1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __LINUX_BACKING_DEV_DEFS_H
3 #define __LINUX_BACKING_DEV_DEFS_H
4
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>
16 #include <linux/android_kabi.h>
17
18 struct page;
19 struct device;
20 struct dentry;
21
22 /*
23 * Bits in bdi_writeback.state
24 */
25 enum wb_state {
26 WB_registered, /* bdi_register() was done */
27 WB_writeback_running, /* Writeback is in progress */
28 WB_has_dirty_io, /* Dirty inodes on ->b_{dirty|io|more_io} */
29 WB_start_all, /* nr_pages == 0 (all) work pending */
30 };
31
32 enum wb_stat_item {
33 WB_RECLAIMABLE,
34 WB_WRITEBACK,
35 WB_DIRTIED,
36 WB_WRITTEN,
37 NR_WB_STAT_ITEMS
38 };
39
40 #define WB_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
41
42 /*
43 * why some writeback work was initiated
44 */
45 enum wb_reason {
46 WB_REASON_BACKGROUND,
47 WB_REASON_VMSCAN,
48 WB_REASON_SYNC,
49 WB_REASON_PERIODIC,
50 WB_REASON_LAPTOP_TIMER,
51 WB_REASON_FS_FREE_SPACE,
52 /*
53 * There is no bdi forker thread any more and works are done
54 * by emergency worker, however, this is TPs userland visible
55 * and we'll be exposing exactly the same information,
56 * so it has a mismatch name.
57 */
58 WB_REASON_FORKER_THREAD,
59 WB_REASON_FOREIGN_FLUSH,
60
61 WB_REASON_MAX,
62 };
63
64 struct wb_completion {
65 atomic_t cnt;
66 wait_queue_head_t *waitq;
67 };
68
69 #define __WB_COMPLETION_INIT(_waitq) \
70 (struct wb_completion){ .cnt = ATOMIC_INIT(1), .waitq = (_waitq) }
71
72 /*
73 * If one wants to wait for one or more wb_writeback_works, each work's
74 * ->done should be set to a wb_completion defined using the following
75 * macro. Once all work items are issued with wb_queue_work(), the caller
76 * can wait for the completion of all using wb_wait_for_completion(). Work
77 * items which are waited upon aren't freed automatically on completion.
78 */
79 #define WB_COMPLETION_INIT(bdi) __WB_COMPLETION_INIT(&(bdi)->wb_waitq)
80
81 #define DEFINE_WB_COMPLETION(cmpl, bdi) \
82 struct wb_completion cmpl = WB_COMPLETION_INIT(bdi)
83
84 /*
85 * Each wb (bdi_writeback) can perform writeback operations, is measured
86 * and throttled, independently. Without cgroup writeback, each bdi
87 * (bdi_writeback) is served by its embedded bdi->wb.
88 *
89 * On the default hierarchy, blkcg implicitly enables memcg. This allows
90 * using memcg's page ownership for attributing writeback IOs, and every
91 * memcg - blkcg combination can be served by its own wb by assigning a
92 * dedicated wb to each memcg, which enables isolation across different
93 * cgroups and propagation of IO back pressure down from the IO layer upto
94 * the tasks which are generating the dirty pages to be written back.
95 *
96 * A cgroup wb is indexed on its bdi by the ID of the associated memcg,
97 * refcounted with the number of inodes attached to it, and pins the memcg
98 * and the corresponding blkcg. As the corresponding blkcg for a memcg may
99 * change as blkcg is disabled and enabled higher up in the hierarchy, a wb
100 * is tested for blkcg after lookup and removed from index on mismatch so
101 * that a new wb for the combination can be created.
102 *
103 * Each bdi_writeback that is not embedded into the backing_dev_info must hold
104 * a reference to the parent backing_dev_info. See cgwb_create() for details.
