fs: implement vfs_iter_read using do_iter_read

De-dupliate some code and allow for passing the flags argument to
vfs_iter_read.  Additional it properly updates atime now.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/coda/file.c b/fs/coda/file.c
index 9d956cd..f110282 100644
--- a/fs/coda/file.c
+++ b/fs/coda/file.c
@@ -34,7 +34,7 @@ coda_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 
 	BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
 
-	return vfs_iter_read(cfi->cfi_container, to, &iocb->ki_pos);
+	return vfs_iter_read(cfi->cfi_container, to, &iocb->ki_pos, 0);
 }
 
 static ssize_t