From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from canpmsgout04.his.huawei.com (canpmsgout04.his.huawei.com [113.46.200.219]) (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 794272AD16; Mon, 9 Mar 2026 13:03:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=113.46.200.219 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773061434; cv=none; b=O/NE7H0BQ4Qk+POas2ozl2HGCcM+HyW6ILEK9MO2JyRp5cZFc4evFAAdN8QVKIj9GgV4+1VzvOdJmew8txZfgXewU5ywW63m2WUdE4QJk9TRqmRH9/US6glAxFLQ0pO+e74lLrXRewrRwNUri3YftOWucvhACXtVZy1TBeofs/Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773061434; c=relaxed/simple; bh=Dd9LSYqMUXZmkEBBz64YKlxWhVycZinslpmqDOHUupU=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=Ia2Iiy6sRL5/kHIKAVOSsdQjxzPNC+/tMCvba9QBcAoCRj8MSW4ug+zWrIK2zUyT9JzSxoqZqzofBmOrwz9hIKBJ8eNPbhViqkF6i/l2Vf6GQ5W9XhiBD5GAYDI9iaxLsKIUUiMp981Z5mTlLsk+2uoD3dUBzQOqJVV1Lfymo3Y= 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=AMHM+E2U; arc=none smtp.client-ip=113.46.200.219 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="AMHM+E2U" dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=LlGfKzzNrehf4vRJwyFPLFBrHXlqlUKxBFzbAvnYCAA=; b=AMHM+E2UzWT8m3EeLvBTXC+7sAVZn6ssbn+z8x0VR0IwuK5HA+CN8QmpMobU/lyTKGt8Vvrdc xc0WyUW37VXKT5CYj1EywOyu0HjcaotxpSh49WtLhjbEGHtLVw3FOj2YKaOocvGT8q5Fs4HBBu9 v6qwNjZAzBOVk7iKphVHTvc= Received: from mail.maildlp.com (unknown [172.19.163.0]) by canpmsgout04.his.huawei.com (SkyGuard) with ESMTPS id 4fTxsS0zrJz1prL6; Mon, 9 Mar 2026 20:58:52 +0800 (CST) Received: from kwepemf100006.china.huawei.com (unknown [7.202.181.220]) by mail.maildlp.com (Postfix) with ESMTPS id 9E00D40561; Mon, 9 Mar 2026 21:03:48 +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; Mon, 9 Mar 2026 21:03:47 +0800 Message-ID: Date: Mon, 9 Mar 2026 21:03:47 +0800 Precedence: bulk X-Mailing-List: linux-kernel@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> <6ffe642b-148c-462e-83a5-0019ce92e87e@huawei.com> From: yangerkun In-Reply-To: <6ffe642b-148c-462e-83a5-0019ce92e87e@huawei.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: kwepems100002.china.huawei.com (7.221.188.206) To kwepemf100006.china.huawei.com (7.202.181.220) ping again 在 2026/2/26 16:34, yangerkun 写道: > 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; >>   }; > > >