btrfs: qgroup: flush reservations during quota disable

[linux-2.6-microblaze.git] / fs / btrfs / qgroup.c

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 1c0efc1..a95c11a 100644 (file)
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -1286,6 +1286,38 @@ out:
        return ret;
 }
 
+/*
+ * It is possible to have outstanding ordered extents which reserved bytes
+ * before we disabled. We need to fully flush delalloc, ordered extents, and a
+ * commit to ensure that we don't leak such reservations, only to have them
+ * come back if we re-enable.
+ *
+ * - enable simple quotas
+ * - reserve space
+ * - release it, store rsv_bytes in OE
+ * - disable quotas
+ * - enable simple quotas (qgroup rsv are all 0)
+ * - OE finishes
+ * - run delayed refs
+ * - free rsv_bytes, resulting in miscounting or even underflow
+ */
+static int flush_reservations(struct btrfs_fs_info *fs_info)
+{
+       struct btrfs_trans_handle *trans;
+       int ret;
+
+       ret = btrfs_start_delalloc_roots(fs_info, LONG_MAX, false);
+       if (ret)
+               return ret;
+       btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
+       trans = btrfs_join_transaction(fs_info->tree_root);
+       if (IS_ERR(trans))
+               return PTR_ERR(trans);
+       btrfs_commit_transaction(trans);
+
+       return ret;
+}
+
 int btrfs_quota_disable(struct btrfs_fs_info *fs_info)
 {
        struct btrfs_root *quota_root;
@@ -1330,6 +1362,10 @@ int btrfs_quota_disable(struct btrfs_fs_info *fs_info)
        clear_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags);
        btrfs_qgroup_wait_for_completion(fs_info, false);
 
+       ret = flush_reservations(fs_info);
+       if (ret)
+               goto out_unlock_cleaner;
+
        /*
         * 1 For the root item
         *
@@ -1391,7 +1427,8 @@ out:
        if (ret && trans)
                btrfs_end_transaction(trans);
        else if (trans)
-               ret = btrfs_end_transaction(trans);
+               ret = btrfs_commit_transaction(trans);
+out_unlock_cleaner:
        mutex_unlock(&fs_info->cleaner_mutex);
 
        return ret;
@@ -4010,8 +4047,12 @@ static int __btrfs_qgroup_release_data(struct btrfs_inode *inode,
        int trace_op = QGROUP_RELEASE;
        int ret;
 
-       if (btrfs_qgroup_mode(inode->root->fs_info) == BTRFS_QGROUP_MODE_DISABLED)
-               return 0;
+       if (btrfs_qgroup_mode(inode->root->fs_info) == BTRFS_QGROUP_MODE_DISABLED) {
+               extent_changeset_init(&changeset);
+               return clear_record_extent_bits(&inode->io_tree, start,
+                                               start + len - 1,
+                                               EXTENT_QGROUP_RESERVED, &changeset);
+       }
 
        /* In release case, we shouldn't have @reserved */
        WARN_ON(!free && reserved);