ocfs2/dlm: wait for dlm recovery done when migrating all lock resources

Wait for dlm recovery done when migrating all lock resources in case that new lock resource left after leaving dlm domain. And the left lock resource will cause other nodes BUG.

NodeA NodeB NodeC

umount:
dlm_unregister_domain()
dlm_migrate_all_locks()

NodeB down

do recovery for NodeB
and collect a new lockres
form other live nodes:

dlm_do_recovery
dlm_remaster_locks
dlm_request_all_locks:

dlm_mig_lockres_handler
dlm_new_lockres
__dlm_insert_lockres

at last NodeA become the
master of the new lockres
and leave domain:
dlm_leave_domain()

mount:
dlm_join_domain()

touch file and request for the owner of the new lockres, but all the other nodes said 'NO', so NodeC decide to be the owner, and send do assert msg to other nodes:
dlmlock()
dlm_get_lock_resource()
dlm_do_assert_master()

other nodes receive the msg and found two masters exist. at last cause BUG in dlm_assert_master_handler() -->BUG();

Fixes bc9838c4d44a ("dlm: allow dlm do recovery during shutdown")

Signed-off-by Jun Piao <[email protected]>

Reviewed-by Alex Chen <[email protected]>

Reviewed-by Yiwen Jiang <[email protected]>

---
  fs/ocfs2/dlm/dlmcommon.h   |  1 +
  fs/ocfs2/dlm/dlmdomain.c   | 15 +++++++++++++++
  fs/ocfs2/dlm/dlmrecovery.c | 13 ++++++++++---
  3 files changed, 26 insertions(+), 3 deletions(-)

fs/ocfs2/dlm/dlmcommon.h +1 -0

index 953c200..d06e27e 100644
@@ -140,6 +140,7 @@ struct dlm_ctxt
  	u8 node_num;
  	u32 key;
  	u8  joining_node;
+	u8 migrate_done; /* set to 1 means node has migrated all lock resources */
  	wait_queue_head_t dlm_join_events;
  	unsigned long live_nodes_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
  	unsigned long domain_map[BITS_TO_LONGS(O2NM_MAX_NODES)];

fs/ocfs2/dlm/dlmdomain.c +15 -0

index 25b76f0..425081b 100644
@@ -461,6 +461,19 @@ static int dlm_migrate_all_locks(struct dlm_ctxt *dlm)
  		cond_resched_lock(&dlm->spinlock);
  		num += n;
  	}
+
+	if (!num) {
+		if (dlm->reco.state & DLM_RECO_STATE_ACTIVE) {
+			mlog(0, "%s: perhaps there are more lock resources "
+			     "need to be migrated after dlm recovery\n", dlm->name);
+			ret = -EAGAIN;
+		} else {
+			mlog(0, "%s: we won't do dlm recovery after migrating "
+			     "all lock resources\n", dlm->name);
+			dlm->migrate_done = 1;
+		}
+	}
+
  	spin_unlock(&dlm->spinlock);
  	wake_up(&dlm->dlm_thread_wq);
 

@@ -2038,6 +2051,8 @@ static struct dlm_ctxt *dlm_alloc_ctxt(const char *domain,
  	dlm->joining_node = DLM_LOCK_RES_OWNER_UNKNOWN;
  	init_waitqueue_head(&dlm->dlm_join_events);
 
+	dlm->migrate_done = 0;
+
  	dlm->reco.new_master = O2NM_INVALID_NODE_NUM;
  	dlm->reco.dead_node = O2NM_INVALID_NODE_NUM;
 

fs/ocfs2/dlm/dlmrecovery.c +10 -3

index 505ab42..d4336a5 100644
@@ -423,12 +423,11 @@ void dlm_wait_for_recovery(struct dlm_ctxt *dlm)
 
  static void dlm_begin_recovery(struct dlm_ctxt *dlm)
  {
-	spin_lock(&dlm->spinlock);
+	assert_spin_locked(&dlm->spinlock);
  	BUG_ON(dlm->reco.state & DLM_RECO_STATE_ACTIVE);
  	printk(KERN_NOTICE "o2dlm: Begin recovery on domain %s for node %u\n",
  	       dlm->name, dlm->reco.dead_node);
  	dlm->reco.state |= DLM_RECO_STATE_ACTIVE;
-	spin_unlock(&dlm->spinlock);
  }
 
  static void dlm_end_recovery(struct dlm_ctxt *dlm)

@@ -456,6 +455,13 @@ static int dlm_do_recovery(struct dlm_ctxt *dlm)
 
  	spin_lock(&dlm->spinlock);
 
+	if (dlm->migrate_done) {
+		mlog(0, "%s: no need do recovery after migrating all "
+		     "lock resources\n", dlm->name);
+		spin_unlock(&dlm->spinlock);
+		return 0;
+	}
+
  	/* check to see if the new master has died */
  	if (dlm->reco.new_master != O2NM_INVALID_NODE_NUM &&
  	    test_bit(dlm->reco.new_master, dlm->recovery_map)) {

