Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs

Pull btrfs fixes from Chris Mason:
 "These are scattered fixes and one performance improvement.  The
  biggest functional change is in how we throttle metadata changes.  The
  new code bumps our average file creation rate up by ~13% in fs_mark,
  and lowers CPU usage.

  Stefan bisected out a regression in our allocation code that made
  balance loop on extents larger than 256MB."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: improve the delayed inode throttling
  Btrfs: fix a mismerge in btrfs_balance()
  Btrfs: enforce min_bytes parameter during extent allocation
  Btrfs: allow running defrag in parallel to administrative tasks
  Btrfs: avoid deadlock on transaction waiting list
  Btrfs: do not BUG_ON on aborted situation
  Btrfs: do not BUG_ON in prepare_to_reloc
  Btrfs: free all recorded tree blocks on error
  Btrfs: build up error handling for merge_reloc_roots
  Btrfs: check for NULL pointer in updating reloc roots
  Btrfs: fix unclosed transaction handler when the async transaction commitment fails
  Btrfs: fix wrong handle at error path of create_snapshot() when the commit fails
  Btrfs: use set_nlink if our i_nlink is 0

9 files changed, 221 insertions, 130 deletions

diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index 0b278b117cbe..14fce27b4780 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -22,8 +22,9 @@
 #include "disk-io.h"
 #include "transaction.h"
 
-#define BTRFS_DELAYED_WRITEBACK		400
-#define BTRFS_DELAYED_BACKGROUND	100
+#define BTRFS_DELAYED_WRITEBACK		512
+#define BTRFS_DELAYED_BACKGROUND	128
+#define BTRFS_DELAYED_BATCH		16
 
 static struct kmem_cache *delayed_node_cache;
 
@@ -494,6 +495,15 @@ static int __btrfs_add_delayed_deletion_item(struct btrfs_delayed_node *node,
 					BTRFS_DELAYED_DELETION_ITEM);
 }
 
+static void finish_one_item(struct btrfs_delayed_root *delayed_root)
+{
+	int seq = atomic_inc_return(&delayed_root->items_seq);
+	if ((atomic_dec_return(&delayed_root->items) <
+	    BTRFS_DELAYED_BACKGROUND || seq % BTRFS_DELAYED_BATCH == 0) &&
+	    waitqueue_active(&delayed_root->wait))
+		wake_up(&delayed_root->wait);
+}
+
 static void __btrfs_remove_delayed_item(struct btrfs_delayed_item *delayed_item)
 {
 	struct rb_root *root;
@@ -512,10 +522,8 @@ static void __btrfs_remove_delayed_item(struct btrfs_delayed_item *delayed_item)
 
 	rb_erase(&delayed_item->rb_node, root);
 	delayed_item->delayed_node->count--;
-	if (atomic_dec_return(&delayed_root->items) <
-	    BTRFS_DELAYED_BACKGROUND &&
-	    waitqueue_active(&delayed_root->wait))
-		wake_up(&delayed_root->wait);
+
+	finish_one_item(delayed_root);
 }
 
 static void btrfs_release_delayed_item(struct btrfs_delayed_item *item)
@@ -1056,10 +1064,7 @@ static void btrfs_release_delayed_inode(struct btrfs_delayed_node *delayed_node)
 		delayed_node->count--;
 
 		delayed_root = delayed_node->root->fs_info->delayed_root;
-		if (atomic_dec_return(&delayed_root->items) <
-		    BTRFS_DELAYED_BACKGROUND &&
-		    waitqueue_active(&delayed_root->wait))
-			wake_up(&delayed_root->wait);
+		finish_one_item(delayed_root);
 	}
 }
 
@@ -1304,35 +1309,44 @@ void btrfs_remove_delayed_node(struct inode *inode)
 	btrfs_release_delayed_node(delayed_node);
 }
 
-struct btrfs_async_delayed_node {
-	struct btrfs_root *root;
-	struct btrfs_delayed_node *delayed_node;
+struct btrfs_async_delayed_work {
+	struct btrfs_delayed_root *delayed_root;
+	int nr;
 	struct btrfs_work work;
 };
 
