new helper: iterate_fd()

iterates through the opened files in given descriptor table,
calling a supplied function; we stop once non-zero is returned.
Callback gets struct file *, descriptor number and const void *
argument passed to iterator.  It is called with files->file_lock
held, so it is not allowed to block.

tty_io, netprio_cgroup and selinux flush_unauthorized_files()
converted to its use.

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

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index de2b71caa0f0..fb7dacae0522 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -98,6 +98,9 @@ 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 *);
+int iterate_fd(struct files_struct *, unsigned,
+                int (*)(const void *, struct file *, unsigned),
+                const void *);
 
 extern int __alloc_fd(struct files_struct *files,
                       unsigned start, unsigned end, unsigned flags);