diff --git a/drivers/staging/lustre/lustre/include/lustre/lustre_idl.h b/drivers/staging/lustre/lustre/include/lustre/lustre_idl.h
index ac7fb379bf74..05c77c0b2d75 100644
--- a/drivers/staging/lustre/lustre/include/lustre/lustre_idl.h
+++ b/drivers/staging/lustre/lustre/include/lustre/lustre_idl.h
@@ -1304,6 +1304,8 @@ extern void lustre_swab_ptlrpc_body(struct ptlrpc_body *pb);
 #define OBD_CONNECT_LIGHTWEIGHT 0x1000000000000ULL/* lightweight connection */
 #define OBD_CONNECT_SHORTIO     0x2000000000000ULL/* short io */
 #define OBD_CONNECT_PINGLESS	0x4000000000000ULL/* pings not required */
+#define OBD_CONNECT_FLOCK_DEAD	0x8000000000000ULL/* flock deadlock detection */
+
 /* XXX README XXX:
  * Please DO NOT add flag values here before first ensuring that this same
  * flag value is not in use on some other branch.  Please clear any such
@@ -1341,7 +1343,8 @@ extern void lustre_swab_ptlrpc_body(struct ptlrpc_body *pb);
 				OBD_CONNECT_EINPROGRESS | \
 				OBD_CONNECT_LIGHTWEIGHT | OBD_CONNECT_UMASK | \
 				OBD_CONNECT_LVB_TYPE | OBD_CONNECT_LAYOUTLOCK |\
-				OBD_CONNECT_PINGLESS | OBD_CONNECT_MAX_EASIZE)
+				OBD_CONNECT_PINGLESS | OBD_CONNECT_MAX_EASIZE |\
+				OBD_CONNECT_FLOCK_DEAD)
 #define OST_CONNECT_SUPPORTED  (OBD_CONNECT_SRVLOCK | OBD_CONNECT_GRANT | \
 				OBD_CONNECT_REQPORTAL | OBD_CONNECT_VERSION | \
 				OBD_CONNECT_TRUNCLOCK | OBD_CONNECT_INDEX | \
diff --git a/drivers/staging/lustre/lustre/include/lustre_dlm_flags.h b/drivers/staging/lustre/lustre/include/lustre_dlm_flags.h
index 75716f17f64b..73fb38ee0a34 100644
--- a/drivers/staging/lustre/lustre/include/lustre_dlm_flags.h
+++ b/drivers/staging/lustre/lustre/include/lustre_dlm_flags.h
@@ -35,10 +35,10 @@
 #ifndef LDLM_ALL_FLAGS_MASK
 
 /** l_flags bits marked as "all_flags" bits */
-#define LDLM_FL_ALL_FLAGS_MASK          0x00FFFFFFC08F132FULL
+#define LDLM_FL_ALL_FLAGS_MASK          0x00FFFFFFC08F932FULL
 
 /** l_flags bits marked as "ast" bits */
-#define LDLM_FL_AST_MASK                0x0000000080000000ULL
+#define LDLM_FL_AST_MASK                0x0000000080008000ULL
 
 /** l_flags bits marked as "blocked" bits */
 #define LDLM_FL_BLOCKED_MASK            0x000000000000000EULL
@@ -56,7 +56,7 @@
 #define LDLM_FL_LOCAL_ONLY_MASK         0x00FFFFFF00000000ULL
 
 /** l_flags bits marked as "on_wire" bits */
-#define LDLM_FL_ON_WIRE_MASK            0x00000000C08F132FULL
+#define LDLM_FL_ON_WIRE_MASK            0x00000000C08F932FULL
 
 /** extent, mode, or resource changed */
 #define LDLM_FL_LOCK_CHANGED            0x0000000000000001ULL // bit   0
@@ -114,6 +114,12 @@
 #define ldlm_set_has_intent(_l)         LDLM_SET_FLAG((  _l), 1ULL << 12)
 #define ldlm_clear_has_intent(_l)       LDLM_CLEAR_FLAG((_l), 1ULL << 12)
 
