Re: [PATCH 2/5 - version 2] NFSv4: add flock_owner to open context

[Jeff Layton <jlayton@redhat.com>]

On Wed, 2016-10-12 at 14:33 +1100, NeilBrown wrote:
> An open file description (struct file) in a given process can be
> associated with two different lock owners.
> 
> It can have a Posix lock owner which will be different in each process
> that has a fd on the file.
> It can have a Flock owner which will be the same in all processes.
> 
> When searching for a lock stateid to use, we need to consider both of these
> owners
> 
> So add a new "flock_owner" to the "nfs_open_context" (of which there
> is one for each open file description).
> 
> This flock_owner does not need to be reference-counted as there is a
> 1-1 relation between 'struct file' and nfs open contexts,
> and it will never be part of a list of contexts.  So there is no need
> for a 'flock_context' - just the owner is enough.
> 
> The io_count included in the (Posix) lock_context provides no
> guarantee that all read-aheads that could use the state have
> completed, so not supporting it for flock locks in not a serious
> problem.  Synchronization between flock and read-ahead can be added
> later if needed.
> 
> When creating an open_context for a non-openning create call, we don't have
> a 'struct file' to pass in, so the lock context gets initialized with
> a NULL owner, but this will never be used.
> 
> The flock_owner is not used at all in this patch, that will come later.
> 
> Signed-off-by: NeilBrown <neilb@suse.com>
> ---
>  fs/nfs/dir.c           | 6 +++---
>  fs/nfs/inode.c         | 7 +++++--
>  fs/nfs/nfs4file.c      | 2 +-
>  fs/nfs/nfs4proc.c      | 2 +-
>  include/linux/nfs_fs.h | 3 ++-
>  5 files changed, 12 insertions(+), 8 deletions(-)
> 
> Sorry, two little errors in previous version....
> 
> diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
> index 06e0bf092ba9..d5b87b28010d 100644
> --- a/fs/nfs/dir.c
> +++ b/fs/nfs/dir.c
> @@ -1453,9 +1453,9 @@ static fmode_t flags_to_mode(int flags)
>  	return res;
>  }
>  
> -static struct nfs_open_context *create_nfs_open_context(struct dentry *dentry, int open_flags)
> +static struct nfs_open_context *create_nfs_open_context(struct dentry *dentry, int open_flags, struct file *filp)
>  {
> -	return alloc_nfs_open_context(dentry, flags_to_mode(open_flags));
> +	return alloc_nfs_open_context(dentry, flags_to_mode(open_flags), filp);
>  }
>  
>  static int do_open(struct inode *inode, struct file *filp)
> @@ -1540,7 +1540,7 @@ int nfs_atomic_open(struct inode *dir, struct dentry *dentry,
>  			return finish_no_open(file, dentry);
>  	}
>  
> -	ctx = create_nfs_open_context(dentry, open_flags);
> +	ctx = create_nfs_open_context(dentry, open_flags, file);
>  	err = PTR_ERR(ctx);
>  	if (IS_ERR(ctx))
>  		goto out;
> diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> index 1752fc7c0024..2138027eaba9 100644
> --- a/fs/nfs/inode.c
> +++ b/fs/nfs/inode.c
> @@ -796,7 +796,9 @@ void nfs_close_context(struct nfs_open_context *ctx, int is_sync)
>  }
>  EXPORT_SYMBOL_GPL(nfs_close_context);
>  
> -struct nfs_open_context *alloc_nfs_open_context(struct dentry *dentry, fmode_t f_mode)
> +struct nfs_open_context *alloc_nfs_open_context(struct dentry *dentry,
> +						fmode_t f_mode,
> +						struct file *filp)
>  {
>  	struct nfs_open_context *ctx;
>  	struct rpc_cred *cred = rpc_lookup_cred();
> @@ -815,6 +817,7 @@ struct nfs_open_context *alloc_nfs_open_context(struct dentry *dentry, fmode_t f
>  	ctx->mode = f_mode;
>  	ctx->flags = 0;
>  	ctx->error = 0;
> +	ctx->flock_owner = (fl_owner_t)filp;
>  	nfs_init_lock_context(&ctx->lock_context);
>  	ctx->lock_context.open_context = ctx;
>  	INIT_LIST_HEAD(&ctx->list);
> @@ -939,7 +942,7 @@ int nfs_open(struct inode *inode, struct file *filp)
>  {
>  	struct nfs_open_context *ctx;
>  
> -	ctx = alloc_nfs_open_context(file_dentry(filp), filp->f_mode);
> +	ctx = alloc_nfs_open_context(file_dentry(filp), filp->f_mode, filp);
>  	if (IS_ERR(ctx))
>  		return PTR_ERR(ctx);
>  	nfs_file_set_open_context(filp, ctx);
> diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
> index 89a77950e0b0..0efba77789b9 100644
> --- a/fs/nfs/nfs4file.c
> +++ b/fs/nfs/nfs4file.c
> @@ -57,7 +57,7 @@ nfs4_file_open(struct inode *inode, struct file *filp)
>  	parent = dget_parent(dentry);
>  	dir = d_inode(parent);
>  
> -	ctx = alloc_nfs_open_context(file_dentry(filp), filp->f_mode);
> +	ctx = alloc_nfs_open_context(file_dentry(filp), filp->f_mode, filp);
>  	err = PTR_ERR(ctx);
>  	if (IS_ERR(ctx))
>  		goto out;
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index b7df3ef84fc3..422ed5ac4efe 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -3792,7 +3792,7 @@ nfs4_proc_create(struct inode *dir, struct dentry *dentry, struct iattr *sattr,
>  	struct nfs4_state *state;
>  	int status = 0;
>  
> -	ctx = alloc_nfs_open_context(dentry, FMODE_READ);
> +	ctx = alloc_nfs_open_context(dentry, FMODE_READ, NULL);
>  	if (IS_ERR(ctx))
>  		return PTR_ERR(ctx);
>  
> diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
> index bf8a713c45b4..0adb02c4744d 100644
> --- a/include/linux/nfs_fs.h
> +++ b/include/linux/nfs_fs.h
> @@ -70,6 +70,7 @@ struct nfs_lock_context {
>  struct nfs4_state;
>  struct nfs_open_context {
>  	struct nfs_lock_context lock_context;
> +	fl_owner_t flock_owner;
>  	struct dentry *dentry;
>  	struct rpc_cred *cred;
>  	struct nfs4_state *state;
> @@ -357,7 +358,7 @@ extern void nfs_setsecurity(struct inode *inode, struct nfs_fattr *fattr,
>  extern struct nfs_open_context *get_nfs_open_context(struct nfs_open_context *ctx);
>  extern void put_nfs_open_context(struct nfs_open_context *ctx);
>  extern struct nfs_open_context *nfs_find_open_context(struct inode *inode, struct rpc_cred *cred, fmode_t mode);
> -extern struct nfs_open_context *alloc_nfs_open_context(struct dentry *dentry, fmode_t f_mode);
> +extern struct nfs_open_context *alloc_nfs_open_context(struct dentry *dentry, fmode_t f_mode, struct file *filp);
>  extern void nfs_inode_attach_open_context(struct nfs_open_context *ctx);
>  extern void nfs_file_set_open_context(struct file *filp, struct nfs_open_context *ctx);
>  extern void nfs_file_clear_open_context(struct file *flip);

Acked-by: Jeff Layton <jlayton@redhat.com>