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1da177e4 LT |
1 | /* |
2 | * fs/fs-writeback.c | |
3 | * | |
4 | * Copyright (C) 2002, Linus Torvalds. | |
5 | * | |
6 | * Contains all the functions related to writing back and waiting | |
7 | * upon dirty inodes against superblocks, and writing back dirty | |
8 | * pages against inodes. ie: data writeback. Writeout of the | |
9 | * inode itself is not handled here. | |
10 | * | |
e1f8e874 | 11 | * 10Apr2002 Andrew Morton |
1da177e4 LT |
12 | * Split out of fs/inode.c |
13 | * Additions for address_space-based writeback | |
14 | */ | |
15 | ||
16 | #include <linux/kernel.h> | |
630d9c47 | 17 | #include <linux/export.h> |
1da177e4 | 18 | #include <linux/spinlock.h> |
5a0e3ad6 | 19 | #include <linux/slab.h> |
1da177e4 LT |
20 | #include <linux/sched.h> |
21 | #include <linux/fs.h> | |
22 | #include <linux/mm.h> | |
bc31b86a | 23 | #include <linux/pagemap.h> |
03ba3782 | 24 | #include <linux/kthread.h> |
1da177e4 LT |
25 | #include <linux/writeback.h> |
26 | #include <linux/blkdev.h> | |
27 | #include <linux/backing-dev.h> | |
455b2864 | 28 | #include <linux/tracepoint.h> |
719ea2fb | 29 | #include <linux/device.h> |
21c6321f | 30 | #include <linux/memcontrol.h> |
07f3f05c | 31 | #include "internal.h" |
1da177e4 | 32 | |
bc31b86a WF |
33 | /* |
34 | * 4MB minimal write chunk size | |
35 | */ | |
36 | #define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_CACHE_SHIFT - 10)) | |
37 | ||
cc395d7f TH |
38 | struct wb_completion { |
39 | atomic_t cnt; | |
40 | }; | |
41 | ||
c4a77a6c JA |
42 | /* |
43 | * Passed into wb_writeback(), essentially a subset of writeback_control | |
44 | */ | |
83ba7b07 | 45 | struct wb_writeback_work { |
c4a77a6c JA |
46 | long nr_pages; |
47 | struct super_block *sb; | |
0dc83bd3 | 48 | unsigned long *older_than_this; |
c4a77a6c | 49 | enum writeback_sync_modes sync_mode; |
6e6938b6 | 50 | unsigned int tagged_writepages:1; |
52957fe1 HS |
51 | unsigned int for_kupdate:1; |
52 | unsigned int range_cyclic:1; | |
53 | unsigned int for_background:1; | |
7747bd4b | 54 | unsigned int for_sync:1; /* sync(2) WB_SYNC_ALL writeback */ |
ac7b19a3 | 55 | unsigned int auto_free:1; /* free on completion */ |
98754bf7 TH |
56 | unsigned int single_wait:1; |
57 | unsigned int single_done:1; | |
0e175a18 | 58 | enum wb_reason reason; /* why was writeback initiated? */ |
c4a77a6c | 59 | |
8010c3b6 | 60 | struct list_head list; /* pending work list */ |
cc395d7f | 61 | struct wb_completion *done; /* set if the caller waits */ |
03ba3782 JA |
62 | }; |
63 | ||
cc395d7f TH |
64 | /* |
65 | * If one wants to wait for one or more wb_writeback_works, each work's | |
66 | * ->done should be set to a wb_completion defined using the following | |
67 | * macro. Once all work items are issued with wb_queue_work(), the caller | |
68 | * can wait for the completion of all using wb_wait_for_completion(). Work | |
69 | * items which are waited upon aren't freed automatically on completion. | |
70 | */ | |
71 | #define DEFINE_WB_COMPLETION_ONSTACK(cmpl) \ | |
72 | struct wb_completion cmpl = { \ | |
73 | .cnt = ATOMIC_INIT(1), \ | |
74 | } | |
75 | ||
76 | ||
a2f48706 TT |
77 | /* |
78 | * If an inode is constantly having its pages dirtied, but then the | |
