diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index 62cad6522c7a..b747cdec1787 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -502,6 +502,11 @@ struct ocfs2_super
 	 */
 	struct workqueue_struct *ocfs2_wq;
 
+	/* deferred reclaim of fully freed suballocator block groups */
+	spinlock_t os_suballoc_reclaim_lock;
+	struct list_head os_suballoc_reclaim_list;
+	struct work_struct os_suballoc_reclaim_work;
+
 	/* sysfs directory per partition */
 	struct kset *osb_dev_kset;
 
diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index 20c3aec6b987..453b56be9624 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -2687,16 +2687,24 @@ static int ocfs2_block_group_clear_bits(handle_t *handle,
  * cleanup rec/alloc_inode job, then switches to the main bitmap
  * to reclaim released space.
  *
+ * Callers must hold inode_lock() and ocfs2_inode_lock() on
+ * main_bm_inode, i.e. the global bitmap inode locks must be taken
+ * before starting the transaction.
+ *
  * handle: The transaction handle
  * alloc_inode: The suballoc inode
  * alloc_bh: The buffer_head of suballoc inode
  * group_bh: The group descriptor buffer_head of suballocator managed.
- *           Caller should release the input group_bh.
+ *           This function takes ownership of it and will release it.
+ * main_bm_inode: The global bitmap inode
+ * main_bm_bh: The buffer_head of the global bitmap inode
  */
 static int _ocfs2_reclaim_suballoc_to_main(handle_t *handle,
 			struct inode *alloc_inode,
 			struct buffer_head *alloc_bh,
-			struct buffer_head *group_bh)
+			struct buffer_head *group_bh,
+			struct inode *main_bm_inode,
+			struct buffer_head *main_bm_bh)
 {
 	int idx, status = 0;
 	int i, next_free_rec, len = 0;
@@ -2706,8 +2714,6 @@ static int _ocfs2_reclaim_suballoc_to_main(handle_t *handle,
 	u64 bg_blkno, start_blk;
 	unsigned int count;
 	struct ocfs2_chain_rec *rec;
-	struct buffer_head *main_bm_bh = NULL;
-	struct inode *main_bm_inode = NULL;
 	struct ocfs2_super *osb = OCFS2_SB(alloc_inode->i_sb);
 	struct ocfs2_dinode *fe = (struct ocfs2_dinode *) alloc_bh->b_data;
 	struct ocfs2_chain_list *cl = &fe->id2.i_chain;
@@ -2794,24 +2800,12 @@ static int _ocfs2_reclaim_suballoc_to_main(handle_t *handle,
 	ocfs2_remove_from_cache(INODE_CACHE(alloc_inode), group_bh);
 	memset(group, 0, sizeof(struct ocfs2_group_desc));
 
-	/* prepare job for reclaim clusters */
-	main_bm_inode = ocfs2_get_system_file_inode(osb,
-						    GLOBAL_BITMAP_SYSTEM_INODE,
-						    OCFS2_INVALID_SLOT);
-	if (!main_bm_inode)
-		goto bail; /* ignore the error in reclaim path */
-
-	inode_lock(main_bm_inode);
-
-	status = ocfs2_inode_lock(main_bm_inode, &main_bm_bh, 1);
-	if (status < 0)
-		goto free_bm_inode; /* ignore the error in reclaim path */
-
 	ocfs2_block_to_cluster_group(main_bm_inode, start_blk, &bg_blkno,
 				     &start_bit);
 	fe = (struct ocfs2_dinode *) main_bm_bh->b_data;
 	cl = &fe->id2.i_chain;
-	/* reuse group_bh, caller will release the input group_bh */
+	/* release the suballocator group descriptor before reuse */
+	brelse(group_bh);
 	group_bh = NULL;
 
