From nobody Mon Feb 9 00:57:06 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1B857C25B47 for ; Fri, 27 Oct 2023 10:14:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345645AbjJ0KOF (ORCPT ); Fri, 27 Oct 2023 06:14:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39894 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230502AbjJ0KOC (ORCPT ); Fri, 27 Oct 2023 06:14:02 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 52386C4 for ; Fri, 27 Oct 2023 03:13:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1698401592; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type; bh=wxcQgKtX6m+qD6u/msT0KhsPiwmGQf0kDwNCqogkF8M=; b=GqSD6Z7nMsKbF9j2bYBckhcX3UKVaXfDOpaC9Uk30xF1h9s0hdXUt9POjP+L7QovovqF9h Zs7Aj3Ot/TmzIDGWh9AbXXXGUzwOhK7pi3z01vllyK4mWlQFipssyRSVpZq9nJzIpR8m1Q anRryAUyCp1yShNpTIigHE9joM6uP30= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-179-vbzuj7P2PXWFSoZWe3dG2A-1; Fri, 27 Oct 2023 06:13:09 -0400 X-MC-Unique: vbzuj7P2PXWFSoZWe3dG2A-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id DB50A1C06904; Fri, 27 Oct 2023 10:13:08 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.226.76]) by smtp.corp.redhat.com (Postfix) with SMTP id 6CD9E2166B26; Fri, 27 Oct 2023 10:13:07 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 27 Oct 2023 12:12:07 +0200 (CEST) Date: Fri, 27 Oct 2023 12:12:05 +0200 From: Oleg Nesterov To: David Howells , Marc Dionne Cc: Chuck Lever , linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] fs/afs: use read_seqbegin() rather than read_seqbegin_or_lock() Message-ID: <20231027101205.GA31430@redhat.com> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.6 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" read_seqbegin_or_lock() makes no sense unless you make "seq" odd after the lockless access failed. See thread_group_cputime() as an example, note that it does nextseq =3D 1 for the 2nd round. So this code can use read_seqbegin() without changing the current behaviour. Signed-off-by: Oleg Nesterov --- fs/afs/callback.c | 7 +++---- fs/afs/inode.c | 15 ++++++--------- fs/afs/server.c | 17 +++++++---------- 3 files changed, 16 insertions(+), 23 deletions(-) diff --git a/fs/afs/callback.c b/fs/afs/callback.c index a484fa642808..b33d8a4901f8 100644 --- a/fs/afs/callback.c +++ b/fs/afs/callback.c @@ -110,14 +110,14 @@ static struct afs_volume *afs_lookup_volume_rcu(struc= t afs_cell *cell, { struct afs_volume *volume =3D NULL; struct rb_node *p; - int seq =3D 0; + int seq; =20 do { /* Unfortunately, rbtree walking doesn't give reliable results * under just the RCU read lock, so we have to check for * changes. */ - read_seqbegin_or_lock(&cell->volume_lock, &seq); + seq =3D read_seqbegin(&cell->volume_lock); =20 p =3D rcu_dereference_raw(cell->volumes.rb_node); while (p) { @@ -132,9 +132,8 @@ static struct afs_volume *afs_lookup_volume_rcu(struct = afs_cell *cell, volume =3D NULL; } =20 - } while (need_seqretry(&cell->volume_lock, seq)); + } while (read_seqretry(&cell->volume_lock, seq)); =20 - done_seqretry(&cell->volume_lock, seq); return volume; } =20 diff --git a/fs/afs/inode.c b/fs/afs/inode.c index 1c794a1896aa..88003fefff71 100644 --- a/fs/afs/inode.c +++ b/fs/afs/inode.c @@ -629,10 +629,10 @@ bool afs_check_validity(struct afs_vnode *vnode) enum afs_cb_break_reason need_clear =3D afs_cb_break_no_break; time64_t now =3D ktime_get_real_seconds(); unsigned int cb_break; - int seq =3D 0; + int