iomap: convert misc simple ops to incremental advance

Update several of the remaining iomap operations to advance the iter
directly rather than via return value. This includes page faults,
fiemap, seek data/hole and swapfile activation.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Link: https://lore.kernel.org/r/20250224144757.237706-4-bfoster@redhat.com
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs/iomap/buffered-io.c

@@ -1478,7 +1478,7 @@ static loff_t iomap_folio_mkwrite_iter(struct iomap_iter *iter,
 		folio_mark_dirty(folio);
 	}
 
-	return length;
+	return iomap_iter_advance(iter, &length);
 }
 
 vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops,

fs/iomap/fiemap.c

@@ -39,24 +39,24 @@ static int iomap_to_fiemap(struct fiemap_extent_info *fi,
 			iomap->length, flags);
 }
 
-static loff_t iomap_fiemap_iter(const struct iomap_iter *iter,
+static loff_t iomap_fiemap_iter(struct iomap_iter *iter,
 		struct fiemap_extent_info *fi, struct iomap *prev)
 {
+	u64 length = iomap_length(iter);
 	int ret;
 
 	if (iter->iomap.type == IOMAP_HOLE)
-		return iomap_length(iter);
+		goto advance;
 
 	ret = iomap_to_fiemap(fi, prev, 0);
 	*prev = iter->iomap;
-	switch (ret) {
-	case 0:		/* success */
-		return iomap_length(iter);
-	case 1:		/* extent array full */
-		return 0;
-	default:	/* error */
+	if (ret < 0)
 		return ret;
-	}
+	if (ret == 1)	/* extent array full */
+		return 0;
+
+advance:
+	return iomap_iter_advance(iter, &length);
 }
 
 int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi,

fs/iomap/seek.c

@@ -10,7 +10,7 @@
 #include <linux/pagemap.h>
 #include <linux/pagevec.h>
 
-static loff_t iomap_seek_hole_iter(const struct iomap_iter *iter,
+static loff_t iomap_seek_hole_iter(struct iomap_iter *iter,
 		loff_t *hole_pos)
 {
 	loff_t length = iomap_length(iter);
@@ -20,13 +20,13 @@ static loff_t iomap_seek_hole_iter(const struct iomap_iter *iter,
 		*hole_pos = mapping_seek_hole_data(iter->inode->i_mapping,
 				iter->pos, iter->pos + length, SEEK_HOLE);
 		if (*hole_pos == iter->pos + length)
-			return length;
+			return iomap_iter_advance(iter, &length);
 		return 0;
 	case IOMAP_HOLE:
 		*hole_pos = iter->pos;
 		return 0;
 	default:
-		return length;
+		return iomap_iter_advance(iter, &length);
 	}
 }
 
@@ -56,19 +56,19 @@ iomap_seek_hole(struct inode *inode, loff_t pos, const struct iomap_ops *ops)
 }
 EXPORT_SYMBOL_GPL(iomap_seek_hole);
 
-static loff_t iomap_seek_data_iter(const struct iomap_iter *iter,
+static loff_t iomap_seek_data_iter(struct iomap_iter *iter,
 		loff_t *hole_pos)
 {
 	loff_t length = iomap_length(iter);
 
 	switch (iter->iomap.type) {
 	case IOMAP_HOLE:
-		return length;
+		return iomap_iter_advance(iter, &length);
 	case IOMAP_UNWRITTEN:
 		*hole_pos = mapping_seek_hole_data(iter->inode->i_mapping,
 				iter->pos, iter->pos + length, SEEK_DATA);
 		if (*hole_pos < 0)
-			return length;
+			return iomap_iter_advance(iter, &length);
 		return 0;
 	default:
 		*hole_pos = iter->pos;

fs/iomap/swapfile.c

@@ -94,9 +94,11 @@ static int iomap_swapfile_fail(struct iomap_swapfile_info *isi, const char *str)
  * swap only cares about contiguous page-aligned physical extents and makes no
  * distinction between written and unwritten extents.
  */
-static loff_t iomap_swapfile_iter(const struct iomap_iter *iter,
+static loff_t iomap_swapfile_iter(struct iomap_iter *iter,
 		struct iomap *iomap, struct iomap_swapfile_info *isi)
 {
+	u64 length = iomap_length(iter);
+
 	switch (iomap->type) {
 	case IOMAP_MAPPED:
 	case IOMAP_UNWRITTEN:
@@ -132,7 +134,8 @@ static loff_t iomap_swapfile_iter(const struct iomap_iter *iter,
 			return error;
 		memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
 	}
-	return iomap_length(iter);
+
+	return iomap_iter_advance(iter, &length);
 }
 
 /*