distribute: bring in feature to do rebalance from inside

do the 'rebalance' on a file with 'setxattr()' with
'distribute.migrate-data' key. the valid 'value' is "force" or
anything else.

current implementation of 'rebalance' is same as 'glusterd-rebalance',
and hence comes with limitation of not rebalancing hardlinks, non-regular
files, and files with open-fds.

Signed-off-by: Amar Tumballi <amar@gluster.com>
Signed-off-by: Anand Avati <avati@gluster.com>

BUG: 3070 (After 'rebalance', the gfid of the file gets changed)
URL: http://bugs.gluster.com/cgi-bin/bugzilla3/show_bug.cgi?id=3070

1 files changed, 8 insertions, 0 deletions

diff --git a/xlators/cluster/dht/src/dht-common.h b/xlators/cluster/dht/src/dht-common.h
index 43056c78c..2fe85d00e 100644
--- a/xlators/cluster/dht/src/dht-common.h
+++ b/xlators/cluster/dht/src/dht-common.h
@@ -24,6 +24,7 @@
 
 #include "dht-mem-types.h"
 #include "libxlator.h"
+#include "syncop.h"
 
 #ifndef _DHT_H
 #define _DHT_H
@@ -140,6 +141,10 @@ struct dht_local {
         /* flag used to make sure we need to return estale in
            {lookup,revalidate}_cbk */
         char    return_estale;
+
+        /* rebalance related */
+#define to_subvol    hashed_subvol
+#define from_subvol  cached_subvol
 };
 typedef struct dht_local dht_local_t;
 
@@ -178,6 +183,8 @@ struct dht_conf {
         /* This is the count used as the distribute layout for a directory */
         /* Will be a global flag to control the layout spread count */
         uint32_t       dir_spread_cnt;
+
+	struct syncenv *env; /* The env pointer to the rebalance synctask */
 };
 typedef struct dht_conf dht_conf_t;
 
@@ -330,4 +337,5 @@ int dht_fix_directory_layout (call_frame_t *frame,
                               dht_selfheal_dir_cbk_t dir_cbk,
                               dht_layout_t *layout);
 
+int dht_start_rebalance_task (xlator_t *this, call_frame_t *frame);
 #endif /* _DHT_H */