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>
diff --git a/fs/file.c b/fs/file.c
index 967bd0d..e6e4181 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -979,3 +979,24 @@
}
return err;
}
+
+int iterate_fd(struct files_struct *files, unsigned n,
+ int (*f)(const void *, struct file *, unsigned),
+ const void *p)
+{
+ struct fdtable *fdt;
+ struct file *file;
+ int res = 0;
+ if (!files)
+ return 0;
+ spin_lock(&files->file_lock);
+ fdt = files_fdtable(files);
+ while (!res && n < fdt->max_fds) {
+ file = rcu_dereference_check_fdtable(files, fdt->fd[n++]);
+ if (file)
+ res = f(p, file, n);
+ }
+ spin_unlock(&files->file_lock);
+ return res;
+}
+EXPORT_SYMBOL(iterate_fd);