[PATCH v5 02/28] mm: Add wait_on_page_writeback_killable()

[David Howells]

Add a function to wait killably on the PG_writeback page flag.

Signed-off-by: David Howells <dhowells at redhat.com>
cc: Matthew Wilcox (Oracle) <willy at infradead.org>
cc: Alexander Viro <viro at zeniv.linux.org.uk>
cc: Christoph Hellwig <hch at lst.de>
cc: linux-mm at kvack.org
cc: linux-cachefs at redhat.com
cc: linux-afs at lists.infradead.org
cc: linux-nfs at vger.kernel.org
cc: linux-cifs at vger.kernel.org
cc: ceph-devel at vger.kernel.org
cc: v9fs-developer at lists.sourceforge.net
cc: linux-fsdevel at vger.kernel.org
---

 include/linux/pagemap.h |    1 +
 mm/page-writeback.c     |   25 +++++++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 20225b067583..444155ae56c0 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -683,6 +683,7 @@ static inline int wait_on_page_locked_killable(struct page *page)
 
 int put_and_wait_on_page_locked(struct page *page, int state);
 void wait_on_page_writeback(struct page *page);
+int wait_on_page_writeback_killable(struct page *page);
 extern void end_page_writeback(struct page *page);
 void wait_for_stable_page(struct page *page);
 
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index eb34d204d4ee..b8bad275f94b 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2833,6 +2833,31 @@ void wait_on_page_writeback(struct page *page)
 }
 EXPORT_SYMBOL_GPL(wait_on_page_writeback);
 
+/**
+ * Wait for a page to complete writeback
+ * @page: The page to wait on
+ *
+ * Wait for the writeback status of a page to clear or a fatal signal to occur.
+ *
+ * Return:
+ * - 0 on success.
+ * - -EINTR if a fatal signal was encountered.
+ */
+int wait_on_page_writeback_killable(struct page *page)
+{
+	int ret = 0;
+
+	while (PageWriteback(page)) {
+		trace_wait_on_page_writeback(page, page_mapping(page));
+		ret = wait_on_page_bit_killable(page, PG_writeback);
+		if (ret < 0)
+			break;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(wait_on_page_writeback_killable);
+
 /**
  * wait_for_stable_page() - wait for writeback to finish, if necessary.
  * @page:	The page to wait on.