79 | * updates stop dirtytime_expire_interval seconds in the past, it's | |
80 | * possible for the worst case time between when an inode has its | |
81 | * timestamps updated and when they finally get written out to be two | |
82 | * dirtytime_expire_intervals. We set the default to 12 hours (in | |
83 | * seconds), which means most of the time inodes will have their | |
84 | * timestamps written to disk after 12 hours, but in the worst case a | |
85 | * few inodes might not their timestamps updated for 24 hours. | |
86 | */ | |
87 | unsigned int dirtytime_expire_interval = 12 * 60 * 60; | |
88 | ||
7ccf19a8 NP |
89 | static inline struct inode *wb_inode(struct list_head *head) |
90 | { | |
91 | return list_entry(head, struct inode, i_wb_list); | |
92 | } | |
93 | ||
15eb77a0 WF |
94 | /* |
95 | * Include the creation of the trace points after defining the | |
96 | * wb_writeback_work structure and inline functions so that the definition | |
97 | * remains local to this file. | |
98 | */ | |
99 | #define CREATE_TRACE_POINTS | |
100 | #include <trace/events/writeback.h> | |
101 | ||
774016b2 SW |
102 | EXPORT_TRACEPOINT_SYMBOL_GPL(wbc_writepage); |
103 | ||
d6c10f1f TH |
104 | static bool wb_io_lists_populated(struct bdi_writeback *wb) |
105 | { | |
106 | if (wb_has_dirty_io(wb)) { | |
107 | return false; | |
108 | } else { | |
109 | set_bit(WB_has_dirty_io, &wb->state); | |
95a46c65 | 110 | WARN_ON_ONCE(!wb->avg_write_bandwidth); |
766a9d6e TH |
111 | atomic_long_add(wb->avg_write_bandwidth, |
112 | &wb->bdi->tot_write_bandwidth); | |
d6c10f1f TH |
113 | return true; |
114 | } | |
115 | } | |
116 | ||
117 | static void wb_io_lists_depopulated(struct bdi_writeback *wb) | |
118 | { | |
119 | if (wb_has_dirty_io(wb) && list_empty(&wb->b_dirty) && | |
766a9d6e | 120 | list_empty(&wb->b_io) && list_empty(&wb->b_more_io)) { |
d6c10f1f | 121 | clear_bit(WB_has_dirty_io, &wb->state); |
95a46c65 TH |
122 | WARN_ON_ONCE(atomic_long_sub_return(wb->avg_write_bandwidth, |
123 | &wb->bdi->tot_write_bandwidth) < 0); | |
766a9d6e | 124 | } |
d6c10f1f TH |
125 | } |
126 | ||
127 | /** | |
128 | * inode_wb_list_move_locked - move an inode onto a bdi_writeback IO list | |
129 | * @inode: inode to be moved | |
130 | * @wb: target bdi_writeback | |
131 | * @head: one of @wb->b_{dirty|io|more_io} | |
132 | * | |
133 | * Move @inode->i_wb_list to @list of @wb and set %WB_has_dirty_io. | |
134 | * Returns %true if @inode is the first occupant of the !dirty_time IO | |
135 | * lists; otherwise, %false. | |
136 | */ | |
137 | static bool inode_wb_list_move_locked(struct inode *inode, | |
138 | struct bdi_writeback *wb, | |
139 | struct list_head *head) | |
140 | { | |
141 | assert_spin_locked(&wb->list_lock); | |
142 | ||
143 | list_move(&inode->i_wb_list, head); | |
144 | ||
145 | /* dirty_time doesn't count as dirty_io until expiration */ | |
146 | if (head != &wb->b_dirty_time) | |
147 | return wb_io_lists_populated(wb); | |
148 | ||
149 | wb_io_lists_depopulated(wb); | |
150 | return false; | |
151 | } | |
152 | ||
153 | /** | |
154 | * inode_wb_list_del_locked - remove an inode from its bdi_writeback IO list | |
155 | * @inode: inode to be removed | |
156 | * @wb: bdi_writeback @inode is being removed from | |
