Commit | Line | Data |
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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* |
3 | * fs/fs-writeback.c | |
4 | * | |
5 | * Copyright (C) 2002, Linus Torvalds. | |
6 | * | |
7 | * Contains all the functions related to writing back and waiting | |
8 | * upon dirty inodes against superblocks, and writing back dirty | |
9 | * pages against inodes. ie: data writeback. Writeout of the | |
10 | * inode itself is not handled here. | |
11 | * | |
e1f8e874 | 12 | * 10Apr2002 Andrew Morton |
1da177e4 LT |
13 | * Split out of fs/inode.c |
14 | * Additions for address_space-based writeback | |
15 | */ | |
16 | ||
17 | #include <linux/kernel.h> | |
630d9c47 | 18 | #include <linux/export.h> |
1da177e4 | 19 | #include <linux/spinlock.h> |
5a0e3ad6 | 20 | #include <linux/slab.h> |
1da177e4 LT |
21 | #include <linux/sched.h> |
22 | #include <linux/fs.h> | |
23 | #include <linux/mm.h> | |
bc31b86a | 24 | #include <linux/pagemap.h> |
03ba3782 | 25 | #include <linux/kthread.h> |
1da177e4 LT |
26 | #include <linux/writeback.h> |
27 | #include <linux/blkdev.h> | |
28 | #include <linux/backing-dev.h> | |
455b2864 | 29 | #include <linux/tracepoint.h> |
719ea2fb | 30 | #include <linux/device.h> |
21c6321f | 31 | #include <linux/memcontrol.h> |
07f3f05c | 32 | #include "internal.h" |
1da177e4 | 33 | |
bc31b86a WF |
34 | /* |
35 | * 4MB minimal write chunk size | |
36 | */ | |
09cbfeaf | 37 | #define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_SHIFT - 10)) |
bc31b86a | 38 | |
c4a77a6c JA |
39 | /* |
40 | * Passed into wb_writeback(), essentially a subset of writeback_control | |
41 | */ | |
83ba7b07 | 42 | struct wb_writeback_work { |
c4a77a6c JA |
43 | long nr_pages; |
44 | struct super_block *sb; | |
45 | enum writeback_sync_modes sync_mode; | |
6e6938b6 | 46 | unsigned int tagged_writepages:1; |
52957fe1 HS |
47 | unsigned int for_kupdate:1; |
48 | unsigned int range_cyclic:1; | |
49 | unsigned int for_background:1; | |
7747bd4b | 50 | unsigned int for_sync:1; /* sync(2) WB_SYNC_ALL writeback */ |
ac7b19a3 | 51 | unsigned int auto_free:1; /* free on completion */ |
0e175a18 | 52 | enum wb_reason reason; /* why was writeback initiated? */ |
c4a77a6c | 53 | |
8010c3b6 | 54 | struct list_head list; /* pending work list */ |
cc395d7f | 55 | struct wb_completion *done; /* set if the caller waits */ |
03ba3782 JA |
56 | }; |
57 | ||
a2f48706 TT |
58 | /* |
59 | * If an inode is constantly having its pages dirtied, but then the | |
60 | * updates stop dirtytime_expire_interval seconds in the past, it's | |
61 | * possible for the worst case time between when an inode has its | |
62 | * timestamps updated and when they finally get written out to be two | |
63 | * dirtytime_expire_intervals. We set the default to 12 hours (in | |
64 | * seconds), which means most of the time inodes will have their | |
65 | * timestamps written to disk after 12 hours, but in the worst case a | |
66 | * few inodes might not their timestamps updated for 24 hours. | |
67 | */ | |
68 | unsigned int dirtytime_expire_interval = 12 * 60 * 60; | |
69 | ||
7ccf19a8 NP |
70 | static inline struct inode *wb_inode(struct list_head *head) |
71 | { | |
c7f54084 | 72 | return list_entry(head, struct inode, i_io_list); |
7ccf19a8 NP |
73 | } |
74 | ||
15eb77a0 WF |
75 | /* |
76 | * Include the creation of the trace points after defining the | |
77 | * wb_writeback_work structure and inline functions so that the definition | |
78 | * remains local to this file. | |
79 | */ | |
80 | #define CREATE_TRACE_POINTS | |
81 | #include <trace/events/writeback.h> | |
82 | ||
774016b2 SW |
83 | EXPORT_TRACEPOINT_SYMBOL_GPL(wbc_writepage); |
84 | ||
d6c10f1f TH |
85 | static bool wb_io_lists_populated(struct bdi_writeback *wb) |
86 | { | |
87 | if (wb_has_dirty_io(wb)) { | |
88 | return false; | |
89 | } else { | |
90 | set_bit(WB_has_dirty_io, &wb->state); | |
95a46c65 | 91 | WARN_ON_ONCE(!wb->avg_write_bandwidth); |
766a9d6e TH |
92 | atomic_long_add(wb->avg_write_bandwidth, |
93 | &wb->bdi->tot_write_bandwidth); | |
d6c10f1f TH |
94 | return true; |
95 | } | |
96 | } | |
97 | ||
98 | static void wb_io_lists_depopulated(struct bdi_writeback *wb) | |
99 | { | |
100 | if (wb_has_dirty_io(wb) && list_empty(&wb->b_dirty) && | |
766a9d6e | 101 | list_empty(&wb->b_io) && list_empty(&wb->b_more_io)) { |
d6c10f1f | 102 | clear_bit(WB_has_dirty_io, &wb->state); |
95a46c65 TH |
103 | WARN_ON_ONCE(atomic_long_sub_return(wb->avg_write_bandwidth, |
104 | &wb->bdi->tot_write_bandwidth) < 0); | |
766a9d6e | 105 | } |
d6c10f1f TH |
106 | } |
107 | ||
108 | /** | |
c7f54084 | 109 | * inode_io_list_move_locked - move an inode onto a bdi_writeback IO list |
d6c10f1f TH |
110 | * @inode: inode to be moved |
111 | * @wb: target bdi_writeback | |
bbbc3c1c | 112 | * @head: one of @wb->b_{dirty|io|more_io|dirty_time} |
d6c10f1f | 113 | * |
c7f54084 | 114 | * Move @inode->i_io_list to @list of @wb and set %WB_has_dirty_io. |
d6c10f1f TH |
115 | * Returns %true if @inode is the first occupant of the !dirty_time IO |
116 | * lists; otherwise, %false. | |
117 | */ | |
c7f54084 | 118 | static bool inode_io_list_move_locked(struct inode *inode, |
d6c10f1f TH |
119 | struct bdi_writeback *wb, |
120 | struct list_head *head) | |
121 | { | |
122 | assert_spin_locked(&wb->list_lock); | |
10e14073 | 123 | assert_spin_locked(&inode->i_lock); |
d6c10f1f | 124 | |
c7f54084 | 125 | list_move(&inode->i_io_list, head); |
d6c10f1f TH |
126 | |
127 | /* dirty_time doesn't count as dirty_io until expiration */ | |
128 | if (head != &wb->b_dirty_time) | |
129 | return wb_io_lists_populated(wb); | |
130 | ||
131 | wb_io_lists_depopulated(wb); | |
132 | return false; | |
133 | } | |
134 | ||
f0054bb1 | 135 | static void wb_wakeup(struct bdi_writeback *wb) |
5acda9d1 | 136 | { |
f87904c0 | 137 | spin_lock_irq(&wb->work_lock); |
f0054bb1 TH |
138 | if (test_bit(WB_registered, &wb->state)) |
139 | mod_delayed_work(bdi_wq, &wb->dwork, 0); | |
f87904c0 | 140 | spin_unlock_irq(&wb->work_lock); |
5acda9d1 JK |
141 | } |
142 | ||
4a3a485b TE |
143 | static void finish_writeback_work(struct bdi_writeback *wb, |
144 | struct wb_writeback_work *work) | |
145 | { | |
146 | struct wb_completion *done = work->done; | |
147 | ||
148 | if (work->auto_free) | |
149 | kfree(work); | |
8e00c4e9 TH |
150 | if (done) { |
151 | wait_queue_head_t *waitq = done->waitq; | |
152 | ||
153 | /* @done can't be accessed after the following dec */ | |
154 | if (atomic_dec_and_test(&done->cnt)) | |
155 | wake_up_all(waitq); | |
156 | } | |
4a3a485b TE |
157 | } |
158 | ||
f0054bb1 TH |
159 | static void wb_queue_work(struct bdi_writeback *wb, |
160 | struct wb_writeback_work *work) | |
6585027a | 161 | { |
5634cc2a | 162 | trace_writeback_queue(wb, work); |
6585027a | 163 | |
cc395d7f TH |
164 | if (work->done) |
165 | atomic_inc(&work->done->cnt); | |
4a3a485b | 166 | |
f87904c0 | 167 | spin_lock_irq(&wb->work_lock); |
4a3a485b TE |
168 | |
169 | if (test_bit(WB_registered, &wb->state)) { | |
170 | list_add_tail(&work->list, &wb->work_list); | |
171 | mod_delayed_work(bdi_wq, &wb->dwork, 0); | |
172 | } else | |
173 | finish_writeback_work(wb, work); | |
174 | ||
f87904c0 | 175 | spin_unlock_irq(&wb->work_lock); |
1da177e4 LT |
176 | } |
177 | ||
cc395d7f TH |
178 | /** |
179 | * wb_wait_for_completion - wait for completion of bdi_writeback_works | |
cc395d7f TH |
180 | * @done: target wb_completion |
181 | * | |
182 | * Wait for one or more work items issued to @bdi with their ->done field | |
5b9cce4c TH |
183 | * set to @done, which should have been initialized with |
184 | * DEFINE_WB_COMPLETION(). This function returns after all such work items | |
185 | * are completed. Work items which are waited upon aren't freed | |
cc395d7f TH |
186 | * automatically on completion. |
187 | */ | |
5b9cce4c | 188 | void wb_wait_for_completion(struct wb_completion *done) |
cc395d7f TH |
189 | { |
190 | atomic_dec(&done->cnt); /* put down the initial count */ | |
5b9cce4c | 191 | wait_event(*done->waitq, !atomic_read(&done->cnt)); |
cc395d7f TH |
192 | } |
193 | ||
703c2708 TH |
194 | #ifdef CONFIG_CGROUP_WRITEBACK |
195 | ||
55a694df TH |
196 | /* |
197 | * Parameters for foreign inode detection, see wbc_detach_inode() to see | |
198 | * how they're used. | |
199 | * | |
200 | * These paramters are inherently heuristical as the detection target | |
201 | * itself is fuzzy. All we want to do is detaching an inode from the | |
202 | * current owner if it's being written to by some other cgroups too much. | |
203 | * | |
204 | * The current cgroup writeback is built on the assumption that multiple | |
205 | * cgroups writing to the same inode concurrently is very rare and a mode | |
206 | * of operation which isn't well supported. As such, the goal is not | |
207 | * taking too long when a different cgroup takes over an inode while | |
208 | * avoiding too aggressive flip-flops from occasional foreign writes. | |
209 | * | |
210 | * We record, very roughly, 2s worth of IO time history and if more than | |
211 | * half of that is foreign, trigger the switch. The recording is quantized | |
212 | * to 16 slots. To avoid tiny writes from swinging the decision too much, | |
213 | * writes smaller than 1/8 of avg size are ignored. | |
214 | */ | |
2a814908 TH |
215 | #define WB_FRN_TIME_SHIFT 13 /* 1s = 2^13, upto 8 secs w/ 16bit */ |
216 | #define WB_FRN_TIME_AVG_SHIFT 3 /* avg = avg * 7/8 + new * 1/8 */ | |
55a694df | 217 | #define WB_FRN_TIME_CUT_DIV 8 /* ignore rounds < avg / 8 */ |
2a814908 TH |
218 | #define WB_FRN_TIME_PERIOD (2 * (1 << WB_FRN_TIME_SHIFT)) /* 2s */ |
219 | ||
220 | #define WB_FRN_HIST_SLOTS 16 /* inode->i_wb_frn_history is 16bit */ | |
221 | #define WB_FRN_HIST_UNIT (WB_FRN_TIME_PERIOD / WB_FRN_HIST_SLOTS) | |
222 | /* each slot's duration is 2s / 16 */ | |
223 | #define WB_FRN_HIST_THR_SLOTS (WB_FRN_HIST_SLOTS / 2) | |
224 | /* if foreign slots >= 8, switch */ | |
225 | #define WB_FRN_HIST_MAX_SLOTS (WB_FRN_HIST_THR_SLOTS / 2 + 1) | |
226 | /* one round can affect upto 5 slots */ | |
6444f47e | 227 | #define WB_FRN_MAX_IN_FLIGHT 1024 /* don't queue too many concurrently */ |
2a814908 | 228 | |
c22d70a1 RG |
229 | /* |
230 | * Maximum inodes per isw. A specific value has been chosen to make | |
231 | * struct inode_switch_wbs_context fit into 1024 bytes kmalloc. | |
232 | */ | |
233 | #define WB_MAX_INODES_PER_ISW ((1024UL - sizeof(struct inode_switch_wbs_context)) \ | |
234 | / sizeof(struct inode *)) | |
235 | ||
a1a0e23e TH |
236 | static atomic_t isw_nr_in_flight = ATOMIC_INIT(0); |
237 | static struct workqueue_struct *isw_wq; | |
238 | ||
21c6321f TH |
239 | void __inode_attach_wb(struct inode *inode, struct page *page) |
240 | { | |
241 | struct backing_dev_info *bdi = inode_to_bdi(inode); | |
242 | struct bdi_writeback *wb = NULL; | |
243 | ||
244 | if (inode_cgwb_enabled(inode)) { | |
245 | struct cgroup_subsys_state *memcg_css; | |
246 | ||
247 | if (page) { | |
248 | memcg_css = mem_cgroup_css_from_page(page); | |
249 | wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); | |
250 | } else { | |
251 | /* must pin memcg_css, see wb_get_create() */ | |
252 | memcg_css = task_get_css(current, memory_cgrp_id); | |
253 | wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); | |
254 | css_put(memcg_css); | |
255 | } | |
256 | } | |
257 | ||
258 | if (!wb) | |
259 | wb = &bdi->wb; | |
260 | ||
261 | /* | |
262 | * There may be multiple instances of this function racing to | |
263 | * update the same inode. Use cmpxchg() to tell the winner. | |
264 | */ | |
265 | if (unlikely(cmpxchg(&inode->i_wb, NULL, wb))) | |
266 | wb_put(wb); | |
267 | } | |
9b0eb69b | 268 | EXPORT_SYMBOL_GPL(__inode_attach_wb); |
21c6321f | 269 | |
f3b6a6df RG |
270 | /** |
271 | * inode_cgwb_move_to_attached - put the inode onto wb->b_attached list | |
272 | * @inode: inode of interest with i_lock held | |
273 | * @wb: target bdi_writeback | |
274 | * | |
275 | * Remove the inode from wb's io lists and if necessarily put onto b_attached | |
276 | * list. Only inodes attached to cgwb's are kept on this list. | |
277 | */ | |
278 | static void inode_cgwb_move_to_attached(struct inode *inode, | |
279 | struct bdi_writeback *wb) | |
280 | { | |
281 | assert_spin_locked(&wb->list_lock); | |
282 | assert_spin_locked(&inode->i_lock); | |
283 | ||
284 | inode->i_state &= ~I_SYNC_QUEUED; | |
285 | if (wb != &wb->bdi->wb) | |
286 | list_move(&inode->i_io_list, &wb->b_attached); | |
287 | else | |
288 | list_del_init(&inode->i_io_list); | |
289 | wb_io_lists_depopulated(wb); | |
290 | } | |
291 | ||
87e1d789 TH |
292 | /** |
293 | * locked_inode_to_wb_and_lock_list - determine a locked inode's wb and lock it | |
294 | * @inode: inode of interest with i_lock held | |
295 | * | |
296 | * Returns @inode's wb with its list_lock held. @inode->i_lock must be | |
297 | * held on entry and is released on return. The returned wb is guaranteed | |
298 | * to stay @inode's associated wb until its list_lock is released. | |
299 | */ | |
300 | static struct bdi_writeback * | |
301 | locked_inode_to_wb_and_lock_list(struct inode *inode) | |
302 | __releases(&inode->i_lock) | |
303 | __acquires(&wb->list_lock) | |
304 | { | |
305 | while (true) { | |
306 | struct bdi_writeback *wb = inode_to_wb(inode); | |
307 | ||
308 | /* | |
309 | * inode_to_wb() association is protected by both | |
310 | * @inode->i_lock and @wb->list_lock but list_lock nests | |
311 | * outside i_lock. Drop i_lock and verify that the | |
312 | * association hasn't changed after acquiring list_lock. | |
313 | */ | |
314 | wb_get(wb); | |
315 | spin_unlock(&inode->i_lock); | |
316 | spin_lock(&wb->list_lock); | |
87e1d789 | 317 | |
aaa2cacf | 318 | /* i_wb may have changed inbetween, can't use inode_to_wb() */ |
614a4e37 TH |
319 | if (likely(wb == inode->i_wb)) { |
320 | wb_put(wb); /* @inode already has ref */ | |
321 | return wb; | |
322 | } | |
87e1d789 TH |
323 | |
324 | spin_unlock(&wb->list_lock); | |
614a4e37 | 325 | wb_put(wb); |
87e1d789 TH |
326 | cpu_relax(); |
327 | spin_lock(&inode->i_lock); | |
328 | } | |
329 | } | |
330 | ||
331 | /** | |
332 | * inode_to_wb_and_lock_list - determine an inode's wb and lock it | |
333 | * @inode: inode of interest | |
334 | * | |
335 | * Same as locked_inode_to_wb_and_lock_list() but @inode->i_lock isn't held | |
336 | * on entry. | |
337 | */ | |
338 | static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode) | |
