- Fix nullfs vnode reference leak in nullfs_reclaim_lowervp(). The

  null_hashget() obtains the reference on the nullfs vnode, which must
  be dropped.

- Fix a wart which existed from the introduction of the nullfs
  caching, do not unlock lower vnode in the nullfs_reclaim_lowervp().
  It should be innocent, but now it is also formally safe.  Inform the
  nullfs_reclaim() about this using the NULLV_NOUNLOCK flag set on
  nullfs inode.

- Add a callback to the upper filesystems for the lower vnode
  unlinking. When inactivating a nullfs vnode, check if the lower
  vnode was unlinked, indicated by nullfs flag NULLV_DROP or VV_NOSYNC
  on the lower vnode, and reclaim upper vnode if so.  This allows
  nullfs to purge cached vnodes for the unlinked lower vnode, avoiding
  excessive caching.

Reported by:	G??ran L??wkrantz <goran.lowkrantz@ismobile.com>
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks

1 files changed, 2 insertions, 0 deletions

diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
index 29cb7bd..a004ea0 100644
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -1846,6 +1846,7 @@ restart:
 		if (error)
 			goto out;
 #endif
+		vfs_notify_upper(vp, VFS_NOTIFY_UPPER_UNLINK);
 		error = VOP_REMOVE(nd.ni_dvp, vp, &nd.ni_cnd);
 #ifdef MAC
 out:
@@ -3825,6 +3826,7 @@ restart:
 			return (error);
 		goto restart;
 	}
+	vfs_notify_upper(vp, VFS_NOTIFY_UPPER_UNLINK);
 	error = VOP_RMDIR(nd.ni_dvp, nd.ni_vp, &nd.ni_cnd);
 	vn_finished_write(mp);
 out: