ocfs2: avoid occurring deadlock by changing ocfs2_wq from global to local.

This patch is solving a scene of deadlock, as follows:

  Node 1                Node 2                  Node 3
1)volume a and b are    only mount vol a        only mount vol b

mounted

2) start to mount b start to mount a

3) check hb of Node 3 check hb of Node 2
in vol a, qs_holds++ in vol b, qs_holds++

4) -------------------- all nodes' network down --------------------

5) progress of mount b the same situation as
failed, and then call Node 2
ocfs2_dismount_volume. but the process is hung, since there is a work in ocfs2_wq cannot beo completed. This work is about vol a, because ocfs2_wq is global wq. BTW, this work which is scheduled in ocfs2_wq is ocfs2_orphan_scan_work, and the context in this work needs to take inode lock of orphan_dir, because lockres owner are Node 1 and all nodes' nework has been down at the same time, so it can't get the inode lock.

6) Why can't this node be fenced
when network disconnected? Because the process of mount is hung what caused qs_holds is not equal 0.

Because all works in the ocfs2_wq are relative to the super block, so the solution is to change the ocfs2_wq from global to local, in other words, moving it into the structure of ocfs2 super.

Signed-off-by Yiwen Jiang <[email protected]>

---
 fs/ocfs2/alloc.c        |  5 +++--
 fs/ocfs2/journal.c      |  9 +++++----
 fs/ocfs2/localalloc.c   |  5 +++--
 fs/ocfs2/ocfs2.h        |  6 ++++++
 fs/ocfs2/quota_global.c |  2 +-
 fs/ocfs2/super.c        | 38 ++++++++++++++++----------------------
 fs/ocfs2/super.h        |  2 --
 7 files changed, 34 insertions(+), 33 deletions(-)

fs/ocfs2/alloc.c +3 -2

index 86181d6..e2e3464 100644
@@ -6079,7 +6079,7 @@ void ocfs2_schedule_truncate_log_flush(struct ocfs2_super *osb,
 		if (cancel)
 			cancel_delayed_work(&osb->osb_truncate_log_wq);
 
-		queue_delayed_work(ocfs2_wq, &osb->osb_truncate_log_wq,
+		queue_delayed_work(osb->ocfs2_wq, &osb->osb_truncate_log_wq,
 				   OCFS2_TRUNCATE_LOG_FLUSH_INTERVAL);
 	}
 }

@@ -6254,7 +6254,8 @@ void ocfs2_truncate_log_shutdown(struct ocfs2_super *osb)
 
 	if (tl_inode) {
 		cancel_delayed_work(&osb->osb_truncate_log_wq);
-		flush_workqueue(ocfs2_wq);
+		if (osb->ocfs2_wq)
+			flush_workqueue(osb->ocfs2_wq);
 
 		status = ocfs2_flush_truncate_log(osb);
 		if (status < 0)

fs/ocfs2/journal.c +5 -4

index ff82b28..264c359 100644
@@ -231,7 +231,8 @@ void ocfs2_recovery_exit(struct ocfs2_super *osb)
 	/* At this point, we know that no more recovery threads can be
 	 * launched, so wait for any recovery completion work to
 	 * complete. */
-	flush_workqueue(ocfs2_wq);
+	if (osb->ocfs2_wq)
+		flush_workqueue(osb->ocfs2_wq);
 
 	/*
 	 * Now that recovery is shut down, and the osb is about to be

@@ -1327,7 +1328,7 @@ static void ocfs2_queue_recovery_completion(struct ocfs2_journal *journal,
 
 	spin_lock(&journal->j_lock);
 	list_add_tail(&item->lri_list, &journal->j_la_cleanups);
-	queue_work(ocfs2_wq, &journal->j_recovery_work);
+	queue_work(journal->j_osb->ocfs2_wq, &journal->j_recovery_work);
 	spin_unlock(&journal->j_lock);
 }
 

@@ -1972,7 +1973,7 @@ static void ocfs2_orphan_scan_work(struct work_struct *work)
 	mutex_lock(&os->os_lock);
 	ocfs2_queue_orphan_scan(osb);
 	if (atomic_read(&os->os_state) == ORPHAN_SCAN_ACTIVE)
-		queue_delayed_work(ocfs2_wq, &os->os_orphan_scan_work,
+		queue_delayed_work(osb->ocfs2_wq, &os->os_orphan_scan_work,
 				      ocfs2_orphan_scan_timeout());
 	mutex_unlock(&os->os_lock);
 }

@@ -2012,7 +2013,7 @@ void ocfs2_orphan_scan_start(struct ocfs2_super *osb)
 		atomic_set(&os->os_state, ORPHAN_SCAN_INACTIVE);
 	else {
 		atomic_set(&os->os_state, ORPHAN_SCAN_ACTIVE);
-		queue_delayed_work(ocfs2_wq, &os->os_orphan_scan_work,
+		queue_delayed_work(osb->ocfs2_wq, &os->os_orphan_scan_work,
 				   ocfs2_orphan_scan_timeout());
 	}
 }

fs/ocfs2/localalloc.c +3 -2

index 0a4457f..7ac972c 100644
@@ -387,7 +387,8 @@ void ocfs2_shutdown_local_alloc(struct ocfs2_super *osb)
 	struct ocfs2_dinode *alloc = NULL;
 
 	cancel_delayed_work(&osb->la_enable_wq);
-	flush_workqueue(ocfs2_wq);
+	if (osb->ocfs2_wq)
+		flush_workqueue(osb->ocfs2_wq);
 
 	if (osb->local_alloc_state == OCFS2_LA_UNUSED)
 		goto out;