 	/* reclaim clusters to global_bitmap */
@@ -2819,7 +2813,7 @@ static int _ocfs2_reclaim_suballoc_to_main(handle_t *handle,
 					     &group_bh);
 	if (status < 0) {
 		mlog_errno(status);
-		goto free_bm_bh;
+		goto bail;
 	}
 	group = (struct ocfs2_group_desc *) group_bh->b_data;
 
@@ -2827,7 +2821,7 @@ static int _ocfs2_reclaim_suballoc_to_main(handle_t *handle,
 		ocfs2_error(alloc_inode->i_sb,
 			"reclaim length (%d) beyands block group length (%d)",
 			count + start_bit, le16_to_cpu(group->bg_bits));
-		goto free_group_bh;
+		goto bail;
 	}
 
 	old_bg_contig_free_bits = group->bg_contig_free_bits;
@@ -2837,7 +2831,7 @@ static int _ocfs2_reclaim_suballoc_to_main(handle_t *handle,
 					      _ocfs2_clear_bit);
 	if (status < 0) {
 		mlog_errno(status);
-		goto free_group_bh;
+		goto bail;
 	}
 
 	status = ocfs2_journal_access_di(handle, INODE_CACHE(main_bm_inode),
@@ -2847,7 +2841,7 @@ static int _ocfs2_reclaim_suballoc_to_main(handle_t *handle,
 		ocfs2_block_group_set_bits(handle, main_bm_inode, group, group_bh,
 				start_bit, count,
 				le16_to_cpu(old_bg_contig_free_bits), 1);
-		goto free_group_bh;
+		goto bail;
 	}
 
 	idx = le16_to_cpu(group->bg_chain);
@@ -2858,19 +2852,168 @@ static int _ocfs2_reclaim_suballoc_to_main(handle_t *handle,
 	fe->id1.bitmap1.i_used = cpu_to_le32(tmp_used - count);
 	ocfs2_journal_dirty(handle, main_bm_bh);
 
