directory for a znode. When the directory already exists, it returns a
referenced but unlocked vnode. When a directory does not yet exist, it
calls zfs_make_xattrdir() to create a new one. zfs_make_xattrdir() returns
the vnode both referenced and and locked and zfs_get_xattrdir() was leaking
this vnode lock to its callers. Fix this by dropping the vnode lock if
zfs_make_xattrdir() successfully creates a new extended attribute
directory.
Reviewed by: pjd
9fca7a854c