105 */
106 struct bdi_writeback {
107 struct backing_dev_info *bdi; /* our parent bdi */
108
109 unsigned long state; /* Always use atomic bitops on this */
110 unsigned long last_old_flush; /* last old data flush */
111
112 struct list_head b_dirty; /* dirty inodes */
113 struct list_head b_io; /* parked for writeback */
114 struct list_head b_more_io; /* parked for more writeback */
115 struct list_head b_dirty_time; /* time stamps are dirty */
116 spinlock_t list_lock; /* protects the b_* lists */
117
118 atomic_t writeback_inodes; /* number of inodes under writeback */
119 struct percpu_counter stat[NR_WB_STAT_ITEMS];
120
121 unsigned long bw_time_stamp; /* last time write bw is updated */
122 unsigned long dirtied_stamp;
123 unsigned long written_stamp; /* pages written at bw_time_stamp */
124 unsigned long write_bandwidth; /* the estimated write bandwidth */
125 unsigned long avg_write_bandwidth; /* further smoothed write bw, > 0 */
126
127 /*
128 * The base dirty throttle rate, re-calculated on every 200ms.
129 * All the bdi tasks' dirty rate will be curbed under it.
130 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit
131 * in small steps and is much more smooth/stable than the latter.
132 */
133 unsigned long dirty_ratelimit;
134 unsigned long balanced_dirty_ratelimit;
135
136 struct fprop_local_percpu completions;
137 int dirty_exceeded;
138 enum wb_reason start_all_reason;
139
140 spinlock_t work_lock; /* protects work_list & dwork scheduling */
141 struct list_head work_list;
142 struct delayed_work dwork; /* work item used for writeback */
143 struct delayed_work bw_dwork; /* work item used for bandwidth estimate */
144
145 struct list_head bdi_node; /* anchored at bdi->wb_list */
146
147 #ifdef CONFIG_CGROUP_WRITEBACK
148 struct percpu_ref refcnt; /* used only for !root wb's */
149 struct fprop_local_percpu memcg_completions;
150 struct cgroup_subsys_state *memcg_css; /* the associated memcg */
151 struct cgroup_subsys_state *blkcg_css; /* and blkcg */
152 struct list_head memcg_node; /* anchored at memcg->cgwb_list */
153 struct list_head blkcg_node; /* anchored at blkcg->cgwb_list */
154 struct list_head b_attached; /* attached inodes, protected by list_lock */
155 struct list_head offline_node; /* anchored at offline_cgwbs */
156
157 union {
158 struct work_struct release_work;
159 struct rcu_head rcu;
160 };
161 #endif
162
163 ANDROID_KABI_RESERVE(1);
164 ANDROID_KABI_RESERVE(2);
165 ANDROID_OEM_DATA_ARRAY(1, 2);
166 };
167
168 struct backing_dev_info {
169 u64 id;
170 struct rb_node rb_node; /* keyed by ->id */
171 struct list_head bdi_list;
172 unsigned long ra_pages; /* max readahead in PAGE_SIZE units */
173 unsigned long io_pages; /* max allowed IO size */
174
175 struct kref refcnt; /* Reference counter for the structure */
176 unsigned int capabilities; /* Device capabilities */
177 unsigned int min_ratio;
178 unsigned int max_ratio, max_prop_frac;
179
180 /*
181 * Sum of avg_write_bw of wbs with dirty inodes. > 0 if there are
182 * any dirty wbs, which is depended upon by bdi_has_dirty().
183 */
184 atomic_long_t tot_write_bandwidth;
185 /*
186 * Jiffies when last process was dirty throttled on this bdi. Used by
187 * blk-wbt.