+/** flock deadlock detected */
+#define LDLM_FL_FLOCK_DEADLOCK          0x0000000000008000ULL /* bit  15 */
+#define ldlm_is_flock_deadlock(_l)      LDLM_TEST_FLAG((_l), 1ULL << 15)
+#define ldlm_set_flock_deadlock(_l)     LDLM_SET_FLAG((_l), 1ULL << 15)
+#define ldlm_clear_flock_deadlock(_l)   LDLM_CLEAR_FLAG((_l), 1ULL << 15)
+
 /** discard (no writeback) on cancel */
 #define LDLM_FL_DISCARD_DATA            0x0000000000010000ULL // bit  16
 #define ldlm_is_discard_data(_l)        LDLM_TEST_FLAG(( _l), 1ULL << 16)
@@ -390,6 +396,7 @@ static int hf_lustre_ldlm_fl_ast_sent            = -1;
 static int hf_lustre_ldlm_fl_replay              = -1;
 static int hf_lustre_ldlm_fl_intent_only         = -1;
 static int hf_lustre_ldlm_fl_has_intent          = -1;
+static int hf_lustre_ldlm_fl_flock_deadlock      = -1;
 static int hf_lustre_ldlm_fl_discard_data        = -1;
 static int hf_lustre_ldlm_fl_no_timeout          = -1;
 static int hf_lustre_ldlm_fl_block_nowait        = -1;
@@ -431,6 +438,7 @@ const value_string lustre_ldlm_flags_vals[] = {
 	{LDLM_FL_REPLAY,              "LDLM_FL_REPLAY"},
 	{LDLM_FL_INTENT_ONLY,         "LDLM_FL_INTENT_ONLY"},
 	{LDLM_FL_HAS_INTENT,          "LDLM_FL_HAS_INTENT"},
+	{LDLM_FL_FLOCK_DEADLOCK,      "LDLM_FL_FLOCK_DEADLOCK"},
 	{LDLM_FL_DISCARD_DATA,        "LDLM_FL_DISCARD_DATA"},
 	{LDLM_FL_NO_TIMEOUT,          "LDLM_FL_NO_TIMEOUT"},
 	{LDLM_FL_BLOCK_NOWAIT,        "LDLM_FL_BLOCK_NOWAIT"},
diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c b/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
index c9aae132f98a..986bf384bff7 100644
--- a/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
+++ b/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
@@ -205,6 +205,26 @@ ldlm_flock_deadlock(struct ldlm_lock *req, struct ldlm_lock *bl_lock)
 	return 0;
 }
 
+static void ldlm_flock_cancel_on_deadlock(struct ldlm_lock *lock,
+					  struct list_head *work_list)
+{
+	CDEBUG(D_INFO, "reprocess deadlock req=%p\n", lock);
+
+	if ((exp_connect_flags(lock->l_export) &
+				OBD_CONNECT_FLOCK_DEAD) == 0) {
+		CERROR(
+		      "deadlock found, but client doesn't support flock canceliation\n");
+	} else {
+		LASSERT(lock->l_completion_ast);
+		LASSERT((lock->l_flags & LDLM_FL_AST_SENT) == 0);
+		lock->l_flags |= LDLM_FL_AST_SENT | LDLM_FL_CANCEL_ON_BLOCK |
+			LDLM_FL_FLOCK_DEADLOCK;
+		ldlm_flock_blocking_unlink(lock);
+		ldlm_resource_unlink_lock(lock);
+		ldlm_add_ast_work_item(lock, NULL, work_list);
+	}
+}
+
 /**
  * Process a granting attempt for flock lock.
  * Must be called under ns lock held.
@@ -272,6 +292,7 @@ reprocess:
 			}
 		}
 	} else {
+		int reprocess_failed = 0;
 		lockmode_verify(mode);
 
 		/* This loop determines if there are existing locks
@@ -293,8 +314,15 @@ reprocess:
 			if (!ldlm_flocks_overlap(lock, req))
 				continue;
 
