Revert "iov_iter: refactor rw_copy_check_uvector and import_iovec"

This reverts commit bfdc59701d.

Bug: 171539436
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ibf840a8fb38cb7d5888fb1bb1313647edf0b336e

include/linux/fs.h

@@ -178,6 +178,14 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
 /* File supports async buffered reads */
 #define FMODE_BUF_RASYNC	((__force fmode_t)0x40000000)
 
+/*
+ * Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector
+ * that indicates that they should check the contents of the iovec are
+ * valid, but not check the memory that the iovec elements
+ * points too.
+ */
+#define CHECK_IOVEC_ONLY -1
+
 /*
  * Attribute flags.  These should be or-ed together to figure out what
  * has been changed!
@@ -1889,6 +1897,11 @@ static inline int call_mmap(struct file *file, struct vm_area_struct *vma)
 	return file->f_op->mmap(file, vma);
 }
 
+ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
+			      unsigned long nr_segs, unsigned long fast_segs,
+			      struct iovec *fast_pointer,
+			      struct iovec **ret_pointer);
+
 extern ssize_t vfs_read(struct file *, char __user *, size_t, loff_t *);
 extern ssize_t vfs_write(struct file *, const char __user *, size_t, loff_t *);
 extern ssize_t vfs_readv(struct file *, const struct iovec __user *,