t's dentry with the
dentry->d_inode->i_mutex held. This way, we'll hit the check for
d_unhashed in dentry_readdir, and won't be included in the
list of subdirs for /spu.

test: spufs-testsuite:tests/01-spu_create/07-destroy-vs-readdir-race

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
J