339 | __acquires(&wb->list_lock) | |
340 | { | |
341 | spin_lock(&inode->i_lock); | |
342 | return locked_inode_to_wb_and_lock_list(inode); | |
343 | } | |
344 | ||
682aa8e1 | 345 | struct inode_switch_wbs_context { |
29264d92 | 346 | struct rcu_work work; |
f5fbe6b7 RG |
347 | |
348 | /* | |
349 | * Multiple inodes can be switched at once. The switching procedure | |
350 | * consists of two parts, separated by a RCU grace period. To make | |
351 | * sure that the second part is executed for each inode gone through | |
352 | * the first part, all inode pointers are placed into a NULL-terminated | |
353 | * array embedded into struct inode_switch_wbs_context. Otherwise | |
354 | * an inode could be left in a non-consistent state. | |
355 | */ | |
356 | struct bdi_writeback *new_wb; | |
357 | struct inode *inodes[]; | |
682aa8e1 TH |
358 | }; |
359 | ||
7fc5854f TH |
360 | static void bdi_down_write_wb_switch_rwsem(struct backing_dev_info *bdi) |
361 | { | |
362 | down_write(&bdi->wb_switch_rwsem); | |
363 | } | |
364 | ||
365 | static void bdi_up_write_wb_switch_rwsem(struct backing_dev_info *bdi) | |
366 | { | |
367 | up_write(&bdi->wb_switch_rwsem); | |
368 | } | |
369 | ||
f5fbe6b7 RG |
370 | static bool inode_do_switch_wbs(struct inode *inode, |
371 | struct bdi_writeback *old_wb, | |
72d4512e | 372 | struct bdi_writeback *new_wb) |
682aa8e1 | 373 | { |
d10c8095 | 374 | struct address_space *mapping = inode->i_mapping; |
04edf02c | 375 | XA_STATE(xas, &mapping->i_pages, 0); |
22b3c8d6 | 376 | struct folio *folio; |
d10c8095 | 377 | bool switched = false; |
682aa8e1 | 378 | |
682aa8e1 | 379 | spin_lock(&inode->i_lock); |
b93b0163 | 380 | xa_lock_irq(&mapping->i_pages); |
d10c8095 TH |
381 | |
382 | /* | |
4ade5867 RG |
383 | * Once I_FREEING or I_WILL_FREE are visible under i_lock, the eviction |
384 | * path owns the inode and we shouldn't modify ->i_io_list. | |
d10c8095 | 385 | */ |
4ade5867 | 386 | if (unlikely(inode->i_state & (I_FREEING | I_WILL_FREE))) |
d10c8095 TH |
387 | goto skip_switch; |
388 | ||
3a8e9ac8 TH |
389 | trace_inode_switch_wbs(inode, old_wb, new_wb); |
390 | ||
d10c8095 TH |
391 | /* |
392 | * Count and transfer stats. Note that PAGECACHE_TAG_DIRTY points | |
22b3c8d6 MWO |
393 | * to possibly dirty folios while PAGECACHE_TAG_WRITEBACK points to |
394 | * folios actually under writeback. | |
d10c8095 | 395 | */ |
22b3c8d6 MWO |
396 | xas_for_each_marked(&xas, folio, ULONG_MAX, PAGECACHE_TAG_DIRTY) { |
397 | if (folio_test_dirty(folio)) { | |
398 | long nr = folio_nr_pages(folio); | |
399 | wb_stat_mod(old_wb, WB_RECLAIMABLE, -nr); | |
400 | wb_stat_mod(new_wb, WB_RECLAIMABLE, nr); | |
d10c8095 TH |
401 | } |
402 | } | |
403 | ||
04edf02c | 404 | xas_set(&xas, 0); |
22b3c8d6 MWO |
405 | xas_for_each_marked(&xas, folio, ULONG_MAX, PAGECACHE_TAG_WRITEBACK) { |
406 | long nr = folio_nr_pages(folio); | |
407 | WARN_ON_ONCE(!folio_test_writeback(folio)); | |
408 | wb_stat_mod(old_wb, WB_WRITEBACK, -nr); | |
409 | wb_stat_mod(new_wb, WB_WRITEBACK, nr); | |
d10c8095 TH |
410 | } |
411 | ||
633a2abb JK |
412 | if (mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK)) { |
413 | atomic_dec(&old_wb->writeback_inodes); | |
414 | atomic_inc(&new_wb->writeback_inodes); | |
415 | } | |
416 | ||
d10c8095 TH |
417 | wb_get(new_wb); |
418 | ||
419 | /* | |
f3b6a6df RG |
420 | * Transfer to @new_wb's IO list if necessary. If the @inode is dirty, |
421 | * the specific list @inode was on is ignored and the @inode is put on | |
422 | * ->b_dirty which is always correct including from ->b_dirty_time. | |
423 | * The transfer preserves @inode->dirtied_when ordering. If the @inode | |
424 | * was clean, it means it was on the b_attached list, so move it onto | |
425 | * the b_attached list of @new_wb. | |
d10c8095 | 426 | */ |
c7f54084 | 427 | if (!list_empty(&inode->i_io_list)) { |
d10c8095 | 428 | inode->i_wb = new_wb; |
f3b6a6df RG |
429 | |
430 | if (inode->i_state & I_DIRTY_ALL) { | |
431 | struct inode *pos; | |
432 | ||
433 | list_for_each_entry(pos, &new_wb->b_dirty, i_io_list) | |
434 | if (time_after_eq(inode->dirtied_when, | |
435 | pos->dirtied_when)) | |
436 | break; | |
437 | inode_io_list_move_locked(inode, new_wb, | |
438 | pos->i_io_list.prev); | |
439 | } else { | |
440 | inode_cgwb_move_to_attached(inode, new_wb); | |
441 | } | |
d10c8095 TH |
442 | } else { |
443 | inode->i_wb = new_wb; | |
444 | } | |
682aa8e1 | 445 | |
d10c8095 | 446 | /* ->i_wb_frn updates may race wbc_detach_inode() but doesn't matter */ |
682aa8e1 TH |
447 | inode->i_wb_frn_winner = 0; |
448 | inode->i_wb_frn_avg_time = 0; | |
449 | inode->i_wb_frn_history = 0; | |
d10c8095 TH |
450 | switched = true; |
451 | skip_switch: | |
682aa8e1 TH |
452 | /* |
453 | * Paired with load_acquire in unlocked_inode_to_wb_begin() and | |
454 | * ensures that the new wb is visible if they see !I_WB_SWITCH. | |
455 | */ | |
456 | smp_store_release(&inode->i_state, inode->i_state & ~I_WB_SWITCH); | |
457 | ||
b93b0163 | 458 | xa_unlock_irq(&mapping->i_pages); |
682aa8e1 | 459 | spin_unlock(&inode->i_lock); |
7fc5854f | 460 | |
f5fbe6b7 | 461 | return switched; |
72d4512e | 462 | } |
d10c8095 | 463 | |
72d4512e RG |
464 | static void inode_switch_wbs_work_fn(struct work_struct *work) |
465 | { | |
466 | struct inode_switch_wbs_context *isw = | |
467 | container_of(to_rcu_work(work), struct inode_switch_wbs_context, work); | |
f5fbe6b7 RG |
468 | struct backing_dev_info *bdi = inode_to_bdi(isw->inodes[0]); |
469 | struct bdi_writeback *old_wb = isw->inodes[0]->i_wb; | |
470 | struct bdi_writeback *new_wb = isw->new_wb; | |
471 | unsigned long nr_switched = 0; | |
472 | struct inode **inodep; | |
473 | ||
474 | /* | |
475 | * If @inode switches cgwb membership while sync_inodes_sb() is | |
476 | * being issued, sync_inodes_sb() might miss it. Synchronize. | |
477 | */ | |
478 | down_read(&bdi->wb_switch_rwsem); | |
479 | ||
480 | /* | |
481 | * By the time control reaches here, RCU grace period has passed | |
482 | * since I_WB_SWITCH assertion and all wb stat update transactions | |
483 | * between unlocked_inode_to_wb_begin/end() are guaranteed to be | |
484 | * synchronizing against the i_pages lock. | |
485 | * | |
486 | * Grabbing old_wb->list_lock, inode->i_lock and the i_pages lock | |
487 | * gives us exclusion against all wb related operations on @inode | |
488 | * including IO list manipulations and stat updates. | |
489 | */ | |
490 | if (old_wb < new_wb) { | |
491 | spin_lock(&old_wb->list_lock); | |
492 | spin_lock_nested(&new_wb->list_lock, SINGLE_DEPTH_NESTING); | |
493 | } else { | |
494 | spin_lock(&new_wb->list_lock); | |
495 | spin_lock_nested(&old_wb->list_lock, SINGLE_DEPTH_NESTING); | |
496 | } | |
497 | ||
498 | for (inodep = isw->inodes; *inodep; inodep++) { | |
499 | WARN_ON_ONCE((*inodep)->i_wb != old_wb); | |
500 | if (inode_do_switch_wbs(*inodep, old_wb, new_wb)) | |
501 | nr_switched++; | |
502 | } | |
503 | ||
504 | spin_unlock(&new_wb->list_lock); | |
505 | spin_unlock(&old_wb->list_lock); | |
506 | ||
507 | up_read(&bdi->wb_switch_rwsem); | |
508 | ||
509 | if (nr_switched) { | |
510 | wb_wakeup(new_wb); | |
511 | wb_put_many(old_wb, nr_switched); | |
512 | } | |
a1a0e23e | 513 | |
f5fbe6b7 RG |
514 | for (inodep = isw->inodes; *inodep; inodep++) |
515 | iput(*inodep); | |
516 | wb_put(new_wb); | |
72d4512e | 517 | kfree(isw); |
a1a0e23e | 518 | atomic_dec(&isw_nr_in_flight); |
682aa8e1 TH |
519 | } |
520 | ||
c22d70a1 RG |
521 | static bool inode_prepare_wbs_switch(struct inode *inode, |
522 | struct bdi_writeback *new_wb) | |
523 | { | |
524 | /* | |
525 | * Paired with smp_mb() in cgroup_writeback_umount(). | |
526 | * isw_nr_in_flight must be increased before checking SB_ACTIVE and | |
527 | * grabbing an inode, otherwise isw_nr_in_flight can be observed as 0 | |
528 | * in cgroup_writeback_umount() and the isw_wq will be not flushed. | |
529 | */ | |
530 | smp_mb(); | |
531 | ||
593311e8 RG |
532 | if (IS_DAX(inode)) |
533 | return false; | |
534 | ||
c22d70a1 RG |
535 | /* while holding I_WB_SWITCH, no one else can update the association */ |
536 | spin_lock(&inode->i_lock); | |
537 | if (!(inode->i_sb->s_flags & SB_ACTIVE) || | |
538 | inode->i_state & (I_WB_SWITCH | I_FREEING | I_WILL_FREE) || | |
539 | inode_to_wb(inode) == new_wb) { | |
540 | spin_unlock(&inode->i_lock); | |
541 | return false; | |
542 | } | |
543 | inode->i_state |= I_WB_SWITCH; | |
544 | __iget(inode); | |
545 | spin_unlock(&inode->i_lock); | |
546 | ||
547 | return true; | |
548 | } | |
549 | ||
682aa8e1 TH |
550 | /** |
551 | * inode_switch_wbs - change the wb association of an inode | |
552 | * @inode: target inode | |
553 | * @new_wb_id: ID of the new wb | |
554 | * | |
555 | * Switch @inode's wb association to the wb identified by @new_wb_id. The | |
556 | * switching is performed asynchronously and may fail silently. | |
557 | */ | |
558 | static void inode_switch_wbs(struct inode *inode, int new_wb_id) | |
559 | { | |
560 | struct backing_dev_info *bdi = inode_to_bdi(inode); | |
561 | struct cgroup_subsys_state *memcg_css; | |
562 | struct inode_switch_wbs_context *isw; | |
563 | ||
564 | /* noop if seems to be already in progress */ | |
565 | if (inode->i_state & I_WB_SWITCH) | |
566 | return; | |
567 | ||
6444f47e TH |
568 | /* avoid queueing a new switch if too many are already in flight */ |
569 | if (atomic_read(&isw_nr_in_flight) > WB_FRN_MAX_IN_FLIGHT) | |
7fc5854f TH |
570 | return; |
571 | ||
98b160c8 | 572 | isw = kzalloc(struct_size(isw, inodes, 2), GFP_ATOMIC); |
682aa8e1 | 573 | if (!isw) |
6444f47e | 574 | return; |
682aa8e1 | 575 | |
8826ee4f RG |
576 | atomic_inc(&isw_nr_in_flight); |
577 | ||
682aa8e1 TH |
578 | /* find and pin the new wb */ |
579 | rcu_read_lock(); | |
580 | memcg_css = css_from_id(new_wb_id, &memory_cgrp_subsys); | |
8b0ed844 MS |
581 | if (memcg_css && !css_tryget(memcg_css)) |
582 | memcg_css = NULL; | |
682aa8e1 | 583 | rcu_read_unlock(); |
8b0ed844 MS |
584 | if (!memcg_css) |
585 | goto out_free; | |
586 | ||
587 | isw->new_wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); | |
588 | css_put(memcg_css); | |
682aa8e1 TH |
589 | if (!isw->new_wb) |
590 | goto out_free; | |
591 | ||
c22d70a1 | 592 | if (!inode_prepare_wbs_switch(inode, isw->new_wb)) |
a1a0e23e | 593 | goto out_free; |
682aa8e1 | 594 | |
f5fbe6b7 | 595 | isw->inodes[0] = inode; |
682aa8e1 TH |
596 | |
597 | /* | |
598 | * In addition to synchronizing among switchers, I_WB_SWITCH tells | |
b93b0163 MW |
599 | * the RCU protected stat update paths to grab the i_page |
600 | * lock so that stat transfer can synchronize against them. | |
682aa8e1 TH |
601 | * Let's continue after I_WB_SWITCH is guaranteed to be visible. |
602 | */ | |
29264d92 RG |
603 | INIT_RCU_WORK(&isw->work, inode_switch_wbs_work_fn); |
604 | queue_rcu_work(isw_wq, &isw->work); | |
6444f47e | 605 | return; |
682aa8e1 TH |
606 | |
607 | out_free: | |
8826ee4f | 608 | atomic_dec(&isw_nr_in_flight); |
682aa8e1 TH |
609 | if (isw->new_wb) |
610 | wb_put(isw->new_wb); | |
611 | kfree(isw); | |
612 | } | |
613 | ||
c22d70a1 RG |
614 | /** |
615 | * cleanup_offline_cgwb - detach associated inodes | |
616 | * @wb: target wb | |
617 | * | |
618 | * Switch all inodes attached to @wb to a nearest living ancestor's wb in order | |
619 | * to eventually release the dying @wb. Returns %true if not all inodes were | |
620 | * switched and the function has to be restarted. | |
621 | */ | |
622 | bool cleanup_offline_cgwb(struct bdi_writeback *wb) | |
623 | { | |
624 | struct cgroup_subsys_state *memcg_css; | |
625 | struct inode_switch_wbs_context *isw; | |
626 | struct inode *inode; | |
627 | int nr; | |
628 | bool restart = false; | |
629 | ||
98b160c8 LB |
630 | isw = kzalloc(struct_size(isw, inodes, WB_MAX_INODES_PER_ISW), |
631 | GFP_KERNEL); | |
c22d70a1 RG |
632 | if (!isw) |
633 | return restart; | |
634 | ||
635 | atomic_inc(&isw_nr_in_flight); | |
636 | ||
637 | for (memcg_css = wb->memcg_css->parent; memcg_css; | |
638 | memcg_css = memcg_css->parent) { | |
639 | isw->new_wb = wb_get_create(wb->bdi, memcg_css, GFP_KERNEL); | |
640 | if (isw->new_wb) | |
641 | break; | |
642 | } | |
643 | if (unlikely(!isw->new_wb)) | |
644 | isw->new_wb = &wb->bdi->wb; /* wb_get() is noop for bdi's wb */ | |
645 | ||
646 | nr = 0; | |
647 | spin_lock(&wb->list_lock); | |
648 | list_for_each_entry(inode, &wb->b_attached, i_io_list) { | |
649 | if (!inode_prepare_wbs_switch(inode, isw->new_wb)) | |
650 | continue; | |
651 | ||
652 | isw->inodes[nr++] = inode; | |
653 | ||
654 | if (nr >= WB_MAX_INODES_PER_ISW - 1) { | |
655 | restart = true; | |
656 | break; | |
657 | } | |
658 | } | |
659 | spin_unlock(&wb->list_lock); | |
660 | ||
661 | /* no attached inodes? bail out */ | |
662 | if (nr == 0) { | |
663 | atomic_dec(&isw_nr_in_flight); | |
664 | wb_put(isw->new_wb); | |
665 | kfree(isw); | |
666 | return restart; | |
667 | } | |
668 | ||
669 | /* | |
670 | * In addition to synchronizing among switchers, I_WB_SWITCH tells | |
671 | * the RCU protected stat update paths to grab the i_page | |
672 | * lock so that stat transfer can synchronize against them. | |
673 | * Let's continue after I_WB_SWITCH is guaranteed to be visible. | |
674 | */ | |
675 | INIT_RCU_WORK(&isw->work, inode_switch_wbs_work_fn); | |
676 | queue_rcu_work(isw_wq, &isw->work); | |
677 | ||
678 | return restart; | |
679 | } | |
680 | ||
b16b1deb TH |
681 | /** |
682 | * wbc_attach_and_unlock_inode - associate wbc with target inode and unlock it | |
683 | * @wbc: writeback_control of interest | |
684 | * @inode: target inode | |
685 | * | |
686 | * @inode is locked and about to be written back under the control of @wbc. | |
687 | * Record @inode's writeback context into @wbc and unlock the i_lock. On | |
688 | * writeback completion, wbc_detach_inode() should be called. This is used | |
689 | * to track the cgroup writeback context. | |
690 | */ | |
691 | void wbc_attach_and_unlock_inode(struct writeback_control *wbc, | |
692 | struct inode *inode) | |
693 | { | |
dd73e4b7 TH |
694 | if (!inode_cgwb_enabled(inode)) { |
695 | spin_unlock(&inode->i_lock); | |
696 | return; | |
697 | } | |
698 | ||
b16b1deb | 699 | wbc->wb = inode_to_wb(inode); |
2a814908 TH |
700 | wbc->inode = inode; |
701 | ||
702 | wbc->wb_id = wbc->wb->memcg_css->id; | |
703 | wbc->wb_lcand_id = inode->i_wb_frn_winner; | |
704 | wbc->wb_tcand_id = 0; | |
705 | wbc->wb_bytes = 0; | |
706 | wbc->wb_lcand_bytes = 0; | |
707 | wbc->wb_tcand_bytes = 0; | |