-			if (!first_enq)
-				return LDLM_ITER_CONTINUE;
+			if (!first_enq) {
+				reprocess_failed = 1;
+				if (ldlm_flock_deadlock(req, lock)) {
+					ldlm_flock_cancel_on_deadlock(req,
+							work_list);
+					return LDLM_ITER_CONTINUE;
+				}
+				continue;
+			}
 
 			if (*flags & LDLM_FL_BLOCK_NOWAIT) {
 				ldlm_flock_destroy(req, mode, *flags);
@@ -330,6 +358,8 @@ reprocess:
 			*flags |= LDLM_FL_BLOCK_GRANTED;
 			return LDLM_ITER_STOP;
 		}
+		if (reprocess_failed)
+			return LDLM_ITER_CONTINUE;
 	}
 
 	if (*flags & LDLM_FL_TEST_LOCK) {
@@ -646,7 +676,10 @@ granted:
 	/* ldlm_lock_enqueue() has already placed lock on the granted list. */
 	list_del_init(&lock->l_res_link);
 
-	if (flags & LDLM_FL_TEST_LOCK) {
+	if (lock->l_flags & LDLM_FL_FLOCK_DEADLOCK) {
+		LDLM_DEBUG(lock, "client-side enqueue deadlock received");
+		rc = -EDEADLK;
+	} else if (flags & LDLM_FL_TEST_LOCK) {
 		/* fcntl(F_GETLK) request */
 		/* The old mode was saved in getlk->fl_type so that if the mode
 		 * in the lock changes we can decref the appropriate refcount.*/
@@ -672,7 +705,7 @@ granted:
 		ldlm_process_flock_lock(lock, &noreproc, 1, &err, NULL);
 	}
 	unlock_res_and_lock(lock);
-	return 0;
+	return rc;
 }
 EXPORT_SYMBOL(ldlm_flock_completion_ast);
 
diff --git a/drivers/staging/lustre/lustre/llite/llite_lib.c b/drivers/staging/lustre/lustre/llite/llite_lib.c
index 3e4c292769e6..b0b694138869 100644
--- a/drivers/staging/lustre/lustre/llite/llite_lib.c
+++ b/drivers/staging/lustre/lustre/llite/llite_lib.c
@@ -206,7 +206,9 @@ static int client_common_fill_super(struct super_block *sb, char *md, char *dt,
 				  OBD_CONNECT_EINPROGRESS |
 				  OBD_CONNECT_JOBSTATS | OBD_CONNECT_LVB_TYPE |
 				  OBD_CONNECT_LAYOUTLOCK |
-				  OBD_CONNECT_PINGLESS | OBD_CONNECT_MAX_EASIZE;
+				  OBD_CONNECT_PINGLESS |
+				  OBD_CONNECT_MAX_EASIZE |
+				  OBD_CONNECT_FLOCK_DEAD;
 
 	if (sbi->ll_flags & LL_SBI_SOM_PREVIEW)
 		data->ocd_connect_flags |= OBD_CONNECT_SOM;
diff --git a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
index ec3b605dae6b..6e7d2e561067 100644
--- a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
+++ b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
@@ -98,6 +98,7 @@ static const char * const obd_connect_names[] = {
 	"lightweight_conn",
 	"short_io",
 	"pingless",
+	"flock_deadlock",
 	"unknown",
 	NULL
 };
diff --git a/drivers/staging/lustre/lustre/ptlrpc/wiretest.c b/drivers/staging/lustre/lustre/ptlrpc/wiretest.c
index 3aa445952024..3c8846006a7b 100644
--- a/drivers/staging/lustre/lustre/ptlrpc/wiretest.c
+++ b/drivers/staging/lustre/lustre/ptlrpc/wiretest.c
@@ -1152,6 +1152,8 @@ void lustre_assert_wire_constants(void)
 		 OBD_CONNECT_SHORTIO);
 	LASSERTF(OBD_CONNECT_PINGLESS == 0x4000000000000ULL, "found 0x%.16llxULL\n",
 		 OBD_CONNECT_PINGLESS);
+	LASSERTF(OBD_CONNECT_FLOCK_DEAD == 0x8000000000000ULL,
+		 "found 0x%.16llxULL\n", OBD_CONNECT_FLOCK_DEAD);
 	LASSERTF(OBD_CKSUM_CRC32 == 0x00000001UL, "found 0x%.8xUL\n",
 		(unsigned)OBD_CKSUM_CRC32);
 	LASSERTF(OBD_CKSUM_ADLER == 0x00000002UL, "found 0x%.8xUL\n",