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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 : :
17 : : struct page;
18 : : struct device;
19 : : struct dentry;
20 : :
21 : : /*
22 : : * Bits in bdi_writeback.state
23 : : */
24 : : enum wb_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 */
29 : : };
30 : :
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 */
34 : : };
35 : :
36 : : typedef int (congested_fn)(void *, int);
37 : :
38 : : enum wb_stat_item {
39 : : WB_RECLAIMABLE,
40 : : WB_WRITEBACK,
41 : : WB_DIRTIED,
42 : : WB_WRITTEN,
43 : : NR_WB_STAT_ITEMS
44 : : };
45 : :
46 : : #define WB_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
47 : :
48 : : /*
49 : : * why some writeback work was initiated
50 : : */
51 : : enum wb_reason {
52 : : WB_REASON_BACKGROUND,
53 : : WB_REASON_VMSCAN,
54 : : WB_REASON_SYNC,
55 : : WB_REASON_PERIODIC,
56 : : WB_REASON_LAPTOP_TIMER,
57 : : WB_REASON_FREE_MORE_MEM,
58 : : WB_REASON_FS_FREE_SPACE,
59 : : /*
60 : : * There is no bdi forker thread any more and works are done
61 : : * by emergency worker, however, this is TPs userland visible
62 : : * and we'll be exposing exactly the same information,
63 : : * so it has a mismatch name.
64 : : */
65 : : WB_REASON_FORKER_THREAD,
66 : : WB_REASON_FOREIGN_FLUSH,
67 : :
68 : : WB_REASON_MAX,
69 : : };
70 : :
71 : : struct wb_completion {
72 : : atomic_t cnt;
73 : : wait_queue_head_t *waitq;
74 : : };
75 : :
76 : : #define __WB_COMPLETION_INIT(_waitq) \
77 : : (struct wb_completion){ .cnt = ATOMIC_INIT(1), .waitq = (_waitq) }
78 : :
79 : : /*
80 : : * If one wants to wait for one or more wb_writeback_works, each work's
81 : : * ->done should be set to a wb_completion defined using the following
82 : : * macro. Once all work items are issued with wb_queue_work(), the caller
83 : : * can wait for the completion of all using wb_wait_for_completion(). Work
84 : : * items which are waited upon aren't freed automatically on completion.
85 : : */
86 : : #define WB_COMPLETION_INIT(bdi) __WB_COMPLETION_INIT(&(bdi)->wb_waitq)
87 : :
88 : : #define DEFINE_WB_COMPLETION(cmpl, bdi) \
89 : : struct wb_completion cmpl = WB_COMPLETION_INIT(bdi)
90 : :
91 : : /*
92 : : * For cgroup writeback, multiple wb's may map to the same blkcg. Those
93 : : * wb's can operate mostly independently but should share the congested
94 : : * state. To facilitate such sharing, the congested state is tracked using
95 : : * the following struct which is created on demand, indexed by blkcg ID on
96 : : * its bdi, and refcounted.
97 : : */
98 : : struct bdi_writeback_congested {
99 : : unsigned long state; /* WB_[a]sync_congested flags */
100 : : refcount_t refcnt; /* nr of attached wb's and blkg */
101 : :
102 : : #ifdef CONFIG_CGROUP_WRITEBACK
103 : : struct backing_dev_info *__bdi; /* the associated bdi, set to NULL
104 : : * on bdi unregistration. For memcg-wb
105 : : * internal use only! */
106 : : int blkcg_id; /* ID of the associated blkcg */
107 : : struct rb_node rb_node; /* on bdi->cgwb_congestion_tree */
108 : : #endif
109 : : };
110 : :
111 : : /*
112 : : * Each wb (bdi_writeback) can perform writeback operations, is measured
113 : : * and throttled, independently. Without cgroup writeback, each bdi
114 : : * (bdi_writeback) is served by its embedded bdi->wb.
115 : : *
116 : : * On the default hierarchy, blkcg implicitly enables memcg. This allows
117 : : * using memcg's page ownership for attributing writeback IOs, and every
118 : : * memcg - blkcg combination can be served by its own wb by assigning a
119 : : * dedicated wb to each memcg, which enables isolation across different
120 : : * cgroups and propagation of IO back pressure down from the IO layer upto
121 : : * the tasks which are generating the dirty pages to be written back.
