[PATCH] iomap: always return status from iomap_write_iter

[Brian Foster <bfoster@redhat.com>]

iomap_write_iter() returns either an error code or 0 if partial
progress has been made. The error sanitization was required in the
past because the return value was used by iomap_iter() to determine
how much progress was made, and thus what to pass to ->iomap_end()
and how much to advance the iter.

Now that iter handlers advance the iter incrementally and progress
is separate from return status, this is no longer needed.
iomap_iter() infers partial progress directly from the iter state
and similarly, iomap_file_buffered_write() uses iter.pos to
determine whether to return a short write or an error code.

This also eliminates a minor quirk in the write iteration where if
an error interrupts a partial write, we'd have to loop back into
iomap_write_iter() once more and run into the error a second time
before iomap terminates the operation and returns the error. With
the error code returned directly and separate from write progress,
we can complete the operation and return from iomap_iter()
immediately.

Signed-off-by: Brian Foster <bfoster@redhat.com>
---
 fs/iomap/buffered-io.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 8d4806dc46d4..fb1f60130cd0 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1156,7 +1156,6 @@ static bool iomap_write_end(struct iomap_iter *iter, size_t len, size_t copied,
 static int iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i,
 		const struct iomap_write_ops *write_ops)
 {
-	ssize_t total_written = 0;
 	int status = 0;
 	struct address_space *mapping = iter->inode->i_mapping;
 	size_t chunk = mapping_max_folio_size(mapping);
@@ -1252,12 +1251,11 @@ static int iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i,
 				goto retry;
 			}
 		} else {
-			total_written += written;
 			iomap_iter_advance(iter, written);
 		}
 	} while (iov_iter_count(i) && iomap_length(iter));
 
-	return total_written ? 0 : status;
+	return status;
 }
 
 ssize_t
-- 
2.54.0