new primitive: iov_iter_for_each_range()
For kvec and bvec: feeds segments to given callback as long as it
returns 0. For iovec and pipe: fails.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 1c1c06d..9702126 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1446,3 +1446,25 @@ int import_single_range(int rw, void __user *buf, size_t len,
return 0;
}
EXPORT_SYMBOL(import_single_range);
+
+int iov_iter_for_each_range(struct iov_iter *i, size_t bytes,
+ int (*f)(struct kvec *vec, void *context),
+ void *context)
+{
+ struct kvec w;
+ int err = -EINVAL;
+ if (!bytes)
+ return 0;
+
+ iterate_all_kinds(i, bytes, v, -EINVAL, ({
+ w.iov_base = kmap(v.bv_page) + v.bv_offset;
+ w.iov_len = v.bv_len;
+ err = f(&w, context);
+ kunmap(v.bv_page);
+ err;}), ({
+ w = v;
+ err = f(&w, context);})
+ )
+ return err;
+}
+EXPORT_SYMBOL(iov_iter_for_each_range);