157 | * | |
158 | * Remove @inode which may be on one of @wb->b_{dirty|io|more_io} lists and | |
159 | * clear %WB_has_dirty_io if all are empty afterwards. | |
160 | */ | |
161 | static void inode_wb_list_del_locked(struct inode *inode, | |
162 | struct bdi_writeback *wb) | |
163 | { | |
164 | assert_spin_locked(&wb->list_lock); | |
165 | ||
166 | list_del_init(&inode->i_wb_list); | |
167 | wb_io_lists_depopulated(wb); | |
168 | } | |
169 | ||
f0054bb1 | 170 | static void wb_wakeup(struct bdi_writeback *wb) |
5acda9d1 | 171 | { |
f0054bb1 TH |
172 | spin_lock_bh(&wb->work_lock); |
173 | if (test_bit(WB_registered, &wb->state)) | |
174 | mod_delayed_work(bdi_wq, &wb->dwork, 0); | |
175 | spin_unlock_bh(&wb->work_lock); | |
5acda9d1 JK |
176 | } |
177 | ||
f0054bb1 TH |
178 | static void wb_queue_work(struct bdi_writeback *wb, |
179 | struct wb_writeback_work *work) | |
6585027a | 180 | { |
f0054bb1 | 181 | trace_writeback_queue(wb->bdi, work); |
6585027a | 182 | |
f0054bb1 | 183 | spin_lock_bh(&wb->work_lock); |
98754bf7 TH |
184 | if (!test_bit(WB_registered, &wb->state)) { |
185 | if (work->single_wait) | |
186 | work->single_done = 1; | |
5acda9d1 | 187 | goto out_unlock; |
98754bf7 | 188 | } |
cc395d7f TH |
189 | if (work->done) |
190 | atomic_inc(&work->done->cnt); | |
f0054bb1 TH |
191 | list_add_tail(&work->list, &wb->work_list); |
192 | mod_delayed_work(bdi_wq, &wb->dwork, 0); | |
5acda9d1 | 193 | out_unlock: |
f0054bb1 | 194 | spin_unlock_bh(&wb->work_lock); |
1da177e4 LT |
195 | } |
196 | ||
cc395d7f TH |
197 | /** |
198 | * wb_wait_for_completion - wait for completion of bdi_writeback_works | |
199 | * @bdi: bdi work items were issued to | |
200 | * @done: target wb_completion | |
201 | * | |
202 | * Wait for one or more work items issued to @bdi with their ->done field | |
203 | * set to @done, which should have been defined with | |
204 | * DEFINE_WB_COMPLETION_ONSTACK(). This function returns after all such | |
205 | * work items are completed. Work items which are waited upon aren't freed | |
206 | * automatically on completion. | |
207 | */ | |
208 | static void wb_wait_for_completion(struct backing_dev_info *bdi, | |
209 | struct wb_completion *done) | |
210 | { | |
211 | atomic_dec(&done->cnt); /* put down the initial count */ | |
212 | wait_event(bdi->wb_waitq, !atomic_read(&done->cnt)); | |
213 | } | |
214 | ||
703c2708 TH |
215 | #ifdef CONFIG_CGROUP_WRITEBACK |
216 | ||
21c6321f TH |
217 | void __inode_attach_wb(struct inode *inode, struct page *page) |
218 | { | |
219 | struct backing_dev_info *bdi = inode_to_bdi(inode); | |
220 | struct bdi_writeback *wb = NULL; | |
221 | ||
222 | if (inode_cgwb_enabled(inode)) { | |
223 | struct cgroup_subsys_state *memcg_css; | |
224 | ||
225 | if (page) { | |
226 | memcg_css = mem_cgroup_css_from_page(page); | |
227 | wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); | |
228 | } else { | |
229 | /* must pin memcg_css, see wb_get_create() */ | |
230 | memcg_css = task_get_css(current, memory_cgrp_id); | |
231 | wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); | |
232 | css_put(memcg_css); | |
233 | } | |
234 | } | |
235 | ||
236 | if (!wb) | |
237 | wb = &bdi->wb; | |
238 | ||
239 | /* | |
240 | * There may be multiple instances of this function racing to | |