@@ -490,12 +496,13 @@ static int dlm_do_recovery(struct dlm_ctxt *dlm)
  	mlog(0, "%s(%d):recovery thread found node %u in the recovery map!\n",
  	     dlm->name, task_pid_nr(dlm->dlm_reco_thread_task),
  	     dlm->reco.dead_node);
-	spin_unlock(&dlm->spinlock);
 
  	/* take write barrier */
  	/* (stops the list reshuffling thread, proxy ast handling) */
  	dlm_begin_recovery(dlm);
 
+	spin_unlock(&dlm->spinlock);
+
  	if (dlm->reco.new_master == dlm->node_num)
  		goto master_here;
 

Hi Jun,

It seems that you have ever posted this patch, If I remember correctly. My concern is still if you disable dlm recovery via ::migrate_done. Then flag DLM_LOCK_RES_RECOVERING can't be cleared.

So we can't purge the problematic lock resource since __dlm_lockres_unused() needs to check that flag.

Finally, umount will run the while loop in dlm_migrate_all_locks() infinitely. Or if I miss something?

Thanks,
Changwei

Quoted 143 lines · piaojun

Wait for dlm recovery done when migrating all lock resources in case that new lock resource left after leaving dlm domain. And the left lock resource will cause other nodes BUG.

NodeA NodeB NodeC

umount:
dlm_unregister_domain()
dlm_migrate_all_locks()

NodeB down

do recovery for NodeB
and collect a new lockres
form other live nodes:

dlm_do_recovery
dlm_remaster_locks
dlm_request_all_locks:

dlm_mig_lockres_handler
dlm_new_lockres
__dlm_insert_lockres

at last NodeA become the
master of the new lockres
and leave domain:
dlm_leave_domain()

mount:
dlm_join_domain()

touch file and request for the owner of the new lockres, but all the other nodes said 'NO', so NodeC decide to be the owner, and send do assert msg to other nodes:
dlmlock()
dlm_get_lock_resource()
dlm_do_assert_master()

other nodes receive the msg and found two masters exist. at last cause BUG in dlm_assert_master_handler() -->BUG();

Fixes bc9838c4d44a ("dlm: allow dlm do recovery during shutdown")

Signed-off-by Jun Piao <[email protected]>

Reviewed-by Alex Chen <[email protected]>

Reviewed-by Yiwen Jiang <[email protected]>

---
  fs/ocfs2/dlm/dlmcommon.h   |  1 +
  fs/ocfs2/dlm/dlmdomain.c   | 15 +++++++++++++++
  fs/ocfs2/dlm/dlmrecovery.c | 13 ++++++++++---
  3 files changed, 26 insertions(+), 3 deletions(-)

fs/ocfs2/dlm/dlmcommon.h +1 -0

index 953c200..d06e27e 100644
@@ -140,6 +140,7 @@ struct dlm_ctxt
  	u8 node_num;
  	u32 key;
  	u8  joining_node;
+	u8 migrate_done; /* set to 1 means node has migrated all lock resources */
  	wait_queue_head_t dlm_join_events;
  	unsigned long live_nodes_map[BITS_TO_LONGS(O2NM_MAX_NODES)];
  	unsigned long domain_map[BITS_TO_LONGS(O2NM_MAX_NODES)];

fs/ocfs2/dlm/dlmdomain.c +15 -0

index 25b76f0..425081b 100644
@@ -461,6 +461,19 @@ static int dlm_migrate_all_locks(struct dlm_ctxt *dlm)
  		cond_resched_lock(&dlm->spinlock);
  		num += n;
  	}
+
+	if (!num) {
+		if (dlm->reco.state & DLM_RECO_STATE_ACTIVE) {
+			mlog(0, "%s: perhaps there are more lock resources "
+			     "need to be migrated after dlm recovery\n", dlm->name);
+			ret = -EAGAIN;
+		} else {
+			mlog(0, "%s: we won't do dlm recovery after migrating "
+			     "all lock resources\n", dlm->name);
+			dlm->migrate_done = 1;
+		}
+	}
+
  	spin_unlock(&dlm->spinlock);
  	wake_up(&dlm->dlm_thread_wq);
 

@@ -2038,6 +2051,8 @@ static struct dlm_ctxt *dlm_alloc_ctxt(const char *domain,
  	dlm->joining_node = DLM_LOCK_RES_OWNER_UNKNOWN;
  	init_waitqueue_head(&dlm->dlm_join_events);
 
