ceph: use ihold when we already have an inode ref

We should use ihold whenever we already have a stable inode ref, even
when we aren't holding i_lock.  This avoids adding new and unnecessary
locking dependencies.

Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/export.c b/fs/ceph/export.c
index a610d3d..f67b687 100644
--- a/fs/ceph/export.c
+++ b/fs/ceph/export.c
@@ -109,7 +109,7 @@
 		err = ceph_mdsc_do_request(mdsc, NULL, req);
 		inode = req->r_target_inode;
 		if (inode)
-			igrab(inode);
+			ihold(inode);
 		ceph_mdsc_put_request(req);
 		if (!inode)
 			return ERR_PTR(-ESTALE);
@@ -167,7 +167,7 @@
 		err = ceph_mdsc_do_request(mdsc, NULL, req);
 		inode = req->r_target_inode;
 		if (inode)
-			igrab(inode);
+			ihold(inode);
 		ceph_mdsc_put_request(req);
 		if (!inode)
 			return ERR_PTR(err ? err : -ESTALE);