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Commit 21c6321f authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
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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: default avatarTejun 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: default avatarJens Axboe <axboe@fb.com>
parent 97c9341f

fs/fs-writeback.c

+31 −0
Original line number Diff line number Diff line
@@ -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

include/linux/backing-dev-defs.h

+50 −0
Original line number Diff line number Diff line
@@ -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 */

include/linux/backing-dev.h

+0 −82
Original line number Diff line number Diff line
@@ -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;

include/linux/writeback.h

+46 −0
Original line number Diff line number Diff line
@@ -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

 */

mm/backing-dev.c

+0 −30
Original line number Diff line number Diff line
@@ -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;