drbd: Allow online change of al-stripes and al-stripe-size

Allow to change the AL layout with an resize operation. For that
the reisze command gets two new fields: al_stripes and al_stripe_size.

In order to make the operation crash save:
1) Lock out all IO and MD-IO
2) Write the super block with MDF_PRIMARY_IND clear
3) write the bitmap to the new location (all zeros, since
   we allow only while connected)
4) Initialize the new AL-area
5) Write the super block with the restored MDF_PRIMARY_IND.
6) Unfreeze all IO

Since the AL-layout has no influence on the protocol, this operation
needs to be beforemed on both sides of a resource (if intended).

Signed-off-by: Andreas Gruenbacher <agruen@linbit.com>
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

3 files changed, 16 insertions, 1 deletions

diff --git a/include/linux/drbd.h b/include/linux/drbd.h
index 1b4d4ee1168f..de7d74ab3de6 100644
--- a/include/linux/drbd.h
+++ b/include/linux/drbd.h
@@ -177,7 +177,11 @@ enum drbd_ret_code {
         ERR_NEED_APV_100        = 163,
         ERR_NEED_ALLOW_TWO_PRI  = 164,
         ERR_MD_UNCLEAN          = 165,
-
+        ERR_MD_LAYOUT_CONNECTED = 166,
+        ERR_MD_LAYOUT_TOO_BIG   = 167,
+        ERR_MD_LAYOUT_TOO_SMALL = 168,
+        ERR_MD_LAYOUT_NO_FIT    = 169,
+        ERR_IMPLICIT_SHRINK     = 170,
         /* insert new ones above this line */
         AFTER_LAST_ERR_CODE
 };
diff --git a/include/linux/drbd_genl.h b/include/linux/drbd_genl.h
index d0d8fac8a6e4..e8c44572b8cb 100644
--- a/include/linux/drbd_genl.h
+++ b/include/linux/drbd_genl.h
@@ -181,6 +181,8 @@ GENL_struct(DRBD_NLA_RESIZE_PARMS, 7, resize_parms,
         __u64_field(1, DRBD_GENLA_F_MANDATORY,  resize_size)
         __flg_field(2, DRBD_GENLA_F_MANDATORY,  resize_force)
         __flg_field(3, DRBD_GENLA_F_MANDATORY,  no_resync)
+        __u32_field_def(4, 0 /* OPTIONAL */, al_stripes, DRBD_AL_STRIPES_DEF)
+        __u32_field_def(5, 0 /* OPTIONAL */, al_stripe_size, DRBD_AL_STRIPE_SIZE_DEF)
 )
 
 GENL_struct(DRBD_NLA_STATE_INFO, 8, state_info,
diff --git a/include/linux/drbd_limits.h b/include/linux/drbd_limits.h
index 1fedf2b17cc8..17e50bb00521 100644
--- a/include/linux/drbd_limits.h
+++ b/include/linux/drbd_limits.h
@@ -215,4 +215,13 @@
 #define DRBD_ALWAYS_ASBP_DEF    0
 #define DRBD_USE_RLE_DEF        1
 
+#define DRBD_AL_STRIPES_MIN     1
+#define DRBD_AL_STRIPES_MAX     1024
+#define DRBD_AL_STRIPES_DEF     1
+#define DRBD_AL_STRIPES_SCALE   '1'
+
+#define DRBD_AL_STRIPE_SIZE_MIN   4
+#define DRBD_AL_STRIPE_SIZE_MAX   16777216
+#define DRBD_AL_STRIPE_SIZE_DEF   32
+#define DRBD_AL_STRIPE_SIZE_SCALE 'k' /* kilobytes */
 #endif