1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __LINUX_BACKING_DEV_DEFS_H
3 #define __LINUX_BACKING_DEV_DEFS_H
5 #include <linux/list.h>
6 #include <linux/radix-tree.h>
7 #include <linux/rbtree.h>
8 #include <linux/spinlock.h>
9 #include <linux/percpu_counter.h>
10 #include <linux/percpu-refcount.h>
11 #include <linux/flex_proportions.h>
12 #include <linux/timer.h>
13 #include <linux/workqueue.h>
14 #include <linux/kref.h>
15 #include <linux/refcount.h>
22 * Bits in bdi_writeback.state
25 WB_registered
, /* bdi_register() was done */
26 WB_writeback_running
, /* Writeback is in progress */
27 WB_has_dirty_io
, /* Dirty inodes on ->b_{dirty|io|more_io} */
28 WB_start_all
, /* nr_pages == 0 (all) work pending */
31 enum wb_congested_state
{
32 WB_async_congested
, /* The async (write) queue is getting full */
33 WB_sync_congested
, /* The sync queue is getting full */
44 #define WB_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
47 * why some writeback work was initiated
54 WB_REASON_LAPTOP_TIMER
,
55 WB_REASON_FS_FREE_SPACE
,
57 * There is no bdi forker thread any more and works are done
58 * by emergency worker, however, this is TPs userland visible
59 * and we'll be exposing exactly the same information,
60 * so it has a mismatch name.
62 WB_REASON_FORKER_THREAD
,
63 WB_REASON_FOREIGN_FLUSH
,
68 struct wb_completion
{
70 wait_queue_head_t
*waitq
;
73 #define __WB_COMPLETION_INIT(_waitq) \
74 (struct wb_completion){ .cnt = ATOMIC_INIT(1), .waitq = (_waitq) }
77 * If one wants to wait for one or more wb_writeback_works, each work's
78 * ->done should be set to a wb_completion defined using the following
79 * macro. Once all work items are issued with wb_queue_work(), the caller
80 * can wait for the completion of all using wb_wait_for_completion(). Work
81 * items which are waited upon aren't freed automatically on completion.
83 #define WB_COMPLETION_INIT(bdi) __WB_COMPLETION_INIT(&(bdi)->wb_waitq)
85 #define DEFINE_WB_COMPLETION(cmpl, bdi) \
86 struct wb_completion cmpl = WB_COMPLETION_INIT(bdi)
89 * Each wb (bdi_writeback) can perform writeback operations, is measured
90 * and throttled, independently. Without cgroup writeback, each bdi
91 * (bdi_writeback) is served by its embedded bdi->wb.
93 * On the default hierarchy, blkcg implicitly enables memcg. This allows
94 * using memcg's page ownership for attributing writeback IOs, and every
95 * memcg - blkcg combination can be served by its own wb by assigning a
96 * dedicated wb to each memcg, which enables isolation across different
97 * cgroups and propagation of IO back pressure down from the IO layer upto
98 * the tasks which are generating the dirty pages to be written back.
100 * A cgroup wb is indexed on its bdi by the ID of the associated memcg,
101 * refcounted with the number of inodes attached to it, and pins the memcg
102 * and the corresponding blkcg. As the corresponding blkcg for a memcg may
103 * change as blkcg is disabled and enabled higher up in the hierarchy, a wb
104 * is tested for blkcg after lookup and removed from index on mismatch so
105 * that a new wb for the combination can be created.
107 struct bdi_writeback
{
108 struct backing_dev_info
*bdi
; /* our parent bdi */
110 unsigned long state
; /* Always use atomic bitops on this */
111 unsigned long last_old_flush
; /* last old data flush */
113 struct list_head b_dirty
; /* dirty inodes */
114 struct list_head b_io
; /* parked for writeback */
115 struct list_head b_more_io
; /* parked for more writeback */
116 struct list_head b_dirty_time
; /* time stamps are dirty */
117 spinlock_t list_lock
; /* protects the b_* lists */
119 struct percpu_counter stat
[NR_WB_STAT_ITEMS
];
121 unsigned long congested
; /* WB_[a]sync_congested flags */
123 unsigned long bw_time_stamp
; /* last time write bw is updated */
124 unsigned long dirtied_stamp
;
125 unsigned long written_stamp
; /* pages written at bw_time_stamp */
126 unsigned long write_bandwidth
; /* the estimated write bandwidth */
127 unsigned long avg_write_bandwidth
; /* further smoothed write bw, > 0 */
130 * The base dirty throttle rate, re-calculated on every 200ms.
131 * All the bdi tasks' dirty rate will be curbed under it.
