From patchwork Thu Jun 3 16:52:30 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 453354 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B573CC47097 for ; Thu, 3 Jun 2021 16:52:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 97747613B1 for ; Thu, 3 Jun 2021 16:52:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230121AbhFCQyT (ORCPT ); Thu, 3 Jun 2021 12:54:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:37066 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229692AbhFCQyS (ORCPT ); Thu, 3 Jun 2021 12:54:18 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C4136613F1; Thu, 3 Jun 2021 16:52:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622739154; bh=aiPLjXN+yoY1Dh8Obp48uNB6EnWsFHSVOMuySQQjySs=; h=From:To:Subject:Date:In-Reply-To:References:From; b=Es2OgesoXakj0EWr/Qm5Bsg1h0pzsFT4CxJ8UywucENG7fFX/lCmsgoihhS3TFeUc arWBGA6qRJWK2U7cy21ZlA4XM0Ry/WYaumB1/tGqSqfH/dsKY3TzQBcXLSI/cHE5DJ Bq/MGKH3Tt4DyNNV8TpcIONmrGY8sl8QjFlKPGVUyB87iCGV8+EK6r2e1vQz4PadAj 5AaXHozJkmTRVSRSfkGEEmF4f68wb/V4HPkFfify0E1/MZMmlWUW4No0MMAHmrc0Fl fyafg729zW1hKz4+foUEERbNSv3eh7aQQcn0svBFZ4Z1mySuzGJ3+XS2hPPDwx+bMG 92uSpgg2h6CTw== From: Jeff Layton To: ceph-devel@vger.kernel.org, idryomov@gmail.com Subject: [PATCH 2/3] ceph: clean up locking annotation for ceph_get_snap_realm and __lookup_snap_realm Date: Thu, 3 Jun 2021 12:52:30 -0400 Message-Id: <20210603165231.110559-3-jlayton@kernel.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210603165231.110559-1-jlayton@kernel.org> References: <20210603165231.110559-1-jlayton@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org They both say that the snap_rwsem must be held for write, but I don't see any real reason for it, and it's not currently always called that way. The lookup is just walking the rbtree, so holding it for read should be fine there. The "get" is bumping the refcount and (possibly) removing it from the empty list. I see no need to hold the snap_rwsem for write for that. Signed-off-by: Jeff Layton Reviewed-by: Ilya Dryomov --- fs/ceph/snap.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c index bc6c33d485e6..f8cac2abab3f 100644 --- a/fs/ceph/snap.c +++ b/fs/ceph/snap.c @@ -60,12 +60,12 @@ /* * increase ref count for the realm * - * caller must hold snap_rwsem for write. + * caller must hold snap_rwsem. */ void ceph_get_snap_realm(struct ceph_mds_client *mdsc, struct ceph_snap_realm *realm) { - lockdep_assert_held_write(&mdsc->snap_rwsem); + lockdep_assert_held(&mdsc->snap_rwsem); dout("get_realm %p %d -> %d\n", realm, atomic_read(&realm->nref), atomic_read(&realm->nref)+1); @@ -139,7 +139,7 @@ static struct ceph_snap_realm *ceph_create_snap_realm( /* * lookup the realm rooted at @ino. * - * caller must hold snap_rwsem for write. + * caller must hold snap_rwsem. */ static struct ceph_snap_realm *__lookup_snap_realm(struct ceph_mds_client *mdsc, u64 ino) @@ -147,7 +147,7 @@ static struct ceph_snap_realm *__lookup_snap_realm(struct ceph_mds_client *mdsc, struct rb_node *n = mdsc->snap_realms.rb_node; struct ceph_snap_realm *r; - lockdep_assert_held_write(&mdsc->snap_rwsem); + lockdep_assert_held(&mdsc->snap_rwsem); while (n) { r = rb_entry(n, struct ceph_snap_realm, node);