-static void btrfs_async_run_delayed_node_done(struct btrfs_work *work)
+static void btrfs_async_run_delayed_root(struct btrfs_work *work)
 {
-	struct btrfs_async_delayed_node *async_node;
+	struct btrfs_async_delayed_work *async_work;
+	struct btrfs_delayed_root *delayed_root;
 	struct btrfs_trans_handle *trans;
 	struct btrfs_path *path;
 	struct btrfs_delayed_node *delayed_node = NULL;
 	struct btrfs_root *root;
 	struct btrfs_block_rsv *block_rsv;
-	int need_requeue = 0;
+	int total_done = 0;
 
-	async_node = container_of(work, struct btrfs_async_delayed_node, work);
+	async_work = container_of(work, struct btrfs_async_delayed_work, work);
+	delayed_root = async_work->delayed_root;
 
 	path = btrfs_alloc_path();
 	if (!path)
 		goto out;
-	path->leave_spinning = 1;
 
-	delayed_node = async_node->delayed_node;
+again:
+	if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND / 2)
+		goto free_path;
+
+	delayed_node = btrfs_first_prepared_delayed_node(delayed_root);
+	if (!delayed_node)
+		goto free_path;
+
+	path->leave_spinning = 1;
 	root = delayed_node->root;
 
 	trans = btrfs_join_transaction(root);
 	if (IS_ERR(trans))
-		goto free_path;
+		goto release_path;
 
 	block_rsv = trans->block_rsv;
 	trans->block_rsv = &root->fs_info->delayed_block_rsv;
@@ -1363,57 +1377,47 @@ static void btrfs_async_run_delayed_node_done(struct btrfs_work *work)
 	 * Task1 will sleep until the transaction is commited.
 	 */
 	mutex_lock(&delayed_node->mutex);
-	if (delayed_node->count)
-		need_requeue = 1;
-	else
-		btrfs_dequeue_delayed_node(root->fs_info->delayed_root,
-					   delayed_node);
+	btrfs_dequeue_delayed_node(root->fs_info->delayed_root, delayed_node);
 	mutex_unlock(&delayed_node->mutex);
 
 	trans->block_rsv = block_rsv;
 	btrfs_end_transaction_dmeta(trans, root);
 	btrfs_btree_balance_dirty_nodelay(root);
+
+release_path:
+	btrfs_release_path(path);
+	total_done++;
+
+	btrfs_release_prepared_delayed_node(delayed_node);
+	if (async_work->nr == 0 || total_done < async_work->nr)
+		goto again;
+
 free_path:
 	btrfs_free_path(path);
 out:
-	if (need_requeue)
-		btrfs_requeue_work(&async_node->work);
-	else {
-		btrfs_release_prepared_delayed_node(delayed_node);
-		kfree(async_node);
-	}
+	wake_up(&delayed_root->wait);
+	kfree(async_work);
 }
 
+
 static int btrfs_wq_run_delayed_node(struct btrfs_delayed_root *delayed_root,
-				     struct btrfs_root *root, int all)
+				     struct btrfs_root *root, int nr)
 {
-	struct btrfs_async_delayed_node *async_node;
-	struct btrfs_delayed_node *curr;
-	int count = 0;
+	struct btrfs_async_delayed_work *async_work;
 
-again:
-	curr = btrfs_first_prepared_delayed_node(delayed_root);
-	if (!curr)
+	if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND)
 		return 0;
 
-	async_node = kmalloc(sizeof(*async_node), GFP_NOFS);
-	if (!async_node) {
-		btrfs_release_prepared_delayed_node(curr);
+	async_work = kmalloc(sizeof(*async_work), GFP_NOFS);
+	if (!async_work)
 		return -ENOMEM;
-	}
-
-	async_node->root = root;
-	async_node->delayed_node = curr;
-
-	async_node->work.func = btrfs_async_run_delayed_node_done;
-	async_node->work.flags = 0;
 
-	btrfs_queue_worker(&root->fs_info->delayed_workers, &async_node->work);
-	count++;
-
-	if (all || count < 4)
-		goto again;
+	async_work->delayed_root = delayed_root;
+	async_work->work.func = btrfs_async_run_delayed_root;
+	async_work->work.flags = 0;
+	async_work->nr = nr;
 
