[PATCH v2 6/7] iomap: advance the iter directly on unshare range

[Brian Foster <bfoster@redhat.com>]

Modify unshare range to advance the iter directly. Replace the local
pos and length calculations with direct advances and loop based on
iter state instead.

Signed-off-by: Brian Foster <bfoster@redhat.com>
---
 fs/iomap/buffered-io.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 5ce5ac13765a..ea140d3098ff 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1267,20 +1267,19 @@ EXPORT_SYMBOL_GPL(iomap_write_delalloc_release);
 static loff_t iomap_unshare_iter(struct iomap_iter *iter)
 {
 	struct iomap *iomap = &iter->iomap;
-	loff_t pos = iter->pos;
-	loff_t length = iomap_length(iter);
-	loff_t written = 0;
+	size_t bytes = iomap_length(iter);
 
 	if (!iomap_want_unshare_iter(iter))
-		return length;
+		return bytes;
 
 	do {
 		struct folio *folio;
 		int status;
 		size_t offset;
-		size_t bytes = min_t(u64, SIZE_MAX, length);
+		loff_t pos = iter->pos;
 		bool ret;
 
+		bytes = min_t(u64, SIZE_MAX, bytes);
 		status = iomap_write_begin(iter, pos, bytes, &folio);
 		if (unlikely(status))
 			return status;
@@ -1298,14 +1297,10 @@ static loff_t iomap_unshare_iter(struct iomap_iter *iter)
 
 		cond_resched();
 
-		pos += bytes;
-		written += bytes;
-		length -= bytes;
-
 		balance_dirty_pages_ratelimited(iter->inode->i_mapping);
-	} while (length > 0);
+	} while ((bytes = iomap_iter_advance(iter, bytes)) > 0);
 
-	return written;
+	return bytes < 0 ? bytes : 0;
 }
 
 int
-- 
2.47.1