708 | ||
b16b1deb TH |
709 | wb_get(wbc->wb); |
710 | spin_unlock(&inode->i_lock); | |
e8a7abf5 TH |
711 | |
712 | /* | |
65de03e2 TH |
713 | * A dying wb indicates that either the blkcg associated with the |
714 | * memcg changed or the associated memcg is dying. In the first | |
715 | * case, a replacement wb should already be available and we should | |
716 | * refresh the wb immediately. In the second case, trying to | |
717 | * refresh will keep failing. | |
e8a7abf5 | 718 | */ |
65de03e2 | 719 | if (unlikely(wb_dying(wbc->wb) && !css_is_dying(wbc->wb->memcg_css))) |
e8a7abf5 | 720 | inode_switch_wbs(inode, wbc->wb_id); |
b16b1deb | 721 | } |
9b0eb69b | 722 | EXPORT_SYMBOL_GPL(wbc_attach_and_unlock_inode); |
b16b1deb TH |
723 | |
724 | /** | |
2a814908 TH |
725 | * wbc_detach_inode - disassociate wbc from inode and perform foreign detection |
726 | * @wbc: writeback_control of the just finished writeback | |
b16b1deb TH |
727 | * |
728 | * To be called after a writeback attempt of an inode finishes and undoes | |
729 | * wbc_attach_and_unlock_inode(). Can be called under any context. | |
2a814908 TH |
730 | * |
731 | * As concurrent write sharing of an inode is expected to be very rare and | |
732 | * memcg only tracks page ownership on first-use basis severely confining | |
733 | * the usefulness of such sharing, cgroup writeback tracks ownership | |
734 | * per-inode. While the support for concurrent write sharing of an inode | |
735 | * is deemed unnecessary, an inode being written to by different cgroups at | |
736 | * different points in time is a lot more common, and, more importantly, | |
737 | * charging only by first-use can too readily lead to grossly incorrect | |
738 | * behaviors (single foreign page can lead to gigabytes of writeback to be | |
739 | * incorrectly attributed). | |
740 | * | |
741 | * To resolve this issue, cgroup writeback detects the majority dirtier of | |
2999e1e3 | 742 | * an inode and transfers the ownership to it. To avoid unnecessary |
2a814908 TH |
743 | * oscillation, the detection mechanism keeps track of history and gives |
744 | * out the switch verdict only if the foreign usage pattern is stable over | |
745 | * a certain amount of time and/or writeback attempts. | |
746 | * | |
747 | * On each writeback attempt, @wbc tries to detect the majority writer | |
748 | * using Boyer-Moore majority vote algorithm. In addition to the byte | |
749 | * count from the majority voting, it also counts the bytes written for the | |
750 | * current wb and the last round's winner wb (max of last round's current | |
751 | * wb, the winner from two rounds ago, and the last round's majority | |
752 | * candidate). Keeping track of the historical winner helps the algorithm | |
753 | * to semi-reliably detect the most active writer even when it's not the | |
754 | * absolute majority. | |
755 | * | |
756 | * Once the winner of the round is determined, whether the winner is | |
757 | * foreign or not and how much IO time the round consumed is recorded in | |
758 | * inode->i_wb_frn_history. If the amount of recorded foreign IO time is | |
759 | * over a certain threshold, the switch verdict is given. | |
b16b1deb TH |
760 | */ |
761 | void wbc_detach_inode(struct writeback_control *wbc) | |
762 | { | |
2a814908 TH |
763 | struct bdi_writeback *wb = wbc->wb; |
764 | struct inode *inode = wbc->inode; | |
dd73e4b7 TH |
765 | unsigned long avg_time, max_bytes, max_time; |
766 | u16 history; | |
2a814908 TH |
767 | int max_id; |
768 | ||
dd73e4b7 TH |
769 | if (!wb) |
770 | return; | |
771 | ||
772 | history = inode->i_wb_frn_history; | |
773 | avg_time = inode->i_wb_frn_avg_time; | |
774 | ||
2a814908 TH |
775 | /* pick the winner of this round */ |
776 | if (wbc->wb_bytes >= wbc->wb_lcand_bytes && | |
777 | wbc->wb_bytes >= wbc->wb_tcand_bytes) { | |
778 | max_id = wbc->wb_id; | |
779 | max_bytes = wbc->wb_bytes; | |
780 | } else if (wbc->wb_lcand_bytes >= wbc->wb_tcand_bytes) { | |
781 | max_id = wbc->wb_lcand_id; | |
782 | max_bytes = wbc->wb_lcand_bytes; | |
783 | } else { | |
784 | max_id = wbc->wb_tcand_id; | |
785 | max_bytes = wbc->wb_tcand_bytes; | |
786 | } | |
787 | ||
788 | /* | |
789 | * Calculate the amount of IO time the winner consumed and fold it | |
790 | * into the running average kept per inode. If the consumed IO | |
791 | * time is lower than avag / WB_FRN_TIME_CUT_DIV, ignore it for | |
792 | * deciding whether to switch or not. This is to prevent one-off | |
793 | * small dirtiers from skewing the verdict. | |
794 | */ | |
795 | max_time = DIV_ROUND_UP((max_bytes >> PAGE_SHIFT) << WB_FRN_TIME_SHIFT, | |
796 | wb->avg_write_bandwidth); | |
797 | if (avg_time) | |
798 | avg_time += (max_time >> WB_FRN_TIME_AVG_SHIFT) - | |
799 | (avg_time >> WB_FRN_TIME_AVG_SHIFT); | |
800 | else | |
801 | avg_time = max_time; /* immediate catch up on first run */ | |
802 | ||
803 | if (max_time >= avg_time / WB_FRN_TIME_CUT_DIV) { | |
804 | int slots; | |
805 | ||
806 | /* | |
807 | * The switch verdict is reached if foreign wb's consume | |
808 | * more than a certain proportion of IO time in a | |
809 | * WB_FRN_TIME_PERIOD. This is loosely tracked by 16 slot | |
810 | * history mask where each bit represents one sixteenth of | |
811 | * the period. Determine the number of slots to shift into | |
812 | * history from @max_time. | |
813 | */ | |
814 | slots = min(DIV_ROUND_UP(max_time, WB_FRN_HIST_UNIT), | |
815 | (unsigned long)WB_FRN_HIST_MAX_SLOTS); | |
816 | history <<= slots; | |
817 | if (wbc->wb_id != max_id) | |
818 | history |= (1U << slots) - 1; | |
819 | ||
3a8e9ac8 TH |
820 | if (history) |
821 | trace_inode_foreign_history(inode, wbc, history); | |
822 | ||
2a814908 TH |
823 | /* |
824 | * Switch if the current wb isn't the consistent winner. | |
825 | * If there are multiple closely competing dirtiers, the | |
826 | * inode may switch across them repeatedly over time, which | |
827 | * is okay. The main goal is avoiding keeping an inode on | |
828 | * the wrong wb for an extended period of time. | |
829 | */ | |
682aa8e1 TH |
830 | if (hweight32(history) > WB_FRN_HIST_THR_SLOTS) |
831 | inode_switch_wbs(inode, max_id); | |
2a814908 TH |
832 | } |
833 | ||
834 | /* | |
835 | * Multiple instances of this function may race to update the | |
836 | * following fields but we don't mind occassional inaccuracies. | |
837 | */ | |
838 | inode->i_wb_frn_winner = max_id; | |
839 | inode->i_wb_frn_avg_time = min(avg_time, (unsigned long)U16_MAX); | |
840 | inode->i_wb_frn_history = history; | |
841 | ||
b16b1deb TH |
842 | wb_put(wbc->wb); |
843 | wbc->wb = NULL; | |
844 | } | |
9b0eb69b | 845 | EXPORT_SYMBOL_GPL(wbc_detach_inode); |
b16b1deb | 846 | |
2a814908 | 847 | /** |
34e51a5e | 848 | * wbc_account_cgroup_owner - account writeback to update inode cgroup ownership |
2a814908 TH |
849 | * @wbc: writeback_control of the writeback in progress |
850 | * @page: page being written out | |
851 | * @bytes: number of bytes being written out | |
852 | * | |
853 | * @bytes from @page are about to written out during the writeback | |
854 | * controlled by @wbc. Keep the book for foreign inode detection. See | |
855 | * wbc_detach_inode(). | |
856 | */ | |
34e51a5e TH |
857 | void wbc_account_cgroup_owner(struct writeback_control *wbc, struct page *page, |
858 | size_t bytes) | |
2a814908 | 859 | { |
66311422 | 860 | struct cgroup_subsys_state *css; |
2a814908 TH |
861 | int id; |
862 | ||
863 | /* | |
864 | * pageout() path doesn't attach @wbc to the inode being written | |
865 | * out. This is intentional as we don't want the function to block | |
866 | * behind a slow cgroup. Ultimately, we want pageout() to kick off | |
867 | * regular writeback instead of writing things out itself. | |
868 | */ | |
27b36d8f | 869 | if (!wbc->wb || wbc->no_cgroup_owner) |
2a814908 TH |
870 | return; |
871 | ||
66311422 TH |
872 | css = mem_cgroup_css_from_page(page); |
873 | /* dead cgroups shouldn't contribute to inode ownership arbitration */ | |
874 | if (!(css->flags & CSS_ONLINE)) | |
875 | return; | |
876 | ||
877 | id = css->id; | |
2a814908 TH |
878 | |
879 | if (id == wbc->wb_id) { | |
880 | wbc->wb_bytes += bytes; | |
881 | return; | |
882 | } | |
883 | ||
884 | if (id == wbc->wb_lcand_id) | |
885 | wbc->wb_lcand_bytes += bytes; | |
886 | ||
887 | /* Boyer-Moore majority vote algorithm */ | |
888 | if (!wbc->wb_tcand_bytes) | |
889 | wbc->wb_tcand_id = id; | |
890 | if (id == wbc->wb_tcand_id) | |
891 | wbc->wb_tcand_bytes += bytes; | |
892 | else | |
893 | wbc->wb_tcand_bytes -= min(bytes, wbc->wb_tcand_bytes); | |
894 | } | |
34e51a5e | 895 | EXPORT_SYMBOL_GPL(wbc_account_cgroup_owner); |
2a814908 | 896 | |
f2b65121 TH |
897 | /** |
898 | * wb_split_bdi_pages - split nr_pages to write according to bandwidth | |
899 | * @wb: target bdi_writeback to split @nr_pages to | |
900 | * @nr_pages: number of pages to write for the whole bdi | |
901 | * | |
902 | * Split @wb's portion of @nr_pages according to @wb's write bandwidth in | |
903 | * relation to the total write bandwidth of all wb's w/ dirty inodes on | |
904 | * @wb->bdi. | |
905 | */ | |
906 | static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages) | |
907 | { | |
908 | unsigned long this_bw = wb->avg_write_bandwidth; | |
909 | unsigned long tot_bw = atomic_long_read(&wb->bdi->tot_write_bandwidth); | |
910 | ||
911 | if (nr_pages == LONG_MAX) | |
912 | return LONG_MAX; | |
913 | ||
914 | /* | |
915 | * This may be called on clean wb's and proportional distribution | |
916 | * may not make sense, just use the original @nr_pages in those | |
917 | * cases. In general, we wanna err on the side of writing more. | |
918 | */ | |
919 | if (!tot_bw || this_bw >= tot_bw) | |
920 | return nr_pages; | |
921 | else | |
922 | return DIV_ROUND_UP_ULL((u64)nr_pages * this_bw, tot_bw); | |
923 | } | |
924 | ||
db125360 TH |
925 | /** |
926 | * bdi_split_work_to_wbs - split a wb_writeback_work to all wb's of a bdi | |
927 | * @bdi: target backing_dev_info | |
928 | * @base_work: wb_writeback_work to issue | |
929 | * @skip_if_busy: skip wb's which already have writeback in progress | |
930 | * | |
931 | * Split and issue @base_work to all wb's (bdi_writeback's) of @bdi which | |
932 | * have dirty inodes. If @base_work->nr_page isn't %LONG_MAX, it's | |
933 | * distributed to the busy wbs according to each wb's proportion in the | |
934 | * total active write bandwidth of @bdi. | |
935 | */ | |
936 | static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, | |
937 | struct wb_writeback_work *base_work, | |
938 | bool skip_if_busy) | |
939 | { | |
b817525a | 940 | struct bdi_writeback *last_wb = NULL; |
b33e18f6 TH |
941 | struct bdi_writeback *wb = list_entry(&bdi->wb_list, |
942 | struct bdi_writeback, bdi_node); | |
db125360 TH |
943 | |
944 | might_sleep(); | |
db125360 TH |
945 | restart: |
946 | rcu_read_lock(); | |
b817525a | 947 | list_for_each_entry_continue_rcu(wb, &bdi->wb_list, bdi_node) { |
5b9cce4c | 948 | DEFINE_WB_COMPLETION(fallback_work_done, bdi); |
8a1270cd TH |
949 | struct wb_writeback_work fallback_work; |
950 | struct wb_writeback_work *work; | |
951 | long nr_pages; | |
952 | ||
b817525a TH |
953 | if (last_wb) { |
954 | wb_put(last_wb); | |
955 | last_wb = NULL; | |
956 | } | |
957 | ||
006a0973 TH |
958 | /* SYNC_ALL writes out I_DIRTY_TIME too */ |
959 | if (!wb_has_dirty_io(wb) && | |
960 | (base_work->sync_mode == WB_SYNC_NONE || | |
961 | list_empty(&wb->b_dirty_time))) | |
962 | continue; | |
963 | if (skip_if_busy && writeback_in_progress(wb)) | |
db125360 TH |
964 | continue; |
965 | ||
8a1270cd TH |
966 | nr_pages = wb_split_bdi_pages(wb, base_work->nr_pages); |
967 | ||
968 | work = kmalloc(sizeof(*work), GFP_ATOMIC); | |
969 | if (work) { | |
970 | *work = *base_work; | |
971 | work->nr_pages = nr_pages; | |
972 | work->auto_free = 1; | |
973 | wb_queue_work(wb, work); | |
974 | continue; | |
db125360 | 975 | } |
8a1270cd TH |
976 | |
977 | /* alloc failed, execute synchronously using on-stack fallback */ | |
978 | work = &fallback_work; | |
979 | *work = *base_work; | |
980 | work->nr_pages = nr_pages; | |
981 | work->auto_free = 0; | |
982 | work->done = &fallback_work_done; | |
983 | ||
984 | wb_queue_work(wb, work); | |
985 | ||
b817525a TH |
986 | /* |
987 | * Pin @wb so that it stays on @bdi->wb_list. This allows | |
988 | * continuing iteration from @wb after dropping and | |
989 | * regrabbing rcu read lock. | |
990 | */ | |
991 | wb_get(wb); | |
992 | last_wb = wb; | |
993 | ||
8a1270cd | 994 | rcu_read_unlock(); |
5b9cce4c | 995 | wb_wait_for_completion(&fallback_work_done); |
8a1270cd | 996 | goto restart; |
db125360 TH |
997 | } |
998 | rcu_read_unlock(); | |
b817525a TH |
999 | |
1000 | if (last_wb) | |
1001 | wb_put(last_wb); | |
db125360 TH |
1002 | } |
1003 | ||
d62241c7 TH |
1004 | /** |
1005 | * cgroup_writeback_by_id - initiate cgroup writeback from bdi and memcg IDs | |
1006 | * @bdi_id: target bdi id | |
1007 | * @memcg_id: target memcg css id | |
d62241c7 TH |
1008 | * @reason: reason why some writeback work initiated |
1009 | * @done: target wb_completion | |
1010 | * | |
1011 | * Initiate flush of the bdi_writeback identified by @bdi_id and @memcg_id | |
1012 | * with the specified parameters. | |
1013 | */ | |
7490a2d2 | 1014 | int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, |
d62241c7 TH |
1015 | enum wb_reason reason, struct wb_completion *done) |
1016 | { | |
1017 | struct backing_dev_info *bdi; | |
1018 | struct cgroup_subsys_state *memcg_css; | |
1019 | struct bdi_writeback *wb; | |
1020 | struct wb_writeback_work *work; | |
7490a2d2 | 1021 | unsigned long dirty; |
d62241c7 TH |
1022 | int ret; |
1023 | ||
1024 | /* lookup bdi and memcg */ | |
1025 | bdi = bdi_get_by_id(bdi_id); | |
1026 | if (!bdi) | |
1027 | return -ENOENT; | |
1028 | ||
1029 | rcu_read_lock(); | |
1030 | memcg_css = css_from_id(memcg_id, &memory_cgrp_subsys); | |
1031 | if (memcg_css && !css_tryget(memcg_css)) | |
1032 | memcg_css = NULL; | |
1033 | rcu_read_unlock(); | |
1034 | if (!memcg_css) { | |
1035 | ret = -ENOENT; | |
1036 | goto out_bdi_put; | |
1037 | } | |
1038 | ||
1039 | /* | |
1040 | * And find the associated wb. If the wb isn't there already | |
1041 | * there's nothing to flush, don't create one. | |
1042 | */ | |
1043 | wb = wb_get_lookup(bdi, memcg_css); | |
1044 | if (!wb) { | |
1045 | ret = -ENOENT; | |
1046 | goto out_css_put; | |
1047 | } | |
1048 | ||
1049 | /* | |
