[PATCH 2/3] NFSv4: change nfs4_select_rw_stateid to take a lock_context inplace of lock_owner

[NeilBrown <neilb@suse.com>]

The only time that a lock_context is not available is in setattr.
In this case, we wont to find a lock context relevant to the process if there is one.
The fallback can easily be handled at a lower level.

So change nfs4_select_rw_stateid to take a lock_context, passing NULL from _nfs4_do_setattr.
nfs4_copy_lock_state() also now takes a lock_context, and falls back to searching
for "owner == current->files" if not lock_context is given.

Note that nfs4_set_rw_stateid is *always* passed a non-NULL l_ctx, so the
fact that we remove the NULL test there does not change correctness.

This change is preparation for correctly support flock stateids.

Signed-off-by: NeilBrown <neilb@suse.com>
---
 fs/nfs/nfs4_fs.h   |    2 +-
 fs/nfs/nfs4proc.c  |   10 ++--------
 fs/nfs/nfs4state.c |   19 +++++++++++--------
 3 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/fs/nfs/nfs4_fs.h b/fs/nfs/nfs4_fs.h
index 9bf64eacba5b..3f0e459f2499 100644
--- a/fs/nfs/nfs4_fs.h
+++ b/fs/nfs/nfs4_fs.h
@@ -445,7 +445,7 @@ extern void nfs41_handle_server_scope(struct nfs_client *,
 extern void nfs4_put_lock_state(struct nfs4_lock_state *lsp);
 extern int nfs4_set_lock_state(struct nfs4_state *state, struct file_lock *fl);
 extern int nfs4_select_rw_stateid(struct nfs4_state *, fmode_t,
-		const struct nfs_lockowner *, nfs4_stateid *,
+		const struct nfs_lock_context *, nfs4_stateid *,
 		struct rpc_cred **);
 
 extern struct nfs_seqid *nfs_alloc_seqid(struct nfs_seqid_counter *counter, gfp_t gfp_mask);
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index a8f8b4720c90..05ae1cecf9f7 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2764,13 +2764,9 @@ static int _nfs4_do_setattr(struct inode *inode,
 	if (nfs4_copy_delegation_stateid(inode, fmode, &arg->stateid, &delegation_cred)) {
 		/* Use that stateid */
 	} else if (truncate && state != NULL) {
-		struct nfs_lockowner lockowner = {
-			.l_owner = current->files,
-			.l_pid = current->tgid,
-		};
 		if (!nfs4_valid_open_stateid(state))
 			return -EBADF;
-		if (nfs4_select_rw_stateid(state, FMODE_WRITE, &lockowner,
+		if (nfs4_select_rw_stateid(state, FMODE_WRITE, NULL,
 				&arg->stateid, &delegation_cred) == -EIO)
 			return -EBADF;
 	} else
@@ -4365,9 +4361,7 @@ int nfs4_set_rw_stateid(nfs4_stateid *stateid,
 {
 	const struct nfs_lockowner *lockowner = NULL;
 
-	if (l_ctx != NULL)
-		lockowner = &l_ctx->lockowner;
-	return nfs4_select_rw_stateid(ctx->state, fmode, lockowner, stateid, NULL);
+	return nfs4_select_rw_stateid(ctx->state, fmode, l_ctx, stateid, NULL);
 }
 EXPORT_SYMBOL_GPL(nfs4_set_rw_stateid);
 
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index cada00aa5096..94a6631e7938 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -939,20 +939,23 @@ int nfs4_set_lock_state(struct nfs4_state *state, struct file_lock *fl)
 
 static int nfs4_copy_lock_stateid(nfs4_stateid *dst,
 		struct nfs4_state *state,
-		const struct nfs_lockowner *lockowner)
+		const struct nfs_lock_context *l_ctx)
 {
+	/*
+	 * If l_ctx is NULL, then this request comes from setattr
+	 * and we can choose a lock context relevant for the current process
+	 */
 	struct nfs4_lock_state *lsp;
 	fl_owner_t fl_owner;
 	int ret = -ENOENT;
 
-
-	if (lockowner == NULL)
-		goto out;
-
 	if (test_bit(LK_STATE_IN_USE, &state->flags) == 0)
 		goto out;
 
-	fl_owner = lockowner->l_owner;
+	if (l_ctx == NULL)
+		fl_owner = current->files;
+	else
+		fl_owner = l_ctx->lockowner.l_owner;
 	spin_lock(&state->state_lock);
 	lsp = __nfs4_find_lock_state(state, fl_owner);
 	if (lsp && test_bit(NFS_LOCK_LOST, &lsp->ls_flags))
@@ -986,14 +989,14 @@ static void nfs4_copy_open_stateid(nfs4_stateid *dst, struct nfs4_state *state)
  * requests.
  */
 int nfs4_select_rw_stateid(struct nfs4_state *state,
-		fmode_t fmode, const struct nfs_lockowner *lockowner,
+		fmode_t fmode, const struct nfs_lock_context *l_ctx,
 		nfs4_stateid *dst, struct rpc_cred **cred)
 {
 	int ret;
 
 	if (cred != NULL)
 		*cred = NULL;
-	ret = nfs4_copy_lock_stateid(dst, state, lockowner);
+	ret = nfs4_copy_lock_stateid(dst, state, l_ctx);
 	if (ret == -EIO)
 		/* A lost lock - don't even consider delegations */
 		goto out;