122 : : *
123 : : * A cgroup wb is indexed on its bdi by the ID of the associated memcg,
124 : : * refcounted with the number of inodes attached to it, and pins the memcg
125 : : * and the corresponding blkcg. As the corresponding blkcg for a memcg may
126 : : * change as blkcg is disabled and enabled higher up in the hierarchy, a wb
127 : : * is tested for blkcg after lookup and removed from index on mismatch so
128 : : * that a new wb for the combination can be created.
129 : : */
130 : : struct bdi_writeback {
131 : : struct backing_dev_info *bdi; /* our parent bdi */
132 : :
133 : : unsigned long state; /* Always use atomic bitops on this */
134 : : unsigned long last_old_flush; /* last old data flush */
135 : :
136 : : struct list_head b_dirty; /* dirty inodes */
137 : : struct list_head b_io; /* parked for writeback */
138 : : struct list_head b_more_io; /* parked for more writeback */
139 : : struct list_head b_dirty_time; /* time stamps are dirty */
140 : : spinlock_t list_lock; /* protects the b_* lists */
141 : :
142 : : struct percpu_counter stat[NR_WB_STAT_ITEMS];
143 : :
144 : : struct bdi_writeback_congested *congested;
145 : :
146 : : unsigned long bw_time_stamp; /* last time write bw is updated */
147 : : unsigned long dirtied_stamp;
148 : : unsigned long written_stamp; /* pages written at bw_time_stamp */
149 : : unsigned long write_bandwidth; /* the estimated write bandwidth */
150 : : unsigned long avg_write_bandwidth; /* further smoothed write bw, > 0 */
151 : :
152 : : /*
153 : : * The base dirty throttle rate, re-calculated on every 200ms.
154 : : * All the bdi tasks' dirty rate will be curbed under it.
155 : : * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit
156 : : * in small steps and is much more smooth/stable than the latter.
157 : : */
158 : : unsigned long dirty_ratelimit;
159 : : unsigned long balanced_dirty_ratelimit;
160 : :
161 : : struct fprop_local_percpu completions;
162 : : int dirty_exceeded;
163 : : enum wb_reason start_all_reason;
164 : :
165 : : spinlock_t work_lock; /* protects work_list & dwork scheduling */
166 : : struct list_head work_list;
167 : : struct delayed_work dwork; /* work item used for writeback */
168 : :
169 : : unsigned long dirty_sleep; /* last wait */
170 : :
171 : : struct list_head bdi_node; /* anchored at bdi->wb_list */
172 : :
173 : : #ifdef CONFIG_CGROUP_WRITEBACK
174 : : struct percpu_ref refcnt; /* used only for !root wb's */
175 : : struct fprop_local_percpu memcg_completions;
176 : : struct cgroup_subsys_state *memcg_css; /* the associated memcg */
177 : : struct cgroup_subsys_state *blkcg_css; /* and blkcg */
178 : : struct list_head memcg_node; /* anchored at memcg->cgwb_list */
179 : : struct list_head blkcg_node; /* anchored at blkcg->cgwb_list */
180 : :
181 : : union {
182 : : struct work_struct release_work;
183 : : struct rcu_head rcu;
184 : : };
185 : : #endif
186 : : };
187 : :
188 : : struct backing_dev_info {
189 : : u64 id;
190 : : struct rb_node rb_node; /* keyed by ->id */
191 : : struct list_head bdi_list;
192 : : unsigned long ra_pages; /* max readahead in PAGE_SIZE units */
193 : : unsigned long io_pages; /* max allowed IO size */
194 : : congested_fn *congested_fn; /* Function pointer if device is md/dm */
195 : : void *congested_data; /* Pointer to aux data for congested func */
196 : :
197 : : const char *name;
198 : :
199 : : struct kref refcnt; /* Reference counter for the structure */
200 : : unsigned int capabilities; /* Device capabilities */
201 : : unsigned int min_ratio;
202 : : unsigned int max_ratio, max_prop_frac;
203 : :
204 : : /*
205 : : * Sum of avg_write_bw of wbs with dirty inodes. > 0 if there are
206 : : * any dirty wbs, which is depended upon by bdi_has_dirty().