241 | * update the same inode. Use cmpxchg() to tell the winner. | |
242 | */ | |
243 | if (unlikely(cmpxchg(&inode->i_wb, NULL, wb))) | |
244 | wb_put(wb); | |
245 | } | |
246 | ||
b16b1deb TH |
247 | /** |
248 | * wbc_attach_and_unlock_inode - associate wbc with target inode and unlock it | |
249 | * @wbc: writeback_control of interest | |
250 | * @inode: target inode | |
251 | * | |
252 | * @inode is locked and about to be written back under the control of @wbc. | |
253 | * Record @inode's writeback context into @wbc and unlock the i_lock. On | |
254 | * writeback completion, wbc_detach_inode() should be called. This is used | |
255 | * to track the cgroup writeback context. | |
256 | */ | |
257 | void wbc_attach_and_unlock_inode(struct writeback_control *wbc, | |
258 | struct inode *inode) | |
259 | { | |
260 | wbc->wb = inode_to_wb(inode); | |
261 | wb_get(wbc->wb); | |
262 | spin_unlock(&inode->i_lock); | |
263 | } | |
264 | ||
265 | /** | |
266 | * wbc_detach_inode - disassociate wbc from its target inode | |
267 | * @wbc: writeback_control of interest | |
268 | * | |
269 | * To be called after a writeback attempt of an inode finishes and undoes | |
270 | * wbc_attach_and_unlock_inode(). Can be called under any context. | |
271 | */ | |
272 | void wbc_detach_inode(struct writeback_control *wbc) | |
273 | { | |
274 | wb_put(wbc->wb); | |
275 | wbc->wb = NULL; | |
276 | } | |
277 | ||
703c2708 TH |
278 | /** |
279 | * inode_congested - test whether an inode is congested | |
280 | * @inode: inode to test for congestion | |
281 | * @cong_bits: mask of WB_[a]sync_congested bits to test | |
282 | * | |
283 | * Tests whether @inode is congested. @cong_bits is the mask of congestion | |
284 | * bits to test and the return value is the mask of set bits. | |
285 | * | |
286 | * If cgroup writeback is enabled for @inode, the congestion state is | |
287 | * determined by whether the cgwb (cgroup bdi_writeback) for the blkcg | |
288 | * associated with @inode is congested; otherwise, the root wb's congestion | |
289 | * state is used. | |
290 | */ | |
291 | int inode_congested(struct inode *inode, int cong_bits) | |
292 | { | |
293 | if (inode) { | |
294 | struct bdi_writeback *wb = inode_to_wb(inode); | |
295 | if (wb) | |
296 | return wb_congested(wb, cong_bits); | |
297 | } | |
298 | ||
299 | return wb_congested(&inode_to_bdi(inode)->wb, cong_bits); | |
300 | } | |
301 | EXPORT_SYMBOL_GPL(inode_congested); | |
302 | ||
98754bf7 TH |
303 | /** |
304 | * wb_wait_for_single_work - wait for completion of a single bdi_writeback_work | |
305 | * @bdi: bdi the work item was issued to | |
306 | * @work: work item to wait for | |
307 | * | |
308 | * Wait for the completion of @work which was issued to one of @bdi's | |
309 | * bdi_writeback's. The caller must have set @work->single_wait before | |
310 | * issuing it. This wait operates independently fo | |
311 | * wb_wait_for_completion() and also disables automatic freeing of @work. | |
312 | */ | |
313 | static void wb_wait_for_single_work(struct backing_dev_info *bdi, | |
314 | struct wb_writeback_work *work) | |
315 | { | |
316 | if (WARN_ON_ONCE(!work->single_wait)) | |
317 | return; | |
318 | ||
