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-rw-r--r--mm/page-writeback.c25
1 files changed, 25 insertions, 0 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 0713bfbf095..7300c9d5e1d 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -35,6 +35,7 @@
#include <linux/buffer_head.h> /* __set_page_dirty_buffers */
#include <linux/pagevec.h>
#include <linux/timer.h>
+#include <linux/sched/rt.h>
#include <trace/events/writeback.h>
/*
@@ -2289,3 +2290,27 @@ int mapping_tagged(struct address_space *mapping, int tag)
return radix_tree_tagged(&mapping->page_tree, tag);
}
EXPORT_SYMBOL(mapping_tagged);
+
+/**
+ * wait_for_stable_page() - wait for writeback to finish, if necessary.
+ * @page: The page to wait on.
+ *
+ * This function determines if the given page is related to a backing device
+ * that requires page contents to be held stable during writeback. If so, then
+ * it will wait for any pending writeback to complete.
+ */
+void wait_for_stable_page(struct page *page)
+{
+ struct address_space *mapping = page_mapping(page);
+ struct backing_dev_info *bdi = mapping->backing_dev_info;
+
+ if (!bdi_cap_stable_pages_required(bdi))
+ return;
+#ifdef CONFIG_NEED_BOUNCE_POOL
+ if (mapping->host->i_sb->s_flags & MS_SNAP_STABLE)
+ return;
+#endif /* CONFIG_NEED_BOUNCE_POOL */
+
+ wait_on_page_writeback(page);
+}
+EXPORT_SYMBOL_GPL(wait_for_stable_page);