iomap: switch iomap_file_unshare to use iomap_iter

Switch iomap_file_unshare to use iomap_iter.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

fs/iomap/buffered-io.c

@@ -817,10 +817,12 @@ iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *i,
 }
 EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
 
-static loff_t
-iomap_unshare_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
-		struct iomap *iomap, struct iomap *srcmap)
+static loff_t iomap_unshare_iter(struct iomap_iter *iter)
 {
+	struct iomap *iomap = &iter->iomap;
+	struct iomap *srcmap = iomap_iter_srcmap(iter);
+	loff_t pos = iter->pos;
+	loff_t length = iomap_length(iter);
 	long status = 0;
 	loff_t written = 0;
 
@@ -836,12 +838,12 @@ iomap_unshare_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 		unsigned long bytes = min_t(loff_t, PAGE_SIZE - offset, length);
 		struct page *page;
 
-		status = iomap_write_begin(inode, pos, bytes,
+		status = iomap_write_begin(iter->inode, pos, bytes,
 				IOMAP_WRITE_F_UNSHARE, &page, iomap, srcmap);
 		if (unlikely(status))
 			return status;
 
-		status = iomap_write_end(inode, pos, bytes, bytes, page, iomap,
+		status = iomap_write_end(iter->inode, pos, bytes, bytes, page, iomap,
 				srcmap);
 		if (WARN_ON_ONCE(status == 0))
 			return -EIO;
@@ -852,7 +854,7 @@ iomap_unshare_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 		written += status;
 		length -= status;
 
-		balance_dirty_pages_ratelimited(inode->i_mapping);
+		balance_dirty_pages_ratelimited(iter->inode->i_mapping);
 	} while (length);
 
 	return written;
@@ -862,18 +864,17 @@ int
 iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
 		const struct iomap_ops *ops)
 {
-	loff_t ret;
-
-	while (len) {
-		ret = iomap_apply(inode, pos, len, IOMAP_WRITE, ops, NULL,
-				iomap_unshare_actor);
-		if (ret <= 0)
-			return ret;
-		pos += ret;
-		len -= ret;
-	}
+	struct iomap_iter iter = {
+		.inode		= inode,
+		.pos		= pos,
+		.len		= len,
+		.flags		= IOMAP_WRITE,
+	};
+	int ret;
 
-	return 0;
+	while ((ret = iomap_iter(&iter, ops)) > 0)
+		iter.processed = iomap_unshare_iter(&iter);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(iomap_file_unshare);