mds: introduce XSYN to SYNC lock state transition

If lock is in XSYN state, Locker::simple_sync() firstly try changing
lock state to EXCL. If it fail to change lock state to EXCL, it just
returns. So Locker::simple_sync() does not guarantee the lock state
eventually changes to SYNC. This issue can cause replica that requests
read lock hang. The fix is introduce an intermediate state for XSYN
to SYNC transition.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>

diff --git a/src/mds/Locker.cc b/src/mds/Locker.cc
index 9b3bfe3992e6a75d4b1f018481455a2ccc541880..e0c149fb7628aca0280a7cd3216a54660cfb6ba3 100644 (file)
--- a/src/mds/Locker.cc
+++ b/src/mds/Locker.cc
@@ -744,6 +744,7 @@ void Locker::eval_gather(SimpleLock *lock, bool first, bool *pneed_issue, list<C
       case LOCK_EXCL_SYNC:
       case LOCK_LOCK_SYNC:
       case LOCK_MIX_SYNC:
+      case LOCK_XSYN_SYNC:
       case LOCK_XLOCK:
       case LOCK_XLOCKDONE:
        if (lock->get_parent()->is_replicated()) {
@@ -3333,11 +3334,7 @@ bool Locker::simple_sync(SimpleLock *lock, bool *need_issue)
     case LOCK_MIX: lock->set_state(LOCK_MIX_SYNC); break;
     case LOCK_SCAN:
     case LOCK_LOCK: lock->set_state(LOCK_LOCK_SYNC); break;
-    case LOCK_XSYN:
-      file_excl((ScatterLock*)lock, need_issue);
-      if (lock->get_state() != LOCK_EXCL)
-       return false;
-      // fall-thru
+    case LOCK_XSYN: lock->set_state(LOCK_XSYN_SYNC); break;
     case LOCK_EXCL: lock->set_state(LOCK_EXCL_SYNC); break;
     default: assert(0);
     }

diff --git a/src/mds/SimpleLock.h b/src/mds/SimpleLock.h
index bfd0e1f41cf1874352c7053604d6e6fb3f8220c9..8eb813469e4c064d20b6111c530fc705e954ce23 100644 (file)
--- a/src/mds/SimpleLock.h
+++ b/src/mds/SimpleLock.h
@@ -110,6 +110,7 @@ public:
     case LOCK_XSYN: return "xsyn";
     case LOCK_XSYN_EXCL: return "xsyn->excl";
     case LOCK_EXCL_XSYN: return "excl->xsyn";
+    case LOCK_XSYN_SYNC: return "xsyn->sync";
 
     case LOCK_SYNC_MIX: return "sync->mix";
     case LOCK_SYNC_MIX2: return "sync->mix(2)";

diff --git a/src/mds/locks.c b/src/mds/locks.c
index 73b99fb85217f094602bc7215647b18afdc42495..69b6bd61f7e65e23cc5c52ab8465f2614b219c32 100644 (file)
--- a/src/mds/locks.c
+++ b/src/mds/locks.c
@@ -94,6 +94,7 @@ const struct sm_state_t filelock[LOCK_MAX] = {
     [LOCK_MIX_SYNC]  = { LOCK_SYNC, false, LOCK_MIX_SYNC2,0,0,   0,   0,   0,   0,   0,   CEPH_CAP_GRD|CEPH_CAP_GLAZYIO,0,0,CEPH_CAP_GRD },
     [LOCK_MIX_SYNC2] = { LOCK_SYNC, false, 0,         0,    0,   0,   0,   0,   0,   0,   CEPH_CAP_GRD|CEPH_CAP_GLAZYIO,0,0,CEPH_CAP_GRD },
     [LOCK_SNAP_SYNC] = { LOCK_SYNC, false, LOCK_LOCK, 0,    0,   0,   0,   AUTH,0,   0,   0,0,0,0 },
+    [LOCK_XSYN_SYNC] = { LOCK_SYNC, true,  LOCK_LOCK, AUTH, 0,   AUTH,0,   0,   0,   0,   0,CEPH_CAP_GCACHE,0,0 },
   
     [LOCK_LOCK]      = { 0,         false, LOCK_LOCK, AUTH, 0,   REQ, AUTH,0,   0,   0,   CEPH_CAP_GCACHE|CEPH_CAP_GBUFFER,0,0,0 },
     [LOCK_SYNC_LOCK] = { LOCK_LOCK, false, LOCK_LOCK, AUTH, 0,   REQ, 0,   0,   0,   0,   CEPH_CAP_GCACHE,0,0,CEPH_CAP_GCACHE },

diff --git a/src/mds/locks.h b/src/mds/locks.h
index 9e09cf2191c184c502ffe83b4624862c19a22a4e..2adcbf21feaa84e18a265b962d0f202bc0abbb81 100644 (file)
--- a/src/mds/locks.h
+++ b/src/mds/locks.h
@@ -93,6 +93,7 @@ enum {
   LOCK_XSYN,
   LOCK_XSYN_EXCL,
   LOCK_EXCL_XSYN,
+  LOCK_XSYN_SYNC,
 
   LOCK_MAX,
 };