+	btrfs_queue_worker(&root->fs_info->delayed_workers, &async_work->work);
 	return 0;
 }
 
@@ -1424,30 +1428,55 @@ void btrfs_assert_delayed_root_empty(struct btrfs_root *root)
 	WARN_ON(btrfs_first_delayed_node(delayed_root));
 }
 
+static int refs_newer(struct btrfs_delayed_root *delayed_root,
+		      int seq, int count)
+{
+	int val = atomic_read(&delayed_root->items_seq);
+
+	if (val < seq || val >= seq + count)
+		return 1;
+	return 0;
+}
+
 void btrfs_balance_delayed_items(struct btrfs_root *root)
 {
 	struct btrfs_delayed_root *delayed_root;
+	int seq;
 
 	delayed_root = btrfs_get_delayed_root(root);
 
 	if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND)
 		return;
 
+	seq = atomic_read(&delayed_root->items_seq);
+
 	if (atomic_read(&delayed_root->items) >= BTRFS_DELAYED_WRITEBACK) {
 		int ret;
-		ret = btrfs_wq_run_delayed_node(delayed_root, root, 1);
+		DEFINE_WAIT(__wait);
+
+		ret = btrfs_wq_run_delayed_node(delayed_root, root, 0);
 		if (ret)
 			return;
 
-		wait_event_interruptible_timeout(
-				delayed_root->wait,
-				(atomic_read(&delayed_root->items) <
-				 BTRFS_DELAYED_BACKGROUND),
-				HZ);
-		return;
+		while (1) {
+			prepare_to_wait(&delayed_root->wait, &__wait,
+					TASK_INTERRUPTIBLE);
+
+			if (refs_newer(delayed_root, seq,
+				       BTRFS_DELAYED_BATCH) ||
+			    atomic_read(&delayed_root->items) <
+			    BTRFS_DELAYED_BACKGROUND) {
+				break;
+			}
+			if (!signal_pending(current))
+				schedule();
+			else
+				break;
+		}
+		finish_wait(&delayed_root->wait, &__wait);
 	}
 
-	btrfs_wq_run_delayed_node(delayed_root, root, 0);
+	btrfs_wq_run_delayed_node(delayed_root, root, BTRFS_DELAYED_BATCH);
 }
 
 /* Will return 0 or -ENOMEM */
diff --git a/fs/btrfs/delayed-inode.h b/fs/btrfs/delayed-inode.h
index 78b6ad0fc669..1d5c5f7abe3e 100644
--- a/fs/btrfs/delayed-inode.h
+++ b/fs/btrfs/delayed-inode.h
@@ -43,6 +43,7 @@ struct btrfs_delayed_root {
 	 */
 	struct list_head prepare_list;
 	atomic_t items;		/* for delayed items */
+	atomic_t items_seq;	/* for delayed items */
 	int nodes;		/* for delayed nodes */
 	wait_queue_head_t wait;
 };
@@ -86,6 +87,7 @@ static inline void btrfs_init_delayed_root(
 				struct btrfs_delayed_root *delayed_root)
 {
 	atomic_set(&delayed_root->items, 0);
+	atomic_set(&delayed_root->items_seq, 0);
 	delayed_root->nodes = 0;
 	spin_lock_init(&delayed_root->lock);
 	init_waitqueue_head(&delayed_root->wait);
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 02369a3c162e..7d84651e850b 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -62,7 +62,7 @@ static void btrfs_destroy_ordered_operations(struct btrfs_transaction *t,
 static void btrfs_destroy_ordered_extents(struct btrfs_root *root);
 static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans,
 				      struct btrfs_root *root);
-static void btrfs_destroy_pending_snapshots(struct btrfs_transaction *t);
+static void btrfs_evict_pending_snapshots(struct btrfs_transaction *t);
 static void btrfs_destroy_delalloc_inodes(struct btrfs_root *root);
 static int btrfs_destroy_marked_extents(struct btrfs_root *root,
 					struct extent_io_tree *dirty_pages,
@@ -3687,7 +3687,7 @@ int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans,
 	return ret;
 }
 
