by Jeff Layton

[permalink] [raw]

Subject: Re: [PATCH v3 05/10] lockd: Plumb nfs_open_context into nlm client unlock

On Tue, 29 Dec 2015 09:08:00 -0500 (EST)
Benjamin Coddington <[email protected]> wrote:

> > On Mon, 28 Dec 2015 11:28:01 -0500
> > Benjamin Coddington <[email protected]> wrote:
> >
> > > We cannot depend on a file_lock->fl_file still being around while
> > > performing unlocks for NFSv2 and NFSv3. Pass along the nfs_open_context to
> > > provide the necessary inode and credential to complete the unlock.
> > >
> > > Signed-off-by: Benjamin Coddington <[email protected]>
> > > ---
> > > fs/lockd/clntproc.c | 16 ++++++++++------
> > > fs/nfs/nfs3proc.c | 4 +---
> > > fs/nfs/proc.c | 4 +---
> > > include/linux/lockd/bind.h | 3 ++-
> > > 4 files changed, 14 insertions(+), 13 deletions(-)
> > >
> > > diff --git a/fs/lockd/clntproc.c b/fs/lockd/clntproc.c
> > > index 1129520..72b65c4 100644
> > > --- a/fs/lockd/clntproc.c
> > > +++ b/fs/lockd/clntproc.c
> > > @@ -25,7 +25,8 @@
> > >
> > > static int nlmclnt_test(struct nlm_rqst *, struct file_lock *);
> > > static int nlmclnt_lock(struct nlm_rqst *, struct file_lock *);
> > > -static int nlmclnt_unlock(struct nlm_rqst *, struct file_lock *);
> > > +static int nlmclnt_unlock(struct nfs_open_context *nfs,
> > > + struct nlm_rqst *, struct file_lock *);
> >
> > This smells a bit like a layering violation. The NLM APIs really
> > shouldn't require stuff that's NFS specific.
>
> I had second thoughts about this too, but it didn't make sense to keep the
> separation if we're just going to use nfs_file_cred() in NLM anyway..
>
> Do you think we should find a way to clean that out too?
>

Ok, good point...

I do think it would be cleaner to try to excise the two, but I'm not
religious about it. FWIW, it looks like this patch added the
nfs_file_cred calls to lockd:

commit d11d10cc05c94a32632d6928d15a1034200dd9a5
Author: Trond Myklebust <[email protected]>
Date: Wed Apr 2 14:44:05 2008 -0400

NLM/lockd: Ensure client locking calls use correct credentials

Now that we've added the 'generic' credentials (that are independent of the
rpc_client) to the nfs_open_context, we can use those in the NLM client to
ensure that the lock/unlock requests are authenticated to whoever
originally opened the file.

Signed-off-by: Trond Myklebust <[email protected]>

I'll let Trond make the call on whether we should try to keep them separate...

> > > static int nlm_stat_to_errno(__be32 stat);
> > > static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host);
> > > static int nlmclnt_cancel(struct nlm_host *, int , struct file_lock *);
> > > @@ -147,13 +148,15 @@ static void nlmclnt_release_lockargs(struct nlm_rqst *req)
> > >
> > > /**
> > > * nlmclnt_proc - Perform a single client-side lock request
> > > - * @host: address of a valid nlm_host context representing the NLM server
> > > + * @ctx: address of the nfs_open_context for lock to operate upon
> > > * @cmd: fcntl-style file lock operation to perform
> > > * @fl: address of arguments for the lock operation
> > > *
> > > */
> > > -int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl)
> > > +int nlmclnt_proc(struct nfs_open_context *ctx, int cmd, struct file_lock *fl)
> > > {
> > > + struct inode *inode = d_inode(ctx->dentry);
> > > + struct nlm_host *host = NFS_SERVER(inode)->nlm_host;
> > > struct nlm_rqst *call;
> > > int status;
> > >
> > > @@ -175,7 +178,7 @@ int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl)
> > > call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
> > > status = nlmclnt_lock(call, fl);
> > > } else
> > > - status = nlmclnt_unlock(call, fl);
> > > + status = nlmclnt_unlock(ctx, call, fl);
> > > } else if (IS_GETLK(cmd))
> > > status = nlmclnt_test(call, fl);
> > > else
> > > @@ -646,7 +649,8 @@ nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl,
> > > * UNLOCK: remove an existing lock
> > > */
> > > static int
> > > -nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
> > > +nlmclnt_unlock(struct nfs_open_context *ctx,
> > > + struct nlm_rqst *req, struct file_lock *fl)
> > > {
> > > struct nlm_host *host = req->a_host;
> > > struct nlm_res *resp = &req->a_res;
> > > @@ -669,7 +673,7 @@ nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
> > > }
> > >
> > > atomic_inc(&req->a_count);
> > > - status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
> > > + status = nlmclnt_async_call(ctx->cred, req,
> > > NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
> >
> > Since this is the only place you're going to fetch anything out of the
> > ctx, maybe it'd be best to just pass down a rpc_cred pointer instead?
>
> Patch 7 changes do_vfs_lock() to take the inode instead of the file, so the
> ctx is useful again to obtain the inode.
>
> Ben
>

