snapshot: Snapshot restore

GL-31: Ability to restore snapshot
Implemented snapshot restore for thin logical volume. As of now snapshot
restore for CG is not tested. Testing for snapshot restore of a volume
is done by changing the snapshot create process to create a thick snapshot.
This is done because --merge option to restore thin volume is not working in
the latest kernel.

Change-Id: Ia3ded7e6c4da5957a74e269a25ba3200e6fb2d8b
Signed-off-by: Rajesh Joseph <rjoseph@redhat.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-mgmt.c b/xlators/mgmt/glusterd/src/glusterd-mgmt.c
index e6f341ada..8e2c0c689 100644
--- a/xlators/mgmt/glusterd/src/glusterd-mgmt.c
+++ b/xlators/mgmt/glusterd/src/glusterd-mgmt.c
@@ -1389,6 +1389,7 @@ glusterd_mgmt_v3_initiate_snap_phases (rpcsvc_request_t *req, glusterd_op_t op,
         gf_boolean_t                is_acquired      = _gf_false;
         uuid_t                      *originator_uuid = NULL;
         gf_boolean_t                success          = _gf_false;
+        char                        *tmp_errstr      = NULL;
 
         this = THIS;
         GF_ASSERT (this);
@@ -1470,6 +1471,13 @@ glusterd_mgmt_v3_initiate_snap_phases (rpcsvc_request_t *req, glusterd_op_t op,
                                       &op_errstr, npeers);
         if (ret) {
                 gf_log ("", GF_LOG_ERROR, "Commit Op Failed");
+                /* If the main op fails, we should save the error string.
+                   Because, op_errstr will be used for unbarrier and
+                   unlock ops also. We might lose the actual error that
+                   caused the failure.
+                */
+                tmp_errstr = op_errstr;
+                op_errstr = NULL;
                 goto unbarrier;
         }
 
@@ -1483,6 +1491,7 @@ unbarrier:
                                         &op_errstr, npeers);
         if (ret || (success == _gf_false)) {
                 gf_log ("", GF_LOG_ERROR, "Brick Ops Failed");
+                ret = -1;
                 goto out;
         }
         /* POST-COMMIT VALIDATE PHASE */
@@ -1500,6 +1509,22 @@ out:
         (void) glusterd_mgmt_v3_release_peer_locks (conf, op, dict, &op_errstr,
                                                    npeers, is_acquired);
 
+        /* If the commit op (snapshot taking) failed, then the error is stored
+           in tmp_errstr and unbarrier is called. Suppose, if unbarrier also
+           fails, then the error happened in unbarrier is logged and freed.
+           The error happened in commit op, which is stored in tmp_errstr
+           is sent to cli.
+        */
+        if (tmp_errstr) {
+                if (ret && op_errstr) {
+                        gf_log (this->name, GF_LOG_ERROR, "unbarrier brick op"
+                                "failed with the error %s", op_errstr);
+                        GF_FREE (op_errstr);
+                        op_errstr = NULL;
+                }
+                op_errstr = tmp_errstr;
+        }
+
         /* SEND CLI RESPONSE */
         glusterd_op_send_cli_response (op, ret, 0, req, dict, op_errstr);