319 | wait_event(bdi->wb_waitq, work->single_done); | |
320 | ||
321 | /* | |
322 | * Paired with smp_wmb() in wb_do_writeback() and ensures that all | |
323 | * modifications to @work prior to assertion of ->single_done is | |
324 | * visible to the caller once this function returns. | |
325 | */ | |
326 | smp_rmb(); | |
327 | } | |
328 | ||
f2b65121 TH |
329 | /** |
330 | * wb_split_bdi_pages - split nr_pages to write according to bandwidth | |
331 | * @wb: target bdi_writeback to split @nr_pages to | |
332 | * @nr_pages: number of pages to write for the whole bdi | |
333 | * | |
334 | * Split @wb's portion of @nr_pages according to @wb's write bandwidth in | |
335 | * relation to the total write bandwidth of all wb's w/ dirty inodes on | |
336 | * @wb->bdi. | |
337 | */ | |
338 | static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages) | |
339 | { | |
340 | unsigned long this_bw = wb->avg_write_bandwidth; | |
341 | unsigned long tot_bw = atomic_long_read(&wb->bdi->tot_write_bandwidth); | |
342 | ||
343 | if (nr_pages == LONG_MAX) | |
344 | return LONG_MAX; | |
345 | ||
346 | /* | |
347 | * This may be called on clean wb's and proportional distribution | |
348 | * may not make sense, just use the original @nr_pages in those | |
349 | * cases. In general, we wanna err on the side of writing more. | |
350 | */ | |
351 | if (!tot_bw || this_bw >= tot_bw) | |
352 | return nr_pages; | |
353 | else | |
354 | return DIV_ROUND_UP_ULL((u64)nr_pages * this_bw, tot_bw); | |
355 | } | |
356 | ||
db125360 TH |
357 | /** |
358 | * wb_clone_and_queue_work - clone a wb_writeback_work and issue it to a wb | |
359 | * @wb: target bdi_writeback | |
360 | * @base_work: source wb_writeback_work | |
361 | * | |
362 | * Try to make a clone of @base_work and issue it to @wb. If cloning | |
363 | * succeeds, %true is returned; otherwise, @base_work is issued directly | |
364 | * and %false is returned. In the latter case, the caller is required to | |
365 | * wait for @base_work's completion using wb_wait_for_single_work(). | |
366 | * | |
367 | * A clone is auto-freed on completion. @base_work never is. | |
368 | */ | |
369 | static bool wb_clone_and_queue_work(struct bdi_writeback *wb, | |
370 | struct wb_writeback_work *base_work) | |
371 | { | |
372 | struct wb_writeback_work *work; | |
373 | ||
374 | work = kmalloc(sizeof(*work), GFP_ATOMIC); | |
375 | if (work) { | |
376 | *work = *base_work; | |
377 | work->auto_free = 1; | |
378 | work->single_wait = 0; | |
379 | } else { | |
380 | work = base_work; | |
381 | work->auto_free = 0; | |
382 | work->single_wait = 1; | |
383 | } | |
384 | work->single_done = 0; | |
385 | wb_queue_work(wb, work); | |
386 | return work != base_work; | |
387 | } | |
388 | ||
389 | /** | |
390 | * bdi_split_work_to_wbs - split a wb_writeback_work to all wb's of a bdi | |
391 | * @bdi: target backing_dev_info | |
392 | * @base_work: wb_writeback_work to issue | |
393 | * @skip_if_busy: skip wb's which already have writeback in progress | |
394 | * | |
395 | * Split and issue @base_work to all wb's (bdi_writeback's) of @bdi which | |
396 | * have dirty inodes. If @base_work->nr_page isn't %LONG_MAX, it's | |
397 | * distributed to the busy wbs according to each wb's proportion in the | |