-static void btrfs_destroy_pending_snapshots(struct btrfs_transaction *t)
+static void btrfs_evict_pending_snapshots(struct btrfs_transaction *t)
 {
 	struct btrfs_pending_snapshot *snapshot;
 	struct list_head splice;
@@ -3700,10 +3700,8 @@ static void btrfs_destroy_pending_snapshots(struct btrfs_transaction *t)
 		snapshot = list_entry(splice.next,
 				      struct btrfs_pending_snapshot,
 				      list);
-
+		snapshot->error = -ECANCELED;
 		list_del_init(&snapshot->list);
-
-		kfree(snapshot);
 	}
 }
 
@@ -3840,6 +3838,8 @@ void btrfs_cleanup_one_transaction(struct btrfs_transaction *cur_trans,
 	cur_trans->blocked = 1;
 	wake_up(&root->fs_info->transaction_blocked_wait);
 
+	btrfs_evict_pending_snapshots(cur_trans);
+
 	cur_trans->blocked = 0;
 	wake_up(&root->fs_info->transaction_wait);
 
@@ -3849,8 +3849,6 @@ void btrfs_cleanup_one_transaction(struct btrfs_transaction *cur_trans,
 	btrfs_destroy_delayed_inodes(root);
 	btrfs_assert_delayed_root_empty(root);
 
-	btrfs_destroy_pending_snapshots(cur_trans);
-
 	btrfs_destroy_marked_extents(root, &cur_trans->dirty_pages,
 				     EXTENT_DIRTY);
 	btrfs_destroy_pinned_extent(root,
@@ -3894,6 +3892,8 @@ int btrfs_cleanup_transaction(struct btrfs_root *root)
 		if (waitqueue_active(&root->fs_info->transaction_blocked_wait))
 			wake_up(&root->fs_info->transaction_blocked_wait);
 
+		btrfs_evict_pending_snapshots(t);
+
 		t->blocked = 0;
 		smp_mb();
 		if (waitqueue_active(&root->fs_info->transaction_wait))
@@ -3907,8 +3907,6 @@ int btrfs_cleanup_transaction(struct btrfs_root *root)
 		btrfs_destroy_delayed_inodes(root);
 		btrfs_assert_delayed_root_empty(root);
 
-		btrfs_destroy_pending_snapshots(t);
-
 		btrfs_destroy_delalloc_inodes(root);
 
 		spin_lock(&root->fs_info->trans_lock);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index c226daefd65d..d1470adca8f8 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8502,6 +8502,7 @@ static int __btrfs_prealloc_file_range(struct inode *inode, int mode,
 	struct btrfs_key ins;
 	u64 cur_offset = start;
 	u64 i_size;
+	u64 cur_bytes;
 	int ret = 0;
 	bool own_trans = true;
 
@@ -8516,8 +8517,9 @@ static int __btrfs_prealloc_file_range(struct inode *inode, int mode,
 			}
 		}
 
-		ret = btrfs_reserve_extent(trans, root,
-					   min(num_bytes, 256ULL * 1024 * 1024),
+		cur_bytes = min(num_bytes, 256ULL * 1024 * 1024);
+		cur_bytes = max(cur_bytes, min_size);
+		ret = btrfs_reserve_extent(trans, root, cur_bytes,
 					   min_size, 0, *alloc_hint, &ins, 1);
 		if (ret) {
 			if (own_trans)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index c83086fdda05..2c02310ff2d9 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -527,6 +527,8 @@ fail:
 	if (async_transid) {
 		*async_transid = trans->transid;
 		err = btrfs_commit_transaction_async(trans, root, 1);
+		if (err)
+			err = btrfs_commit_transaction(trans, root);
 	} else {
 		err = btrfs_commit_transaction(trans, root);
 	}
@@ -592,16 +594,14 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir,
 		*async_transid = trans->transid;
 		ret = btrfs_commit_transaction_async(trans,
 				     root->fs_info->extent_root, 1);
+		if (ret)
+			ret = btrfs_commit_transaction(trans, root);
 	} else {
 		ret = btrfs_commit_transaction(trans,
 					       root->fs_info->extent_root);
 	}
-	if (ret) {
-		/* cleanup_transaction has freed this for us */
-		if (trans->aborted)
-			pending_snapshot = NULL;
+	if (ret)
 		goto fail;
-	}
 
 	ret = pending_snapshot->error;
 	if (ret)
@@ -2245,13 +2245,6 @@ static int btrfs_ioctl_defrag(struct file *file, void __user *argp)
 	if (ret)
 		return ret;
 
