From: Yan, Zheng <zheng.z.yan@intel.com>
Date: Fri, 4 Jan 2013 02:36:50 +0000 (+0800)
Subject: mds: introduce XSYN to SYNC lock state transition
X-Git-Tag: v0.57~88^2~25
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=6daec53059b60346eda928fbc7b4d8696cca6041;p=ceph.git

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 9b3bfe3992e6..e0c149fb7628 100644
--- 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 bfd0e1f41cf1..8eb813469e4c 100644
--- 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 73b99fb85217..69b6bd61f7e6 100644
--- 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 9e09cf2191c1..2adcbf21feaa 100644
--- 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,
 };