seq; =20 do { - read_seqbegin_or_lock(&vnode->cb_lock, &seq); + seq =3D read_seqbegin(&vnode->cb_lock); cb_break =3D vnode->cb_break; =20 if (test_bit(AFS_VNODE_CB_PROMISED, &vnode->flags)) { @@ -650,9 +650,7 @@ bool afs_check_validity(struct afs_vnode *vnode) need_clear =3D afs_cb_break_no_promise; } =20 - } while (need_seqretry(&vnode->cb_lock, seq)); - - done_seqretry(&vnode->cb_lock, seq); + } while (read_seqretry(&vnode->cb_lock, seq)); =20 if (need_clear =3D=3D afs_cb_break_no_break) return true; @@ -755,7 +753,7 @@ int afs_getattr(struct mnt_idmap *idmap, const struct p= ath *path, struct inode *inode =3D d_inode(path->dentry); struct afs_vnode *vnode =3D AFS_FS_I(inode); struct key *key; - int ret, seq =3D 0; + int ret, seq; =20 _enter("{ ino=3D%lu v=3D%u }", inode->i_ino, inode->i_generation); =20 @@ -772,7 +770,7 @@ int afs_getattr(struct mnt_idmap *idmap, const struct p= ath *path, } =20 do { - read_seqbegin_or_lock(&vnode->cb_lock, &seq); + seq =3D read_seqbegin(&vnode->cb_lock); generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat); if (test_bit(AFS_VNODE_SILLY_DELETED, &vnode->flags) && stat->nlink > 0) @@ -784,9 +782,8 @@ int afs_getattr(struct mnt_idmap *idmap, const struct p= ath *path, */ if (S_ISDIR(inode->i_mode)) stat->size =3D vnode->netfs.remote_i_size; - } while (need_seqretry(&vnode->cb_lock, seq)); + } while (read_seqretry(&vnode->cb_lock, seq)); =20 - done_seqretry(&vnode->cb_lock, seq); return 0; } =20 diff --git a/fs/afs/server.c b/fs/afs/server.c index b5237206eac3..01a26c0e0d28 100644 --- a/fs/afs/server.c +++ b/fs/afs/server.c @@ -27,7 +27,7 @@ struct afs_server *afs_find_server(struct afs_net *net, const struct afs_addr_list *alist; struct afs_server *server =3D NULL; unsigned int i; - int seq =3D 0, diff; + int seq, diff; =20 rcu_read_lock(); =20 @@ -35,7 +35,8 @@ struct afs_server *afs_find_server(struct afs_net *net, if (server) afs_unuse_server_notime(net, server, afs_server_trace_put_find_rsq); server =3D NULL; - read_seqbegin_or_lock(&net->fs_addr_lock, &seq); + + seq =3D read_seqbegin(&net->fs_addr_lock); =20 if (srx->transport.family =3D=3D AF_INET6) { const struct sockaddr_in6 *a =3D &srx->transport.sin6, *b; @@ -75,9 +76,7 @@ struct afs_server *afs_find_server(struct afs_net *net, found: server =3D afs_maybe_use_server(server, afs_server_trace_get_by_addr); =20 - } while (need_seqretry(&net->fs_addr_lock, seq)); - - done_seqretry(&net->fs_addr_lock, seq); + } while (read_seqretry(&net->fs_addr_lock, seq)); =20 rcu_read_unlock(); return server; @@ -90,7 +89,7 @@ struct afs_server *afs_find_server_by_uuid(struct afs_net= *net, const uuid_t *uu { struct afs_server *server =3D NULL; struct rb_node *p; - int diff, seq =3D 0; + int diff, seq; =20 _enter("%pU", uuid); =20 @@ -103,7 +102,7 @@ struct afs_server *afs_find_server_by_uuid(struct afs_n= et *net, const uuid_t *uu afs_unuse_server(net, server, afs_server_trace_put_uuid_rsq); server =3D NULL; =20 - read_seqbegin_or_lock(&net->fs_lock, &seq); + seq =3D read_seqbegin(&net->fs_lock); =20 p =3D net->fs_servers.rb_node; while (p) { @@ -121,9 +120,7 @@ struct afs_server *afs_find_server_by_uuid(struct afs_n= et *net, const uuid_t *uu =20 server =3D NULL; } - } while (need_seqretry(&net->fs_lock, seq)); - - done_seqretry(&net->fs_lock, seq); + } while (read_seqretry(&net->fs_lock, seq)); =20 _leave(" =3D %p", server); return server; --=20 2.25.1.362.g51ebf55