protocol/client,server: fcntl lock self healing.

Currently(with out this patch), on a disconnect the server cleans up
the transport which inturn closes the fd's and releases the locks acquired on
those fd's by that client. On a reconnect, client just reopens the fd's but
doesn't reacquire the locks. The application that had previously acquired
the locks still is under the assumption that it is the owner of those locks
which might have been granted to other clients(if they request) by the server
leading to data corruption.

This patch allows the client to reacquire the fcntl locks (held on the fd's)
during client-server handshake.

* The server identifies the client via process-uuid-xl (which is a combination
  of uuid and client-protocol name, it is assumed to be unique) and lk-version
  number.

* The client maintains a list of process-uuid-xl, lk-version pair for each
  accepted connection. On a connect, the server traverses the list for a
  matching pair, if a matching pair is not found the the server returns
  lk-version with value 0, else it returns the lk-version it has in store.

* On a disconnect, the server and client enter grace period, and on the
  completion of the grace period, the client bumps up its lk-version number
  (which means, it will reacquire the locks the next time) and the server will
  distroy the connection. If reconnection happens within the grace period, the
  server will find the matching (process-uuid-xl, lk-version) pair in its list
  which guarantees that the fd's and there corresponding locks are still valid
  for this client.

Configurable options:
  To set grace-timeout, the following options are
    option server.grace-timeout value
    option client.grace-timeout value

  To enable or disable the lk-heal,
    option lk-heal [on|off]

gluster volume set command can be used to configurable options
Change-Id: Id677ef1087b300d649f278b8b2aa0d94eae85ed2
BUG: 795386
Signed-off-by: Mohammed Junaid <junaid@redhat.com>
Reviewed-on: http://review.gluster.com/2766
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vijay@gluster.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/xlators/protocol/client/src/client.h b/xlators/protocol/client/src/client.h
index 2dda451c9..00addf34c 100644
--- a/xlators/protocol/client/src/client.h
+++ b/xlators/protocol/client/src/client.h
@@ -29,6 +29,7 @@
 #include "client-mem-types.h"
 #include "protocol-common.h"
 #include "glusterfs3.h"
+#include "fd-lk.h"
 
 /* FIXME: Needs to be defined in a common file */
 #define CLIENT_CMD_CONNECT    "trusted.glusterfs.client-connect"
@@ -91,6 +92,12 @@ typedef struct clnt_conf {
         char                   need_different_port; /* flag used to change the
                                                        portmap path in case of
                                                        'tcp,rdma' on server */
+        gf_boolean_t           lk_heal;
+        uint16_t               lk_version; /* this variable is used to distinguish
+                                              client-server transaction while
+                                              performing lock healing */
+        struct timeval         grace_tv;
+        gf_timer_t            *grace_timer;
 } clnt_conf_t;
 
 typedef struct _client_fd_ctx {
@@ -105,7 +112,7 @@ typedef struct _client_fd_ctx {
         char              released;
         int32_t           flags;
         int32_t           wbflags;
-
+        fd_lk_ctx_t      *lk_ctx;
         pthread_mutex_t   mutex;
         struct list_head  lock_list;     /* List of all granted locks on this fd */
 } clnt_fd_ctx_t;
@@ -211,4 +218,11 @@ int32_t client_dump_locks (char *name, inode_t *inode,
                            dict_t *dict);
 int client_fdctx_destroy (xlator_t *this, clnt_fd_ctx_t *fdctx);
 
+uint32_t client_get_lk_ver (clnt_conf_t *conf);
+
+int32_t client_type_to_gf_type (short l_type);
+
+int client_mark_fd_bad (xlator_t *this);
+
+int client_set_lk_version (xlator_t *this);
 #endif /* !_CLIENT_H */