writeback: relocate wb[_try]_get(), wb_put(), inode_{attach|detach}_wb()
Currently, majority of cgroup writeback support including all the
above functions are implemented in include/linux/backing-dev.h and
mm/backing-dev.c; however, the portion closely related to writeback
logic implemented in include/linux/writeback.h and mm/page-writeback.c
will expand to support foreign writeback detection and correction.
This patch moves wb[_try]_get() and wb_put() to
include/linux/backing-dev-defs.h so that they can be used from
writeback.h and inode_{attach|detach}_wb() to writeback.h and
page-writeback.c.
This is pure reorganization and doesn't introduce any functional
changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 3b73e97..6726b7e 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -8,6 +8,7 @@
#include <linux/workqueue.h>
#include <linux/fs.h>
#include <linux/flex_proportions.h>
+#include <linux/backing-dev-defs.h>
DECLARE_PER_CPU(int, dirty_throttle_leaks);
@@ -173,6 +174,51 @@
wait_on_bit(&inode->i_state, __I_NEW, TASK_UNINTERRUPTIBLE);
}
+#ifdef CONFIG_CGROUP_WRITEBACK
+
+void __inode_attach_wb(struct inode *inode, struct page *page);
+
+/**
+ * inode_attach_wb - associate an inode with its wb
+ * @inode: inode of interest
+ * @page: page being dirtied (may be NULL)
+ *
+ * If @inode doesn't have its wb, associate it with the wb matching the
+ * memcg of @page or, if @page is NULL, %current. May be called w/ or w/o
+ * @inode->i_lock.
+ */
+static inline void inode_attach_wb(struct inode *inode, struct page *page)
+{
+ if (!inode->i_wb)
+ __inode_attach_wb(inode, page);
+}
+
+/**
+ * inode_detach_wb - disassociate an inode from its wb
+ * @inode: inode of interest
+ *
+ * @inode is being freed. Detach from its wb.
+ */
+static inline void inode_detach_wb(struct inode *inode)
+{
+ if (inode->i_wb) {
+ wb_put(inode->i_wb);
+ inode->i_wb = NULL;
+ }
+}
+
+#else /* CONFIG_CGROUP_WRITEBACK */
+
+static inline void inode_attach_wb(struct inode *inode, struct page *page)
+{
+}
+
+static inline void inode_detach_wb(struct inode *inode)
+{
+}
+
+#endif /* CONFIG_CGROUP_WRITEBACK */
+
/*
* mm/page-writeback.c
*/