-	if (atomic_xchg(&root->fs_info->mutually_exclusive_operation_running,
-			1)) {
-		pr_info("btrfs: dev add/delete/balance/replace/resize operation in progress\n");
-		mnt_drop_write_file(file);
-		return -EINVAL;
-	}
-
 	if (btrfs_root_readonly(root)) {
 		ret = -EROFS;
 		goto out;
@@ -2306,7 +2299,6 @@ static int btrfs_ioctl_defrag(struct file *file, void __user *argp)
 		ret = -EINVAL;
 	}
 out:
-	atomic_set(&root->fs_info->mutually_exclusive_operation_running, 0);
 	mnt_drop_write_file(file);
 	return ret;
 }
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 50695dc5e2ab..b67171e6d688 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -1269,6 +1269,8 @@ static int __update_reloc_root(struct btrfs_root *root, int del)
 	}
 	spin_unlock(&rc->reloc_root_tree.lock);
 
+	if (!node)
+		return 0;
 	BUG_ON((struct btrfs_root *)node->data != root);
 
 	if (!del) {
@@ -2238,13 +2240,28 @@ again:
 }
 
 static noinline_for_stack
+void free_reloc_roots(struct list_head *list)
+{
+	struct btrfs_root *reloc_root;
+
+	while (!list_empty(list)) {
+		reloc_root = list_entry(list->next, struct btrfs_root,
+					root_list);
+		__update_reloc_root(reloc_root, 1);
+		free_extent_buffer(reloc_root->node);
+		free_extent_buffer(reloc_root->commit_root);
+		kfree(reloc_root);
+	}
+}
+
+static noinline_for_stack
 int merge_reloc_roots(struct reloc_control *rc)
 {
 	struct btrfs_root *root;
 	struct btrfs_root *reloc_root;
 	LIST_HEAD(reloc_roots);
 	int found = 0;
-	int ret;
+	int ret = 0;
 again:
 	root = rc->extent_root;
 
@@ -2270,20 +2287,33 @@ again:
 			BUG_ON(root->reloc_root != reloc_root);
 
 			ret = merge_reloc_root(rc, root);
-			BUG_ON(ret);
+			if (ret)
+				goto out;
 		} else {
 			list_del_init(&reloc_root->root_list);
 		}
 		ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
-		BUG_ON(ret < 0);
+		if (ret < 0) {
+			if (list_empty(&reloc_root->root_list))
+				list_add_tail(&reloc_root->root_list,
+					      &reloc_roots);
+			goto out;
+		}
 	}
 
 	if (found) {
 		found = 0;
 		goto again;
 	}
+out:
+	if (ret) {
+		btrfs_std_error(root->fs_info, ret);
+		if (!list_empty(&reloc_roots))
+			free_reloc_roots(&reloc_roots);
+	}
+
 	BUG_ON(!RB_EMPTY_ROOT(&rc->reloc_root_tree.rb_root));
-	return 0;
+	return ret;
 }
 
 static void free_block_list(struct rb_root *blocks)
@@ -2818,8 +2848,10 @@ int relocate_tree_blocks(struct btrfs_trans_handle *trans,
 	int err = 0;
 
 	path = btrfs_alloc_path();
-	if (!path)
-		return -ENOMEM;
+	if (!path) {
+		err = -ENOMEM;
+		goto out_path;
+	}
 
 	rb_node = rb_first(blocks);
 	while (rb_node) {
@@ -2858,10 +2890,11 @@ int relocate_tree_blocks(struct btrfs_trans_handle *trans,
 		rb_node = rb_next(rb_node);
 	}
 out:
-	free_block_list(blocks);
 	err = finish_pending_nodes(trans, rc, path, err);
 
