ceph: remove the incorrect Fw reference check when dirtying pages

[ Upstream commit c08dfb1b49 ]

When doing the direct-io reads it will also try to mark pages dirty,
but for the read path it won't hold the Fw caps and there is case
will it get the Fw reference.

Fixes: 5dda377cf0 ("ceph: set i_head_snapc when getting CEPH_CAP_FILE_WR reference")
Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Patrick Donnelly <pdonnell@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

fs/ceph/addr.c

@@ -95,7 +95,6 @@ static int ceph_set_page_dirty(struct page *page)
 
 	/* dirty the head */
 	spin_lock(&ci->i_ceph_lock);
-	BUG_ON(ci->i_wr_ref == 0); // caller should hold Fw reference
 	if (__ceph_have_pending_cap_snap(ci)) {
 		struct ceph_cap_snap *capsnap =
 				list_last_entry(&ci->i_cap_snaps,