take close-on-exec logics to fs/file.c, clean it up a bit

... and add cond_resched() there, while we are at it.  We can
get large latencies as is...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/exec.c

@@ -1006,40 +1006,6 @@ static int de_thread(struct task_struct *tsk)
 	return 0;
 }
 
-/*
- * These functions flushes out all traces of the currently running executable
- * so that a new one can be started
- */
-static void flush_old_files(struct files_struct * files)
-{
-	long j = -1;
-	struct fdtable *fdt;
-
-	spin_lock(&files->file_lock);
-	for (;;) {
-		unsigned long set, i;
-
-		j++;
-		i = j * BITS_PER_LONG;
-		fdt = files_fdtable(files);
-		if (i >= fdt->max_fds)
-			break;
-		set = fdt->close_on_exec[j];
-		if (!set)
-			continue;
-		fdt->close_on_exec[j] = 0;
-		spin_unlock(&files->file_lock);
-		for ( ; set ; i++,set >>= 1) {
-			if (set & 1) {
-				sys_close(i);
-			}
-		}
-		spin_lock(&files->file_lock);
-
-	}
-	spin_unlock(&files->file_lock);
-}
-
 char *get_task_comm(char *buf, struct task_struct *tsk)
 {
 	/* buf must be at least sizeof(tsk->comm) in size */
@@ -1050,6 +1016,11 @@ char *get_task_comm(char *buf, struct task_struct *tsk)
 }
 EXPORT_SYMBOL_GPL(get_task_comm);
 
+/*
+ * These functions flushes out all traces of the currently running executable
+ * so that a new one can be started
+ */
+
 void set_task_comm(struct task_struct *tsk, char *buf)
 {
 	task_lock(tsk);
@@ -1171,7 +1142,7 @@ void setup_new_exec(struct linux_binprm * bprm)
 	current->self_exec_id++;
 
 	flush_signal_handlers(current, 0);
-	flush_old_files(current->files);
+	do_close_on_exec(current->files);
 }
 EXPORT_SYMBOL(setup_new_exec);
 

fs/file.c

@@ -652,6 +652,43 @@ int __close_fd(struct files_struct *files, unsigned fd)
 	return -EBADF;
 }
 
+void do_close_on_exec(struct files_struct *files)
+{
+	unsigned i;
+	struct fdtable *fdt;
+
+	/* exec unshares first */
+	BUG_ON(atomic_read(&files->count) != 1);
+	spin_lock(&files->file_lock);
+	for (i = 0; ; i++) {
+		unsigned long set;
+		unsigned fd = i * BITS_PER_LONG;
+		fdt = files_fdtable(files);
+		if (fd >= fdt->max_fds)
+			break;
+		set = fdt->close_on_exec[i];
+		if (!set)
+			continue;
+		fdt->close_on_exec[i] = 0;
+		for ( ; set ; fd++, set >>= 1) {
+			struct file *file;
+			if (!(set & 1))
+				continue;
+			file = fdt->fd[fd];
+			if (!file)
+				continue;
+			rcu_assign_pointer(fdt->fd[fd], NULL);
+			__put_unused_fd(files, fd);
+			spin_unlock(&files->file_lock);
+			filp_close(file, files);
+			cond_resched();
+			spin_lock(&files->file_lock);
+		}
+
+	}
+	spin_unlock(&files->file_lock);
+}
+
 struct file *fget(unsigned int fd)
 {
 	struct file *file;

include/linux/fdtable.h

@@ -118,6 +118,7 @@ void put_files_struct(struct files_struct *fs);
 void reset_files_struct(struct files_struct *);
 int unshare_files(struct files_struct **);
 struct files_struct *dup_fd(struct files_struct *, int *);
+void do_close_on_exec(struct files_struct *);
 
 extern int __alloc_fd(struct files_struct *files,
 		      unsigned start, unsigned end, unsigned flags);