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/fs/fs-writeback.c b/fs/fs-writeback.c
index da35587..cf6ccfb 100644 (file)
--- 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

diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h
index 8d470b7..e047b49 100644 (file)
--- a/include/linux/backing-dev-defs.h
+++ b/include/linux/backing-dev-defs.h
@@ -186,4 +186,54 @@ static inline void set_bdi_congested(struct backing_dev_info *bdi, int sync)
        set_wb_congested(bdi->wb.congested, sync);
 }
 
+#ifdef CONFIG_CGROUP_WRITEBACK
+
+/**
+ * wb_tryget - try to increment a wb's refcount
+ * @wb: bdi_writeback to get
+ */
+static inline bool wb_tryget(struct bdi_writeback *wb)
+{
+       if (wb != &wb->bdi->wb)
+               return percpu_ref_tryget(&wb->refcnt);
+       return true;
+}
+
+/**
+ * wb_get - increment a wb's refcount
+ * @wb: bdi_writeback to get
+ */
+static inline void wb_get(struct bdi_writeback *wb)
+{
+       if (wb != &wb->bdi->wb)
+               percpu_ref_get(&wb->refcnt);
+}
+
+/**
+ * wb_put - decrement a wb's refcount
+ * @wb: bdi_writeback to put
+ */
+static inline void wb_put(struct bdi_writeback *wb)
+{
+       if (wb != &wb->bdi->wb)
+               percpu_ref_put(&wb->refcnt);
+}
+
+#else  /* CONFIG_CGROUP_WRITEBACK */
+
+static inline bool wb_tryget(struct bdi_writeback *wb)
+{
+       return true;
+}
+
+static inline void wb_get(struct bdi_writeback *wb)
+{
+}
+
+static inline void wb_put(struct bdi_writeback *wb)
+{
+}
+
+#endif /* CONFIG_CGROUP_WRITEBACK */
+
 #endif /* __LINUX_BACKING_DEV_DEFS_H */

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index e9d7373..5c978a9 100644 (file)
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -243,7 +243,6 @@ void wb_congested_put(struct bdi_writeback_congested *congested);
 struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
                                    struct cgroup_subsys_state *memcg_css,
                                    gfp_t gfp);
-void __inode_attach_wb(struct inode *inode, struct page *page);
 void wb_memcg_offline(struct mem_cgroup *memcg);
 void wb_blkcg_offline(struct blkcg *blkcg);
 int inode_congested(struct inode *inode, int cong_bits);
@@ -264,37 +263,6 @@ static inline bool inode_cgwb_enabled(struct inode *inode)
                (inode->i_sb->s_type->fs_flags & FS_CGROUP_WRITEBACK);
 }
 
-/**
- * wb_tryget - try to increment a wb's refcount
- * @wb: bdi_writeback to get
- */
-static inline bool wb_tryget(struct bdi_writeback *wb)
-{
-       if (wb != &wb->bdi->wb)
-               return percpu_ref_tryget(&wb->refcnt);
-       return true;
-}
-
-/**
- * wb_get - increment a wb's refcount
- * @wb: bdi_writeback to get
- */
-static inline void wb_get(struct bdi_writeback *wb)
-{
-       if (wb != &wb->bdi->wb)
-               percpu_ref_get(&wb->refcnt);
-}
-
-/**
- * wb_put - decrement a wb's refcount
- * @wb: bdi_writeback to put
- */
-static inline void wb_put(struct bdi_writeback *wb)
-{
-       if (wb != &wb->bdi->wb)
-               percpu_ref_put(&wb->refcnt);
-}
-
 /**
  * wb_find_current - find wb for %current on a bdi
  * @bdi: bdi of interest
@@ -353,35 +321,6 @@ wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
        return wb;
 }
 
-/**
- * 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;
-       }
-}
-
 /**
  * inode_to_wb - determine the wb of an inode
  * @inode: inode of interest
@@ -471,19 +410,6 @@ static inline void wb_congested_put(struct bdi_writeback_congested *congested)
 {
 }
 
-static inline bool wb_tryget(struct bdi_writeback *wb)
-{
-       return true;
-}
-
-static inline void wb_get(struct bdi_writeback *wb)
-{
-}
-
-static inline void wb_put(struct bdi_writeback *wb)
-{
-}
-
 static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
 {
        return &bdi->wb;
@@ -495,14 +421,6 @@ wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
        return &bdi->wb;
 }
 
-static inline void inode_attach_wb(struct inode *inode, struct page *page)
-{
-}
-
-static inline void inode_detach_wb(struct inode *inode)
-{
-}
-
 static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
 {
        return &inode_to_bdi(inode)->wb;

diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 3b73e97..6726b7e 100644 (file)
--- 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 @@ static inline void wait_on_inode(struct inode *inode)
        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
  */

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 84ebf7c..887d72a 100644 (file)
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -660,36 +660,6 @@ struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
        return wb;
 }
 
-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);
-}
-
 static void cgwb_bdi_init(struct backing_dev_info *bdi)
 {
        bdi->wb.memcg_css = mem_cgroup_root_css;