Btrfs: update drop progress before stopping snapshot dropping

Alex pointed out a problem and fix that exists in the drop one snapshot at a
time patch.  If we decide we need to exit for whatever reason (umount for
example) we will just exit the snapshot dropping without updating the drop
progress.  So the next time we go to resume we will BUG_ON() because we can't
find the extent we left off at because we never updated it.  This patch fixes
the problem.

Cc: stable@vger.kernel.org
Reported-by: Alex Lyakas <alex.btrfs@zadarastorage.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 0236de711989097bbf5191dbb6871281d840de22..a429704dd95f7d23ce1287fd27d4f0628610dfb5 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -7552,11 +7552,6 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
        wc->reada_count = BTRFS_NODEPTRS_PER_BLOCK(root);
 
        while (1) {
-               if (!for_reloc && btrfs_need_cleaner_sleep(root)) {
-                       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) {
@@ -7584,7 +7579,8 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
                }
 
                BUG_ON(wc->level == 0);
-               if (btrfs_should_end_transaction(trans, tree_root)) {
+               if (btrfs_should_end_transaction(trans, tree_root) ||
+                   (!for_reloc && btrfs_need_cleaner_sleep(root))) {
                        ret = btrfs_update_root(trans, tree_root,
                                                &root->root_key,
                                                root_item);
@@ -7595,6 +7591,12 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
                        }
 
                        btrfs_end_transaction_throttle(trans, tree_root);
+                       if (!for_reloc && btrfs_need_cleaner_sleep(root)) {
+                               pr_debug("btrfs: drop snapshot early exit\n");
+                               err = -EAGAIN;
+                               goto out_free;
+                       }
+
                        trans = btrfs_start_transaction(tree_root, 0);
                        if (IS_ERR(trans)) {
                                err = PTR_ERR(trans);