@@ -1087,7 +1088,7 @@ static int ocfs2_recalc_la_window(struct ocfs2_super *osb,
 		} else {
 			osb->local_alloc_state = OCFS2_LA_DISABLED;
 		}
-		queue_delayed_work(ocfs2_wq, &osb->la_enable_wq,
+		queue_delayed_work(osb->ocfs2_wq, &osb->la_enable_wq,
 				   OCFS2_LA_ENABLE_INTERVAL);
 		goto out_unlock;
 	}

fs/ocfs2/ocfs2.h +6 -0

index 7a01262..2ce47bf 100644
@@ -464,6 +464,12 @@ struct ocfs2_super
 	struct ocfs2_refcount_tree *osb_ref_tree_lru;
 
 	struct mutex system_file_mutex;
+
+	/* OCFS2 needs to schedule several different types of work which
+	 * require cluster locking, disk I/O, recovery waits, etc. Since these
+	 * types of work tend to be heavy we avoid using the kernel events
+	 * workqueue and schedule on our own. */
+	struct workqueue_struct *ocfs2_wq;
 };
 
 #define OCFS2_SB(sb)	    ((struct ocfs2_super *)(sb)->s_fs_info)

fs/ocfs2/quota_global.c +1 -1

index c93d672..44df24b 100644
@@ -726,7 +726,7 @@ static int ocfs2_release_dquot(struct dquot *dquot)
 		dqgrab(dquot);
 		/* First entry on list -> queue work */
 		if (llist_add(&OCFS2_DQUOT(dquot)->list, &osb->dquot_drop_list))
-			queue_work(ocfs2_wq, &osb->dquot_drop_work);
+			queue_work(osb->ocfs2_wq, &osb->dquot_drop_work);
 		goto out;
 	}
 	status = ocfs2_lock_global_qf(oinfo, 1);

fs/ocfs2/super.c +16 -22

index 2de4c8a..4bac9e2 100644
@@ -79,12 +79,6 @@ static struct kmem_cache *ocfs2_inode_cachep;
 struct kmem_cache *ocfs2_dquot_cachep;
 struct kmem_cache *ocfs2_qf_chunk_cachep;
 
-/* OCFS2 needs to schedule several different types of work which
- * require cluster locking, disk I/O, recovery waits, etc. Since these
- * types of work tend to be heavy we avoid using the kernel events
- * workqueue and schedule on our own. */
-struct workqueue_struct *ocfs2_wq = NULL;
-
 static struct dentry *ocfs2_debugfs_root;
 
 MODULE_AUTHOR("Oracle");

@@ -1612,33 +1606,25 @@ static int __init ocfs2_init(void)
 	if (status < 0)
 		goto out2;
 
-	ocfs2_wq = create_singlethread_workqueue("ocfs2_wq");
-	if (!ocfs2_wq) {
-		status = -ENOMEM;
-		goto out3;
-	}
-
 	ocfs2_debugfs_root = debugfs_create_dir("ocfs2", NULL);
 	if (!ocfs2_debugfs_root) {
 		status = -ENOMEM;
 		mlog(ML_ERROR, "Unable to create ocfs2 debugfs root.\n");
-		goto out4;
+		goto out3;
 	}
 
 	ocfs2_set_locking_protocol();
 
 	status = register_quota_format(&ocfs2_quota_format);
 	if (status < 0)
-		goto out4;
+		goto out3;
 	status = register_filesystem(&ocfs2_fs_type);
 	if (!status)
 		return 0;
 
 	unregister_quota_format(&ocfs2_quota_format);
-out4:
-	destroy_workqueue(ocfs2_wq);
-	debugfs_remove(ocfs2_debugfs_root);
 out3:
+	debugfs_remove(ocfs2_debugfs_root);
 	ocfs2_free_mem_caches();
 out2:
 	exit_ocfs2_uptodate_cache();

@@ -1649,11 +1635,6 @@ out1:
 
 static void __exit ocfs2_exit(void)
 {
-	if (ocfs2_wq) {
-		flush_workqueue(ocfs2_wq);
-		destroy_workqueue(ocfs2_wq);
-	}
-
 	unregister_quota_format(&ocfs2_quota_format);
 
 	debugfs_remove(ocfs2_debugfs_root);

@@ -2128,6 +2109,13 @@ static int ocfs2_initialize_super(struct super_block *sb,
 		goto bail;
 	}
 
+	osb->ocfs2_wq = create_singlethread_workqueue("ocfs2_wq");
+	if (!osb->ocfs2_wq) {
+		status = -ENOMEM;
+		mlog_errno(status);
+		goto bail;
+	}
+
 	ocfs2_orphan_scan_init(osb);
 
 	status = ocfs2_recovery_init(osb);

@@ -2535,6 +2523,12 @@ static void ocfs2_delete_osb(struct ocfs2_super *osb)
 {
 	/* This function assumes that the caller has the main osb resource */
 
+	/* ocfs2_initializer_super have already created this workqueue */
+	if (osb->ocfs2_wq) {
+		flush_workqueue(osb->ocfs2_wq);
+		destroy_workqueue(osb->ocfs2_wq);
+	}
+
 	ocfs2_free_slot_info(osb);
 
 	kfree(osb->osb_orphan_wipes);

fs/ocfs2/super.h +0 -2

index b477d0b..b023e4f 100644
@@ -26,8 +26,6 @@
 #ifndef OCFS2_SUPER_H
 #define OCFS2_SUPER_H
 
-extern struct workqueue_struct *ocfs2_wq;
-
 int ocfs2_publish_get_mount_state(struct ocfs2_super *osb,
 				  int node_num);