From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from canpmsgout06.his.huawei.com (canpmsgout06.his.huawei.com [113.46.200.221]) (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 CD8CE2D978C; Fri, 8 May 2026 08:33:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=113.46.200.221 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778229218; cv=none; b=s9z1aKRsYrRdBE3DNUwkc9IPWhyHLozBZcrRCdEyneenjRq3lFgr3fjfvyGrnIR6aucGVUtN7VnAM5TWwr2R+TtjZvB2xViKUnlx1FRsfh3WhISutQFXI4wiJfOMcQgzMQz84e/fG+7it52ur45qnc4rL5fbW73vmFvl/44yLzk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778229218; c=relaxed/simple; bh=ndm9qotnyz85MD2ynikAViwEFwSkkqe/owp4wyOhQu4=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=Cr3eEW7DKJ87pERk1yTKBDs8cz1OYvmmNbRgFs6Hf1LYkOLYsaxht1v30LIo9MHcfoEgi8iLzpWcBfLL/tppeHL43KmTMBjGUsymJ7/+Z/NtuwmHxADJ+rKqyizeGQxo9MdqDz3xi5Mxnu4sYTF+QtwwyzPImbCiA4ZYgaW4msc= 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=qhOtxgCj; arc=none smtp.client-ip=113.46.200.221 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="qhOtxgCj" dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=I0h0GPxprVTLdB2AuDeIq2HPPUlky6orxuIW+09iwhQ=; b=qhOtxgCjVwUGXbmUDhN/glYIcHYXP9D3N1He+vN3w1ZrtRsSnTETgki8OVmOmzeVQkK2odxbL 4SFTtqnHMKwPVJqaPou0n63LNZMQixIgYfcF7L5lA4Gn8FagKUeGxh3GBraB03SPmq5AmUYFpAZ sGcDMVUrKvt5Ef5wAVnN2mI= Received: from mail.maildlp.com (unknown [172.19.163.104]) by canpmsgout06.his.huawei.com (SkyGuard) with ESMTPS id 4gBhyt3TfszRhRr; Fri, 8 May 2026 16:25:58 +0800 (CST) Received: from kwepemf100006.china.huawei.com (unknown [7.202.181.220]) by mail.maildlp.com (Postfix) with ESMTPS id 327D44056A; Fri, 8 May 2026 16:33:32 +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; Fri, 8 May 2026 16:33:31 +0800 Message-ID: <403e3267-70ef-4fb3-9700-0a14d28abc4c@huawei.com> Date: Fri, 8 May 2026 16:33:30 +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: Jeff Layton , , , CC: , , , , , References: <20260226012203.3962997-1-yangerkun@huawei.com> <163aebb3-4233-4aaa-872c-c36aa3fcb3af@huawei.com> From: yangerkun In-Reply-To: <163aebb3-4233-4aaa-872c-c36aa3fcb3af@huawei.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: kwepems200002.china.huawei.com (7.221.188.68) To kwepemf100006.china.huawei.com (7.202.181.220) Gently ping... 在 2026/4/16 11:01, yangerkun 写道: > Hi Anna and Trond, > > Could you please help check if there are any issues with this patch, and > if there are none, could you help merge it in? > > Thanks, > Erkun. > > 在 2026/3/9 22:09, Jeff Layton 写道: >> On Thu, 2026-02-26 at 09:22 +0800, Yang Erkun wrote: >>> 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; >>>   }; >> >> Nice work! >> >> Reviewed-by: Jeff Layton >> >> >