-free_group_bh:
+bail:
 	brelse(group_bh);
+	return status;
+}
 
-free_bm_bh:
+/*
+ * When a suballocator block group becomes fully freed, its space is
+ * reclaimed back to the global bitmap. Taking the global bitmap inode
+ * lock inside the freeing transaction would create a lock dependency
+ * of "j_trans_barrier -> global bitmap inode i_rwsem", which forms a
+ * circular dependency with paths like ocfs2_shutdown_local_alloc() that
+ * take the inode lock before starting a transaction, and can lead to a
+ * real deadlock with the ocfs2cmt journal commit thread. So queue the
+ * reclaim to the workqueue and let it run outside the freeing
+ * transaction.
+ */
+struct ocfs2_suballoc_reclaim_work {
+	struct list_head list;
+	struct inode *alloc_inode;
+	u64 bg_blkno;
+};
+
+static void ocfs2_queue_suballoc_reclaim(struct ocfs2_super *osb,
+					 struct inode *alloc_inode,
+					 u64 bg_blkno)
+{
+	struct ocfs2_suballoc_reclaim_work *reclaim_work;
+
+	reclaim_work = kmalloc_obj(*reclaim_work, GFP_NOFS);
+	if (!reclaim_work) {
+		/*
+		 * Reclaim is only a space return optimization. If we can't
+		 * queue it, the freed block group just stays owned by the
+		 * suballocator.
+		 */
+		return;
+	}
+
+	igrab(alloc_inode);
+	reclaim_work->alloc_inode = alloc_inode;
+	reclaim_work->bg_blkno = bg_blkno;
+
+	spin_lock(&osb->os_suballoc_reclaim_lock);
+	list_add_tail(&reclaim_work->list, &osb->os_suballoc_reclaim_list);
+	spin_unlock(&osb->os_suballoc_reclaim_lock);
+
+	queue_work(osb->ocfs2_wq, &osb->os_suballoc_reclaim_work);
+}
+
+static void ocfs2_do_suballoc_reclaim(struct ocfs2_super *osb,
+				struct ocfs2_suballoc_reclaim_work *reclaim_work)
+{
+	int status, i;
+	handle_t *handle;
+	struct inode *alloc_inode = reclaim_work->alloc_inode;
+	struct inode *main_bm_inode;
+	struct buffer_head *alloc_bh = NULL, *group_bh = NULL;
+	struct buffer_head *main_bm_bh = NULL;
+	struct ocfs2_dinode *fe;
+	struct ocfs2_chain_list *cl;
+	struct ocfs2_chain_rec *rec;
+
+	/* journal already gone, e.g. during dismount cleanup */
+	if (!osb->journal)
+		return;
+
+	inode_lock(alloc_inode);
+	status = ocfs2_inode_lock(alloc_inode, &alloc_bh, 1);
+	if (status < 0)
+		goto out_alloc;
+
+	fe = (struct ocfs2_dinode *) alloc_bh->b_data;
+	cl = &fe->id2.i_chain;
+
+	/*
+	 * The block group may have been allocated from again since the
+	 * reclaim work was queued, re-check that it is still fully freed.
+	 * A stale work item can also reference a group that is no longer
+	 * chained, whose descriptor would fail validation and trigger a
+	 * spurious ocfs2_error(), so verify chain membership first.
+	 */
+	for (i = 0; i < le16_to_cpu(cl->cl_next_free_rec); i++) {
+		rec = &cl->cl_recs[i];
+		if (le64_to_cpu(rec->c_blkno) == reclaim_work->bg_blkno)
+			break;
+	}
+	if (i == le16_to_cpu(cl->cl_next_free_rec) ||
+	    ocfs2_is_cluster_bitmap(alloc_inode) ||
+	    (le32_to_cpu(rec->c_free) != (le32_to_cpu(rec->c_total) - 1)) ||
+	    (le16_to_cpu(cl->cl_next_free_rec) == 1))
+		goto out_alloc_unlock;
+
+	status = ocfs2_read_group_descriptor(alloc_inode, fe,
+					     reclaim_work->bg_blkno, &group_bh);
+	if (status < 0)
+		goto out_alloc_unlock;
+
+	main_bm_inode = ocfs2_get_system_file_inode(osb,
+						    GLOBAL_BITMAP_SYSTEM_INODE,
+						    OCFS2_INVALID_SLOT);
+	if (!main_bm_inode)
+		goto out_group;
+
+	inode_lock(main_bm_inode);
+	status = ocfs2_inode_lock(main_bm_inode, &main_bm_bh, 1);
+	if (status < 0)
+		goto out_main;
+
+	handle = ocfs2_start_trans(osb, OCFS2_SUBALLOC_FREE);
+	if (IS_ERR(handle)) {
+		status = PTR_ERR(handle);
+		mlog_errno(status);
+		goto out_main_unlock;
+	}
+
+	status = _ocfs2_reclaim_suballoc_to_main(handle, alloc_inode,
+						 alloc_bh, group_bh,
+						 main_bm_inode, main_bm_bh);
+	/* group_bh ownership passed to _ocfs2_reclaim_suballoc_to_main() */
+	group_bh = NULL;
+	if (status < 0)
+		mlog_errno(status);
+
+	ocfs2_commit_trans(osb, handle);
+
+out_main_unlock:
 	ocfs2_inode_unlock(main_bm_inode, 1);
 	brelse(main_bm_bh);
-
-free_bm_inode:
+out_main:
 	inode_unlock(main_bm_inode);
 	iput(main_bm_inode);
+out_group:
+	brelse(group_bh);
+out_alloc_unlock:
+	ocfs2_inode_unlock(alloc_inode, 1);
+	brelse(alloc_bh);
+out_alloc:
+	inode_unlock(alloc_inode);
+}
 