 	btrfs_free_path(path);
+out_path:
+	free_block_list(blocks);
 	return err;
 }
 
@@ -3698,7 +3731,15 @@ int prepare_to_relocate(struct reloc_control *rc)
 	set_reloc_control(rc);
 
 	trans = btrfs_join_transaction(rc->extent_root);
-	BUG_ON(IS_ERR(trans));
+	if (IS_ERR(trans)) {
+		unset_reloc_control(rc);
+		/*
+		 * extent tree is not a ref_cow tree and has no reloc_root to
+		 * cleanup.  And callers are responsible to free the above
+		 * block rsv.
+		 */
+		return PTR_ERR(trans);
+	}
 	btrfs_commit_transaction(trans, rc->extent_root);
 	return 0;
 }
@@ -3730,7 +3771,11 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
 	while (1) {
 		progress++;
 		trans = btrfs_start_transaction(rc->extent_root, 0);
-		BUG_ON(IS_ERR(trans));
+		if (IS_ERR(trans)) {
+			err = PTR_ERR(trans);
+			trans = NULL;
+			break;
+		}
 restart:
 		if (update_backref_cache(trans, &rc->backref_cache)) {
 			btrfs_end_transaction(trans, rc->extent_root);
@@ -4264,14 +4309,9 @@ int btrfs_recover_relocation(struct btrfs_root *root)
 out_free:
 	kfree(rc);
 out:
-	while (!list_empty(&reloc_roots)) {
-		reloc_root = list_entry(reloc_roots.next,
-					struct btrfs_root, root_list);
-		list_del(&reloc_root->root_list);
-		free_extent_buffer(reloc_root->node);
-		free_extent_buffer(reloc_root->commit_root);
-		kfree(reloc_root);
-	}
+	if (!list_empty(&reloc_roots))
+		free_reloc_roots(&reloc_roots);
+
 	btrfs_free_path(path);
 
 	if (err == 0) {
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index e52da6fb1165..9250b9c4f01e 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1052,7 +1052,12 @@ int btrfs_defrag_root(struct btrfs_root *root)
 
 /*
  * new snapshots need to be created at a very specific time in the
- * transaction commit.  This does the actual creation
+ * transaction commit.  This does the actual creation.
+ *
+ * Note:
+ * If the error which may affect the commitment of the current transaction
+ * happens, we should return the error number. If the error which just affect
+ * the creation of the pending snapshots, just return 0.
  */
 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 				   struct btrfs_fs_info *fs_info,
@@ -1071,7 +1076,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 	struct extent_buffer *tmp;
 	struct extent_buffer *old;
 	struct timespec cur_time = CURRENT_TIME;
-	int ret;
+	int ret = 0;
 	u64 to_reserve = 0;
 	u64 index = 0;
 	u64 objectid;
@@ -1080,40 +1085,36 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 
 	path = btrfs_alloc_path();
 	if (!path) {
-		ret = pending->error = -ENOMEM;
-		return ret;
+		pending->error = -ENOMEM;
+		return 0;
 	}
 
 	new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 	if (!new_root_item) {
-		ret = pending->error = -ENOMEM;
+		pending->error = -ENOMEM;
 		goto root_item_alloc_fail;
 	}
 
-	ret = btrfs_find_free_objectid(tree_root, &objectid);
-	if (ret) {
-		pending->error = ret;
+	pending->error = btrfs_find_free_objectid(tree_root, &objectid);
+	if (pending->error)
 		goto no_free_objectid;
-	}
 
 	btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
 
 	if (to_reserve > 0) {
-		ret = btrfs_block_rsv_add(root, &pending->block_rsv,
-					  to_reserve,
-					  BTRFS_RESERVE_NO_FLUSH);
-		if (ret) {
-			pending->error = ret;
+		pending->error = btrfs_block_rsv_add(root,
+						     &pending->block_rsv,
+						     to_reserve,
+						     BTRFS_RESERVE_NO_FLUSH);
+		if (pending->error)
 			goto no_free_objectid;
-		}
 	}
 
