iomap: use a new variable to handle the written bytes in iomap_write_iter()

In iomap_write_iter(), the status variable used to receive the return
value from iomap_write_end() is confusing, replace it with a new written
variable to represent the written bytes in each cycle, no logic changes.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://lore.kernel.org/r/20240320110548.2200662-8-yi.zhang@huaweicloud.comReviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs/iomap/buffered-io.c

@@ -889,7 +889,7 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
 	loff_t length = iomap_length(iter);
 	size_t chunk = PAGE_SIZE << MAX_PAGECACHE_ORDER;
 	loff_t pos = iter->pos;
-	ssize_t written = 0;
+	ssize_t total_written = 0;
 	long status = 0;
 	struct address_space *mapping = iter->inode->i_mapping;
 	unsigned int bdp_flags = (iter->flags & IOMAP_NOWAIT) ? BDP_ASYNC : 0;
@@ -900,6 +900,7 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
 		size_t offset;		/* Offset into folio */
 		size_t bytes;		/* Bytes to write to folio */
 		size_t copied;		/* Bytes copied from user */
+		size_t written;		/* Bytes have been written */
 
 		bytes = iov_iter_count(i);
 retry:
@@ -944,7 +945,7 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
 			flush_dcache_folio(folio);
 
 		copied = copy_folio_from_iter_atomic(folio, offset, bytes, i);
-		status = iomap_write_end(iter, pos, bytes, copied, folio);
+		written = iomap_write_end(iter, pos, bytes, copied, folio);
 
 		/*
 		 * Update the in-memory inode size after copying the data into
@@ -954,22 +955,22 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
 		 * unlock and release the folio.
 		 */
 		old_size = iter->inode->i_size;
-		if (pos + status > old_size) {
-			i_size_write(iter->inode, pos + status);
+		if (pos + written > old_size) {
+			i_size_write(iter->inode, pos + written);
 			iter->iomap.flags |= IOMAP_F_SIZE_CHANGED;
 		}
-		__iomap_put_folio(iter, pos, status, folio);
+		__iomap_put_folio(iter, pos, written, folio);
 
 		if (old_size < pos)
 			pagecache_isize_extended(iter->inode, old_size, pos);
-		if (status < bytes)
-			iomap_write_failed(iter->inode, pos + status,
-					   bytes - status);
-		if (unlikely(copied != status))
-			iov_iter_revert(i, copied - status);
+		if (written < bytes)
+			iomap_write_failed(iter->inode, pos + written,
+					   bytes - written);
+		if (unlikely(copied != written))
+			iov_iter_revert(i, copied - written);
 
 		cond_resched();
-		if (unlikely(status == 0)) {
+		if (unlikely(written == 0)) {
 			/*
 			 * A short copy made iomap_write_end() reject the
 			 * thing entirely.  Might be memory poisoning
@@ -983,17 +984,17 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
 				goto retry;
 			}
 		} else {
-			pos += status;
-			written += status;
-			length -= status;
+			pos += written;
+			total_written += written;
+			length -= written;
 		}
 	} while (iov_iter_count(i) && length);
 
 	if (status == -EAGAIN) {
-		iov_iter_revert(i, written);
+		iov_iter_revert(i, total_written);
 		return -EAGAIN;
 	}
-	return written ? written : status;
+	return total_written ? total_written : status;
 }
 
 ssize_t