badblock list is non-empty, to
ensure old kernels don't load and trust the whole device.

We only update the on-disk badblocklist when it has changed.
If the badblocklist (or other metadata) is stored on a bad block, we
don't cope very well.

If metadata has no room for bad block, flag bad-blocks as disabled,
and do the same for 0.90 metadata.

Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 10 insertions, 4 deletions

diff --git a/include/linux/raid/md_p.h b/include/linux/raid/md_p.h
index 75cbf4f62fe8..9e65d9e20662 100644
--- a/include/linux/raid/md_p.h
+++ b/include/linux/raid/md_p.h
@@ -245,10 +245,16 @@ struct mdp_superblock_1 {
         __u8    device_uuid[16]; /* user-space setable, ignored by kernel */
         __u8    devflags;       /* per-device flags.  Only one defined...*/
 #define WriteMostly1    1       /* mask for writemostly flag in above */
-        __u8    pad2[64-57];    /* set to 0 when writing */
+        /* Bad block log.  If there are any bad blocks the feature flag is set.
+         * If offset and size are non-zero, that space is reserved and available
+         */
+        __u8    bblog_shift;    /* shift from sectors to block size */
+        __le16  bblog_size;     /* number of sectors reserved for list */
+        __le32  bblog_offset;   /* sector offset from superblock to bblog,
+                                 * signed - not unsigned */
 
         /* array state information - 64 bytes */
-        __le64  utime;          /* 40 bits second, 24 btes microseconds */
+        __le64  utime;          /* 40 bits second, 24 bits microseconds */
         __le64  events;         /* incremented when superblock updated */
         __le64  resync_offset;  /* data before this offset (from data_offset) known to be in sync */
         __le32  sb_csum;        /* checksum up to devs[max_dev] */
@@ -270,8 +276,8 @@ struct mdp_superblock_1 {
                                            * must be honoured
                                            */
 #define MD_FEATURE_RESHAPE_ACTIVE       4
+#define MD_FEATURE_BAD_BLOCKS           8 /* badblock list is not empty */
 
-#define MD_FEATURE_ALL                  (1|2|4)
+#define MD_FEATURE_ALL                  (1|2|4|8)
 
 #endif 
-