don't bother with tid_fd_revalidate() in lookups

what we want it for is actually updating inode metadata;
take _that_ into a separate helper and use it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/proc/fd.c

@@ -98,12 +98,27 @@ static bool tid_fd_mode(struct task_struct *task, unsigned fd, fmode_t *mode)
 	return !!file;
 }
 
+static void tid_fd_update_inode(struct task_struct *task, struct inode *inode,
+				fmode_t f_mode)
+{
+	task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
+
+	if (S_ISLNK(inode->i_mode)) {
+		unsigned i_mode = S_IFLNK;
+		if (f_mode & FMODE_READ)
+			i_mode |= S_IRUSR | S_IXUSR;
+		if (f_mode & FMODE_WRITE)
+			i_mode |= S_IWUSR | S_IXUSR;
+		inode->i_mode = i_mode;
+	}
+	security_task_to_inode(task, inode);
+}
+
 static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
 {
 	struct task_struct *task;
 	struct inode *inode;
 	unsigned int fd;
-	fmode_t f_mode;
 
 	if (flags & LOOKUP_RCU)
 		return -ECHILD;
@@ -113,18 +128,9 @@ static int tid_fd_revalidate(struct dentry *dentry, unsigned int flags)
 	fd = proc_fd(inode);
 
 	if (task) {
+		fmode_t f_mode;
 		if (tid_fd_mode(task, fd, &f_mode)) {
-			task_dump_owner(task, 0, &inode->i_uid, &inode->i_gid);
-
-			if (S_ISLNK(inode->i_mode)) {
-				unsigned i_mode = S_IFLNK;
-				if (f_mode & FMODE_READ)
-					i_mode |= S_IRUSR | S_IXUSR;
-				if (f_mode & FMODE_WRITE)
-					i_mode |= S_IWUSR | S_IXUSR;
-				inode->i_mode = i_mode;
-			}
-			security_task_to_inode(task, inode);
+			tid_fd_update_inode(task, inode, f_mode);
 			put_task_struct(task);
 			return 1;
 		}
@@ -168,34 +174,35 @@ static int proc_fd_link(struct dentry *dentry, struct path *path)
 	return ret;
 }
 
+struct fd_data {
+	fmode_t mode;
+	unsigned fd;
+};
+
 static int
 proc_fd_instantiate(struct inode *dir, struct dentry *dentry,
 		    struct task_struct *task, const void *ptr)
 {
-	unsigned fd = (unsigned long)ptr;
+	const struct fd_data *data = ptr;
 	struct proc_inode *ei;
 	struct inode *inode;
 
 	inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK);
 	if (!inode)
-		goto out;
+		return -ENOENT;
 
 	ei = PROC_I(inode);
-	ei->fd = fd;
+	ei->fd = data->fd;
 
 	inode->i_op = &proc_pid_link_inode_operations;
 	inode->i_size = 64;
 
 	ei->op.proc_get_link = proc_fd_link;
+	tid_fd_update_inode(task, inode, data->mode);
 
 	d_set_d_op(dentry, &tid_fd_dentry_operations);
 	d_add(dentry, inode);
-
-	/* Close the race of the process dying before we return the dentry */
-	if (tid_fd_revalidate(dentry, 0))
 	return 0;
- out:
-	return -ENOENT;
 }
 
 static struct dentry *proc_lookupfd_common(struct inode *dir,
@@ -204,17 +211,16 @@ static struct dentry *proc_lookupfd_common(struct inode *dir,
 {
 	struct task_struct *task = get_proc_task(dir);
 	int result = -ENOENT;
-	unsigned fd = name_to_int(&dentry->d_name);
-	fmode_t f_mode;
+	struct fd_data data = {.fd = name_to_int(&dentry->d_name)};
 
 	if (!task)
 		goto out_no_task;
-	if (fd == ~0U)
+	if (data.fd == ~0U)
 		goto out;
-	if (!tid_fd_mode(task, fd, &f_mode))
+	if (!tid_fd_mode(task, data.fd, &data.mode))
 		goto out;
 
-	result = instantiate(dir, dentry, task, (void *)(unsigned long)fd);
+	result = instantiate(dir, dentry, task, &data);
 out:
 	put_task_struct(task);
 out_no_task:
@@ -241,17 +247,22 @@ static int proc_readfd_common(struct file *file, struct dir_context *ctx,
 	for (fd = ctx->pos - 2;
 	     fd < files_fdtable(files)->max_fds;
 	     fd++, ctx->pos++) {
+		struct file *f;
+		struct fd_data data;
 		char name[10 + 1];
 		int len;
 
-		if (!fcheck_files(files, fd))
+		f = fcheck_files(files, fd);
+		if (!f)
 			continue;
+		data.mode = f->f_mode;
 		rcu_read_unlock();
+		data.fd = fd;
 
 		len = snprintf(name, sizeof(name), "%u", fd);
 		if (!proc_fill_cache(file, ctx,
 				     name, len, instantiate, p,
-				     (void *)(unsigned long)fd))
+				     &data))
 			goto out_fd_loop;
 		cond_resched();
 		rcu_read_lock();
@@ -313,27 +324,23 @@ static int
 proc_fdinfo_instantiate(struct inode *dir, struct dentry *dentry,
 			struct task_struct *task, const void *ptr)
 {
-	unsigned fd = (unsigned long)ptr;
+	const struct fd_data *data = ptr;
 	struct proc_inode *ei;
 	struct inode *inode;
 
 	inode = proc_pid_make_inode(dir->i_sb, task, S_IFREG | S_IRUSR);
 	if (!inode)
-		goto out;
+		return -ENOENT;
 
 	ei = PROC_I(inode);
-	ei->fd = fd;
+	ei->fd = data->fd;
 
 	inode->i_fop = &proc_fdinfo_file_operations;
+	tid_fd_update_inode(task, inode, 0);
 
 	d_set_d_op(dentry, &tid_fd_dentry_operations);
 	d_add(dentry, inode);
-
-	/* Close the race of the process dying before we return the dentry */
-	if (tid_fd_revalidate(dentry, 0))
 	return 0;
- out:
-	return -ENOENT;
 }
 
 static struct dentry *