From: Filipe Manana <fdmanana@suse.com>
Date: Mon, 2 Mar 2015 20:53:52 +0000
Subject: [PATCH] Btrfs: send, add missing check for dead clone root

After we locked the root's root item, a concurrent snapshot deletion
call might have set the dead flag on it. So check if the dead flag
is set and abort if it is, just like we do for the parent root.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
---
 fs/btrfs/send.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index d6033f540cc7..6ec28f13659e 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -5855,7 +5855,8 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_)
 			clone_sources_to_rollback = i + 1;
 			spin_lock(&clone_root->root_item_lock);
 			clone_root->send_in_progress++;
-			if (!btrfs_root_readonly(clone_root)) {
+			if (!btrfs_root_readonly(clone_root) ||
+			    btrfs_root_dead(clone_root)) {
 				spin_unlock(&clone_root->root_item_lock);
 				srcu_read_unlock(&fs_info->subvol_srcu, index);
 				ret = -EPERM;