-	ret = btrfs_qgroup_inherit(trans, fs_info, root->root_key.objectid,
-				   objectid, pending->inherit);
-	if (ret) {
-		pending->error = ret;
+	pending->error = btrfs_qgroup_inherit(trans, fs_info,
+					      root->root_key.objectid,
+					      objectid, pending->inherit);
+	if (pending->error)
 		goto no_free_objectid;
-	}
 
 	key.objectid = objectid;
 	key.offset = (u64)-1;
@@ -1141,7 +1142,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 					 dentry->d_name.len, 0);
 	if (dir_item != NULL && !IS_ERR(dir_item)) {
 		pending->error = -EEXIST;
-		goto fail;
+		goto dir_item_existed;
 	} else if (IS_ERR(dir_item)) {
 		ret = PTR_ERR(dir_item);
 		btrfs_abort_transaction(trans, root, ret);
@@ -1272,6 +1273,8 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 	if (ret)
 		btrfs_abort_transaction(trans, root, ret);
 fail:
+	pending->error = ret;
+dir_item_existed:
 	trans->block_rsv = rsv;
 	trans->bytes_reserved = 0;
 no_free_objectid:
@@ -1287,12 +1290,17 @@ root_item_alloc_fail:
 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
 					     struct btrfs_fs_info *fs_info)
 {
-	struct btrfs_pending_snapshot *pending;
+	struct btrfs_pending_snapshot *pending, *next;
 	struct list_head *head = &trans->transaction->pending_snapshots;
+	int ret = 0;
 
-	list_for_each_entry(pending, head, list)
-		create_pending_snapshot(trans, fs_info, pending);
-	return 0;
+	list_for_each_entry_safe(pending, next, head, list) {
+		list_del(&pending->list);
+		ret = create_pending_snapshot(trans, fs_info, pending);
+		if (ret)
+			break;
+	}
+	return ret;
 }
 
 static void update_super_roots(struct btrfs_root *root)
@@ -1448,6 +1456,13 @@ static void cleanup_transaction(struct btrfs_trans_handle *trans,
 	btrfs_abort_transaction(trans, root, err);
 
 	spin_lock(&root->fs_info->trans_lock);
+
+	if (list_empty(&cur_trans->list)) {
+		spin_unlock(&root->fs_info->trans_lock);
+		btrfs_end_transaction(trans, root);
+		return;
+	}
+
 	list_del_init(&cur_trans->list);
 	if (cur_trans == root->fs_info->running_transaction) {
 		root->fs_info->trans_no_join = 1;
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index c7ef569eb22a..451fad96ecd1 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -1382,7 +1382,10 @@ static noinline int link_to_fixup_dir(struct btrfs_trans_handle *trans,
 
 	btrfs_release_path(path);
 	if (ret == 0) {
-		btrfs_inc_nlink(inode);
+		if (!inode->i_nlink)
+			set_nlink(inode, 1);
+		else
+			btrfs_inc_nlink(inode);
 		ret = btrfs_update_inode(trans, root, inode);
 	} else if (ret == -EEXIST) {
 		ret = 0;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 35bb2d4ed29f..6b9cff42265d 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2379,7 +2379,11 @@ static int btrfs_relocate_chunk(struct btrfs_root *root,
 		return ret;
 
 	trans = btrfs_start_transaction(root, 0);
-	BUG_ON(IS_ERR(trans));
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		btrfs_std_error(root->fs_info, ret);
+		return ret;
+	}
 
 	lock_chunks(root);
 
@@ -3050,7 +3054,8 @@ static void __cancel_balance(struct btrfs_fs_info *fs_info)
 
 	unset_balance_control(fs_info);
 	ret = del_balance_item(fs_info->tree_root);
-	BUG_ON(ret);
+	if (ret)
+		btrfs_std_error(fs_info, ret);
 
 	atomic_set(&fs_info->mutually_exclusive_operation_running, 0);
 }
@@ -3230,6 +3235,11 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
 		update_ioctl_balance_args(fs_info, 0, bargs);
 	}
 
+	if ((ret && ret != -ECANCELED && ret != -ENOSPC) ||
+	    balance_need_close(fs_info)) {
+		__cancel_balance(fs_info);
+	}
+
 	wake_up(&fs_info->balance_wait_q);
 
 	return ret;