7490a2d2 | 1050 | * The caller is attempting to write out most of |
d62241c7 TH |
1051 | * the currently dirty pages. Let's take the current dirty page |
1052 | * count and inflate it by 25% which should be large enough to | |
1053 | * flush out most dirty pages while avoiding getting livelocked by | |
1054 | * concurrent dirtiers. | |
7490a2d2 SB |
1055 | * |
1056 | * BTW the memcg stats are flushed periodically and this is best-effort | |
1057 | * estimation, so some potential error is ok. | |
d62241c7 | 1058 | */ |
7490a2d2 SB |
1059 | dirty = memcg_page_state(mem_cgroup_from_css(memcg_css), NR_FILE_DIRTY); |
1060 | dirty = dirty * 10 / 8; | |
d62241c7 TH |
1061 | |
1062 | /* issue the writeback work */ | |
1063 | work = kzalloc(sizeof(*work), GFP_NOWAIT | __GFP_NOWARN); | |
1064 | if (work) { | |
7490a2d2 | 1065 | work->nr_pages = dirty; |
d62241c7 TH |
1066 | work->sync_mode = WB_SYNC_NONE; |
1067 | work->range_cyclic = 1; | |
1068 | work->reason = reason; | |
1069 | work->done = done; | |
1070 | work->auto_free = 1; | |
1071 | wb_queue_work(wb, work); | |
1072 | ret = 0; | |
1073 | } else { | |
1074 | ret = -ENOMEM; | |
1075 | } | |
1076 | ||
1077 | wb_put(wb); | |
1078 | out_css_put: | |
1079 | css_put(memcg_css); | |
1080 | out_bdi_put: | |
1081 | bdi_put(bdi); | |
1082 | return ret; | |
1083 | } | |
1084 | ||
a1a0e23e TH |
1085 | /** |
1086 | * cgroup_writeback_umount - flush inode wb switches for umount | |
1087 | * | |
1088 | * This function is called when a super_block is about to be destroyed and | |
1089 | * flushes in-flight inode wb switches. An inode wb switch goes through | |
1090 | * RCU and then workqueue, so the two need to be flushed in order to ensure | |
1091 | * that all previously scheduled switches are finished. As wb switches are | |
1092 | * rare occurrences and synchronize_rcu() can take a while, perform | |
1093 | * flushing iff wb switches are in flight. | |
1094 | */ | |
1095 | void cgroup_writeback_umount(void) | |
1096 | { | |
592fa002 RG |
1097 | /* |
1098 | * SB_ACTIVE should be reliably cleared before checking | |
1099 | * isw_nr_in_flight, see generic_shutdown_super(). | |
1100 | */ | |
1101 | smp_mb(); | |
1102 | ||
a1a0e23e | 1103 | if (atomic_read(&isw_nr_in_flight)) { |
ec084de9 JX |
1104 | /* |
1105 | * Use rcu_barrier() to wait for all pending callbacks to | |
1106 | * ensure that all in-flight wb switches are in the workqueue. | |
1107 | */ | |
1108 | rcu_barrier(); | |
a1a0e23e TH |
1109 | flush_workqueue(isw_wq); |
1110 | } | |
1111 | } | |
1112 | ||
1113 | static int __init cgroup_writeback_init(void) | |
1114 | { | |
1115 | isw_wq = alloc_workqueue("inode_switch_wbs", 0, 0); | |
1116 | if (!isw_wq) | |
1117 | return -ENOMEM; | |
1118 | return 0; | |
1119 | } | |
1120 | fs_initcall(cgroup_writeback_init); | |
1121 | ||
f2b65121 TH |
1122 | #else /* CONFIG_CGROUP_WRITEBACK */ |
1123 | ||
7fc5854f TH |
1124 | static void bdi_down_write_wb_switch_rwsem(struct backing_dev_info *bdi) { } |
1125 | static void bdi_up_write_wb_switch_rwsem(struct backing_dev_info *bdi) { } | |
1126 | ||
f3b6a6df RG |
1127 | static void inode_cgwb_move_to_attached(struct inode *inode, |
1128 | struct bdi_writeback *wb) | |
1129 | { | |
1130 | assert_spin_locked(&wb->list_lock); | |
1131 | assert_spin_locked(&inode->i_lock); | |
1132 | ||
1133 | inode->i_state &= ~I_SYNC_QUEUED; | |
1134 | list_del_init(&inode->i_io_list); | |
1135 | wb_io_lists_depopulated(wb); | |
1136 | } | |
1137 | ||
87e1d789 TH |
1138 | static struct bdi_writeback * |
1139 | locked_inode_to_wb_and_lock_list(struct inode *inode) | |
1140 | __releases(&inode->i_lock) | |
1141 | __acquires(&wb->list_lock) | |
1142 | { | |
1143 | struct bdi_writeback *wb = inode_to_wb(inode); | |
1144 | ||
1145 | spin_unlock(&inode->i_lock); | |
1146 | spin_lock(&wb->list_lock); | |
1147 | return wb; | |
1148 | } | |
1149 | ||
1150 | static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode) | |
1151 | __acquires(&wb->list_lock) | |
1152 | { | |
1153 | struct bdi_writeback *wb = inode_to_wb(inode); | |
1154 | ||
1155 | spin_lock(&wb->list_lock); | |
1156 | return wb; | |
1157 | } | |
1158 | ||
f2b65121 TH |
1159 | static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages) |
1160 | { | |
1161 | return nr_pages; | |
1162 | } | |
1163 | ||
db125360 TH |
1164 | static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, |
1165 | struct wb_writeback_work *base_work, | |
1166 | bool skip_if_busy) | |
1167 | { | |
1168 | might_sleep(); | |
1169 | ||
006a0973 | 1170 | if (!skip_if_busy || !writeback_in_progress(&bdi->wb)) { |
db125360 | 1171 | base_work->auto_free = 0; |
db125360 TH |
1172 | wb_queue_work(&bdi->wb, base_work); |
1173 | } | |
1174 | } | |
1175 | ||
703c2708 TH |
1176 | #endif /* CONFIG_CGROUP_WRITEBACK */ |
1177 | ||
e8e8a0c6 JA |
1178 | /* |
1179 | * Add in the number of potentially dirty inodes, because each inode | |
1180 | * write can dirty pagecache in the underlying blockdev. | |
1181 | */ | |
1182 | static unsigned long get_nr_dirty_pages(void) | |
1183 | { | |
1184 | return global_node_page_state(NR_FILE_DIRTY) + | |
e8e8a0c6 JA |
1185 | get_nr_dirty_inodes(); |
1186 | } | |
1187 | ||
1188 | static void wb_start_writeback(struct bdi_writeback *wb, enum wb_reason reason) | |
b6e51316 | 1189 | { |
c00ddad3 TH |
1190 | if (!wb_has_dirty_io(wb)) |
1191 | return; | |
1192 | ||
aac8d41c JA |
1193 | /* |
1194 | * All callers of this function want to start writeback of all | |
1195 | * dirty pages. Places like vmscan can call this at a very | |
1196 | * high frequency, causing pointless allocations of tons of | |
1197 | * work items and keeping the flusher threads busy retrieving | |
1198 | * that work. Ensure that we only allow one of them pending and | |
85009b4f | 1199 | * inflight at the time. |
aac8d41c | 1200 | */ |
85009b4f JA |
1201 | if (test_bit(WB_start_all, &wb->state) || |
1202 | test_and_set_bit(WB_start_all, &wb->state)) | |
aac8d41c JA |
1203 | return; |
1204 | ||
85009b4f JA |
1205 | wb->start_all_reason = reason; |
1206 | wb_wakeup(wb); | |
c5444198 | 1207 | } |
d3ddec76 | 1208 | |
c5444198 | 1209 | /** |
9ecf4866 TH |
1210 | * wb_start_background_writeback - start background writeback |
1211 | * @wb: bdi_writback to write from | |
c5444198 CH |
1212 | * |
1213 | * Description: | |
6585027a | 1214 | * This makes sure WB_SYNC_NONE background writeback happens. When |
9ecf4866 | 1215 | * this function returns, it is only guaranteed that for given wb |
6585027a JK |
1216 | * some IO is happening if we are over background dirty threshold. |
1217 | * Caller need not hold sb s_umount semaphore. | |
c5444198 | 1218 | */ |
9ecf4866 | 1219 | void wb_start_background_writeback(struct bdi_writeback *wb) |
c5444198 | 1220 | { |
6585027a JK |
1221 | /* |
1222 | * We just wake up the flusher thread. It will perform background | |
1223 | * writeback as soon as there is no other work to do. | |
1224 | */ | |
5634cc2a | 1225 | trace_writeback_wake_background(wb); |
9ecf4866 | 1226 | wb_wakeup(wb); |
1da177e4 LT |
1227 | } |
1228 | ||
a66979ab DC |
1229 | /* |
1230 | * Remove the inode from the writeback list it is on. | |
1231 | */ | |
c7f54084 | 1232 | void inode_io_list_del(struct inode *inode) |
a66979ab | 1233 | { |
87e1d789 | 1234 | struct bdi_writeback *wb; |
f758eeab | 1235 | |
87e1d789 | 1236 | wb = inode_to_wb_and_lock_list(inode); |
b35250c0 | 1237 | spin_lock(&inode->i_lock); |
f3b6a6df RG |
1238 | |
1239 | inode->i_state &= ~I_SYNC_QUEUED; | |
1240 | list_del_init(&inode->i_io_list); | |
1241 | wb_io_lists_depopulated(wb); | |
1242 | ||
b35250c0 | 1243 | spin_unlock(&inode->i_lock); |
52ebea74 | 1244 | spin_unlock(&wb->list_lock); |
a66979ab | 1245 | } |
4301efa4 | 1246 | EXPORT_SYMBOL(inode_io_list_del); |
a66979ab | 1247 | |
6c60d2b5 DC |
1248 | /* |
1249 | * mark an inode as under writeback on the sb | |
1250 | */ | |
1251 | void sb_mark_inode_writeback(struct inode *inode) | |
1252 | { | |
1253 | struct super_block *sb = inode->i_sb; | |
1254 | unsigned long flags; | |
1255 | ||
1256 | if (list_empty(&inode->i_wb_list)) { | |
1257 | spin_lock_irqsave(&sb->s_inode_wblist_lock, flags); | |
9a46b04f | 1258 | if (list_empty(&inode->i_wb_list)) { |
6c60d2b5 | 1259 | list_add_tail(&inode->i_wb_list, &sb->s_inodes_wb); |
9a46b04f BF |
1260 | trace_sb_mark_inode_writeback(inode); |
1261 | } | |
6c60d2b5 DC |
1262 | spin_unlock_irqrestore(&sb->s_inode_wblist_lock, flags); |
1263 | } | |
1264 | } | |
1265 | ||
1266 | /* | |
1267 | * clear an inode as under writeback on the sb | |
1268 | */ | |
1269 | void sb_clear_inode_writeback(struct inode *inode) | |
1270 | { | |
1271 | struct super_block *sb = inode->i_sb; | |
1272 | unsigned long flags; | |
1273 | ||
1274 | if (!list_empty(&inode->i_wb_list)) { | |
1275 | spin_lock_irqsave(&sb->s_inode_wblist_lock, flags); | |
9a46b04f BF |
1276 | if (!list_empty(&inode->i_wb_list)) { |
1277 | list_del_init(&inode->i_wb_list); | |
1278 | trace_sb_clear_inode_writeback(inode); | |
1279 | } | |
6c60d2b5 DC |
1280 | spin_unlock_irqrestore(&sb->s_inode_wblist_lock, flags); |
1281 | } | |
1282 | } | |
1283 | ||
6610a0bc AM |
1284 | /* |
1285 | * Redirty an inode: set its when-it-was dirtied timestamp and move it to the | |
1286 | * furthest end of its superblock's dirty-inode list. | |
1287 | * | |
1288 | * Before stamping the inode's ->dirtied_when, we check to see whether it is | |
66f3b8e2 | 1289 | * already the most-recently-dirtied inode on the b_dirty list. If that is |
6610a0bc AM |
1290 | * the case then the inode must have been redirtied while it was being written |
1291 | * out and we don't reset its dirtied_when. | |
1292 | */ | |
b35250c0 | 1293 | static void redirty_tail_locked(struct inode *inode, struct bdi_writeback *wb) |
6610a0bc | 1294 | { |
b35250c0 JK |
1295 | assert_spin_locked(&inode->i_lock); |
1296 | ||
03ba3782 | 1297 | if (!list_empty(&wb->b_dirty)) { |
66f3b8e2 | 1298 | struct inode *tail; |
6610a0bc | 1299 | |
7ccf19a8 | 1300 | tail = wb_inode(wb->b_dirty.next); |
66f3b8e2 | 1301 | if (time_before(inode->dirtied_when, tail->dirtied_when)) |
6610a0bc AM |
1302 | inode->dirtied_when = jiffies; |
1303 | } | |
c7f54084 | 1304 | inode_io_list_move_locked(inode, wb, &wb->b_dirty); |
5afced3b | 1305 | inode->i_state &= ~I_SYNC_QUEUED; |
6610a0bc AM |
1306 | } |
1307 | ||
b35250c0 JK |
1308 | static void redirty_tail(struct inode *inode, struct bdi_writeback *wb) |
1309 | { | |
1310 | spin_lock(&inode->i_lock); | |
1311 | redirty_tail_locked(inode, wb); | |
1312 | spin_unlock(&inode->i_lock); | |
1313 | } | |
1314 | ||
c986d1e2 | 1315 | /* |
66f3b8e2 | 1316 | * requeue inode for re-scanning after bdi->b_io list is exhausted. |
c986d1e2 | 1317 | */ |
f758eeab | 1318 | static void requeue_io(struct inode *inode, struct bdi_writeback *wb) |
c986d1e2 | 1319 | { |
c7f54084 | 1320 | inode_io_list_move_locked(inode, wb, &wb->b_more_io); |
c986d1e2 AM |
1321 | } |
1322 | ||
1c0eeaf5 JE |
1323 | static void inode_sync_complete(struct inode *inode) |
1324 | { | |
365b94ae | 1325 | inode->i_state &= ~I_SYNC; |
4eff96dd JK |
1326 | /* If inode is clean an unused, put it into LRU now... */ |
1327 | inode_add_lru(inode); | |
365b94ae | 1328 | /* Waiters must see I_SYNC cleared before being woken up */ |
1c0eeaf5 JE |
1329 | smp_mb(); |
1330 | wake_up_bit(&inode->i_state, __I_SYNC); | |
1331 | } | |
1332 | ||
d2caa3c5 JL |
1333 | static bool inode_dirtied_after(struct inode *inode, unsigned long t) |
1334 | { | |
1335 | bool ret = time_after(inode->dirtied_when, t); | |
1336 | #ifndef CONFIG_64BIT | |
1337 | /* | |
1338 | * For inodes being constantly redirtied, dirtied_when can get stuck. | |
1339 | * It _appears_ to be in the future, but is actually in distant past. | |
1340 | * This test is necessary to prevent such wrapped-around relative times | |
5b0830cb | 1341 | * from permanently stopping the whole bdi writeback. |
d2caa3c5 JL |
1342 | */ |
1343 | ret = ret && time_before_eq(inode->dirtied_when, jiffies); | |
1344 | #endif | |
1345 | return ret; | |
1346 | } | |
1347 | ||
0ae45f63 TT |
1348 | #define EXPIRE_DIRTY_ATIME 0x0001 |
1349 | ||
2c136579 | 1350 | /* |
f9cae926 | 1351 | * Move expired (dirtied before dirtied_before) dirty inodes from |
697e6fed | 1352 | * @delaying_queue to @dispatch_queue. |
2c136579 | 1353 | */ |
e84d0a4f | 1354 | static int move_expired_inodes(struct list_head *delaying_queue, |
2c136579 | 1355 | struct list_head *dispatch_queue, |
5fcd5750 | 1356 | unsigned long dirtied_before) |
2c136579 | 1357 | { |
5c03449d SL |
1358 | LIST_HEAD(tmp); |
1359 | struct list_head *pos, *node; | |
cf137307 | 1360 | struct super_block *sb = NULL; |
5c03449d | 1361 | struct inode *inode; |
cf137307 | 1362 | int do_sb_sort = 0; |
e84d0a4f | 1363 | int moved = 0; |
5c03449d | 1364 | |
2c136579 | 1365 | while (!list_empty(delaying_queue)) { |
7ccf19a8 | 1366 | inode = wb_inode(delaying_queue->prev); |
f9cae926 | 1367 | if (inode_dirtied_after(inode, dirtied_before)) |
2c136579 | 1368 | break; |
10e14073 | 1369 | spin_lock(&inode->i_lock); |
c7f54084 | 1370 | list_move(&inode->i_io_list, &tmp); |
a8855990 | 1371 | moved++; |
5afced3b JK |
1372 | inode->i_state |= I_SYNC_QUEUED; |
1373 | spin_unlock(&inode->i_lock); | |
a8855990 JK |
1374 | if (sb_is_blkdev_sb(inode->i_sb)) |
1375 | continue; | |
cf137307 JA |
1376 | if (sb && sb != inode->i_sb) |
1377 | do_sb_sort = 1; | |
1378 | sb = inode->i_sb; | |
5c03449d SL |
1379 | } |
1380 | ||
cf137307 JA |
1381 | /* just one sb in list, splice to dispatch_queue and we're done */ |
1382 | if (!do_sb_sort) { | |
1383 | list_splice(&tmp, dispatch_queue); | |
e84d0a4f | 1384 | goto out; |
cf137307 JA |
1385 | } |
1386 | ||
10e14073 JS |
1387 | /* |
1388 | * Although inode's i_io_list is moved from 'tmp' to 'dispatch_queue', | |
1389 | * we don't take inode->i_lock here because it is just a pointless overhead. | |
1390 | * Inode is already marked as I_SYNC_QUEUED so writeback list handling is | |
1391 | * fully under our control. | |
1392 | */ | |
5c03449d | 1393 | while (!list_empty(&tmp)) { |
7ccf19a8 | 1394 | sb = wb_inode(tmp.prev)->i_sb; |
5c03449d | 1395 | list_for_each_prev_safe(pos, node, &tmp) { |
7ccf19a8 | 1396 | inode = wb_inode(pos); |
5c03449d | 1397 | if (inode->i_sb == sb) |
c7f54084 | 1398 | list_move(&inode->i_io_list, dispatch_queue); |
5c03449d | 1399 | } |
2c136579 | 1400 | } |
e84d0a4f WF |
1401 | out: |
1402 | return moved; | |
2c136579 FW |
1403 | } |
1404 | ||
1405 | /* | |
