From: Bruno Faccini <bruno.faccini@intel.com>
Date: Thu, 1 Aug 2013 07:09:05 +0000 (+0200)
Subject: LU-1126 ldlm: Fix a race during FLock handling
X-Git-Tag: 2.4.93~63
X-Git-Url: https://git.whamcloud.com/?p=fs%2Flustre-release.git;a=commitdiff_plain;h=22287c7951209525f1f33abefff4f2f069f17c40

LU-1126 ldlm: Fix a race during FLock handling

Protect against race where lock could have been just destroyed
due to overlap, in ldlm_process_flock_lock().
Easy reproducer is BULL's NFS Locktests in pthread mode.
(http://nfsv4.bullopensource.org/tools/tests/locktest.php)

Signed-off-by: Bruno Faccini <bruno.faccini@intel.com>
Change-Id: I4f4183098e8e7aaacb2c6b80787d3c7a7ad5688b
Reviewed-on: http://review.whamcloud.com/7134
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
---

diff --git a/lustre/ldlm/ldlm_flock.c b/lustre/ldlm/ldlm_flock.c
index 6273b72..d9cc416 100644
--- a/lustre/ldlm/ldlm_flock.c
+++ b/lustre/ldlm/ldlm_flock.c
@@ -697,11 +697,6 @@ ldlm_flock_completion_ast(struct ldlm_lock *lock, __u64 flags, void *data)
 granted:
         OBD_FAIL_TIMEOUT(OBD_FAIL_LDLM_CP_CB_WAIT, 10);
 
-	if (lock->l_flags & LDLM_FL_DESTROYED) {
-		LDLM_DEBUG(lock, "client-side enqueue waking up: destroyed");
-		RETURN(0);
-	}
-
         if (lock->l_flags & LDLM_FL_FAILED) {
                 LDLM_DEBUG(lock, "client-side enqueue waking up: failed");
                 RETURN(-EIO);
@@ -711,6 +706,16 @@ granted:
 
 	lock_res_and_lock(lock);
 
+
+	/* Protect against race where lock could have been just destroyed
+	 * due to overlap in ldlm_process_flock_lock().
+	 */
+	if (lock->l_flags & LDLM_FL_DESTROYED) {
+		unlock_res_and_lock(lock);
+		LDLM_DEBUG(lock, "client-side enqueue waking up: destroyed");
+		RETURN(0);
+	}
+
 	/* take lock off the deadlock detection hash list. */
         ldlm_flock_blocking_unlink(lock);