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From:   Tejun Heo <tj@kernel.org>
To:     dsterba@suse.com, clm@fb.com, josef@toxicpanda.com,
        axboe@kernel.dk, jack@suse.cz
Cc:     linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-block@vger.kernel.org, kernel-team@fb.com,
        Tejun Heo <tj@kernel.org>
Subject: [PATCH 2/8] blkcg, writeback: Implement wbc_blkcg_css()
Date:   Thu, 13 Jun 2019 17:33:44 -0700
Message-Id: <20190614003350.1178444-3-tj@kernel.org>
In-Reply-To: <20190614003350.1178444-1-tj@kernel.org>
References: <20190614003350.1178444-1-tj@kernel.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Add a helper to determine the target blkcg from wbc.

Signed-off-by: Tejun Heo <tj@kernel.org>
---
 include/linux/writeback.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index b8f5f000cde4..1c85563f035d 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -93,6 +93,16 @@ static inline int wbc_to_write_flags(struct writeback_control *wbc)
 	return 0;
 }
 
+static inline struct cgroup_subsys_state *
+wbc_blkcg_css(struct writeback_control *wbc)
+{
+#ifdef CONFIG_CGROUP_WRITEBACK
+	if (wbc->wb)
+		return wbc->wb->blkcg_css;
+#endif
+	return blkcg_root_css;
+}
+
 /*
  * A wb_domain represents a domain that wb's (bdi_writeback's) belong to
  * and are measured against each other in.  There always is one global
-- 
2.17.1