1406 | * Queue all expired dirty inodes for io, eldest first. | |
4ea879b9 WF |
1407 | * Before |
1408 | * newly dirtied b_dirty b_io b_more_io | |
1409 | * =============> gf edc BA | |
1410 | * After | |
1411 | * newly dirtied b_dirty b_io b_more_io | |
1412 | * =============> g fBAedc | |
1413 | * | | |
1414 | * +--> dequeue for IO | |
2c136579 | 1415 | */ |
f9cae926 JK |
1416 | static void queue_io(struct bdi_writeback *wb, struct wb_writeback_work *work, |
1417 | unsigned long dirtied_before) | |
66f3b8e2 | 1418 | { |
e84d0a4f | 1419 | int moved; |
f9cae926 | 1420 | unsigned long time_expire_jif = dirtied_before; |
0ae45f63 | 1421 | |
f758eeab | 1422 | assert_spin_locked(&wb->list_lock); |
4ea879b9 | 1423 | list_splice_init(&wb->b_more_io, &wb->b_io); |
5fcd5750 | 1424 | moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, dirtied_before); |
f9cae926 JK |
1425 | if (!work->for_sync) |
1426 | time_expire_jif = jiffies - dirtytime_expire_interval * HZ; | |
0ae45f63 | 1427 | moved += move_expired_inodes(&wb->b_dirty_time, &wb->b_io, |
5fcd5750 | 1428 | time_expire_jif); |
d6c10f1f TH |
1429 | if (moved) |
1430 | wb_io_lists_populated(wb); | |
f9cae926 | 1431 | trace_writeback_queue_io(wb, work, dirtied_before, moved); |
66f3b8e2 JA |
1432 | } |
1433 | ||
a9185b41 | 1434 | static int write_inode(struct inode *inode, struct writeback_control *wbc) |
08d8e974 | 1435 | { |
9fb0a7da TH |
1436 | int ret; |
1437 | ||
1438 | if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) { | |
1439 | trace_writeback_write_inode_start(inode, wbc); | |
1440 | ret = inode->i_sb->s_op->write_inode(inode, wbc); | |
1441 | trace_writeback_write_inode(inode, wbc); | |
1442 | return ret; | |
1443 | } | |
03ba3782 | 1444 | return 0; |
08d8e974 | 1445 | } |
08d8e974 | 1446 | |
1da177e4 | 1447 | /* |
169ebd90 JK |
1448 | * Wait for writeback on an inode to complete. Called with i_lock held. |
1449 | * Caller must make sure inode cannot go away when we drop i_lock. | |
01c03194 | 1450 | */ |
169ebd90 JK |
1451 | static void __inode_wait_for_writeback(struct inode *inode) |
1452 | __releases(inode->i_lock) | |
1453 | __acquires(inode->i_lock) | |
01c03194 CH |
1454 | { |
1455 | DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); | |
1456 | wait_queue_head_t *wqh; | |
1457 | ||
1458 | wqh = bit_waitqueue(&inode->i_state, __I_SYNC); | |
250df6ed DC |
1459 | while (inode->i_state & I_SYNC) { |
1460 | spin_unlock(&inode->i_lock); | |
74316201 N |
1461 | __wait_on_bit(wqh, &wq, bit_wait, |
1462 | TASK_UNINTERRUPTIBLE); | |
250df6ed | 1463 | spin_lock(&inode->i_lock); |
58a9d3d8 | 1464 | } |
01c03194 CH |
1465 | } |
1466 | ||
169ebd90 JK |
1467 | /* |
1468 | * Wait for writeback on an inode to complete. Caller must have inode pinned. | |
1469 | */ | |
1470 | void inode_wait_for_writeback(struct inode *inode) | |
1471 | { | |
1472 | spin_lock(&inode->i_lock); | |
1473 | __inode_wait_for_writeback(inode); | |
1474 | spin_unlock(&inode->i_lock); | |
1475 | } | |
1476 | ||
1477 | /* | |
1478 | * Sleep until I_SYNC is cleared. This function must be called with i_lock | |
1479 | * held and drops it. It is aimed for callers not holding any inode reference | |
1480 | * so once i_lock is dropped, inode can go away. | |
1481 | */ | |
1482 | static void inode_sleep_on_writeback(struct inode *inode) | |
1483 | __releases(inode->i_lock) | |
1484 | { | |
1485 | DEFINE_WAIT(wait); | |
1486 | wait_queue_head_t *wqh = bit_waitqueue(&inode->i_state, __I_SYNC); | |
1487 | int sleep; | |
1488 | ||
1489 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
1490 | sleep = inode->i_state & I_SYNC; | |
1491 | spin_unlock(&inode->i_lock); | |
1492 | if (sleep) | |
1493 | schedule(); | |
1494 | finish_wait(wqh, &wait); | |
1495 | } | |
1496 | ||
ccb26b5a JK |
1497 | /* |
1498 | * Find proper writeback list for the inode depending on its current state and | |
1499 | * possibly also change of its state while we were doing writeback. Here we | |
1500 | * handle things such as livelock prevention or fairness of writeback among | |
1501 | * inodes. This function can be called only by flusher thread - noone else | |
1502 | * processes all inodes in writeback lists and requeueing inodes behind flusher | |
1503 | * thread's back can have unexpected consequences. | |
1504 | */ | |
1505 | static void requeue_inode(struct inode *inode, struct bdi_writeback *wb, | |
1506 | struct writeback_control *wbc) | |
1507 | { | |
1508 | if (inode->i_state & I_FREEING) | |
1509 | return; | |
1510 | ||
1511 | /* | |
1512 | * Sync livelock prevention. Each inode is tagged and synced in one | |
1513 | * shot. If still dirty, it will be redirty_tail()'ed below. Update | |
1514 | * the dirty time to prevent enqueue and sync it again. | |
1515 | */ | |
1516 | if ((inode->i_state & I_DIRTY) && | |
1517 | (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)) | |
1518 | inode->dirtied_when = jiffies; | |
1519 | ||
4f8ad655 JK |
1520 | if (wbc->pages_skipped) { |
1521 | /* | |
1522 | * writeback is not making progress due to locked | |
1523 | * buffers. Skip this inode for now. | |
1524 | */ | |
b35250c0 | 1525 | redirty_tail_locked(inode, wb); |
4f8ad655 JK |
1526 | return; |
1527 | } | |
1528 | ||
ccb26b5a JK |
1529 | if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) { |
1530 | /* | |
1531 | * We didn't write back all the pages. nfs_writepages() | |
1532 | * sometimes bales out without doing anything. | |
1533 | */ | |
1534 | if (wbc->nr_to_write <= 0) { | |
1535 | /* Slice used up. Queue for next turn. */ | |
1536 | requeue_io(inode, wb); | |
1537 | } else { | |
1538 | /* | |
1539 | * Writeback blocked by something other than | |
1540 | * congestion. Delay the inode for some time to | |
1541 | * avoid spinning on the CPU (100% iowait) | |
1542 | * retrying writeback of the dirty page/inode | |
1543 | * that cannot be performed immediately. | |
1544 | */ | |
b35250c0 | 1545 | redirty_tail_locked(inode, wb); |
ccb26b5a JK |
1546 | } |
1547 | } else if (inode->i_state & I_DIRTY) { | |
1548 | /* | |
1549 | * Filesystems can dirty the inode during writeback operations, | |
1550 | * such as delayed allocation during submission or metadata | |
1551 | * updates after data IO completion. | |
1552 | */ | |
b35250c0 | 1553 | redirty_tail_locked(inode, wb); |
0ae45f63 | 1554 | } else if (inode->i_state & I_DIRTY_TIME) { |
a2f48706 | 1555 | inode->dirtied_when = jiffies; |
c7f54084 | 1556 | inode_io_list_move_locked(inode, wb, &wb->b_dirty_time); |
5afced3b | 1557 | inode->i_state &= ~I_SYNC_QUEUED; |
ccb26b5a JK |
1558 | } else { |
1559 | /* The inode is clean. Remove from writeback lists. */ | |
f3b6a6df | 1560 | inode_cgwb_move_to_attached(inode, wb); |
ccb26b5a JK |
1561 | } |
1562 | } | |
1563 | ||
01c03194 | 1564 | /* |
da0c4c60 EB |
1565 | * Write out an inode and its dirty pages (or some of its dirty pages, depending |
1566 | * on @wbc->nr_to_write), and clear the relevant dirty flags from i_state. | |
1567 | * | |
1568 | * This doesn't remove the inode from the writeback list it is on, except | |
1569 | * potentially to move it from b_dirty_time to b_dirty due to timestamp | |
1570 | * expiration. The caller is otherwise responsible for writeback list handling. | |
1571 | * | |
1572 | * The caller is also responsible for setting the I_SYNC flag beforehand and | |
1573 | * calling inode_sync_complete() to clear it afterwards. | |
1da177e4 LT |
1574 | */ |
1575 | static int | |
cd8ed2a4 | 1576 | __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) |
1da177e4 | 1577 | { |
1da177e4 | 1578 | struct address_space *mapping = inode->i_mapping; |
251d6a47 | 1579 | long nr_to_write = wbc->nr_to_write; |
01c03194 | 1580 | unsigned dirty; |
1da177e4 LT |
1581 | int ret; |
1582 | ||
4f8ad655 | 1583 | WARN_ON(!(inode->i_state & I_SYNC)); |
1da177e4 | 1584 | |
9fb0a7da TH |
1585 | trace_writeback_single_inode_start(inode, wbc, nr_to_write); |
1586 | ||
1da177e4 LT |
1587 | ret = do_writepages(mapping, wbc); |
1588 | ||
26821ed4 CH |
1589 | /* |
1590 | * Make sure to wait on the data before writing out the metadata. | |
1591 | * This is important for filesystems that modify metadata on data | |
7747bd4b DC |
1592 | * I/O completion. We don't do it for sync(2) writeback because it has a |
1593 | * separate, external IO completion path and ->sync_fs for guaranteeing | |
1594 | * inode metadata is written back correctly. | |
26821ed4 | 1595 | */ |
7747bd4b | 1596 | if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync) { |
26821ed4 | 1597 | int err = filemap_fdatawait(mapping); |
1da177e4 LT |
1598 | if (ret == 0) |
1599 | ret = err; | |
1600 | } | |
1601 | ||
5547e8aa | 1602 | /* |
1e249cb5 EB |
1603 | * If the inode has dirty timestamps and we need to write them, call |
1604 | * mark_inode_dirty_sync() to notify the filesystem about it and to | |
1605 | * change I_DIRTY_TIME into I_DIRTY_SYNC. | |
5547e8aa | 1606 | */ |
5fcd5750 | 1607 | if ((inode->i_state & I_DIRTY_TIME) && |
83dc881d | 1608 | (wbc->sync_mode == WB_SYNC_ALL || |
5fcd5750 JK |
1609 | time_after(jiffies, inode->dirtied_time_when + |
1610 | dirtytime_expire_interval * HZ))) { | |
5fcd5750 | 1611 | trace_writeback_lazytime(inode); |
1e249cb5 | 1612 | mark_inode_dirty_sync(inode); |
5fcd5750 | 1613 | } |
1e249cb5 EB |
1614 | |
1615 | /* | |
da0c4c60 EB |
1616 | * Get and clear the dirty flags from i_state. This needs to be done |
1617 | * after calling writepages because some filesystems may redirty the | |
1618 | * inode during writepages due to delalloc. It also needs to be done | |
1619 | * after handling timestamp expiration, as that may dirty the inode too. | |
1e249cb5 EB |
1620 | */ |
1621 | spin_lock(&inode->i_lock); | |
1622 | dirty = inode->i_state & I_DIRTY; | |
0ae45f63 | 1623 | inode->i_state &= ~dirty; |
9c6ac78e TH |
1624 | |
1625 | /* | |
1626 | * Paired with smp_mb() in __mark_inode_dirty(). This allows | |
1627 | * __mark_inode_dirty() to test i_state without grabbing i_lock - | |
1628 | * either they see the I_DIRTY bits cleared or we see the dirtied | |
1629 | * inode. | |
1630 | * | |
1631 | * I_DIRTY_PAGES is always cleared together above even if @mapping | |
1632 | * still has dirty pages. The flag is reinstated after smp_mb() if | |
1633 | * necessary. This guarantees that either __mark_inode_dirty() | |
1634 | * sees clear I_DIRTY_PAGES or we see PAGECACHE_TAG_DIRTY. | |
1635 | */ | |
1636 | smp_mb(); | |
1637 | ||
1638 | if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) | |
1639 | inode->i_state |= I_DIRTY_PAGES; | |
08276bda DH |
1640 | else if (unlikely(inode->i_state & I_PINNING_FSCACHE_WB)) { |
1641 | if (!(inode->i_state & I_DIRTY_PAGES)) { | |
1642 | inode->i_state &= ~I_PINNING_FSCACHE_WB; | |
1643 | wbc->unpinned_fscache_wb = true; | |
1644 | dirty |= I_PINNING_FSCACHE_WB; /* Cause write_inode */ | |
1645 | } | |
1646 | } | |
9c6ac78e | 1647 | |
250df6ed | 1648 | spin_unlock(&inode->i_lock); |
9c6ac78e | 1649 | |
26821ed4 | 1650 | /* Don't write the inode if only I_DIRTY_PAGES was set */ |
0ae45f63 | 1651 | if (dirty & ~I_DIRTY_PAGES) { |
a9185b41 | 1652 | int err = write_inode(inode, wbc); |
1da177e4 LT |
1653 | if (ret == 0) |
1654 | ret = err; | |
1655 | } | |
08276bda | 1656 | wbc->unpinned_fscache_wb = false; |
4f8ad655 JK |
1657 | trace_writeback_single_inode(inode, wbc, nr_to_write); |
1658 | return ret; | |
1659 | } | |
1660 | ||
1661 | /* | |
da0c4c60 EB |
1662 | * Write out an inode's dirty data and metadata on-demand, i.e. separately from |
1663 | * the regular batched writeback done by the flusher threads in | |
1664 | * writeback_sb_inodes(). @wbc controls various aspects of the write, such as | |
1665 | * whether it is a data-integrity sync (%WB_SYNC_ALL) or not (%WB_SYNC_NONE). | |
4f8ad655 | 1666 | * |
da0c4c60 EB |
1667 | * To prevent the inode from going away, either the caller must have a reference |
1668 | * to the inode, or the inode must have I_WILL_FREE or I_FREEING set. | |
4f8ad655 | 1669 | */ |
aaf25593 TH |
1670 | static int writeback_single_inode(struct inode *inode, |
1671 | struct writeback_control *wbc) | |
4f8ad655 | 1672 | { |
aaf25593 | 1673 | struct bdi_writeback *wb; |
4f8ad655 JK |
1674 | int ret = 0; |
1675 | ||
1676 | spin_lock(&inode->i_lock); | |
1677 | if (!atomic_read(&inode->i_count)) | |
1678 | WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); | |
1679 | else | |
1680 | WARN_ON(inode->i_state & I_WILL_FREE); | |
1681 | ||
1682 | if (inode->i_state & I_SYNC) { | |
4f8ad655 | 1683 | /* |
da0c4c60 EB |
1684 | * Writeback is already running on the inode. For WB_SYNC_NONE, |
1685 | * that's enough and we can just return. For WB_SYNC_ALL, we | |
1686 | * must wait for the existing writeback to complete, then do | |
1687 | * writeback again if there's anything left. | |
4f8ad655 | 1688 | */ |
da0c4c60 EB |
1689 | if (wbc->sync_mode != WB_SYNC_ALL) |
1690 | goto out; | |
169ebd90 | 1691 | __inode_wait_for_writeback(inode); |
4f8ad655 JK |
1692 | } |
1693 | WARN_ON(inode->i_state & I_SYNC); | |
1694 | /* | |
da0c4c60 EB |
1695 | * If the inode is already fully clean, then there's nothing to do. |
1696 | * | |
1697 | * For data-integrity syncs we also need to check whether any pages are | |
1698 | * still under writeback, e.g. due to prior WB_SYNC_NONE writeback. If | |
1699 | * there are any such pages, we'll need to wait for them. | |
4f8ad655 | 1700 | */ |
0ae45f63 | 1701 | if (!(inode->i_state & I_DIRTY_ALL) && |
f9b0e058 JK |
1702 | (wbc->sync_mode != WB_SYNC_ALL || |
1703 | !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))) | |
4f8ad655 JK |
1704 | goto out; |
1705 | inode->i_state |= I_SYNC; | |
b16b1deb | 1706 | wbc_attach_and_unlock_inode(wbc, inode); |
4f8ad655 | 1707 | |
cd8ed2a4 | 1708 | ret = __writeback_single_inode(inode, wbc); |
1da177e4 | 1709 | |
b16b1deb | 1710 | wbc_detach_inode(wbc); |
aaf25593 TH |
1711 | |
1712 | wb = inode_to_wb_and_lock_list(inode); | |
250df6ed | 1713 | spin_lock(&inode->i_lock); |
4f8ad655 | 1714 | /* |
da0c4c60 EB |
1715 | * If the inode is now fully clean, then it can be safely removed from |
1716 | * its writeback list (if any). Otherwise the flusher threads are | |
1717 | * responsible for the writeback lists. | |
4f8ad655 | 1718 | */ |
0ae45f63 | 1719 | if (!(inode->i_state & I_DIRTY_ALL)) |
f3b6a6df | 1720 | inode_cgwb_move_to_attached(inode, wb); |
cbfecb92 LC |
1721 | else if (!(inode->i_state & I_SYNC_QUEUED)) { |
1722 | if ((inode->i_state & I_DIRTY)) | |
1723 | redirty_tail_locked(inode, wb); | |
