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

[Jeff Layton <jeff.layton@primarydata.com>]

On Mon, 28 Dec 2015 11:28:01 -0500
Benjamin Coddington <bcodding@redhat.com> 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 <bcodding@redhat.com>
> ---
>  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.

>  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?

>  	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 <jeff.layton@primarydata.com>