From: Josef Bacik <josef@toxicpanda.com>
Date: Fri, 24 Jan 2020 09:32:29 -0500
Git-commit: bdf70b9e75f54a04941dc450abe61694e03fead4
Patch-mainline: 5.7-rc1
References: bsc#1176019
Subject: [PATCH] btrfs: hold a root ref in btrfs_get_dentry

Looking up the inode we need to search the root, make sure we hold a
reference on that root while we're doing the lookup.

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/export.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/btrfs/export.c b/fs/btrfs/export.c
index 08cd8c4a02a5..eba6c6d27bad 100644
--- a/fs/btrfs/export.c
+++ b/fs/btrfs/export.c
@@ -82,12 +82,17 @@ static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
 		err = PTR_ERR(root);
 		goto fail;
 	}
+	if (!btrfs_grab_fs_root(root)) {
+		err = -ENOENT;
+		goto fail;
+	}
 
 	key.objectid = objectid;
 	key.type = BTRFS_INODE_ITEM_KEY;
 	key.offset = 0;
 
 	inode = btrfs_iget(sb, &key, root);
+	btrfs_put_fs_root(root);
 	if (IS_ERR(inode)) {
 		err = PTR_ERR(inode);
 		goto fail;
-- 
2.26.2