+	dlm->migrate_done = 0;
+
  	dlm->reco.new_master = O2NM_INVALID_NODE_NUM;
  	dlm->reco.dead_node = O2NM_INVALID_NODE_NUM;
 

fs/ocfs2/dlm/dlmrecovery.c +8 -3

index 505ab42..d4336a5 100644
@@ -423,12 +423,11 @@ void dlm_wait_for_recovery(struct dlm_ctxt *dlm)
 
  static void dlm_begin_recovery(struct dlm_ctxt *dlm)
  {
-	spin_lock(&dlm->spinlock);
+	assert_spin_locked(&dlm->spinlock);
  	BUG_ON(dlm->reco.state & DLM_RECO_STATE_ACTIVE);
  	printk(KERN_NOTICE "o2dlm: Begin recovery on domain %s for node %u\n",
  	       dlm->name, dlm->reco.dead_node);
  	dlm->reco.state |= DLM_RECO_STATE_ACTIVE;
-	spin_unlock(&dlm->spinlock);
  }
 
  static void dlm_end_recovery(struct dlm_ctxt *dlm)

@@ -456,6 +455,13 @@ static int dlm_do_recovery(struct dlm_ctxt *dlm)
 
  	spin_lock(&dlm->spinlock);
 
+	if (dlm->migrate_done) {
+		mlog(0, "%s: no need do recovery after migrating all "
+		     "lock resources\n", dlm->name);
+		spin_unlock(&dlm->spinlock);
+		return 0;
+	}
+
  	/* check to see if the new master has died */
  	if (dlm->reco.new_master != O2NM_INVALID_NODE_NUM &&
  	    test_bit(dlm->reco.new_master, dlm->recovery_map)) {

@@ -490,12 +496,13 @@ static int dlm_do_recovery(struct dlm_ctxt *dlm)
  	mlog(0, "%s(%d):recovery thread found node %u in the recovery map!\n",
  	     dlm->name, task_pid_nr(dlm->dlm_reco_thread_task),
  	     dlm->reco.dead_node);
-	spin_unlock(&dlm->spinlock);

fs/ocfs2/dlm/dlmrecovery.c static int dlm_do_recovery(struct dlm_ctxt *dlm) · line 508

Quoted 10 lines

fs/ocfs2/dlm/dlmrecovery.c +2 -0

 
  	/* take write barrier */
  	/* (stops the list reshuffling thread, proxy ast handling) */
  	dlm_begin_recovery(dlm);
 
+	spin_unlock(&dlm->spinlock);
+
  	if (dlm->reco.new_master == dlm->node_num)
  		goto master_here;
 

.

Hi Changwei,

Quoted 5 lines · Changwei Ge

Hi Jun,

It seems that you have ever posted this patch, If I remember correctly. My concern is still if you disable dlm recovery via ::migrate_done. Then flag DLM_LOCK_RES_RECOVERING can't be cleared.

After I set migrate_done, all lockres had been migrated. So there won't be any lockres with DLM_LOCK_RES_RECOVERING. And I have tested this patch for a few months.

thanks,
Jun

Quoted 18 lines

So we can't purge the problematic lock resource since __dlm_lockres_unused() needs to check that flag.

Finally, umount will run the while loop in dlm_migrate_all_locks() infinitely. Or if I miss something?

Thanks,
Changwei

Quoted 6 lines · piaojun

Fixes bc9838c4d44a ("dlm: allow dlm do recovery during shutdown")

Signed-off-by Jun Piao <[email protected]>

Reviewed-by Alex Chen <[email protected]>

Reviewed-by Yiwen Jiang <[email protected]>

Quoted 7 lines

Quoted 7 lines

---
   fs/ocfs2/dlm/dlmcommon.h   |  1 +
   fs/ocfs2/dlm/dlmdomain.c   | 15 +++++++++++++++
   fs/ocfs2/dlm/dlmrecovery.c | 13 ++++++++++---
   3 files changed, 26 insertions(+), 3 deletions(-)

fs/ocfs2/dlm/dlmcommon.h +0 -0

Wait for dlm recovery done when migrating all lock resources in case that new lock resource left after leaving dlm domain. And the left lock resource will cause other nodes BUG.

NodeA NodeB NodeC

umount:
dlm_unregister_domain()
dlm_migrate_all_locks()

NodeB down

do recovery for NodeB
and collect a new lockres
form other live nodes:

dlm_do_recovery
dlm_remaster_locks
dlm_request_all_locks:

dlm_mig_lockres_handler
dlm_new_lockres
__dlm_insert_lockres

at last NodeA become the
master of the new lockres
and leave domain:
dlm_leave_domain()

mount:
dlm_join_domain()

touch file and request for the owner of the new lockres, but all the other nodes said 'NO', so NodeC decide to be the owner, and send do assert msg to other nodes:
dlmlock()
dlm_get_lock_resource()
dlm_do_assert_master()

other nodes receive the msg and found two masters exist. at last cause BUG in dlm_assert_master_handler() -->BUG();

Fixes bc9838c4d44a ("dlm: allow dlm do recovery during shutdown")

Signed-off-by Jun Piao <[email protected]>

Reviewed-by Alex Chen <[email protected]>

Reviewed-by Yiwen Jiang <[email protected]>