132 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit
133 * in small steps and is much more smooth/stable than the latter.
135 unsigned long dirty_ratelimit
;
136 unsigned long balanced_dirty_ratelimit
;
138 struct fprop_local_percpu completions
;
140 enum wb_reason start_all_reason
;
142 spinlock_t work_lock
; /* protects work_list & dwork scheduling */
143 struct list_head work_list
;
144 struct delayed_work dwork
; /* work item used for writeback */
146 unsigned long dirty_sleep
; /* last wait */
148 struct list_head bdi_node
; /* anchored at bdi->wb_list */
150 #ifdef CONFIG_CGROUP_WRITEBACK
151 struct percpu_ref refcnt
; /* used only for !root wb's */
152 struct fprop_local_percpu memcg_completions
;
153 struct cgroup_subsys_state
*memcg_css
; /* the associated memcg */
154 struct cgroup_subsys_state
*blkcg_css
; /* and blkcg */
155 struct list_head memcg_node
; /* anchored at memcg->cgwb_list */
156 struct list_head blkcg_node
; /* anchored at blkcg->cgwb_list */
159 struct work_struct release_work
;
165 struct backing_dev_info
{
167 struct rb_node rb_node
; /* keyed by ->id */
168 struct list_head bdi_list
;
169 unsigned long ra_pages
; /* max readahead in PAGE_SIZE units */
170 unsigned long io_pages
; /* max allowed IO size */
172 struct kref refcnt
; /* Reference counter for the structure */
173 unsigned int capabilities
; /* Device capabilities */
174 unsigned int min_ratio
;
175 unsigned int max_ratio
, max_prop_frac
;
178 * Sum of avg_write_bw of wbs with dirty inodes. > 0 if there are
179 * any dirty wbs, which is depended upon by bdi_has_dirty().
181 atomic_long_t tot_write_bandwidth
;
183 struct bdi_writeback wb
; /* the root writeback info for this bdi */
184 struct list_head wb_list
; /* list of all wbs */
185 #ifdef CONFIG_CGROUP_WRITEBACK
186 struct radix_tree_root cgwb_tree
; /* radix tree of active cgroup wbs */
187 struct mutex cgwb_release_mutex
; /* protect shutdown of wb structs */
188 struct rw_semaphore wb_switch_rwsem
; /* no cgwb switch while syncing */
190 wait_queue_head_t wb_waitq
;
194 struct device
*owner
;
196 struct timer_list laptop_mode_wb_timer
;
198 #ifdef CONFIG_DEBUG_FS
199 struct dentry
*debug_dir
;
208 void clear_bdi_congested(struct backing_dev_info
*bdi
, int sync
);
209 void set_bdi_congested(struct backing_dev_info
*bdi
, int sync
);
211 struct wb_lock_cookie
{
216 #ifdef CONFIG_CGROUP_WRITEBACK
219 * wb_tryget - try to increment a wb's refcount
220 * @wb: bdi_writeback to get
222 static inline bool wb_tryget(struct bdi_writeback
*wb
)
224 if (wb
!= &wb
->bdi
->wb
)
225 return percpu_ref_tryget(&wb
->refcnt
);
230 * wb_get - increment a wb's refcount
231 * @wb: bdi_writeback to get
233 static inline void wb_get(struct bdi_writeback
*wb
)
235 if (wb
!= &wb
->bdi
->wb
)
236 percpu_ref_get(&wb
->refcnt
);
240 * wb_put - decrement a wb's refcount
241 * @wb: bdi_writeback to put
243 static inline void wb_put(struct bdi_writeback
*wb
)
245 if (WARN_ON_ONCE(!wb
->bdi
)) {
247 * A driver bug might cause a file to be removed before bdi was
253 if (wb
!= &wb
->bdi
->wb
)
254 percpu_ref_put(&wb
->refcnt
);
258 * wb_dying - is a wb dying?
259 * @wb: bdi_writeback of interest
261 * Returns whether @wb is unlinked and being drained.
263 static inline bool wb_dying(struct bdi_writeback
*wb
)
265 return percpu_ref_is_dying(&wb
->refcnt
);
268 #else /* CONFIG_CGROUP_WRITEBACK */
270 static inline bool wb_tryget(struct bdi_writeback
*wb
)
275 static inline void wb_get(struct bdi_writeback
*wb
)
279 static inline void wb_put(struct bdi_writeback
*wb
)
283 static inline bool wb_dying(struct bdi_writeback
*wb
)
288 #endif /* CONFIG_CGROUP_WRITEBACK */
290 #endif /* __LINUX_BACKING_DEV_DEFS_H */