[PATCH v4 10/10] iomap: advance the iter directly on zero range

[Brian Foster <bfoster@redhat.com>]

Modify zero 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>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/iomap/buffered-io.c | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index f953bf66beb1..ec227b45f3aa 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1345,17 +1345,16 @@ static inline int iomap_zero_iter_flush_and_stale(struct iomap_iter *i)
 
 static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero)
 {
-	loff_t pos = iter->pos;
-	loff_t length = iomap_length(iter);
-	loff_t written = 0;
+	u64 bytes = iomap_length(iter);
+	int status;
 
 	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 (status)
 			return status;
@@ -1376,14 +1375,14 @@ static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero)
 		if (WARN_ON_ONCE(!ret))
 			return -EIO;
 
-		pos += bytes;
-		length -= bytes;
-		written += bytes;
-	} while (length > 0);
+		status = iomap_iter_advance(iter, &bytes);
+		if (status)
+			break;
+	} while (bytes > 0);
 
 	if (did_zero)
 		*did_zero = true;
-	return written;
+	return status;
 }
 
 int
@@ -1436,11 +1435,14 @@ iomap_zero_range(struct inode *inode, loff_t pos, loff_t len, bool *did_zero,
 
 		if (srcmap->type == IOMAP_HOLE ||
 		    srcmap->type == IOMAP_UNWRITTEN) {
-			loff_t proc = iomap_length(&iter);
+			s64 proc;
 
 			if (range_dirty) {
 				range_dirty = false;
 				proc = iomap_zero_iter_flush_and_stale(&iter);
+			} else {
+				u64 length = iomap_length(&iter);
+				proc = iomap_iter_advance(&iter, &length);
 			}
 			iter.processed = proc;
 			continue;
-- 
2.48.1