fs/iomap/buffered-io.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 8ce8720093b9..eb1973792c68 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -758,13 +758,20 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
 		if (bytes > length)
 			bytes = length;
 
+		/* Nobody _should_ call us with an empty iter, but.. */
+		if (WARN_ON_ONCE(!bytes)) {
+			status = 0;
+			break;
+		}
+
 		/*
 		 * Bring in the user page that we'll copy from _first_.
 		 * Otherwise there's a nasty deadlock on copying from the
 		 * same page as we're writing to, without it being marked
 		 * up-to-date.
 		 */
-		if (unlikely(fault_in_iov_iter_readable(i, bytes) == bytes)) {
+		bytes -= fault_in_iov_iter_readable(i, bytes);
+		if (unlikely(!bytes)) {
 			status = -EFAULT;
 			break;
 		}