From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Add a loop counter inside the folio_batch to let us iterate from 0-nr
instead of decrementing nr and treating the batch as a stack. It would
generate some very weird and suboptimal I/O patterns for page writeback
to iterate over the batch as a stack.
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
include/linux/pagevec.h | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/include/linux/pagevec.h b/include/linux/pagevec.h
index 87cc678adc850b..fcc06c300a72c3 100644
--- a/include/linux/pagevec.h
+++ b/include/linux/pagevec.h
@@ -27,6 +27,7 @@ struct folio;
*/
struct folio_batch {
unsigned char nr;
+ unsigned char i;
bool percpu_pvec_drained;
struct folio *folios[PAGEVEC_SIZE];
};
@@ -40,12 +41,14 @@ struct folio_batch {
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(struct folio_batch *fbatch)
@@ -75,6 +78,21 @@ static inline unsigned folio_batch_add(struct folio_batch *fbatch,
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 *pvec);
static inline void folio_batch_release(struct folio_batch *fbatch)
--
2.39.2
