1 files changed, 12 insertions, 2 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 60f7cbe815e9..6f49b2872a64 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1000,10 +1000,20 @@ int btrfs_sync_fs(struct super_block *sb, int wait)
                          */
                         if (fs_info->pending_changes == 0)
                                 return 0;
+                        /*
+                         * A non-blocking test if the fs is frozen. We must not
+                         * start a new transaction here otherwise a deadlock
+                         * happens. The pending operations are delayed to the
+                         * next commit after thawing.
+                         */
+                        if (__sb_start_write(sb, SB_FREEZE_WRITE, false))
+                                __sb_end_write(sb, SB_FREEZE_WRITE);
+                        else
+                                return 0;
                         trans = btrfs_start_transaction(root, 0);
-                } else {
-                        return PTR_ERR(trans);
                 }
+                if (IS_ERR(trans))
+                        return PTR_ERR(trans);
         }
         return btrfs_commit_transaction(trans, root);
 }