NFS: remove l_pid field from nfs_lockowner

this field is not used in any important way and probably should
have been removed by

Commit: 8003d3c4 ("nfs4: treat lock owners as opaque values")

which removed the pid argument from nfs4_get_lock_state.

Except in unusual and uninteresting cases, two threads with the same
->tgid will have the same ->files pointer, so keeping them both
for comparison brings no benefit.
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>

fs/nfs/inode.c

@@ -703,7 +703,6 @@ static void nfs_init_lock_context(struct nfs_lock_context *l_ctx)
 {
 	atomic_set(&l_ctx->count, 1);
 	l_ctx->lockowner.l_owner = current->files;
-	l_ctx->lockowner.l_pid = current->tgid;
 	INIT_LIST_HEAD(&l_ctx->list);
 	atomic_set(&l_ctx->io_count, 0);
 }
@@ -716,8 +715,6 @@ static struct nfs_lock_context *__nfs_find_lock_context(struct nfs_open_context
 	do {
 		if (pos->lockowner.l_owner != current->files)
 			continue;
-		if (pos->lockowner.l_pid != current->tgid)
-			continue;
 		atomic_inc(&pos->count);
 		return pos;
 	} while ((pos = list_entry(pos->list.next, typeof(*pos), list)) != head);

fs/nfs/nfs4proc.c

@@ -2947,7 +2947,6 @@ static int _nfs4_do_setattr(struct inode *inode,
 	} 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;

fs/nfs/pagelist.c

@@ -867,8 +867,7 @@ static void nfs_pageio_cleanup_mirroring(struct nfs_pageio_descriptor *pgio)
 static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
 		const struct nfs_lock_context *l2)
 {
-	return l1->lockowner.l_owner == l2->lockowner.l_owner
-		&& l1->lockowner.l_pid == l2->lockowner.l_pid;
+	return l1->lockowner.l_owner == l2->lockowner.l_owner;
 }
 
 /**

fs/nfs/write.c

@@ -1151,8 +1151,7 @@ int nfs_flush_incompatible(struct file *file, struct page *page)
 		if (l_ctx && flctx &&
 		    !(list_empty_careful(&flctx->flc_posix) &&
 		      list_empty_careful(&flctx->flc_flock))) {
-			do_flush |= l_ctx->lockowner.l_owner != current->files
-				|| l_ctx->lockowner.l_pid != current->tgid;
+			do_flush |= l_ctx->lockowner.l_owner != current->files;
 		}
 		nfs_release_request(req);
 		if (!do_flush)

include/linux/nfs_fs.h

@@ -57,7 +57,6 @@ struct nfs_access_entry {
 
 struct nfs_lockowner {
 	fl_owner_t l_owner;
-	pid_t l_pid;
 };
 
 struct nfs_lock_context {