207 : : */
208 : : atomic_long_t tot_write_bandwidth;
209 : :
210 : : struct bdi_writeback wb; /* the root writeback info for this bdi */
211 : : struct list_head wb_list; /* list of all wbs */
212 : : #ifdef CONFIG_CGROUP_WRITEBACK
213 : : struct radix_tree_root cgwb_tree; /* radix tree of active cgroup wbs */
214 : : struct rb_root cgwb_congested_tree; /* their congested states */
215 : : struct mutex cgwb_release_mutex; /* protect shutdown of wb structs */
216 : : struct rw_semaphore wb_switch_rwsem; /* no cgwb switch while syncing */
217 : : #else
218 : : struct bdi_writeback_congested *wb_congested;
219 : : #endif
220 : : wait_queue_head_t wb_waitq;
221 : :
222 : : struct device *dev;
223 : : char dev_name[64];
224 : : struct device *owner;
225 : :
226 : : struct timer_list laptop_mode_wb_timer;
227 : :
228 : : #ifdef CONFIG_DEBUG_FS
229 : : struct dentry *debug_dir;
230 : : #endif
231 : : };
232 : :
233 : : enum {
234 : : BLK_RW_ASYNC = 0,
235 : : BLK_RW_SYNC = 1,
236 : : };
237 : :
238 : : void clear_wb_congested(struct bdi_writeback_congested *congested, int sync);
239 : : void set_wb_congested(struct bdi_writeback_congested *congested, int sync);
240 : :
241 : : static inline void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
242 : : {
243 : 0 : clear_wb_congested(bdi->wb.congested, sync);
244 : : }
245 : :
246 : : static inline void set_bdi_congested(struct backing_dev_info *bdi, int sync)
247 : : {
248 : 0 : set_wb_congested(bdi->wb.congested, sync);
249 : : }
250 : :
251 : : struct wb_lock_cookie {
252 : : bool locked;
253 : : unsigned long flags;
254 : : };
255 : :
256 : : #ifdef CONFIG_CGROUP_WRITEBACK
257 : :
258 : : /**
259 : : * wb_tryget - try to increment a wb's refcount
260 : : * @wb: bdi_writeback to get
261 : : */
262 : : static inline bool wb_tryget(struct bdi_writeback *wb)
263 : : {
264 [ # # ]: 0 : if (wb != &wb->bdi->wb)
265 : 0 : return percpu_ref_tryget(&wb->refcnt);
266 : : return true;
267 : : }
268 : :
269 : : /**
270 : : * wb_get - increment a wb's refcount
271 : : * @wb: bdi_writeback to get
272 : : */
273 : : static inline void wb_get(struct bdi_writeback *wb)
274 : : {
275 [ # # - + : 863930 : if (wb != &wb->bdi->wb)
# # - + ]
276 : 0 : percpu_ref_get(&wb->refcnt);
277 : : }
278 : :
279 : : /**
280 : : * wb_put - decrement a wb's refcount
281 : : * @wb: bdi_writeback to put
282 : : */
283 : 1626166 : static inline void wb_put(struct bdi_writeback *wb)
284 : : {
285 [ - + # # : 1626166 : if (WARN_ON_ONCE(!wb->bdi)) {
+ - ]
286 : : /*
287 : : * A driver bug might cause a file to be removed before bdi was
288 : : * initialized.
289 : : */
290 : 1626166 : return;
291 : : }
292 : :
293 [ - + ]: 1626166 : if (wb != &wb->bdi->wb)
294 : 0 : percpu_ref_put(&wb->refcnt);
295 : : }
296 : :
297 : : /**
298 : : * wb_dying - is a wb dying?
299 : : * @wb: bdi_writeback of interest
300 : : *
301 : : * Returns whether @wb is unlinked and being drained.
302 : : */
303 : : static inline bool wb_dying(struct bdi_writeback *wb)
304 : : {
305 : : return percpu_ref_is_dying(&wb->refcnt);
306 : : }
307 : :
308 : : #else /* CONFIG_CGROUP_WRITEBACK */
309 : :
310 : : static inline bool wb_tryget(struct bdi_writeback *wb)
311 : : {
312 : : return true;
313 : : }
314 : :
315 : : static inline void wb_get(struct bdi_writeback *wb)
316 : : {
317 : : }
318 : :
319 : : static inline void wb_put(struct bdi_writeback *wb)
320 : : {
321 : : }
322 : :
323 : : static inline bool wb_dying(struct bdi_writeback *wb)
324 : : {
325 : : return false;
326 : : }
327 : :
328 : : #endif /* CONFIG_CGROUP_WRITEBACK */
329 : :
330 : : #endif /* __LINUX_BACKING_DEV_DEFS_H */
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