/* SPDX-License-Identifier: GPL-2.0 */#ifndef __LINUX_BACKING_DEV_DEFS_H#define __LINUX_BACKING_DEV_DEFS_H #include <linux/list.h>#include <linux/radix-tree.h>#include <linux/rbtree.h>#include <linux/spinlock.h>#include <linux/percpu_counter.h>#include <linux/percpu-refcount.h>#include <linux/flex_proportions.h>#include <linux/timer.h>#include <linux/workqueue.h>#include <linux/kref.h>#include <linux/refcount.h> struct page;struct device;struct dentry; /* * Bits in bdi_writeback.state */enum wb_state {	WB_registered,		/* bdi_register() was done */	WB_writeback_running,	/* Writeback is in progress */	WB_has_dirty_io,	/* Dirty inodes on ->b_{dirty|io|more_io} */	WB_start_all,		/* nr_pages == 0 (all) work pending */}; enum wb_stat_item {	WB_RECLAIMABLE,	WB_WRITEBACK,	WB_DIRTIED,	WB_WRITTEN,	NR_WB_STAT_ITEMS}; #define WB_STAT_BATCH (8*(1+ilog2(nr_cpu_ids))) /* * why some writeback work was initiated */enum wb_reason {	WB_REASON_BACKGROUND,	WB_REASON_VMSCAN,	WB_REASON_SYNC,	WB_REASON_PERIODIC,	WB_REASON_LAPTOP_TIMER,	WB_REASON_FS_FREE_SPACE,	/*	 * There is no bdi forker thread any more and works are done	 * by emergency worker, however, this is TPs userland visible	 * and we'll be exposing exactly the same information,	 * so it has a mismatch name.	 */	WB_REASON_FORKER_THREAD,	WB_REASON_FOREIGN_FLUSH, 	WB_REASON_MAX,}; struct wb_completion {	atomic_t		cnt;	wait_queue_head_t	*waitq;}; #define __WB_COMPLETION_INIT(_waitq)	\	(struct wb_completion){ .cnt = ATOMIC_INIT(1), .waitq = (_waitq) } /* * If one wants to wait for one or more wb_writeback_works, each work's * ->done should be set to a wb_completion defined using the following * macro.  Once all work items are issued with wb_queue_work(), the caller * can wait for the completion of all using wb_wait_for_completion().  Work * items which are waited upon aren't freed automatically on completion. */#define WB_COMPLETION_INIT(bdi)		__WB_COMPLETION_INIT(&(bdi)->wb_waitq) #define DEFINE_WB_COMPLETION(cmpl, bdi)	\	struct wb_completion cmpl = WB_COMPLETION_INIT(bdi) /* * Each wb (bdi_writeback) can perform writeback operations, is measured * and throttled, independently.  Without cgroup writeback, each bdi * (bdi_writeback) is served by its embedded bdi->wb. * * On the default hierarchy, blkcg implicitly enables memcg.  This allows * using memcg's page ownership for attributing writeback IOs, and every * memcg - blkcg combination can be served by its own wb by assigning a * dedicated wb to each memcg, which enables isolation across different * cgroups and propagation of IO back pressure down from the IO layer upto * the tasks which are generating the dirty pages to be written back. * * A cgroup wb is indexed on its bdi by the ID of the associated memcg, * refcounted with the number of inodes attached to it, and pins the memcg * and the corresponding blkcg.  As the corresponding blkcg for a memcg may * change as blkcg is disabled and enabled higher up in the hierarchy, a wb * is tested for blkcg after lookup and removed from index on mismatch so * that a new wb for the combination can be created. * * Each bdi_writeback that is not embedded into the backing_dev_info must hold * a reference to the parent backing_dev_info.  See cgwb_create() for details. */struct bdi_writeback {	struct backing_dev_info *bdi;	/* our parent bdi */ 	unsigned long state;		/* Always use atomic bitops on this */	unsigned long last_old_flush;	/* last old data flush */ 	struct list_head b_dirty;	/* dirty inodes */	struct list_head b_io;		/* parked for writeback */	struct list_head b_more_io;	/* parked for more writeback */	struct list_head b_dirty_time;	/* time stamps are dirty */	spinlock_t list_lock;		/* protects the b_* lists */ 	atomic_t writeback_inodes;	/* number of inodes under writeback */	struct percpu_counter stat[NR_WB_STAT_ITEMS]; 	unsigned long bw_time_stamp;	/* last time write bw is updated */	unsigned long dirtied_stamp;	unsigned long written_stamp;	/* pages written at bw_time_stamp */	unsigned long write_bandwidth;	/* the estimated write bandwidth */	unsigned long avg_write_bandwidth; /* further smoothed write bw, > 0 */ 	/*	 * The base dirty throttle rate, re-calculated on every 200ms.	 * All the bdi tasks' dirty rate will be curbed under it.	 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit	 * in small steps and is much more smooth/stable than the latter.	 */	unsigned long dirty_ratelimit;	unsigned long balanced_dirty_ratelimit; 	struct fprop_local_percpu completions;	int dirty_exceeded;	enum wb_reason start_all_reason; 	spinlock_t work_lock;		/* protects work_list & dwork scheduling */	struct list_head work_list;	struct delayed_work dwork;	/* work item used for writeback */	struct delayed_work bw_dwork;	/* work item used for bandwidth estimate */ 	struct list_head bdi_node;	/* anchored at bdi->wb_list */ #ifdef CONFIG_CGROUP_WRITEBACK	struct percpu_ref refcnt;	/* used only for !root wb's */	struct fprop_local_percpu memcg_completions;	struct cgroup_subsys_state *memcg_css; /* the associated memcg */	struct cgroup_subsys_state *blkcg_css; /* and blkcg */	struct list_head memcg_node;	/* anchored at memcg->cgwb_list */	struct list_head blkcg_node;	/* anchored at blkcg->cgwb_list */	struct list_head b_attached;	/* attached inodes, protected by list_lock */	struct list_head offline_node;	/* anchored at offline_cgwbs */ 	union {		struct work_struct release_work;		struct rcu_head rcu;	};#endif}; struct backing_dev_info {	u64 id;	struct rb_node rb_node; /* keyed by ->id */	struct list_head bdi_list;	unsigned long ra_pages;	/* max readahead in PAGE_SIZE units */	unsigned long io_pages;	/* max allowed IO size */ 	struct kref refcnt;	/* Reference counter for the structure */	unsigned int capabilities; /* Device capabilities */	unsigned int min_ratio;	unsigned int max_ratio, max_prop_frac; 	/*	 * Sum of avg_write_bw of wbs with dirty inodes.  > 0 if there are	 * any dirty wbs, which is depended upon by bdi_has_dirty().	 */	atomic_long_t tot_write_bandwidth;	/*	 * Jiffies when last process was dirty throttled on this bdi. Used by	 * blk-wbt.	 */	unsigned long last_bdp_sleep; 	struct bdi_writeback wb;  /* the root writeback info for this bdi */	struct list_head wb_list; /* list of all wbs */#ifdef CONFIG_CGROUP_WRITEBACK	struct radix_tree_root cgwb_tree; /* radix tree of active cgroup wbs */	struct mutex cgwb_release_mutex;  /* protect shutdown of wb structs */	struct rw_semaphore wb_switch_rwsem; /* no cgwb switch while syncing */#endif	wait_queue_head_t wb_waitq; 	struct device *dev;	char dev_name[64];	struct device *owner; 	struct timer_list laptop_mode_wb_timer; #ifdef CONFIG_DEBUG_FS	struct dentry *debug_dir;#endif}; struct wb_lock_cookie {	bool locked;	unsigned long flags;}; #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 * @nr: number of references to put */static inline void wb_put_many(struct bdi_writeback *wb, unsigned long nr){	if (WARN_ON_ONCE(!wb->bdi)) {		/*		 * A driver bug might cause a file to be removed before bdi was		 * initialized.		 */		return;	} 	if (wb != &wb->bdi->wb)		percpu_ref_put_many(&wb->refcnt, nr);} /** * wb_put - decrement a wb's refcount * @wb: bdi_writeback to put */static inline void wb_put(struct bdi_writeback *wb){	wb_put_many(wb, 1);} /** * wb_dying - is a wb dying? * @wb: bdi_writeback of interest * * Returns whether @wb is unlinked and being drained. */static inline bool wb_dying(struct bdi_writeback *wb){	return percpu_ref_is_dying(&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){} static inline void wb_put_many(struct bdi_writeback *wb, unsigned long nr){} static inline bool wb_dying(struct bdi_writeback *wb){	return false;} #endif	/* CONFIG_CGROUP_WRITEBACK */ #endif	/* __LINUX_BACKING_DEV_DEFS_H */