188 */
189 unsigned long last_bdp_sleep;
190
191 struct bdi_writeback wb; /* the root writeback info for this bdi */
192 struct list_head wb_list; /* list of all wbs */
193 #ifdef CONFIG_CGROUP_WRITEBACK
194 struct radix_tree_root cgwb_tree; /* radix tree of active cgroup wbs */
195 struct mutex cgwb_release_mutex; /* protect shutdown of wb structs */
196 struct rw_semaphore wb_switch_rwsem; /* no cgwb switch while syncing */
197 #endif
198 wait_queue_head_t wb_waitq;
199
200 struct device *dev;
201 char dev_name[64];
202 struct device *owner;
203
204 struct timer_list laptop_mode_wb_timer;
205
206 #ifdef CONFIG_DEBUG_FS
207 struct dentry *debug_dir;
208 #endif
209
210 ANDROID_KABI_RESERVE(1);
211 ANDROID_KABI_RESERVE(2);
212 };
213
214 struct wb_lock_cookie {
215 bool locked;
216 unsigned long flags;
217 };
218
219 #ifdef CONFIG_CGROUP_WRITEBACK
220
221 /**
222 * wb_tryget - try to increment a wb's refcount
223 * @wb: bdi_writeback to get
224 */
wb_tryget(struct bdi_writeback * wb)225 static inline bool wb_tryget(struct bdi_writeback *wb)
226 {
227 if (wb != &wb->bdi->wb)
228 return percpu_ref_tryget(&wb->refcnt);
229 return true;
230 }
231
232 /**
233 * wb_get - increment a wb's refcount
234 * @wb: bdi_writeback to get
235 */
wb_get(struct bdi_writeback * wb)236 static inline void wb_get(struct bdi_writeback *wb)
237 {
238 if (wb != &wb->bdi->wb)
239 percpu_ref_get(&wb->refcnt);
240 }
241
242 /**
243 * wb_put - decrement a wb's refcount
244 * @wb: bdi_writeback to put
245 * @nr: number of references to put
246 */
wb_put_many(struct bdi_writeback * wb,unsigned long nr)247 static inline void wb_put_many(struct bdi_writeback *wb, unsigned long nr)
248 {
249 if (WARN_ON_ONCE(!wb->bdi)) {
250 /*
251 * A driver bug might cause a file to be removed before bdi was
252 * initialized.
253 */
254 return;
255 }
256
257 if (wb != &wb->bdi->wb)
258 percpu_ref_put_many(&wb->refcnt, nr);
259 }
260
261 /**
262 * wb_put - decrement a wb's refcount
263 * @wb: bdi_writeback to put
264 */
wb_put(struct bdi_writeback * wb)265 static inline void wb_put(struct bdi_writeback *wb)
266 {
267 wb_put_many(wb, 1);
268 }
269
270 /**
271 * wb_dying - is a wb dying?
272 * @wb: bdi_writeback of interest
273 *
274 * Returns whether @wb is unlinked and being drained.
275 */
wb_dying(struct bdi_writeback * wb)276 static inline bool wb_dying(struct bdi_writeback *wb)
277 {
278 return percpu_ref_is_dying(&wb->refcnt);
279 }
280
281 #else /* CONFIG_CGROUP_WRITEBACK */
282
wb_tryget(struct bdi_writeback * wb)283 static inline bool wb_tryget(struct bdi_writeback *wb)
284 {
285 return true;
286 }
287
wb_get(struct bdi_writeback * wb)288 static inline void wb_get(struct bdi_writeback *wb)
289 {
290 }
291
wb_put(struct bdi_writeback * wb)292 static inline void wb_put(struct bdi_writeback *wb)
293 {
294 }
295
wb_put_many(struct bdi_writeback * wb,unsigned long nr)296 static inline void wb_put_many(struct bdi_writeback *wb, unsigned long nr)
297 {
298 }
299
wb_dying(struct bdi_writeback * wb)300 static inline bool wb_dying(struct bdi_writeback *wb)
301 {
302 return false;
303 }
304
305 #endif /* CONFIG_CGROUP_WRITEBACK */
306
307 #endif /* __LINUX_BACKING_DEV_DEFS_H */
308