1 files changed, 105 insertions, 0 deletions
diff --git a/include/linux/folio_batch.h b/include/linux/folio_batch.h
new file mode 100644
index 000000000000..b45946adc50b
--- /dev/null
+++ b/include/linux/folio_batch.h
@@ -0,0 +1,105 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * include/linux/folio_batch.h
+ *
+ * In many places it is efficient to batch an operation up against multiple
+ * folios.  A folio_batch is a container which is used for that.
+ */
+
+#ifndef _LINUX_FOLIO_BATCH_H
+#define _LINUX_FOLIO_BATCH_H
+
+#include <linux/types.h>
+
+/* 31 pointers + header align the folio_batch structure to a power of two */
+#define FOLIO_BATCH_SIZE	31
+
+struct folio;
+
+/**
+ * struct folio_batch - A collection of folios.
+ *
+ * The folio_batch is used to amortise the cost of retrieving and
+ * operating on a set of folios.  The order of folios in the batch may be
+ * significant (eg delete_from_page_cache_batch()).  Some users of the
+ * folio_batch store "exceptional" entries in it which can be removed
+ * by calling folio_batch_remove_exceptionals().
+ */
+struct folio_batch {
+	unsigned char nr;
+	unsigned char i;
+	bool percpu_pvec_drained;
+	struct folio *folios[FOLIO_BATCH_SIZE];
+};
+
+/**
+ * folio_batch_init() - Initialise a batch of folios
+ * @fbatch: The folio batch.
+ *
+ * A freshly initialised folio_batch contains zero folios.
+ */
+static inline void folio_batch_init(struct folio_batch *fbatch)
+{
+	fbatch->nr = 0;
+	fbatch->i = 0;
+	fbatch->percpu_pvec_drained = false;
+}
+
+static inline void folio_batch_reinit(struct folio_batch *fbatch)
+{
+	fbatch->nr = 0;
+	fbatch->i = 0;
+}
+
+static inline unsigned int folio_batch_count(const struct folio_batch *fbatch)
+{
+	return fbatch->nr;
+}
+
+static inline unsigned int folio_batch_space(const struct folio_batch *fbatch)
+{
+	return FOLIO_BATCH_SIZE - fbatch->nr;
+}
+
+/**
+ * folio_batch_add() - Add a folio to a batch.
+ * @fbatch: The folio batch.
+ * @folio: The folio to add.
+ *
+ * The folio is added to the end of the batch.
+ * The batch must have previously been initialised using folio_batch_init().
+ *
+ * Return: The number of slots still available.
+ */
+static inline unsigned folio_batch_add(struct folio_batch *fbatch,
+		struct folio *folio)
+{
+	fbatch->folios[fbatch->nr++] = folio;
+	return folio_batch_space(fbatch);
+}
+
+/**
+ * folio_batch_next - Return the next folio to process.
+ * @fbatch: The folio batch being processed.
+ *
+ * Use this function to implement a queue of folios.
+ *
+ * Return: The next folio in the queue, or NULL if the queue is empty.
+ */
+static inline struct folio *folio_batch_next(struct folio_batch *fbatch)
+{
+	if (fbatch->i == fbatch->nr)
+		return NULL;
+	return fbatch->folios[fbatch->i++];
+}
+
+void __folio_batch_release(struct folio_batch *fbatch);
+
+static inline void folio_batch_release(struct folio_batch *fbatch)
+{
+	if (folio_batch_count(fbatch))
+		__folio_batch_release(fbatch);
+}
+
+void folio_batch_remove_exceptionals(struct folio_batch *fbatch);
+#endif /* _LINUX_FOLIO_BATCH_H */