-bail:
-	return status;
+void ocfs2_suballoc_reclaim_worker(struct work_struct *work)
+{
+	struct ocfs2_super *osb = container_of(work, struct ocfs2_super,
+					       os_suballoc_reclaim_work);
+	struct ocfs2_suballoc_reclaim_work *reclaim_work;
+
+	while (1) {
+		spin_lock(&osb->os_suballoc_reclaim_lock);
+		if (list_empty(&osb->os_suballoc_reclaim_list)) {
+			spin_unlock(&osb->os_suballoc_reclaim_lock);
+			break;
+		}
+		reclaim_work = list_first_entry(&osb->os_suballoc_reclaim_list,
+					struct ocfs2_suballoc_reclaim_work,
+					list);
+		list_del(&reclaim_work->list);
+		spin_unlock(&osb->os_suballoc_reclaim_lock);
+
+		ocfs2_do_suballoc_reclaim(osb, reclaim_work);
+		iput(reclaim_work->alloc_inode);
+		kfree(reclaim_work);
+	}
 }
 
 /*
@@ -2955,7 +3098,8 @@ static int _ocfs2_free_suballoc_bits(handle_t *handle,
 		goto bail;
 	}
 
-	_ocfs2_reclaim_suballoc_to_main(handle, alloc_inode, alloc_bh, group_bh);
+	ocfs2_queue_suballoc_reclaim(OCFS2_SB(alloc_inode->i_sb), alloc_inode,
+				     bg_blkno);
 
 bail:
 	brelse(group_bh);
diff --git a/fs/ocfs2/suballoc.h b/fs/ocfs2/suballoc.h
index bcf2ed4a8631..6042abc032f9 100644
--- a/fs/ocfs2/suballoc.h
+++ b/fs/ocfs2/suballoc.h
@@ -206,7 +206,7 @@ int ocfs2_lock_allocators(struct inode *inode, struct ocfs2_extent_tree *et,
 
 int ocfs2_test_inode_bit(struct ocfs2_super *osb, u64 blkno, int *res);
 
-
+void ocfs2_suballoc_reclaim_worker(struct work_struct *work);
 
 /*
  * The following two interfaces are for ocfs2_create_inode_in_orphan().
diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index 6a8092b65bb5..1e76b1d9fe0a 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -1784,6 +1784,9 @@ static int ocfs2_mount_volume(struct super_block *sb)
 out_system_inodes:
 	if (osb->local_alloc_state == OCFS2_LA_ENABLED)
 		ocfs2_shutdown_local_alloc(osb);
+	/* Drain pending suballoc reclaim work before the journal goes away */
+	if (osb->ocfs2_wq)
+		flush_workqueue(osb->ocfs2_wq);
 	ocfs2_release_system_inodes(osb);
 	/* before journal shutdown, we should release slot_info */
 	ocfs2_free_slot_info(osb);
@@ -1854,6 +1857,14 @@ static void ocfs2_dismount_volume(struct super_block *sb, int mnt_err)
 	if (osb->cconn)
 		ocfs2_super_unlock(osb, 1);
 
+	/*
+	 * Drain pending suballoc reclaim work while the system inodes and
+	 * the journal are still alive, since the worker needs to look up
+	 * the global bitmap inode and start a transaction.
+	 */
+	if (osb->ocfs2_wq)
+		flush_workqueue(osb->ocfs2_wq);
+
 	ocfs2_release_system_inodes(osb);
 
 	ocfs2_journal_shutdown(osb);
@@ -2140,6 +2151,11 @@ static int ocfs2_initialize_super(struct super_block *sb,
 	INIT_WORK(&osb->dquot_drop_work, ocfs2_drop_dquot_refs);
 	init_llist_head(&osb->dquot_drop_list);
 
+	spin_lock_init(&osb->os_suballoc_reclaim_lock);
+	INIT_LIST_HEAD(&osb->os_suballoc_reclaim_list);
+	INIT_WORK(&osb->os_suballoc_reclaim_work,
+		  ocfs2_suballoc_reclaim_worker);
+
 	/* get some pseudo constants for clustersize bits */
 	osb->s_clustersize_bits =
 		le32_to_cpu(di->id2.i_super.s_clustersize_bits);