---

yaml
---
r: 374833
b: refs/heads/master
c: 9d1a2a3
h: refs/heads/master
i:
  374831: 8f999d9
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 6841ebee6b02abe178abd30f40806e385cd96777
+refs/heads/master: 9d1a2a3ad59f7ae810bf04a5a05995bf2d79300c

trunk/fs/btrfs/disk-io.c

@@ -1658,15 +1658,20 @@ static int cleaner_kthread(void *arg)
 	struct btrfs_root *root = arg;
 
 	do {
+		int again = 0;
+
 		if (!(root->fs_info->sb->s_flags & MS_RDONLY) &&
-		    mutex_trylock(&root->fs_info->cleaner_mutex)) {
-			btrfs_run_delayed_iputs(root);
-			btrfs_clean_old_snapshots(root);
-			mutex_unlock(&root->fs_info->cleaner_mutex);
+		    down_read_trylock(&root->fs_info->sb->s_umount)) {
+			if (mutex_trylock(&root->fs_info->cleaner_mutex)) {
+				btrfs_run_delayed_iputs(root);
+				again = btrfs_clean_one_deleted_snapshot(root);
+				mutex_unlock(&root->fs_info->cleaner_mutex);
+			}
 			btrfs_run_defrag_inodes(root->fs_info);
+			up_read(&root->fs_info->sb->s_umount);
 		}
 
-		if (!try_to_freeze()) {
+		if (!try_to_freeze() && !again) {
 			set_current_state(TASK_INTERRUPTIBLE);
 			if (!kthread_should_stop())
 				schedule();
@@ -3358,8 +3363,8 @@ int btrfs_commit_super(struct btrfs_root *root)
 
 	mutex_lock(&root->fs_info->cleaner_mutex);
 	btrfs_run_delayed_iputs(root);
-	btrfs_clean_old_snapshots(root);
 	mutex_unlock(&root->fs_info->cleaner_mutex);
+	wake_up_process(root->fs_info->cleaner_kthread);
 
 	/* wait until ongoing cleanup work done */
 	down_write(&root->fs_info->cleanup_work_sem);

trunk/fs/btrfs/extent-tree.c

@@ -7286,6 +7286,8 @@ static noinline int walk_up_tree(struct btrfs_trans_handle *trans,
  * reference count by one. if update_ref is true, this function
  * also make sure backrefs for the shared block and all lower level
  * blocks are properly updated.
+ *
+ * If called with for_reloc == 0, may exit early with -EAGAIN
  */
 int btrfs_drop_snapshot(struct btrfs_root *root,
 			 struct btrfs_block_rsv *block_rsv, int update_ref,
@@ -7386,6 +7388,12 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
 	wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(root);
 
 	while (1) {
+		if (!for_reloc && btrfs_fs_closing(root->fs_info)) {
+			pr_debug("btrfs: drop snapshot early exit\n");
+			err = -EAGAIN;
+			goto out_end_trans;
+		}
+
 		ret = walk_down_tree(trans, root, path, wc);
 		if (ret < 0) {
 			err = ret;

trunk/fs/btrfs/relocation.c

@@ -4148,10 +4148,7 @@ int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
 
 	while (1) {
 		mutex_lock(&fs_info->cleaner_mutex);
-
-		btrfs_clean_old_snapshots(fs_info->tree_root);
 		ret = relocate_block_group(rc);
-
 		mutex_unlock(&fs_info->cleaner_mutex);
 		if (ret < 0) {
 			err = ret;

trunk/fs/btrfs/transaction.c

@@ -948,7 +948,7 @@ static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 int btrfs_add_dead_root(struct btrfs_root *root)
 {
 	spin_lock(&root->fs_info->trans_lock);
-	list_add(&root->root_list, &root->fs_info->dead_roots);
+	list_add_tail(&root->root_list, &root->fs_info->dead_roots);
 	spin_unlock(&root->fs_info->trans_lock);
 	return 0;
 }
@@ -1873,31 +1873,49 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 }
 
 /*
- * interface function to delete all the snapshots we have scheduled for deletion
+ * return < 0 if error
+ * 0 if there are no more dead_roots at the time of call
+ * 1 there are more to be processed, call me again
+ *
+ * The return value indicates there are certainly more snapshots to delete, but
+ * if there comes a new one during processing, it may return 0. We don't mind,
+ * because btrfs_commit_super will poke cleaner thread and it will process it a
+ * few seconds later.
  */
-int btrfs_clean_old_snapshots(struct btrfs_root *root)
+int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root)
 {
-	LIST_HEAD(list);
+	int ret;
 	struct btrfs_fs_info *fs_info = root->fs_info;
 
+	if (fs_info->sb->s_flags & MS_RDONLY) {
+		pr_debug("btrfs: cleaner called for RO fs!\n");
+		return 0;
+	}
+
 	spin_lock(&fs_info->trans_lock);
-	list_splice_init(&fs_info->dead_roots, &list);
+	if (list_empty(&fs_info->dead_roots)) {
+		spin_unlock(&fs_info->trans_lock);
+		return 0;
+	}
+	root = list_first_entry(&fs_info->dead_roots,
+			struct btrfs_root, root_list);
+	list_del(&root->root_list);
 	spin_unlock(&fs_info->trans_lock);
 
-	while (!list_empty(&list)) {
-		int ret;
-
-		root = list_entry(list.next, struct btrfs_root, root_list);
-		list_del(&root->root_list);
+	pr_debug("btrfs: cleaner removing %llu\n",
+			(unsigned long long)root->objectid);
 
-		btrfs_kill_all_delayed_nodes(root);
+	btrfs_kill_all_delayed_nodes(root);
 
-		if (btrfs_header_backref_rev(root->node) <
-		    BTRFS_MIXED_BACKREF_REV)
-			ret = btrfs_drop_snapshot(root, NULL, 0, 0);
-		else
-			ret =btrfs_drop_snapshot(root, NULL, 1, 0);
-		BUG_ON(ret < 0);
-	}
-	return 0;
+	if (btrfs_header_backref_rev(root->node) <
+			BTRFS_MIXED_BACKREF_REV)
+		ret = btrfs_drop_snapshot(root, NULL, 0, 0);
+	else
+		ret = btrfs_drop_snapshot(root, NULL, 1, 0);
+	/*
+	 * If we encounter a transaction abort during snapshot cleaning, we
+	 * don't want to crash here
+	 */
+	BUG_ON(ret < 0 && ret != -EAGAIN && ret != -EROFS);
+	return 1;
 }

trunk/fs/btrfs/transaction.h

@@ -123,7 +123,7 @@ int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 
 int btrfs_add_dead_root(struct btrfs_root *root);
 int btrfs_defrag_root(struct btrfs_root *root);
-int btrfs_clean_old_snapshots(struct btrfs_root *root);
+int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root);
 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 			     struct btrfs_root *root);
 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,