commit 3c8f24225752fba30f7265202ce6092318ed9fac
author Josef Bacik <jbacik@fusionio.com> Mon Jul 15 11:57:06 2013 -0400
committer Josef Bacik <jbacik@fusionio.com> Fri Jul 19 15:07:03 2013 -0400
tree 203f2d8658a50529179d9e976e4fd93a263b90c8
parent b8a33fc7258f9e6e42b15571d0284b7c0ef0d0a9

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>

fs/btrfs/extent-tree.c

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 0236de7..a429704 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -7552,11 +7552,6 @@
 	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 @@
 		}
 
 		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 @@
 			}
 
 			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);