From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from canpmsgout10.his.huawei.com (canpmsgout10.his.huawei.com [113.46.200.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 02D1F394465; Thu, 26 Feb 2026 08:34:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=113.46.200.225 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772094858; cv=none; b=UkFaHvP9zoWFtZdMnj7vTWJC1xveFEOdXbmwpl/sDspKU+n4Ni500kGJrzGkHbLxobBAIB+h+xosixC4yxjw0WhWOPKSxJjkmgFikjE9pW5Bq6kZq7B/vsuCz0BrXm+NkzGbFL7P0SixNgbixt4BFcfpBh/B1h8ry95wVzwizXg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772094858; c=relaxed/simple; bh=VBRnKydwyb9rmp9mJLILzMVACEA0F0hDliHQq5zrjJk=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=aBEsC0f9wEWVX4qvBldld8cB7FbwEV5WWrAPOO9GxLsuiNs2GDhZLRkIx5+n10exWshyrG3fq+JXQg1XwLiPUEnJxAuuxpk3XAME/lUNtBbll0ACcwbLhPqFnKi1XelRE2WK9RHazO/1iWRuf77h4+DjDYwY88lYQNllDbyu9hs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b=muAVjgRr; arc=none smtp.client-ip=113.46.200.225 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b="muAVjgRr" dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=4vtmQrQDBtzHPF/dkeyVbrNQBQef3q+OahkMeqRajRA=; b=muAVjgRrdpn903t7Q5nfFjus27sJY21f3A0eSXEKLlyVONp3XwNeq2u+aIn4+7q5JXA63gOHi SmejkHhB6mXsDH8fYCzt8yr2kXE4vsOUh/zaBLppDOxefrMaDn+1n/zacEclpwMClcwKFntZqzZ Imvy1K2SO/cxoRJMZzs1TrU= Received: from mail.maildlp.com (unknown [172.19.163.127]) by canpmsgout10.his.huawei.com (SkyGuard) with ESMTPS id 4fM4Pd75Hdz1K96h; Thu, 26 Feb 2026 16:29:25 +0800 (CST) Received: from kwepemf100006.china.huawei.com (unknown [7.202.181.220]) by mail.maildlp.com (Postfix) with ESMTPS id 17B97402AB; Thu, 26 Feb 2026 16:34:11 +0800 (CST) Received: from [10.174.176.240] (10.174.176.240) by kwepemf100006.china.huawei.com (7.202.181.220) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.36; Thu, 26 Feb 2026 16:34:10 +0800 Message-ID: <6ffe642b-148c-462e-83a5-0019ce92e87e@huawei.com> Date: Thu, 26 Feb 2026 16:34:09 +0800 Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH] nfs: use nfsi->rwsem to protect traversal of the file lock list To: , , , CC: , , , , , References: <20260226012203.3962997-1-yangerkun@huawei.com> From: yangerkun In-Reply-To: <20260226012203.3962997-1-yangerkun@huawei.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: kwepems500002.china.huawei.com (7.221.188.17) To kwepemf100006.china.huawei.com (7.202.181.220) Hi all, This issue has been known for a long time now, and I am really looking forward to some discussion on this problem and the solution I have proposed. Thanks, Erkun. 在 2026/2/26 9:22, Yang Erkun 写道: > Lingfeng identified a bug and suggested two solutions, but both appear > to have issues. > > Generally, we cannot release flc_lock while iterating over the file lock > list to avoid use-after-free (UAF) problems with file locks. However, > functions like nfs_delegation_claim_locks and nfs4_reclaim_locks cannot > adhere to this rule because recover_lock or nfs4_lock_delegation_recall > may take a long time. To resolve this, NFS switches to using nfsi->rwsem > for the same protection, and nfs_reclaim_locks follows this approach. > Although nfs_delegation_claim_locks uses so_delegreturn_mutex instead, > this is inadequate since a single inode can have multiple nfs4_state > instances. Therefore, the fix is to also use nfsi->rwsem in this case. > > Furthermore, after commit c69899a17ca4 ("NFSv4: Update of VFS byte range > lock must be atomic with the stateid update"), the functions > nfs4_locku_done and nfs4_lock_done also break this rule because they > call locks_lock_inode_wait without holding nfsi->rwsem. Simply adding > this protection could cause many deadlocks, so instead, the call to > locks_lock_inode_wait is moved into _nfs4_proc_setlk. Regarding the bug > fixed by commit c69899a17ca4 ("NFSv4: Update of VFS byte range > lock must be atomic with the stateid update"), it has been resolved > after commit 0460253913e5 ("NFSv4: nfs4_do_open() is incorrectly triggering > state recovery") because all slots are drained before calling > nfs4_do_reclaim, which prevents concurrent stateid changes along this path. > Also, nfs_delegation_claim_locks does not cause this concurrency either > since when _nfs4_proc_setlk is called with NFS_DELEGATED_STATE, no RPC is > sent, so nfs4_lock_done is not called. Therefore, > nfs4_lock_delegation_recall from nfs_delegation_claim_locks