From 74c7ff1a0e940fd35af0390f31ec96767da5f8e2 Mon Sep 17 00:00:00 2001 From: Konstantin Belousov Date: Tue, 21 May 2013 11:31:56 +0000 Subject: [PATCH] Do not leak the NULLV_NOUNLOCK flag from the nullfs_unlink_lowervp(), for the case when the nullfs vnode is not reclaimed. Otherwise, later reclamation would not unlock the lower vnode. Reported by: antoine Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week --- sys/fs/nullfs/null_vfsops.c | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) diff --git a/sys/fs/nullfs/null_vfsops.c b/sys/fs/nullfs/null_vfsops.c index ad0223664aec..80824a5f714a 100644 --- a/sys/fs/nullfs/null_vfsops.c +++ b/sys/fs/nullfs/null_vfsops.c @@ -409,16 +409,28 @@ nullfs_unlink_lowervp(struct mount *mp, struct vnode *lowervp) vhold(vp); vunref(vp); - /* - * If vunref() dropped the last use reference on the nullfs - * vnode, it must be reclaimed, and its lock was split from - * the lower vnode lock. Need to do extra unlock before - * allowing the final vdrop() to free the vnode. - */ if (vp->v_usecount == 0) { + /* + * If vunref() dropped the last use reference on the + * nullfs vnode, it must be reclaimed, and its lock + * was split from the lower vnode lock. Need to do + * extra unlock before allowing the final vdrop() to + * free the vnode. + */ KASSERT((vp->v_iflag & VI_DOOMED) != 0, - ("not reclaimed %p", vp)); + ("not reclaimed nullfs vnode %p", vp)); VOP_UNLOCK(vp, 0); + } else { + /* + * Otherwise, the nullfs vnode still shares the lock + * with the lower vnode, and must not be unlocked. + * Also clear the NULLV_NOUNLOCK, the flag is not + * relevant for future reclamations. + */ + ASSERT_VOP_ELOCKED(vp, "unlink_lowervp"); + KASSERT((vp->v_iflag & VI_DOOMED) == 0, + ("reclaimed nullfs vnode %p", vp)); + xp->null_flags &= ~NULLV_NOUNLOCK; } vdrop(vp); }