4 files changed, 18 insertions, 58 deletions

diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 63f4ea4dac9b..6d1b08d0ae93 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -330,12 +330,19 @@ struct iomap_dio_ops {
   */
 #define IOMAP_DIO_OVERWRITE_ONLY	(1 << 1)
 
+/*
+ * When a page fault occurs, return a partial synchronous result and allow
+ * the caller to retry the rest of the operation after dealing with the page
+ * fault.
+ */
+#define IOMAP_DIO_PARTIAL		(1 << 2)
+
 ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 		const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
-		unsigned int dio_flags);
+		unsigned int dio_flags, size_t done_before);
 struct iomap_dio *__iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 		const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
-		unsigned int dio_flags);
+		unsigned int dio_flags, size_t done_before);
 ssize_t iomap_dio_complete(struct iomap_dio *dio);
 
 #ifdef CONFIG_SWAP
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 40ff114aaf9e..a62b91e769c8 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2976,7 +2976,8 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
 #define FOLL_FORCE	0x10	/* get_user_pages read/write w/o permission */
 #define FOLL_NOWAIT	0x20	/* if a disk transfer is needed, start the IO
 				 * and return without waiting upon it */
-#define FOLL_POPULATE	0x40	/* fault in page */
+#define FOLL_POPULATE	0x40	/* fault in pages (with FOLL_MLOCK) */
+#define FOLL_NOFAULT	0x80	/* do not fault in pages */
 #define FOLL_HWPOISON	0x100	/* check page is hwpoisoned */
 #define FOLL_NUMA	0x200	/* force NUMA hinting page fault */
 #define FOLL_MIGRATION	0x400	/* wait for page to replace migration entry */
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 013cdc90f5fd..db2c3e3eb1cf 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -824,61 +824,11 @@ int folio_wait_private_2_killable(struct folio *folio);
 void folio_add_wait_queue(struct folio *folio, wait_queue_entry_t *waiter);
 
 /*
- * Fault everything in given userspace address range in.
+ * Fault in userspace address range.
  */
-static inline int fault_in_pages_writeable(char __user *uaddr, size_t size)
-{
-	char __user *end = uaddr + size - 1;
-
-	if (unlikely(size == 0))
-		return 0;
-
-	if (unlikely(uaddr > end))
-		return -EFAULT;
-	/*
-	 * Writing zeroes into userspace here is OK, because we know that if
-	 * the zero gets there, we'll be overwriting it.
-	 */
-	do {
-		if (unlikely(__put_user(0, uaddr) != 0))
-			return -EFAULT;
-		uaddr += PAGE_SIZE;
-	} while (uaddr <= end);
-
-	/* Check whether the range spilled into the next page. */
-	if (((unsigned long)uaddr & PAGE_MASK) ==
-			((unsigned long)end & PAGE_MASK))
-		return __put_user(0, end);
-
-	return 0;
-}
-
-static inline int fault_in_pages_readable(const char __user *uaddr, size_t size)
-{
-	volatile char c;
-	const char __user *end = uaddr + size - 1;
-
-	if (unlikely(size == 0))
-		return 0;
-
-	if (unlikely(uaddr > end))
-		return -EFAULT;
-
-	do {
-		if (unlikely(__get_user(c, uaddr) != 0))
-			return -EFAULT;
-		uaddr += PAGE_SIZE;
-	} while (uaddr <= end);
-
-	/* Check whether the range spilled into the next page. */
-	if (((unsigned long)uaddr & PAGE_MASK) ==
-			((unsigned long)end & PAGE_MASK)) {
-		return __get_user(c, end);
-	}
-
-	(void)c;
-	return 0;
-}
+size_t fault_in_writeable(char __user *uaddr, size_t size);
+size_t fault_in_safe_writeable(const char __user *uaddr, size_t size);
+size_t fault_in_readable(const char __user *uaddr, size_t size);
 
 int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
 		pgoff_t index, gfp_t gfp);
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 207101a9c5c3..6350354f97e9 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -35,6 +35,7 @@ struct iov_iter_state {
 
 struct iov_iter {
 	u8 iter_type;
+	bool nofault;
 	bool data_source;
 	size_t iov_offset;
 	size_t count;
@@ -133,7 +134,8 @@ size_t copy_page_from_iter_atomic(struct page *page, unsigned offset,
 				  size_t bytes, struct iov_iter *i);
 void iov_iter_advance(struct iov_iter *i, size_t bytes);
 void iov_iter_revert(struct iov_iter *i, size_t bytes);
-int iov_iter_fault_in_readable(const struct iov_iter *i, size_t bytes);
+size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t bytes);
+size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t bytes);
 size_t iov_iter_single_seg_count(const struct iov_iter *i);
 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
 			 struct iov_iter *i);