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