Re: [RFC PATCH] nfs: use nfsi->rwsem to protect traversal of the file lock list

在 2026/6/24 3:52, Anna Schumaker 写道:
> Hi Erkun,
> 
> On Tue, Jun 23, 2026, at 3:37 AM, yangerkun wrote:
>> Gently ping...
>>
>> This patch has been reviewed, but leave alone here for a long time...
> 
> The patch is in my linux-next branch right here: https://git.linux-nfs.org/?p=anna/linux-nfs.git;a=commit;h=4837fb36219e6c08b666bc31a86841bad8526358

Aha, thanks for this! MAINTAINERS only point 
git://git.linux-nfs.org/projects/trondmy/linux-nfs.git and I did not 
found this commit exists. Sorry for the noise....

> 
> Anna
> 
>>
>> 在 2026/5/8 16:33, yangerkun 写道:
>>> 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 <[email protected]>
>>>>>> Closes: https://lore.kernel.org/all/20250419085709.1452492-1-
>>>>>> [email protected]/
>>>>>> Closes: https://lore.kernel.org/all/20250715030559.2906634-1-
>>>>>> [email protected]/
>>>>>> Fixes: c69899a17ca4 ("NFSv4: Update of VFS byte range lock must be
>>>>>> atomic with the stateid update")
>>>>>> Signed-off-by: Yang Erkun <[email protected]>
>>>>>> ---
>>>>>>    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 <[email protected]>
>>>>>
>>>>>
>>>>
>>>
>>>
>>>