pnfs_nfs: fix _cancel_empty_pagelist

pnfs_nfs: fix _cancel_empty_pagelist

Orabug: 25308027

[ Upstream commit 5e3a98883e7ebdd1440f829a9e9dd5c3d2c5903b ]

pnfs_generic_commit_cancel_empty_pagelist calls nfs_commitdata_release,
but that is wrong: nfs_commitdata_release puts the open context, something
that isn't valid until nfs_init_commit is called, which is never the case
when pnfs_generic_commit_cancel_empty_pagelist is called.

This was introduced in "nfs: avoid race that crashes nfs_init_commit".

Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
(cherry picked from commit eba391c749fe8a47aea9de2e78fadc02434b5417)
Signed-off-by: Dhaval Giani <dhaval.giani@oracle.com>