is the first > time the stateid is set. > > Reported-by: Li Lingfeng > Closes: https://lore.kernel.org/all/20250419085709.1452492-1-lilingfeng3@huawei.com/ > Closes: https://lore.kernel.org/all/20250715030559.2906634-1-lilingfeng3@huawei.com/ > Fixes: c69899a17ca4 ("NFSv4: Update of VFS byte range lock must be atomic with the stateid update") > Signed-off-by: Yang Erkun > --- > fs/nfs/delegation.c | 9 ++++++++- > fs/nfs/nfs4proc.c | 22 +++++++++++----------- > include/linux/nfs_xdr.h | 1 - > 3 files changed, 19 insertions(+), 13 deletions(-) > > diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c > index 122fb3f14ffb..9546d2195c25 100644 > --- a/fs/nfs/delegation.c > +++ b/fs/nfs/delegation.c > @@ -173,6 +173,7 @@ int nfs4_check_delegation(struct inode *inode, fmode_t type) > static int nfs_delegation_claim_locks(struct nfs4_state *state, const nfs4_stateid *stateid) > { > struct inode *inode = state->inode; > + struct nfs_inode *nfsi = NFS_I(inode); > struct file_lock *fl; > struct file_lock_context *flctx = locks_inode_context(inode); > struct list_head *list; > @@ -182,6 +183,9 @@ static int nfs_delegation_claim_locks(struct nfs4_state *state, const nfs4_state > goto out; > > list = &flctx->flc_posix; > + > + /* Guard against reclaim and new lock/unlock calls */ > + down_write(&nfsi->rwsem); > spin_lock(&flctx->flc_lock); > restart: > for_each_file_lock(fl, list) { > @@ -189,8 +193,10 @@ static int nfs_delegation_claim_locks(struct nfs4_state *state, const nfs4_state > continue; > spin_unlock(&flctx->flc_lock); > status = nfs4_lock_delegation_recall(fl, state, stateid); > - if (status < 0) > + if (status < 0) { > + up_write(&nfsi->rwsem); > goto out; > + } > spin_lock(&flctx->flc_lock); > } > if (list == &flctx->flc_posix) { > @@ -198,6 +204,7 @@ static int nfs_delegation_claim_locks(struct nfs4_state *state, const nfs4_state > goto restart; > } > spin_unlock(&flctx->flc_lock); > + up_write(&nfsi->rwsem); > out: > return status; > } > diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c > index 91bcf67bd743..9d6fbca8798b 100644 > --- a/fs/nfs/nfs4proc.c > +++ b/fs/nfs/nfs4proc.c > @@ -7076,7 +7076,6 @@ static void nfs4_locku_done(struct rpc_task *task, void *data) > switch (task->tk_status) { > case 0: > renew_lease(calldata->server, calldata->timestamp); > - locks_lock_inode_wait(calldata->lsp->ls_state->inode, &calldata->fl); > if (nfs4_update_lock_stateid(calldata->lsp, > &calldata->res.stateid)) > break; > @@ -7344,11 +7343,6 @@ static void nfs4_lock_done(struct rpc_task *task, void *calldata) > case 0: > renew_lease(NFS_SERVER(d_inode(data->ctx->dentry)), > data->timestamp); > - if (data->arg.new_lock && !data->cancelled) { > - data->fl.c.flc_flags &= ~(FL_SLEEP | FL_ACCESS); > - if (locks_lock_inode_wait(lsp->ls_state->inode, &data->fl) < 0) > - goto out_restart; > - } > if (data->arg.new_lock_owner != 0) { > nfs_confirm_seqid(&lsp->ls_seqid, 0); > nfs4_stateid_copy(&lsp->ls_stateid, &data->res.stateid); > @@ -7459,11 +7453,10 @@ static int _nfs4_do_setlk(struct nfs4_state *state, int cmd, struct file_lock *f > msg.rpc_argp = &data->arg; > msg.rpc_resp = &data->res; > task_setup_data.callback_data = data; > - if (recovery_type > NFS_LOCK_NEW) { > - if (recovery_type == NFS_LOCK_RECLAIM) > - data->arg.reclaim = NFS_LOCK_RECLAIM; > - } else > - data->arg.new_lock = 1; > + > + if (recovery_type == NFS_LOCK_RECLAIM) > + data->arg.reclaim = NFS_LOCK_RECLAIM; > + > task = rpc_run_task(&task_setup_data); > if (IS_ERR(task)) > return PTR_ERR(task); > @@ -7573,6 +7566,13 @@ static int _nfs4_proc_setlk(struct nfs4_state *state, int cmd, struct file_lock > up_read(&nfsi->rwsem); > mutex_unlock(&sp->so_delegreturn_mutex); > status = _nfs4_do_setlk(state, cmd, request, NFS_LOCK_NEW); > + if (status) > + goto out; > + > + down_read(&nfsi->rwsem); > + request->c.flc_flags &= ~(FL_SLEEP | FL_ACCESS); > + status = locks_lock_inode_wait(state->inode, request); > + up_read(&nfsi->rwsem); > out: > request->c.flc_flags = flags; > return status; > diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h > index ff1f12aa73d2..9599ad15c3ad 100644 > --- a/include/linux/nfs_xdr.h > +++ b/include/linux/nfs_xdr.h > @@ -580,7 +580,6 @@ struct nfs_lock_args { > struct nfs_lowner lock_owner; > unsigned char block : 1; > unsigned char reclaim : 1; > - unsigned char new_lock : 1; > unsigned char new_lock_owner : 1; > }; >