linux-wandboard

Btrfs: pass the correct root to lookup_free_space_inode()

Free space items are located in tree of tree roots, not in the extent
tree.  It didn't pop up because lookup_free_space_inode() grabs the
inode all the time instead of actually searching the tree.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>