1724 | else if (inode->i_state & I_DIRTY_TIME) { | |
1725 | inode->dirtied_when = jiffies; | |
1726 | inode_io_list_move_locked(inode, wb, &wb->b_dirty_time); | |
1727 | } | |
1728 | } | |
846a3351 | 1729 | |
4f8ad655 | 1730 | spin_unlock(&wb->list_lock); |
1c0eeaf5 | 1731 | inode_sync_complete(inode); |
4f8ad655 JK |
1732 | out: |
1733 | spin_unlock(&inode->i_lock); | |
1da177e4 LT |
1734 | return ret; |
1735 | } | |
1736 | ||
a88a341a | 1737 | static long writeback_chunk_size(struct bdi_writeback *wb, |
1a12d8bd | 1738 | struct wb_writeback_work *work) |
d46db3d5 WF |
1739 | { |
1740 | long pages; | |
1741 | ||
1742 | /* | |
1743 | * WB_SYNC_ALL mode does livelock avoidance by syncing dirty | |
1744 | * inodes/pages in one big loop. Setting wbc.nr_to_write=LONG_MAX | |
1745 | * here avoids calling into writeback_inodes_wb() more than once. | |
1746 | * | |
1747 | * The intended call sequence for WB_SYNC_ALL writeback is: | |
1748 | * | |
1749 | * wb_writeback() | |
1750 | * writeback_sb_inodes() <== called only once | |
1751 | * write_cache_pages() <== called once for each inode | |
1752 | * (quickly) tag currently dirty pages | |
1753 | * (maybe slowly) sync all tagged pages | |
1754 | */ | |
1755 | if (work->sync_mode == WB_SYNC_ALL || work->tagged_writepages) | |
1756 | pages = LONG_MAX; | |
1a12d8bd | 1757 | else { |
a88a341a | 1758 | pages = min(wb->avg_write_bandwidth / 2, |
dcc25ae7 | 1759 | global_wb_domain.dirty_limit / DIRTY_SCOPE); |
1a12d8bd WF |
1760 | pages = min(pages, work->nr_pages); |
1761 | pages = round_down(pages + MIN_WRITEBACK_PAGES, | |
1762 | MIN_WRITEBACK_PAGES); | |
1763 | } | |
d46db3d5 WF |
1764 | |
1765 | return pages; | |
1766 | } | |
1767 | ||
f11c9c5c ES |
1768 | /* |
1769 | * Write a portion of b_io inodes which belong to @sb. | |
edadfb10 | 1770 | * |
d46db3d5 | 1771 | * Return the number of pages and/or inodes written. |
0ba13fd1 LT |
1772 | * |
1773 | * NOTE! This is called with wb->list_lock held, and will | |
1774 | * unlock and relock that for each inode it ends up doing | |
1775 | * IO for. | |
f11c9c5c | 1776 | */ |
d46db3d5 WF |
1777 | static long writeback_sb_inodes(struct super_block *sb, |
1778 | struct bdi_writeback *wb, | |
1779 | struct wb_writeback_work *work) | |
1da177e4 | 1780 | { |
d46db3d5 WF |
1781 | struct writeback_control wbc = { |
1782 | .sync_mode = work->sync_mode, | |
1783 | .tagged_writepages = work->tagged_writepages, | |
1784 | .for_kupdate = work->for_kupdate, | |
1785 | .for_background = work->for_background, | |
7747bd4b | 1786 | .for_sync = work->for_sync, |
d46db3d5 WF |
1787 | .range_cyclic = work->range_cyclic, |
1788 | .range_start = 0, | |
1789 | .range_end = LLONG_MAX, | |
1790 | }; | |
1791 | unsigned long start_time = jiffies; | |
1792 | long write_chunk; | |
68f4c6eb | 1793 | long total_wrote = 0; /* count both pages and inodes */ |
d46db3d5 | 1794 | |
03ba3782 | 1795 | while (!list_empty(&wb->b_io)) { |
7ccf19a8 | 1796 | struct inode *inode = wb_inode(wb->b_io.prev); |
aaf25593 | 1797 | struct bdi_writeback *tmp_wb; |
68f4c6eb | 1798 | long wrote; |
edadfb10 CH |
1799 | |
1800 | if (inode->i_sb != sb) { | |
d46db3d5 | 1801 | if (work->sb) { |
edadfb10 CH |
1802 | /* |
1803 | * We only want to write back data for this | |
1804 | * superblock, move all inodes not belonging | |
1805 | * to it back onto the dirty list. | |
1806 | */ | |
f758eeab | 1807 | redirty_tail(inode, wb); |
edadfb10 CH |
1808 | continue; |
1809 | } | |
1810 | ||
1811 | /* | |
1812 | * The inode belongs to a different superblock. | |
1813 | * Bounce back to the caller to unpin this and | |
1814 | * pin the next superblock. | |
1815 | */ | |
d46db3d5 | 1816 | break; |
edadfb10 CH |
1817 | } |
1818 | ||
9843b76a | 1819 | /* |
331cbdee WL |
1820 | * Don't bother with new inodes or inodes being freed, first |
1821 | * kind does not need periodic writeout yet, and for the latter | |
9843b76a CH |
1822 | * kind writeout is handled by the freer. |
1823 | */ | |
250df6ed | 1824 | spin_lock(&inode->i_lock); |
9843b76a | 1825 | if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { |
b35250c0 | 1826 | redirty_tail_locked(inode, wb); |
250df6ed | 1827 | spin_unlock(&inode->i_lock); |
7ef0d737 NP |
1828 | continue; |
1829 | } | |
cc1676d9 JK |
1830 | if ((inode->i_state & I_SYNC) && wbc.sync_mode != WB_SYNC_ALL) { |
1831 | /* | |
1832 | * If this inode is locked for writeback and we are not | |
1833 | * doing writeback-for-data-integrity, move it to | |
1834 | * b_more_io so that writeback can proceed with the | |
1835 | * other inodes on s_io. | |
1836 | * | |
1837 | * We'll have another go at writing back this inode | |
1838 | * when we completed a full scan of b_io. | |
1839 | */ | |
cc1676d9 | 1840 | requeue_io(inode, wb); |
10e14073 | 1841 | spin_unlock(&inode->i_lock); |
cc1676d9 JK |
1842 | trace_writeback_sb_inodes_requeue(inode); |
1843 | continue; | |
1844 | } | |
f0d07b7f JK |
1845 | spin_unlock(&wb->list_lock); |
1846 | ||
4f8ad655 JK |
1847 | /* |
1848 | * We already requeued the inode if it had I_SYNC set and we | |
1849 | * are doing WB_SYNC_NONE writeback. So this catches only the | |
1850 | * WB_SYNC_ALL case. | |
1851 | */ | |
169ebd90 JK |
1852 | if (inode->i_state & I_SYNC) { |
1853 | /* Wait for I_SYNC. This function drops i_lock... */ | |
1854 | inode_sleep_on_writeback(inode); | |
1855 | /* Inode may be gone, start again */ | |
ead188f9 | 1856 | spin_lock(&wb->list_lock); |
169ebd90 JK |
1857 | continue; |
1858 | } | |
4f8ad655 | 1859 | inode->i_state |= I_SYNC; |
b16b1deb | 1860 | wbc_attach_and_unlock_inode(&wbc, inode); |
169ebd90 | 1861 | |
a88a341a | 1862 | write_chunk = writeback_chunk_size(wb, work); |
d46db3d5 WF |
1863 | wbc.nr_to_write = write_chunk; |
1864 | wbc.pages_skipped = 0; | |
250df6ed | 1865 | |
169ebd90 JK |
1866 | /* |
1867 | * We use I_SYNC to pin the inode in memory. While it is set | |
1868 | * evict_inode() will wait so the inode cannot be freed. | |
1869 | */ | |
cd8ed2a4 | 1870 | __writeback_single_inode(inode, &wbc); |
250df6ed | 1871 | |
b16b1deb | 1872 | wbc_detach_inode(&wbc); |
d46db3d5 | 1873 | work->nr_pages -= write_chunk - wbc.nr_to_write; |
68f4c6eb ZC |
1874 | wrote = write_chunk - wbc.nr_to_write - wbc.pages_skipped; |
1875 | wrote = wrote < 0 ? 0 : wrote; | |
1876 | total_wrote += wrote; | |
590dca3a CM |
1877 | |
1878 | if (need_resched()) { | |
1879 | /* | |
1880 | * We're trying to balance between building up a nice | |
1881 | * long list of IOs to improve our merge rate, and | |
1882 | * getting those IOs out quickly for anyone throttling | |
1883 | * in balance_dirty_pages(). cond_resched() doesn't | |
1884 | * unplug, so get our IOs out the door before we | |
1885 | * give up the CPU. | |
1886 | */ | |
aa8dccca | 1887 | blk_flush_plug(current->plug, false); |
590dca3a CM |
1888 | cond_resched(); |
1889 | } | |
1890 | ||
aaf25593 TH |
1891 | /* |
1892 | * Requeue @inode if still dirty. Be careful as @inode may | |
1893 | * have been switched to another wb in the meantime. | |
1894 | */ | |
1895 | tmp_wb = inode_to_wb_and_lock_list(inode); | |
4f8ad655 | 1896 | spin_lock(&inode->i_lock); |
0ae45f63 | 1897 | if (!(inode->i_state & I_DIRTY_ALL)) |
68f4c6eb | 1898 | total_wrote++; |
aaf25593 | 1899 | requeue_inode(inode, tmp_wb, &wbc); |
4f8ad655 | 1900 | inode_sync_complete(inode); |
0f1b1fd8 | 1901 | spin_unlock(&inode->i_lock); |
590dca3a | 1902 | |
aaf25593 TH |
1903 | if (unlikely(tmp_wb != wb)) { |
1904 | spin_unlock(&tmp_wb->list_lock); | |
1905 | spin_lock(&wb->list_lock); | |
1906 | } | |
1907 | ||
d46db3d5 WF |
1908 | /* |
1909 | * bail out to wb_writeback() often enough to check | |
1910 | * background threshold and other termination conditions. | |
1911 | */ | |
68f4c6eb | 1912 | if (total_wrote) { |
d46db3d5 WF |
1913 | if (time_is_before_jiffies(start_time + HZ / 10UL)) |
1914 | break; | |
1915 | if (work->nr_pages <= 0) | |
1916 | break; | |
8bc3be27 | 1917 | } |
1da177e4 | 1918 | } |
68f4c6eb | 1919 | return total_wrote; |
f11c9c5c ES |
1920 | } |
1921 | ||
d46db3d5 WF |
1922 | static long __writeback_inodes_wb(struct bdi_writeback *wb, |
1923 | struct wb_writeback_work *work) | |
f11c9c5c | 1924 | { |
d46db3d5 WF |
1925 | unsigned long start_time = jiffies; |
1926 | long wrote = 0; | |
38f21977 | 1927 | |
f11c9c5c | 1928 | while (!list_empty(&wb->b_io)) { |
7ccf19a8 | 1929 | struct inode *inode = wb_inode(wb->b_io.prev); |
f11c9c5c | 1930 | struct super_block *sb = inode->i_sb; |
9ecc2738 | 1931 | |
eb6ef3df | 1932 | if (!trylock_super(sb)) { |
0e995816 | 1933 | /* |
eb6ef3df | 1934 | * trylock_super() may fail consistently due to |
0e995816 WF |
1935 | * s_umount being grabbed by someone else. Don't use |
1936 | * requeue_io() to avoid busy retrying the inode/sb. | |
1937 | */ | |
1938 | redirty_tail(inode, wb); | |
edadfb10 | 1939 | continue; |
f11c9c5c | 1940 | } |
d46db3d5 | 1941 | wrote += writeback_sb_inodes(sb, wb, work); |
eb6ef3df | 1942 | up_read(&sb->s_umount); |
f11c9c5c | 1943 | |
d46db3d5 WF |
1944 | /* refer to the same tests at the end of writeback_sb_inodes */ |
1945 | if (wrote) { | |
1946 | if (time_is_before_jiffies(start_time + HZ / 10UL)) | |
1947 | break; | |
1948 | if (work->nr_pages <= 0) | |
1949 | break; | |
1950 | } | |
f11c9c5c | 1951 | } |
66f3b8e2 | 1952 | /* Leave any unwritten inodes on b_io */ |
d46db3d5 | 1953 | return wrote; |
66f3b8e2 JA |
1954 | } |
1955 | ||
7d9f073b | 1956 | static long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, |
0e175a18 | 1957 | enum wb_reason reason) |
edadfb10 | 1958 | { |
d46db3d5 WF |
1959 | struct wb_writeback_work work = { |
1960 | .nr_pages = nr_pages, | |
1961 | .sync_mode = WB_SYNC_NONE, | |
1962 | .range_cyclic = 1, | |
0e175a18 | 1963 | .reason = reason, |
d46db3d5 | 1964 | }; |
505a666e | 1965 | struct blk_plug plug; |
edadfb10 | 1966 | |
505a666e | 1967 | blk_start_plug(&plug); |
f758eeab | 1968 | spin_lock(&wb->list_lock); |
424b351f | 1969 | if (list_empty(&wb->b_io)) |
f9cae926 | 1970 | queue_io(wb, &work, jiffies); |
d46db3d5 | 1971 | __writeback_inodes_wb(wb, &work); |
f758eeab | 1972 | spin_unlock(&wb->list_lock); |
505a666e | 1973 | blk_finish_plug(&plug); |
edadfb10 | 1974 | |
d46db3d5 WF |
1975 | return nr_pages - work.nr_pages; |
1976 | } | |
03ba3782 | 1977 | |
03ba3782 JA |
1978 | /* |
1979 | * Explicit flushing or periodic writeback of "old" data. | |
66f3b8e2 | 1980 | * |
03ba3782 JA |
1981 | * Define "old": the first time one of an inode's pages is dirtied, we mark the |
1982 | * dirtying-time in the inode's address_space. So this periodic writeback code | |
1983 | * just walks the superblock inode list, writing back any inodes which are | |
1984 | * older than a specific point in time. | |
66f3b8e2 | 1985 | * |
03ba3782 JA |
1986 | * Try to run once per dirty_writeback_interval. But if a writeback event |
1987 | * takes longer than a dirty_writeback_interval interval, then leave a | |
1988 | * one-second gap. | |
66f3b8e2 | 1989 | * |
f9cae926 | 1990 | * dirtied_before takes precedence over nr_to_write. So we'll only write back |
03ba3782 | 1991 | * all dirty pages if they are all attached to "old" mappings. |
66f3b8e2 | 1992 | */ |
c4a77a6c | 1993 | static long wb_writeback(struct bdi_writeback *wb, |
83ba7b07 | 1994 | struct wb_writeback_work *work) |
66f3b8e2 | 1995 | { |
d46db3d5 | 1996 | long nr_pages = work->nr_pages; |
f9cae926 | 1997 | unsigned long dirtied_before = jiffies; |
a5989bdc | 1998 | struct inode *inode; |
d46db3d5 | 1999 | long progress; |
505a666e | 2000 | struct blk_plug plug; |
66f3b8e2 | 2001 | |
505a666e | 2002 | blk_start_plug(&plug); |
e8dfc305 | 2003 | spin_lock(&wb->list_lock); |
03ba3782 JA |
2004 | for (;;) { |
2005 | /* | |
d3ddec76 | 2006 | * Stop writeback when nr_pages has been consumed |
03ba3782 | 2007 | */ |
83ba7b07 | 2008 | if (work->nr_pages <= 0) |
03ba3782 | 2009 | break; |
66f3b8e2 | 2010 | |
aa373cf5 JK |
2011 | /* |
2012 | * Background writeout and kupdate-style writeback may | |
2013 | * run forever. Stop them if there is other work to do | |
2014 | * so that e.g. sync can proceed. They'll be restarted | |
2015 | * after the other works are all done. | |
2016 | */ | |
2017 | if ((work->for_background || work->for_kupdate) && | |
f0054bb1 | 2018 | !list_empty(&wb->work_list)) |
aa373cf5 JK |
2019 | break; |
2020 | ||
38f21977 | 2021 | /* |
d3ddec76 WF |
2022 | * For background writeout, stop when we are below the |
2023 | * background dirty threshold | |
38f21977 | 2024 | */ |
aa661bbe | 2025 | if (work->for_background && !wb_over_bg_thresh(wb)) |
03ba3782 | 2026 | break; |
38f21977 | 2027 | |
1bc36b64 JK |
2028 | /* |
2029 | * Kupdate and background works are special and we want to | |
2030 | * include all inodes that need writing. Livelock avoidance is | |
2031 | * handled by these works yielding to any other work so we are | |
2032 | * safe. | |
2033 | */ | |
ba9aa839 | 2034 | if (work->for_kupdate) { |
f9cae926 | 2035 | dirtied_before = jiffies - |
ba9aa839 | 2036 | msecs_to_jiffies(dirty_expire_interval * 10); |
1bc36b64 | 2037 | } else if (work->for_background) |
f9cae926 | 2038 | dirtied_before = jiffies; |
028c2dd1 | 2039 | |
5634cc2a | 2040 | trace_writeback_start(wb, work); |
e8dfc305 | 2041 | if (list_empty(&wb->b_io)) |
f9cae926 | 2042 | queue_io(wb, work, dirtied_before); |
83ba7b07 | 2043 | if (work->sb) |
d46db3d5 | 2044 | progress = writeback_sb_inodes(work->sb, wb, work); |
edadfb10 | 2045 | else |
d46db3d5 | 2046 | progress = __writeback_inodes_wb(wb, work); |
5634cc2a | 2047 | trace_writeback_written(wb, work); |
028c2dd1 | 2048 | |
03ba3782 | 2049 | /* |
e6fb6da2 WF |
2050 | * Did we write something? Try for more |
2051 | * | |
2052 | * Dirty inodes are moved to b_io for writeback in batches. | |
2053 | * The completion of the current batch does not necessarily | |
2054 | * mean the overall work is done. So we keep looping as long | |
2055 | * as made some progress on cleaning pages or inodes. | |
03ba3782 | 2056 | */ |
d46db3d5 | 2057 | if (progress) |
71fd05a8 JA |
2058 | continue; |
2059 | /* | |
e6fb6da2 | 2060 | * No more inodes for IO, bail |
71fd05a8 | 2061 | */ |
b7a2441f | 2062 | if (list_empty(&wb->b_more_io)) |
03ba3782 | 2063 | break; |
71fd05a8 JA |
2064 | /* |
2065 | * Nothing written. Wait for some inode to | |
2066 | * become available for writeback. Otherwise | |
2067 | * we'll just busyloop. | |
2068 | */ | |
bace9248 TE |
2069 | trace_writeback_wait(wb, work); |
2070 | inode = wb_inode(wb->b_more_io.prev); | |
2071 | spin_lock(&inode->i_lock); | |
