Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/ke…

…rnel/git/viro/vfs

Pull iov_iter updates from Al Viro:
 "A couple of iov_iter patches - Christoph's crapectomy (the last
  remaining user of iov_for_each() went away with lustre, IIRC) and
  Eric'c optimization of sanity checks"

* 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  iov_iter: optimize page_copy_sane()
  uio: remove the unused iov_for_each macro

.clang-format

@@ -290,7 +290,6 @@ ForEachMacros:
   - 'idr_for_each_entry_ul'
   - 'inet_bind_bucket_for_each'
   - 'inet_lhash2_for_each_icsk_rcu'
-  - 'iov_for_each'
   - 'key_for_each'
   - 'key_for_each_safe'
   - 'klp_for_each_func'

include/linux/uio.h

@@ -110,14 +110,6 @@ static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
 	};
 }
 
-#define iov_for_each(iov, iter, start)				\
-	if (iov_iter_type(start) == ITER_IOVEC ||		\
-	    iov_iter_type(start) == ITER_KVEC)			\
-	for (iter = (start);					\
-	     (iter).count &&					\
-	     ((iov = iov_iter_iovec(&(iter))), 1);		\
-	     iov_iter_advance(&(iter), (iov).iov_len))
-
 size_t iov_iter_copy_from_user_atomic(struct page *page,
 		struct iov_iter *i, unsigned long offset, size_t bytes);
 void iov_iter_advance(struct iov_iter *i, size_t bytes);

lib/iov_iter.c

@@ -861,8 +861,21 @@ EXPORT_SYMBOL(_copy_from_iter_full_nocache);
 
 static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
 {
-	struct page *head = compound_head(page);
-	size_t v = n + offset + page_address(page) - page_address(head);
+	struct page *head;
+	size_t v = n + offset;
+
+	/*
+	 * The general case needs to access the page order in order
+	 * to compute the page size.
+	 * However, we mostly deal with order-0 pages and thus can
+	 * avoid a possible cache line miss for requests that fit all
+	 * page orders.
+	 */
+	if (n <= v && v <= PAGE_SIZE)
+		return true;
+
+	head = compound_head(page);
+	v += (page - head) << PAGE_SHIFT;
 
 	if (likely(n <= v && v <= (PAGE_SIZE << compound_order(head))))
 		return true;