f2fs: fix to flush multiple device in checkpoint

If f2fs manages multiple devices, in checkpoint, we need to issue flush
in those devices which contain dirty data/node in their cache before
we write checkpoint region, otherwise, filesystem metadata could be
corrupted if hitting SPO after checkpoint.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index d464337..674b6c8 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -659,6 +659,28 @@
 	}
 }
 
+int f2fs_flush_device_cache(struct f2fs_sb_info *sbi)
+{
+	int ret = 0, i;
+
+	if (!sbi->s_ndevs)
+		return 0;
+
+	for (i = 1; i < sbi->s_ndevs; i++) {
+		if (!f2fs_test_bit(i, (char *)&sbi->dirty_device))
+			continue;
+		ret = __submit_flush_wait(sbi, FDEV(i).bdev);
+		if (ret)
+			break;
+
+		spin_lock(&sbi->dev_lock);
+		f2fs_clear_bit(i, (char *)&sbi->dirty_device);
+		spin_unlock(&sbi->dev_lock);
+	}
+
+	return ret;
+}
+
 static void __locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno,
 		enum dirty_type dirty_type)
 {
@@ -2402,6 +2424,13 @@
 
 	/* update device state for fsync */
 	set_dirty_device(sbi, fio->ino, devidx, FLUSH_INO);
+
+	/* update device state for checkpoint */
+	if (!f2fs_test_bit(devidx, (char *)&sbi->dirty_device)) {
+		spin_lock(&sbi->dev_lock);
+		f2fs_set_bit(devidx, (char *)&sbi->dirty_device);
+		spin_unlock(&sbi->dev_lock);
+	}
 }
 
 static void do_write_page(struct f2fs_summary *sum, struct f2fs_io_info *fio)