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-rw-r--r--fs/fs-writeback.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index da355879ba7c..cf6ccfb01e03 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -27,6 +27,7 @@
#include <linux/backing-dev.h>
#include <linux/tracepoint.h>
#include <linux/device.h>
+#include <linux/memcontrol.h>
#include "internal.h"
/*
@@ -213,6 +214,36 @@ static void wb_wait_for_completion(struct backing_dev_info *bdi,
#ifdef CONFIG_CGROUP_WRITEBACK
+void __inode_attach_wb(struct inode *inode, struct page *page)
+{
+ struct backing_dev_info *bdi = inode_to_bdi(inode);
+ struct bdi_writeback *wb = NULL;
+
+ if (inode_cgwb_enabled(inode)) {
+ struct cgroup_subsys_state *memcg_css;
+
+ if (page) {
+ memcg_css = mem_cgroup_css_from_page(page);
+ wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC);
+ } else {
+ /* must pin memcg_css, see wb_get_create() */
+ memcg_css = task_get_css(current, memory_cgrp_id);
+ wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC);
+ css_put(memcg_css);
+ }
+ }
+
+ if (!wb)
+ wb = &bdi->wb;
+
+ /*
+ * There may be multiple instances of this function racing to
+ * update the same inode. Use cmpxchg() to tell the winner.
+ */
+ if (unlikely(cmpxchg(&inode->i_wb, NULL, wb)))
+ wb_put(wb);
+}
+
/**
* inode_congested - test whether an inode is congested
* @inode: inode to test for congestion