NFSv4: add flock_owner to open context

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.

Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index fd9913249713..3a7601fe9dee 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);