2072 | spin_unlock(&wb->list_lock); | |
2073 | /* This function drops i_lock... */ | |
2074 | inode_sleep_on_writeback(inode); | |
2075 | spin_lock(&wb->list_lock); | |
03ba3782 | 2076 | } |
e8dfc305 | 2077 | spin_unlock(&wb->list_lock); |
505a666e | 2078 | blk_finish_plug(&plug); |
03ba3782 | 2079 | |
d46db3d5 | 2080 | return nr_pages - work->nr_pages; |
03ba3782 JA |
2081 | } |
2082 | ||
2083 | /* | |
83ba7b07 | 2084 | * Return the next wb_writeback_work struct that hasn't been processed yet. |
03ba3782 | 2085 | */ |
f0054bb1 | 2086 | static struct wb_writeback_work *get_next_work_item(struct bdi_writeback *wb) |
03ba3782 | 2087 | { |
83ba7b07 | 2088 | struct wb_writeback_work *work = NULL; |
03ba3782 | 2089 | |
f87904c0 | 2090 | spin_lock_irq(&wb->work_lock); |
f0054bb1 TH |
2091 | if (!list_empty(&wb->work_list)) { |
2092 | work = list_entry(wb->work_list.next, | |
83ba7b07 CH |
2093 | struct wb_writeback_work, list); |
2094 | list_del_init(&work->list); | |
03ba3782 | 2095 | } |
f87904c0 | 2096 | spin_unlock_irq(&wb->work_lock); |
83ba7b07 | 2097 | return work; |
03ba3782 JA |
2098 | } |
2099 | ||
6585027a JK |
2100 | static long wb_check_background_flush(struct bdi_writeback *wb) |
2101 | { | |
aa661bbe | 2102 | if (wb_over_bg_thresh(wb)) { |
6585027a JK |
2103 | |
2104 | struct wb_writeback_work work = { | |
2105 | .nr_pages = LONG_MAX, | |
2106 | .sync_mode = WB_SYNC_NONE, | |
2107 | .for_background = 1, | |
2108 | .range_cyclic = 1, | |
0e175a18 | 2109 | .reason = WB_REASON_BACKGROUND, |
6585027a JK |
2110 | }; |
2111 | ||
2112 | return wb_writeback(wb, &work); | |
2113 | } | |
2114 | ||
2115 | return 0; | |
2116 | } | |
2117 | ||
03ba3782 JA |
2118 | static long wb_check_old_data_flush(struct bdi_writeback *wb) |
2119 | { | |
2120 | unsigned long expired; | |
2121 | long nr_pages; | |
2122 | ||
69b62d01 JA |
2123 | /* |
2124 | * When set to zero, disable periodic writeback | |
2125 | */ | |
2126 | if (!dirty_writeback_interval) | |
2127 | return 0; | |
2128 | ||
03ba3782 JA |
2129 | expired = wb->last_old_flush + |
2130 | msecs_to_jiffies(dirty_writeback_interval * 10); | |
2131 | if (time_before(jiffies, expired)) | |
2132 | return 0; | |
2133 | ||
2134 | wb->last_old_flush = jiffies; | |
cdf01dd5 | 2135 | nr_pages = get_nr_dirty_pages(); |
03ba3782 | 2136 | |
c4a77a6c | 2137 | if (nr_pages) { |
83ba7b07 | 2138 | struct wb_writeback_work work = { |
c4a77a6c JA |
2139 | .nr_pages = nr_pages, |
2140 | .sync_mode = WB_SYNC_NONE, | |
2141 | .for_kupdate = 1, | |
2142 | .range_cyclic = 1, | |
0e175a18 | 2143 | .reason = WB_REASON_PERIODIC, |
c4a77a6c JA |
2144 | }; |
2145 | ||
83ba7b07 | 2146 | return wb_writeback(wb, &work); |
c4a77a6c | 2147 | } |
03ba3782 JA |
2148 | |
2149 | return 0; | |
2150 | } | |
2151 | ||
85009b4f JA |
2152 | static long wb_check_start_all(struct bdi_writeback *wb) |
2153 | { | |
2154 | long nr_pages; | |
2155 | ||
2156 | if (!test_bit(WB_start_all, &wb->state)) | |
2157 | return 0; | |
2158 | ||
2159 | nr_pages = get_nr_dirty_pages(); | |
2160 | if (nr_pages) { | |
2161 | struct wb_writeback_work work = { | |
2162 | .nr_pages = wb_split_bdi_pages(wb, nr_pages), | |
2163 | .sync_mode = WB_SYNC_NONE, | |
2164 | .range_cyclic = 1, | |
2165 | .reason = wb->start_all_reason, | |
2166 | }; | |
2167 | ||
2168 | nr_pages = wb_writeback(wb, &work); | |
2169 | } | |
2170 | ||
2171 | clear_bit(WB_start_all, &wb->state); | |
2172 | return nr_pages; | |
2173 | } | |
2174 | ||
2175 | ||
03ba3782 JA |
2176 | /* |
2177 | * Retrieve work items and do the writeback they describe | |
2178 | */ | |
25d130ba | 2179 | static long wb_do_writeback(struct bdi_writeback *wb) |
03ba3782 | 2180 | { |
83ba7b07 | 2181 | struct wb_writeback_work *work; |
c4a77a6c | 2182 | long wrote = 0; |
03ba3782 | 2183 | |
4452226e | 2184 | set_bit(WB_writeback_running, &wb->state); |
f0054bb1 | 2185 | while ((work = get_next_work_item(wb)) != NULL) { |
5634cc2a | 2186 | trace_writeback_exec(wb, work); |
83ba7b07 | 2187 | wrote += wb_writeback(wb, work); |
4a3a485b | 2188 | finish_writeback_work(wb, work); |
03ba3782 JA |
2189 | } |
2190 | ||
85009b4f JA |
2191 | /* |
2192 | * Check for a flush-everything request | |
2193 | */ | |
2194 | wrote += wb_check_start_all(wb); | |
2195 | ||
03ba3782 JA |
2196 | /* |
2197 | * Check for periodic writeback, kupdated() style | |
2198 | */ | |
2199 | wrote += wb_check_old_data_flush(wb); | |
6585027a | 2200 | wrote += wb_check_background_flush(wb); |
4452226e | 2201 | clear_bit(WB_writeback_running, &wb->state); |
03ba3782 JA |
2202 | |
2203 | return wrote; | |
2204 | } | |
2205 | ||
2206 | /* | |
2207 | * Handle writeback of dirty data for the device backed by this bdi. Also | |
839a8e86 | 2208 | * reschedules periodically and does kupdated style flushing. |
03ba3782 | 2209 | */ |
f0054bb1 | 2210 | void wb_workfn(struct work_struct *work) |
03ba3782 | 2211 | { |
839a8e86 TH |
2212 | struct bdi_writeback *wb = container_of(to_delayed_work(work), |
2213 | struct bdi_writeback, dwork); | |
03ba3782 JA |
2214 | long pages_written; |
2215 | ||
68f23b89 | 2216 | set_worker_desc("flush-%s", bdi_dev_name(wb->bdi)); |
455b2864 | 2217 | |
839a8e86 | 2218 | if (likely(!current_is_workqueue_rescuer() || |
4452226e | 2219 | !test_bit(WB_registered, &wb->state))) { |
6467716a | 2220 | /* |
f0054bb1 | 2221 | * The normal path. Keep writing back @wb until its |
839a8e86 | 2222 | * work_list is empty. Note that this path is also taken |
f0054bb1 | 2223 | * if @wb is shutting down even when we're running off the |
839a8e86 | 2224 | * rescuer as work_list needs to be drained. |
6467716a | 2225 | */ |
839a8e86 | 2226 | do { |
25d130ba | 2227 | pages_written = wb_do_writeback(wb); |
839a8e86 | 2228 | trace_writeback_pages_written(pages_written); |
f0054bb1 | 2229 | } while (!list_empty(&wb->work_list)); |
839a8e86 TH |
2230 | } else { |
2231 | /* | |
2232 | * bdi_wq can't get enough workers and we're running off | |
2233 | * the emergency worker. Don't hog it. Hopefully, 1024 is | |
2234 | * enough for efficient IO. | |
2235 | */ | |
f0054bb1 | 2236 | pages_written = writeback_inodes_wb(wb, 1024, |
839a8e86 | 2237 | WB_REASON_FORKER_THREAD); |
455b2864 | 2238 | trace_writeback_pages_written(pages_written); |
03ba3782 JA |
2239 | } |
2240 | ||
f0054bb1 | 2241 | if (!list_empty(&wb->work_list)) |
b8b78495 | 2242 | wb_wakeup(wb); |
6ca738d6 | 2243 | else if (wb_has_dirty_io(wb) && dirty_writeback_interval) |
f0054bb1 | 2244 | wb_wakeup_delayed(wb); |
03ba3782 JA |
2245 | } |
2246 | ||
595043e5 JA |
2247 | /* |
2248 | * Start writeback of `nr_pages' pages on this bdi. If `nr_pages' is zero, | |
2249 | * write back the whole world. | |
2250 | */ | |
2251 | static void __wakeup_flusher_threads_bdi(struct backing_dev_info *bdi, | |
e8e8a0c6 | 2252 | enum wb_reason reason) |
595043e5 JA |
2253 | { |
2254 | struct bdi_writeback *wb; | |
2255 | ||
2256 | if (!bdi_has_dirty_io(bdi)) | |
2257 | return; | |
2258 | ||
2259 | list_for_each_entry_rcu(wb, &bdi->wb_list, bdi_node) | |
e8e8a0c6 | 2260 | wb_start_writeback(wb, reason); |
595043e5 JA |
2261 | } |
2262 | ||
2263 | void wakeup_flusher_threads_bdi(struct backing_dev_info *bdi, | |
2264 | enum wb_reason reason) | |
2265 | { | |
595043e5 | 2266 | rcu_read_lock(); |
e8e8a0c6 | 2267 | __wakeup_flusher_threads_bdi(bdi, reason); |
595043e5 JA |
2268 | rcu_read_unlock(); |
2269 | } | |
2270 | ||
03ba3782 | 2271 | /* |
9ba4b2df | 2272 | * Wakeup the flusher threads to start writeback of all currently dirty pages |
03ba3782 | 2273 | */ |
9ba4b2df | 2274 | void wakeup_flusher_threads(enum wb_reason reason) |
03ba3782 | 2275 | { |
b8c2f347 | 2276 | struct backing_dev_info *bdi; |
03ba3782 | 2277 | |
51350ea0 KK |
2278 | /* |
2279 | * If we are expecting writeback progress we must submit plugged IO. | |
2280 | */ | |
aa8dccca | 2281 | blk_flush_plug(current->plug, true); |
51350ea0 | 2282 | |
b8c2f347 | 2283 | rcu_read_lock(); |
595043e5 | 2284 | list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) |
e8e8a0c6 | 2285 | __wakeup_flusher_threads_bdi(bdi, reason); |
cfc4ba53 | 2286 | rcu_read_unlock(); |
1da177e4 LT |
2287 | } |
2288 | ||
a2f48706 TT |
2289 | /* |
2290 | * Wake up bdi's periodically to make sure dirtytime inodes gets | |
2291 | * written back periodically. We deliberately do *not* check the | |
2292 | * b_dirtytime list in wb_has_dirty_io(), since this would cause the | |
2293 | * kernel to be constantly waking up once there are any dirtytime | |
2294 | * inodes on the system. So instead we define a separate delayed work | |
2295 | * function which gets called much more rarely. (By default, only | |
2296 | * once every 12 hours.) | |
2297 | * | |
2298 | * If there is any other write activity going on in the file system, | |
2299 | * this function won't be necessary. But if the only thing that has | |
2300 | * happened on the file system is a dirtytime inode caused by an atime | |
2301 | * update, we need this infrastructure below to make sure that inode | |
2302 | * eventually gets pushed out to disk. | |
2303 | */ | |
2304 | static void wakeup_dirtytime_writeback(struct work_struct *w); | |
2305 | static DECLARE_DELAYED_WORK(dirtytime_work, wakeup_dirtytime_writeback); | |
2306 | ||
2307 | static void wakeup_dirtytime_writeback(struct work_struct *w) | |
2308 | { | |
2309 | struct backing_dev_info *bdi; | |
2310 | ||
2311 | rcu_read_lock(); | |
2312 | list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { | |
001fe6f6 | 2313 | struct bdi_writeback *wb; |
001fe6f6 | 2314 | |
b817525a | 2315 | list_for_each_entry_rcu(wb, &bdi->wb_list, bdi_node) |
6fdf860f TH |
2316 | if (!list_empty(&wb->b_dirty_time)) |
2317 | wb_wakeup(wb); | |
a2f48706 TT |
2318 | } |
2319 | rcu_read_unlock(); | |
2320 | schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ); | |
2321 | } | |
2322 | ||
2323 | static int __init start_dirtytime_writeback(void) | |
2324 | { | |
2325 | schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ); | |
2326 | return 0; | |
2327 | } | |
2328 | __initcall(start_dirtytime_writeback); | |
2329 | ||
1efff914 | 2330 | int dirtytime_interval_handler(struct ctl_table *table, int write, |
9ca48e20 | 2331 | void *buffer, size_t *lenp, loff_t *ppos) |
1efff914 TT |
2332 | { |
2333 | int ret; | |
2334 | ||
2335 | ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); | |
2336 | if (ret == 0 && write) | |
2337 | mod_delayed_work(system_wq, &dirtytime_work, 0); | |
2338 | return ret; | |
2339 | } | |
2340 | ||
03ba3782 | 2341 | /** |
35d14f27 | 2342 | * __mark_inode_dirty - internal function to mark an inode dirty |
0117d427 MCC |
2343 | * |
2344 | * @inode: inode to mark | |
35d14f27 EB |
2345 | * @flags: what kind of dirty, e.g. I_DIRTY_SYNC. This can be a combination of |
2346 | * multiple I_DIRTY_* flags, except that I_DIRTY_TIME can't be combined | |
2347 | * with I_DIRTY_PAGES. | |
0117d427 | 2348 | * |
35d14f27 EB |
2349 | * Mark an inode as dirty. We notify the filesystem, then update the inode's |
2350 | * dirty flags. Then, if needed we add the inode to the appropriate dirty list. | |
1da177e4 | 2351 | * |
35d14f27 EB |
2352 | * Most callers should use mark_inode_dirty() or mark_inode_dirty_sync() |
2353 | * instead of calling this directly. | |
03ba3782 | 2354 | * |
35d14f27 EB |
2355 | * CAREFUL! We only add the inode to the dirty list if it is hashed or if it |
2356 | * refers to a blockdev. Unhashed inodes will never be added to the dirty list | |
2357 | * even if they are later hashed, as they will have been marked dirty already. | |
03ba3782 | 2358 | * |
35d14f27 | 2359 | * In short, ensure you hash any inodes _before_ you start marking them dirty. |
1da177e4 | 2360 | * |
03ba3782 JA |
2361 | * Note that for blockdevs, inode->dirtied_when represents the dirtying time of |
2362 | * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of | |
2363 | * the kernel-internal blockdev inode represents the dirtying time of the | |
2364 | * blockdev's pages. This is why for I_DIRTY_PAGES we always use | |
2365 | * page->mapping->host, so the page-dirtying time is recorded in the internal | |
2366 | * blockdev inode. | |
1da177e4 | 2367 | */ |
03ba3782 | 2368 | void __mark_inode_dirty(struct inode *inode, int flags) |
1da177e4 | 2369 | { |
03ba3782 | 2370 | struct super_block *sb = inode->i_sb; |
35d14f27 | 2371 | int dirtytime = 0; |
10e14073 | 2372 | struct bdi_writeback *wb = NULL; |
0ae45f63 TT |
2373 | |
2374 | trace_writeback_mark_inode_dirty(inode, flags); | |
1da177e4 | 2375 | |
e2728c56 | 2376 | if (flags & I_DIRTY_INODE) { |
cbfecb92 LC |
2377 | /* |
2378 | * Inode timestamp update will piggback on this dirtying. | |
2379 | * We tell ->dirty_inode callback that timestamps need to | |
2380 | * be updated by setting I_DIRTY_TIME in flags. | |
2381 | */ | |
2382 | if (inode->i_state & I_DIRTY_TIME) { | |
2383 | spin_lock(&inode->i_lock); | |
2384 | if (inode->i_state & I_DIRTY_TIME) { | |
2385 | inode->i_state &= ~I_DIRTY_TIME; | |
2386 | flags |= I_DIRTY_TIME; | |
2387 | } | |
2388 | spin_unlock(&inode->i_lock); | |
2389 | } | |
2390 | ||
35d14f27 EB |
2391 | /* |
2392 | * Notify the filesystem about the inode being dirtied, so that | |
2393 | * (if needed) it can update on-disk fields and journal the | |
2394 | * inode. This is only needed when the inode itself is being | |
2395 | * dirtied now. I.e. it's only needed for I_DIRTY_INODE, not | |
2396 | * for just I_DIRTY_PAGES or I_DIRTY_TIME. | |
2397 | */ | |
9fb0a7da | 2398 | trace_writeback_dirty_inode_start(inode, flags); |
03ba3782 | 2399 | if (sb->s_op->dirty_inode) |
cbfecb92 LC |
2400 | sb->s_op->dirty_inode(inode, |
2401 | flags & (I_DIRTY_INODE | I_DIRTY_TIME)); | |
9fb0a7da | 2402 | trace_writeback_dirty_inode(inode, flags); |
e2728c56 | 2403 | |
35d14f27 | 2404 | /* I_DIRTY_INODE supersedes I_DIRTY_TIME. */ |
0ae45f63 | 2405 | flags &= ~I_DIRTY_TIME; |
35d14f27 EB |
2406 | } else { |
2407 | /* | |
2408 | * Else it's either I_DIRTY_PAGES, I_DIRTY_TIME, or nothing. | |
2409 | * (We don't support setting both I_DIRTY_PAGES and I_DIRTY_TIME | |
2410 | * in one call to __mark_inode_dirty().) | |
2411 | */ | |
2412 | dirtytime = flags & I_DIRTY_TIME; | |
2413 | WARN_ON_ONCE(dirtytime && flags != I_DIRTY_TIME); | |
e2728c56 | 2414 | } |
03ba3782 JA |
2415 | |
2416 | /* | |
9c6ac78e TH |
2417 | * Paired with smp_mb() in __writeback_single_inode() for the |
2418 | * following lockless i_state test. See there for details. | |
03ba3782 JA |
2419 | */ |
2420 | smp_mb(); | |
2421 | ||
