From: Josef Bacik <josef@toxicpanda.com>
Date: Fri, 24 Jan 2020 09:32:31 -0500
Git-commit: 8727002f79095d006a642f4f1f42372e84a77082
Patch-mainline: 5.7-rc1
References: bsc#1176019
Subject: [PATCH] btrfs: hold a ref on the root in fixup_tree_root_location

Looking up the inode from an arbitrary tree means we need to hold a ref
on that root.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
---
 fs/btrfs/inode.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index d105d4d9e9aa..324fc79174e6 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5158,6 +5158,10 @@ static int fixup_tree_root_location(struct btrfs_fs_info *fs_info,
 		err = PTR_ERR(new_root);
 		goto out;
 	}
+	if (!btrfs_grab_fs_root(new_root)) {
+		err = -ENOENT;
+		goto out;
+	}
 
 	*sub_root = new_root;
 	location->objectid = btrfs_root_dirid(&new_root->root_item);
@@ -5400,6 +5404,8 @@ struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry)
 	} else {
 		inode = btrfs_iget(dir->i_sb, &location, sub_root);
 	}
+	if (root != sub_root)
+		btrfs_put_fs_root(sub_root);
 	srcu_read_unlock(&fs_info->subvol_srcu, index);
 
 	if (!IS_ERR(inode) && root != sub_root) {
-- 
2.26.2