Hmm ok. It's still possible to pass the inode separately as well, but
again I'll leave that decision up to Trond.

> > > if (status < 0)
> > > goto out;
> > > diff --git a/fs/nfs/nfs3proc.c b/fs/nfs/nfs3proc.c
> > > index a10e147..2941ab7 100644
> > > --- a/fs/nfs/nfs3proc.c
> > > +++ b/fs/nfs/nfs3proc.c
> > > @@ -868,9 +868,7 @@ static void nfs3_proc_commit_setup(struct
> > > nfs_commit_data *data, struct rpc_mess static int
> > > nfs3_proc_lock(struct nfs_open_context *ctx, int cmd, struct
> > > file_lock *fl) {
> > > - struct inode *inode = d_inode(ctx->dentry);
> > > -
> > > - return nlmclnt_proc(NFS_SERVER(inode)->nlm_host, cmd, fl);
> > > + return nlmclnt_proc(ctx, cmd, fl);
> > > }
> > >
> > > static int nfs3_have_delegation(struct inode *inode, fmode_t flags)
> > > diff --git a/fs/nfs/proc.c b/fs/nfs/proc.c
> > > index 185deb9..17d892e 100644
> > > --- a/fs/nfs/proc.c
> > > +++ b/fs/nfs/proc.c
> > > @@ -636,9 +636,7 @@ nfs_proc_commit_setup(struct nfs_commit_data
> > > *data, struct rpc_message *msg) static int
> > > nfs_proc_lock(struct nfs_open_context *ctx, int cmd, struct
> > > file_lock *fl) {
> > > - struct inode *inode = d_inode(ctx->dentry);
> > > -
> > > - return nlmclnt_proc(NFS_SERVER(inode)->nlm_host, cmd, fl);
> > > + return nlmclnt_proc(ctx, cmd, fl);
> > > }
> > >
> > > /* Helper functions for NFS lock bounds checking */
> > > diff --git a/include/linux/lockd/bind.h b/include/linux/lockd/bind.h
> > > index 4d24d64..1d62e85 100644
> > > --- a/include/linux/lockd/bind.h
> > > +++ b/include/linux/lockd/bind.h
> > > @@ -18,6 +18,7 @@
> > >
> > > /* Dummy declarations */
> > > struct svc_rqst;
> > > +struct nfs_open_context;
> > >
> > > /*
> > > * This is the set of functions for lockd->nfsd communication
> > > @@ -52,7 +53,7 @@ struct nlmclnt_initdata {
> > > extern struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata
> > > *nlm_init); extern void nlmclnt_done(struct nlm_host *host);
> > >
> > > -extern int nlmclnt_proc(struct nlm_host *host, int cmd,
> > > +extern int nlmclnt_proc(struct nfs_open_context *ctx, int cmd,
> > > struct file_lock *fl);
> > > extern int lockd_up(struct net *net);
> > > extern void lockd_down(struct net *net);
> >
> >
> > --
> > Jeff Layton <[email protected]>
> >

--
Jeff Layton <[email protected]>