[PATCH 3.16.y-ckt 44/71] Btrfs: send, add missing check for dead clone root

[Luis Henriques]

3.16.7-ckt14 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Filipe Manana <fdmanana at suse.com>

commit 5cc2b17e80cf5770f2e585c2d90fd8af1b901258 upstream.

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 at suse.com>
Reviewed-by: David Sterba <dsterba at suse.cz>
Signed-off-by: Chris Mason <clm at fb.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.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 6528aa662181..61205f6db114 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -5647,7 +5647,8 @@ 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;