398 | * total active write bandwidth of @bdi. | |
399 | */ | |
400 | static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, | |
401 | struct wb_writeback_work *base_work, | |
402 | bool skip_if_busy) | |
403 | { | |
404 | long nr_pages = base_work->nr_pages; | |
405 | int next_blkcg_id = 0; | |
406 | struct bdi_writeback *wb; | |
407 | struct wb_iter iter; | |
408 | ||
409 | might_sleep(); | |
410 | ||
411 | if (!bdi_has_dirty_io(bdi)) | |
412 | return; | |
413 | restart: | |
414 | rcu_read_lock(); | |
415 | bdi_for_each_wb(wb, bdi, &iter, next_blkcg_id) { | |
416 | if (!wb_has_dirty_io(wb) || | |
417 | (skip_if_busy && writeback_in_progress(wb))) | |
418 | continue; | |
419 | ||
420 | base_work->nr_pages = wb_split_bdi_pages(wb, nr_pages); | |
421 | if (!wb_clone_and_queue_work(wb, base_work)) { | |
422 | next_blkcg_id = wb->blkcg_css->id + 1; | |
423 | rcu_read_unlock(); | |
424 | wb_wait_for_single_work(bdi, base_work); | |
425 | goto restart; | |
426 | } | |
427 | } | |
428 | rcu_read_unlock(); | |
429 | } | |
430 | ||
f2b65121 TH |
431 | #else /* CONFIG_CGROUP_WRITEBACK */ |
432 | ||
433 | static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages) | |
434 | { | |
435 | return nr_pages; | |
436 | } | |
437 | ||
db125360 TH |
438 | static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, |
439 | struct wb_writeback_work *base_work, | |
440 | bool skip_if_busy) | |
441 | { | |
442 | might_sleep(); | |
443 | ||
444 | if (bdi_has_dirty_io(bdi) && | |
445 | (!skip_if_busy || !writeback_in_progress(&bdi->wb))) { | |
446 | base_work->auto_free = 0; | |
447 | base_work->single_wait = 0; | |
448 | base_work->single_done = 0; | |
449 | wb_queue_work(&bdi->wb, base_work); | |
450 | } | |
451 | } | |
452 | ||
703c2708 TH |
453 | #endif /* CONFIG_CGROUP_WRITEBACK */ |
454 | ||
c00ddad3 TH |
455 | void wb_start_writeback(struct bdi_writeback *wb, long nr_pages, |
456 | bool range_cyclic, enum wb_reason reason) | |
b6e51316 | 457 | { |
c00ddad3 TH |
458 | struct wb_writeback_work *work; |
459 | ||
460 | if (!wb_has_dirty_io(wb)) | |
461 | return; | |
462 | ||
463 | /* | |
464 | * This is WB_SYNC_NONE writeback, so if allocation fails just | |
465 | * wakeup the thread for old dirty data writeback | |
466 | */ | |
467 | work = kzalloc(sizeof(*work), GFP_ATOMIC); | |
468 | if (!work) { | |
469 | trace_writeback_nowork(wb->bdi); | |
470 | wb_wakeup(wb); | |
471 | return; | |
472 | } | |
473 | ||
474 | work->sync_mode = WB_SYNC_NONE; | |
475 | work->nr_pages = nr_pages; | |
476 | work->range_cyclic = range_cyclic; | |
477 | work->reason = reason; | |
ac7b19a3 | 478 | work->auto_free = 1; |
c00ddad3 TH |
479 | |
480 | wb_queue_work(wb, work); | |
c5444198 | 481 | } |
d3ddec76 | 482 | |
c5444198 | 483 | /** |
9ecf4866 TH |
484 | * wb_start_background_writeback - start background writeback |
485 | * @wb: bdi_writback to write from | |
c5444198 CH |
486 | * |
487 | * Description: | |
6585027a | 488 | * This makes sure WB_SYNC_NONE background writeback happens. When |
9ecf4866 | 489 | * this function returns, it is only guaranteed that for given wb |
6585027a JK |
490 | * some IO is happening if we are over background dirty threshold. |
491 | * Caller need not hold sb s_umount semaphore. | |
c5444198 | 492 | */ |
