mgmt/glusterd: delete only the oldest snapshot as part of autodelete

Now this is how autodelete behaves:
1) Upon creation when the max-soft-limit exceeds, the oldest snapshot is
   deleted. i.e if hard limit is 100 and by default soft limit is 90.
   Whenever snap count reaches 90, every new create results in the deletion
   of the oldest snapshot.
2) If the snap limit (hard) is reconfigured and brought down
   the current snap count, then no snapshot is deleted and the next snapshot
   create fails as the current snapcount is more than the hard limit.
3) When soft limit is brought down: say max limit is 100 and by default soft
   limit is 90 and current snap count is 90. Now, soft limit is changed to
   70 (70%). In this case the snapshot count remains 90 itself (i.e extra
   20 snapshots more than the soft limit are not deleted) and for every new
   create the oldest snapshot is deleted.

Change-Id: I1f3b4b9eb093649f8628ebf09a15bd2570ddf340
BUG: 1103665
Signed-off-by: Raghavendra Bhat <raghavendra@redhat.com>
Reviewed-on: http://review.gluster.org/7951
Reviewed-by: Rajesh Joseph <rjoseph@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Kaushal M <kaushal@redhat.com>

1 files changed, 21 insertions, 27 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-snapshot.c b/xlators/mgmt/glusterd/src/glusterd-snapshot.c
index 7d3c795b436..7a6d143e5de 100644
--- a/xlators/mgmt/glusterd/src/glusterd-snapshot.c
+++ b/xlators/mgmt/glusterd/src/glusterd-snapshot.c
@@ -5681,7 +5681,6 @@ glusterd_handle_snap_limit (dict_t *dict, dict_t *rsp_dict)
         glusterd_snap_t    *snap                = NULL;
         glusterd_volinfo_t *tmp_volinfo         = NULL;
         glusterd_volinfo_t *other_volinfo       = NULL;
-        int64_t             var                 = 0;
 
         this = THIS;
         GF_ASSERT (this);
@@ -5727,35 +5726,30 @@ glusterd_handle_snap_limit (dict_t *dict, dict_t *rsp_dict)
                 if (count <= 0)
                         goto out;
 
-                list_for_each_entry_safe (tmp_volinfo, other_volinfo,
-                                         &volinfo->snap_volumes, snapvol_list) {
-                        if (var == count)
-                                break;
-
-                        snap = tmp_volinfo->snapshot;
-                        GF_ASSERT (snap);
-
-                        LOCK (&snap->lock);
-                        {
-                                snap->snap_status = GD_SNAP_STATUS_DECOMMISSION;
-                                ret = glusterd_store_snap (snap);
-                                if (ret) {
-                                        gf_log (this->name, GF_LOG_ERROR, "could "
-                                                "not store snap object %s",
-                                                snap->snapname);
-                                        goto unlock;
-                                }
+                tmp_volinfo = list_entry (volinfo->snap_volumes.next,
+                                          glusterd_volinfo_t, snapvol_list);
+                snap = tmp_volinfo->snapshot;
+                GF_ASSERT (snap);
 
-                                ret = glusterd_snap_remove (rsp_dict, snap,
-                                                            _gf_true, _gf_true);
-                                if (ret)
-                                        gf_log (this->name, GF_LOG_WARNING,
-                                                "failed to remove snap %s",
-                                                snap->snapname);
+                LOCK (&snap->lock);
+                {
+                        snap->snap_status = GD_SNAP_STATUS_DECOMMISSION;
+                        ret = glusterd_store_snap (snap);
+                        if (ret) {
+                                gf_log (this->name, GF_LOG_ERROR, "could "
+                                        "not store snap object %s",
+                                        snap->snapname);
+                                goto unlock;
                         }
-                unlock: UNLOCK (&snap->lock);
-                        var++;
+
+                        ret = glusterd_snap_remove (rsp_dict, snap,
+                                                    _gf_true, _gf_true);
+                        if (ret)
+                                gf_log (this->name, GF_LOG_WARNING,
+                                        "failed to remove snap %s",
+                                        snap->snapname);
                 }
+        unlock: UNLOCK (&snap->lock);
         }
 
 out: