From: Josef Bacik <josef@toxicpanda.com>
Date: Fri, 15 Nov 2019 15:43:06 -0500
Git-commit: 3e1740993e43116b3bc71b0aad1e6872f6ccf341
Patch-mainline: 5.5-rc1
Subject: [PATCH] btrfs: record all roots for rename exchange on a subvol
References: bsc#1161933

Testing with the new fsstress support for subvolumes uncovered a pretty
bad problem with rename exchange on subvolumes.  We're modifying two
different subvolumes, but we only start the transaction on one of them,
so the other one is not added to the dirty root list.  This is caught by
btrfs_cow_block() with a warning because the root has not been updated,
however if we do not modify this root again we'll end up pointing at an
invalid root because the root item is never updated.

Fix this by making sure we add the destination root to the trans list,
the same as we do with normal renames.  This fixes the corruption.

Fixes: cdd1fedf8261 ("btrfs: add support for RENAME_EXCHANGE and RENAME_WHITEOUT")
CC: stable@vger.kernel.org # 4.9+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
---
 fs/btrfs/inode.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 8ec46239a7ca..fe0ae52757b4 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -9473,6 +9473,9 @@ static int btrfs_rename_exchange(struct inode *old_dir,
 		goto out_notrans;
 	}
 
+	if (dest != root)
+		btrfs_record_root_in_trans(trans, dest);
+
 	/*
 	 * We need to find a free sequence number both in the source and
 	 * in the destination directory for the exchange.
-- 
2.16.4