cbfecb92 | 2422 | if ((inode->i_state & flags) == flags) |
03ba3782 JA |
2423 | return; |
2424 | ||
250df6ed | 2425 | spin_lock(&inode->i_lock); |
03ba3782 JA |
2426 | if ((inode->i_state & flags) != flags) { |
2427 | const int was_dirty = inode->i_state & I_DIRTY; | |
2428 | ||
52ebea74 TH |
2429 | inode_attach_wb(inode, NULL); |
2430 | ||
03ba3782 JA |
2431 | inode->i_state |= flags; |
2432 | ||
10e14073 JS |
2433 | /* |
2434 | * Grab inode's wb early because it requires dropping i_lock and we | |
2435 | * need to make sure following checks happen atomically with dirty | |
2436 | * list handling so that we don't move inodes under flush worker's | |
2437 | * hands. | |
2438 | */ | |
2439 | if (!was_dirty) { | |
2440 | wb = locked_inode_to_wb_and_lock_list(inode); | |
2441 | spin_lock(&inode->i_lock); | |
2442 | } | |
2443 | ||
03ba3782 | 2444 | /* |
5afced3b JK |
2445 | * If the inode is queued for writeback by flush worker, just |
2446 | * update its dirty state. Once the flush worker is done with | |
2447 | * the inode it will place it on the appropriate superblock | |
2448 | * list, based upon its state. | |
03ba3782 | 2449 | */ |
5afced3b | 2450 | if (inode->i_state & I_SYNC_QUEUED) |
10e14073 | 2451 | goto out_unlock; |
03ba3782 JA |
2452 | |
2453 | /* | |
2454 | * Only add valid (hashed) inodes to the superblock's | |
2455 | * dirty list. Add blockdev inodes as well. | |
2456 | */ | |
2457 | if (!S_ISBLK(inode->i_mode)) { | |
1d3382cb | 2458 | if (inode_unhashed(inode)) |
10e14073 | 2459 | goto out_unlock; |
03ba3782 | 2460 | } |
a4ffdde6 | 2461 | if (inode->i_state & I_FREEING) |
10e14073 | 2462 | goto out_unlock; |
03ba3782 JA |
2463 | |
2464 | /* | |
2465 | * If the inode was already on b_dirty/b_io/b_more_io, don't | |
2466 | * reposition it (that would break b_dirty time-ordering). | |
2467 | */ | |
2468 | if (!was_dirty) { | |
d6c10f1f | 2469 | struct list_head *dirty_list; |
a66979ab | 2470 | bool wakeup_bdi = false; |
253c34e9 | 2471 | |
03ba3782 | 2472 | inode->dirtied_when = jiffies; |
a2f48706 TT |
2473 | if (dirtytime) |
2474 | inode->dirtied_time_when = jiffies; | |
d6c10f1f | 2475 | |
0e11f644 | 2476 | if (inode->i_state & I_DIRTY) |
0747259d | 2477 | dirty_list = &wb->b_dirty; |
a2f48706 | 2478 | else |
0747259d | 2479 | dirty_list = &wb->b_dirty_time; |
d6c10f1f | 2480 | |
c7f54084 | 2481 | wakeup_bdi = inode_io_list_move_locked(inode, wb, |
d6c10f1f TH |
2482 | dirty_list); |
2483 | ||
0747259d | 2484 | spin_unlock(&wb->list_lock); |
10e14073 | 2485 | spin_unlock(&inode->i_lock); |
0ae45f63 | 2486 | trace_writeback_dirty_inode_enqueue(inode); |
a66979ab | 2487 | |
d6c10f1f TH |
2488 | /* |
2489 | * If this is the first dirty inode for this bdi, | |
2490 | * we have to wake-up the corresponding bdi thread | |
2491 | * to make sure background write-back happens | |
2492 | * later. | |
2493 | */ | |
f56753ac CH |
2494 | if (wakeup_bdi && |
2495 | (wb->bdi->capabilities & BDI_CAP_WRITEBACK)) | |
0747259d | 2496 | wb_wakeup_delayed(wb); |
a66979ab | 2497 | return; |
1da177e4 | 2498 | } |
1da177e4 | 2499 | } |
10e14073 JS |
2500 | out_unlock: |
2501 | if (wb) | |
2502 | spin_unlock(&wb->list_lock); | |
250df6ed | 2503 | spin_unlock(&inode->i_lock); |
03ba3782 JA |
2504 | } |
2505 | EXPORT_SYMBOL(__mark_inode_dirty); | |
2506 | ||
e97fedb9 DC |
2507 | /* |
2508 | * The @s_sync_lock is used to serialise concurrent sync operations | |
2509 | * to avoid lock contention problems with concurrent wait_sb_inodes() calls. | |
2510 | * Concurrent callers will block on the s_sync_lock rather than doing contending | |
2511 | * walks. The queueing maintains sync(2) required behaviour as all the IO that | |
2512 | * has been issued up to the time this function is enter is guaranteed to be | |
2513 | * completed by the time we have gained the lock and waited for all IO that is | |
2514 | * in progress regardless of the order callers are granted the lock. | |
2515 | */ | |
b6e51316 | 2516 | static void wait_sb_inodes(struct super_block *sb) |
03ba3782 | 2517 | { |
6c60d2b5 | 2518 | LIST_HEAD(sync_list); |
03ba3782 JA |
2519 | |
2520 | /* | |
2521 | * We need to be protected against the filesystem going from | |
2522 | * r/o to r/w or vice versa. | |
2523 | */ | |
b6e51316 | 2524 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
03ba3782 | 2525 | |
e97fedb9 | 2526 | mutex_lock(&sb->s_sync_lock); |
03ba3782 JA |
2527 | |
2528 | /* | |
6c60d2b5 DC |
2529 | * Splice the writeback list onto a temporary list to avoid waiting on |
2530 | * inodes that have started writeback after this point. | |
2531 | * | |
2532 | * Use rcu_read_lock() to keep the inodes around until we have a | |
2533 | * reference. s_inode_wblist_lock protects sb->s_inodes_wb as well as | |
2534 | * the local list because inodes can be dropped from either by writeback | |
2535 | * completion. | |
2536 | */ | |
2537 | rcu_read_lock(); | |
2538 | spin_lock_irq(&sb->s_inode_wblist_lock); | |
2539 | list_splice_init(&sb->s_inodes_wb, &sync_list); | |
2540 | ||
2541 | /* | |
2542 | * Data integrity sync. Must wait for all pages under writeback, because | |
2543 | * there may have been pages dirtied before our sync call, but which had | |
2544 | * writeout started before we write it out. In which case, the inode | |
2545 | * may not be on the dirty list, but we still have to wait for that | |
2546 | * writeout. | |
03ba3782 | 2547 | */ |
6c60d2b5 DC |
2548 | while (!list_empty(&sync_list)) { |
2549 | struct inode *inode = list_first_entry(&sync_list, struct inode, | |
2550 | i_wb_list); | |
250df6ed | 2551 | struct address_space *mapping = inode->i_mapping; |
03ba3782 | 2552 | |
6c60d2b5 DC |
2553 | /* |
2554 | * Move each inode back to the wb list before we drop the lock | |
2555 | * to preserve consistency between i_wb_list and the mapping | |
2556 | * writeback tag. Writeback completion is responsible to remove | |
2557 | * the inode from either list once the writeback tag is cleared. | |
2558 | */ | |
2559 | list_move_tail(&inode->i_wb_list, &sb->s_inodes_wb); | |
2560 | ||
2561 | /* | |
2562 | * The mapping can appear untagged while still on-list since we | |
2563 | * do not have the mapping lock. Skip it here, wb completion | |
2564 | * will remove it. | |
2565 | */ | |
2566 | if (!mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK)) | |
2567 | continue; | |
2568 | ||
2569 | spin_unlock_irq(&sb->s_inode_wblist_lock); | |
2570 | ||
250df6ed | 2571 | spin_lock(&inode->i_lock); |
6c60d2b5 | 2572 | if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) { |
250df6ed | 2573 | spin_unlock(&inode->i_lock); |
6c60d2b5 DC |
2574 | |
2575 | spin_lock_irq(&sb->s_inode_wblist_lock); | |
03ba3782 | 2576 | continue; |
250df6ed | 2577 | } |
03ba3782 | 2578 | __iget(inode); |
250df6ed | 2579 | spin_unlock(&inode->i_lock); |
6c60d2b5 | 2580 | rcu_read_unlock(); |
03ba3782 | 2581 | |
aa750fd7 JN |
2582 | /* |
2583 | * We keep the error status of individual mapping so that | |
2584 | * applications can catch the writeback error using fsync(2). | |
2585 | * See filemap_fdatawait_keep_errors() for details. | |
2586 | */ | |
2587 | filemap_fdatawait_keep_errors(mapping); | |
03ba3782 JA |
2588 | |
2589 | cond_resched(); | |
2590 | ||
6c60d2b5 DC |
2591 | iput(inode); |
2592 | ||
2593 | rcu_read_lock(); | |
2594 | spin_lock_irq(&sb->s_inode_wblist_lock); | |
03ba3782 | 2595 | } |
6c60d2b5 DC |
2596 | spin_unlock_irq(&sb->s_inode_wblist_lock); |
2597 | rcu_read_unlock(); | |
e97fedb9 | 2598 | mutex_unlock(&sb->s_sync_lock); |
1da177e4 LT |
2599 | } |
2600 | ||
f30a7d0c TH |
2601 | static void __writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr, |
2602 | enum wb_reason reason, bool skip_if_busy) | |
1da177e4 | 2603 | { |
5b9cce4c TH |
2604 | struct backing_dev_info *bdi = sb->s_bdi; |
2605 | DEFINE_WB_COMPLETION(done, bdi); | |
83ba7b07 | 2606 | struct wb_writeback_work work = { |
6e6938b6 WF |
2607 | .sb = sb, |
2608 | .sync_mode = WB_SYNC_NONE, | |
2609 | .tagged_writepages = 1, | |
2610 | .done = &done, | |
2611 | .nr_pages = nr, | |
0e175a18 | 2612 | .reason = reason, |
3c4d7165 | 2613 | }; |
d8a8559c | 2614 | |
e7972912 | 2615 | if (!bdi_has_dirty_io(bdi) || bdi == &noop_backing_dev_info) |
6eedc701 | 2616 | return; |
cf37e972 | 2617 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
f30a7d0c | 2618 | |
db125360 | 2619 | bdi_split_work_to_wbs(sb->s_bdi, &work, skip_if_busy); |
5b9cce4c | 2620 | wb_wait_for_completion(&done); |
e913fc82 | 2621 | } |
f30a7d0c TH |
2622 | |
2623 | /** | |
2624 | * writeback_inodes_sb_nr - writeback dirty inodes from given super_block | |
2625 | * @sb: the superblock | |
2626 | * @nr: the number of pages to write | |
2627 | * @reason: reason why some writeback work initiated | |
2628 | * | |
2629 | * Start writeback on some inodes on this super_block. No guarantees are made | |
2630 | * on how many (if any) will be written, and this function does not wait | |
2631 | * for IO completion of submitted IO. | |
2632 | */ | |
2633 | void writeback_inodes_sb_nr(struct super_block *sb, | |
2634 | unsigned long nr, | |
2635 | enum wb_reason reason) | |
2636 | { | |
2637 | __writeback_inodes_sb_nr(sb, nr, reason, false); | |
2638 | } | |
3259f8be CM |
2639 | EXPORT_SYMBOL(writeback_inodes_sb_nr); |
2640 | ||
2641 | /** | |
2642 | * writeback_inodes_sb - writeback dirty inodes from given super_block | |
2643 | * @sb: the superblock | |
786228ab | 2644 | * @reason: reason why some writeback work was initiated |
3259f8be CM |
2645 | * |
2646 | * Start writeback on some inodes on this super_block. No guarantees are made | |
2647 | * on how many (if any) will be written, and this function does not wait | |
2648 | * for IO completion of submitted IO. | |
2649 | */ | |
0e175a18 | 2650 | void writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) |
3259f8be | 2651 | { |
0e175a18 | 2652 | return writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); |
3259f8be | 2653 | } |
0e3c9a22 | 2654 | EXPORT_SYMBOL(writeback_inodes_sb); |
e913fc82 | 2655 | |
17bd55d0 | 2656 | /** |
8264c321 | 2657 | * try_to_writeback_inodes_sb - try to start writeback if none underway |
17bd55d0 | 2658 | * @sb: the superblock |
8264c321 | 2659 | * @reason: reason why some writeback work was initiated |
17bd55d0 | 2660 | * |
8264c321 | 2661 | * Invoke __writeback_inodes_sb_nr if no writeback is currently underway. |
17bd55d0 | 2662 | */ |
8264c321 | 2663 | void try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) |
17bd55d0 | 2664 | { |
10ee27a0 | 2665 | if (!down_read_trylock(&sb->s_umount)) |
8264c321 | 2666 | return; |
10ee27a0 | 2667 | |
8264c321 | 2668 | __writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason, true); |
10ee27a0 | 2669 | up_read(&sb->s_umount); |
3259f8be | 2670 | } |
10ee27a0 | 2671 | EXPORT_SYMBOL(try_to_writeback_inodes_sb); |
3259f8be | 2672 | |
d8a8559c JA |
2673 | /** |
2674 | * sync_inodes_sb - sync sb inode pages | |
0dc83bd3 | 2675 | * @sb: the superblock |
d8a8559c JA |
2676 | * |
2677 | * This function writes and waits on any dirty inode belonging to this | |
0dc83bd3 | 2678 | * super_block. |
d8a8559c | 2679 | */ |
0dc83bd3 | 2680 | void sync_inodes_sb(struct super_block *sb) |
d8a8559c | 2681 | { |
5b9cce4c TH |
2682 | struct backing_dev_info *bdi = sb->s_bdi; |
2683 | DEFINE_WB_COMPLETION(done, bdi); | |
83ba7b07 | 2684 | struct wb_writeback_work work = { |
3c4d7165 CH |
2685 | .sb = sb, |
2686 | .sync_mode = WB_SYNC_ALL, | |
2687 | .nr_pages = LONG_MAX, | |
2688 | .range_cyclic = 0, | |
83ba7b07 | 2689 | .done = &done, |
0e175a18 | 2690 | .reason = WB_REASON_SYNC, |
7747bd4b | 2691 | .for_sync = 1, |
3c4d7165 CH |
2692 | }; |
2693 | ||
006a0973 TH |
2694 | /* |
2695 | * Can't skip on !bdi_has_dirty() because we should wait for !dirty | |
2696 | * inodes under writeback and I_DIRTY_TIME inodes ignored by | |
2697 | * bdi_has_dirty() need to be written out too. | |
2698 | */ | |
2699 | if (bdi == &noop_backing_dev_info) | |
6eedc701 | 2700 | return; |
cf37e972 CH |
2701 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
2702 | ||
7fc5854f TH |
2703 | /* protect against inode wb switch, see inode_switch_wbs_work_fn() */ |
2704 | bdi_down_write_wb_switch_rwsem(bdi); | |
db125360 | 2705 | bdi_split_work_to_wbs(bdi, &work, false); |
5b9cce4c | 2706 | wb_wait_for_completion(&done); |
7fc5854f | 2707 | bdi_up_write_wb_switch_rwsem(bdi); |
83ba7b07 | 2708 | |
b6e51316 | 2709 | wait_sb_inodes(sb); |
1da177e4 | 2710 | } |
d8a8559c | 2711 | EXPORT_SYMBOL(sync_inodes_sb); |
1da177e4 | 2712 | |
1da177e4 | 2713 | /** |
7f04c26d AA |
2714 | * write_inode_now - write an inode to disk |
2715 | * @inode: inode to write to disk | |
2716 | * @sync: whether the write should be synchronous or not | |
2717 | * | |
2718 | * This function commits an inode to disk immediately if it is dirty. This is | |
2719 | * primarily needed by knfsd. | |
1da177e4 | 2720 | * |
7f04c26d | 2721 | * The caller must either have a ref on the inode or must have set I_WILL_FREE. |
1da177e4 | 2722 | */ |
1da177e4 LT |
2723 | int write_inode_now(struct inode *inode, int sync) |
2724 | { | |
1da177e4 LT |
2725 | struct writeback_control wbc = { |
2726 | .nr_to_write = LONG_MAX, | |
18914b18 | 2727 | .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, |
111ebb6e OH |
2728 | .range_start = 0, |
2729 | .range_end = LLONG_MAX, | |
1da177e4 LT |
2730 | }; |
2731 | ||
f56753ac | 2732 | if (!mapping_can_writeback(inode->i_mapping)) |
49364ce2 | 2733 | wbc.nr_to_write = 0; |
1da177e4 LT |
2734 | |
2735 | might_sleep(); | |
aaf25593 | 2736 | return writeback_single_inode(inode, &wbc); |
1da177e4 LT |
2737 | } |
2738 | EXPORT_SYMBOL(write_inode_now); | |
2739 | ||
c3765016 | 2740 | /** |
c691b9d9 | 2741 | * sync_inode_metadata - write an inode to disk |
c3765016 CH |
2742 | * @inode: the inode to sync |
2743 | * @wait: wait for I/O to complete. | |
2744 | * | |
c691b9d9 | 2745 | * Write an inode to disk and adjust its dirty state after completion. |
c3765016 CH |
2746 | * |
2747 | * Note: only writes the actual inode, no associated data or other metadata. | |
2748 | */ | |
2749 | int sync_inode_metadata(struct inode *inode, int wait) | |
2750 | { | |
2751 | struct writeback_control wbc = { | |
2752 | .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_NONE, | |
2753 | .nr_to_write = 0, /* metadata-only */ | |
2754 | }; | |
2755 | ||
5662c967 | 2756 | return writeback_single_inode(inode, &wbc); |
c3765016 CH |
2757 | } |
2758 | EXPORT_SYMBOL(sync_inode_metadata); |