9ecf4866 | 493 | void wb_start_background_writeback(struct bdi_writeback *wb) |
c5444198 | 494 | { |
6585027a JK |
495 | /* |
496 | * We just wake up the flusher thread. It will perform background | |
497 | * writeback as soon as there is no other work to do. | |
498 | */ | |
9ecf4866 TH |
499 | trace_writeback_wake_background(wb->bdi); |
500 | wb_wakeup(wb); | |
1da177e4 LT |
501 | } |
502 | ||
a66979ab DC |
503 | /* |
504 | * Remove the inode from the writeback list it is on. | |
505 | */ | |
506 | void inode_wb_list_del(struct inode *inode) | |
507 | { | |
52ebea74 | 508 | struct bdi_writeback *wb = inode_to_wb(inode); |
f758eeab | 509 | |
52ebea74 | 510 | spin_lock(&wb->list_lock); |
d6c10f1f | 511 | inode_wb_list_del_locked(inode, wb); |
52ebea74 | 512 | spin_unlock(&wb->list_lock); |
a66979ab DC |
513 | } |
514 | ||
6610a0bc AM |
515 | /* |
516 | * Redirty an inode: set its when-it-was dirtied timestamp and move it to the | |
517 | * furthest end of its superblock's dirty-inode list. | |
518 | * | |
519 | * Before stamping the inode's ->dirtied_when, we check to see whether it is | |
66f3b8e2 | 520 | * already the most-recently-dirtied inode on the b_dirty list. If that is |
6610a0bc AM |
521 | * the case then the inode must have been redirtied while it was being written |
522 | * out and we don't reset its dirtied_when. | |
523 | */ | |
f758eeab | 524 | static void redirty_tail(struct inode *inode, struct bdi_writeback *wb) |
6610a0bc | 525 | { |
03ba3782 | 526 | if (!list_empty(&wb->b_dirty)) { |
66f3b8e2 | 527 | struct inode *tail; |
6610a0bc | 528 | |
7ccf19a8 | 529 | tail = wb_inode(wb->b_dirty.next); |
66f3b8e2 | 530 | if (time_before(inode->dirtied_when, tail->dirtied_when)) |
6610a0bc AM |
531 | inode->dirtied_when = jiffies; |
532 | } | |
d6c10f1f | 533 | inode_wb_list_move_locked(inode, wb, &wb->b_dirty); |
6610a0bc AM |
534 | } |
535 | ||
c986d1e2 | 536 | /* |
66f3b8e2 | 537 | * requeue inode for re-scanning after bdi->b_io list is exhausted. |
c986d1e2 | 538 | */ |
f758eeab | 539 | static void requeue_io(struct inode *inode, struct bdi_writeback *wb) |
c986d1e2 | 540 | { |
d6c10f1f | 541 | inode_wb_list_move_locked(inode, wb, &wb->b_more_io); |
c986d1e2 AM |
542 | } |
543 | ||
1c0eeaf5 JE |
544 | static void inode_sync_complete(struct inode *inode) |
545 | { | |
365b94ae | 546 | inode->i_state &= ~I_SYNC; |
4eff96dd JK |
547 | /* If inode is clean an unused, put it into LRU now... */ |
548 | inode_add_lru(inode); | |
365b94ae | 549 | /* Waiters must see I_SYNC cleared before being woken up */ |
1c0eeaf5 JE |
550 | smp_mb(); |
551 | wake_up_bit(&inode->i_state, __I_SYNC); | |
552 | } | |
553 | ||
d2caa3c5 JL |
554 | static bool inode_dirtied_after(struct inode *inode, unsigned long t) |
555 | { | |
556 | bool ret = time_after(inode->dirtied_when, t); | |
557 | #ifndef CONFIG_64BIT | |
558 | /* | |
559 | * For inodes being constantly redirtied, dirtied_when can get stuck. | |
560 | * It _appears_ to be in the future, but is actually in distant past. | |
561 | * This test is necessary to prevent such wrapped-around relative times | |
5b0830cb | 562 | * from permanently stopping the whole bdi writeback. |
d2caa3c5 JL |
563 | */ |
564 | ret = ret && time_before_eq(inode->dirtied_when, jiffies); | |
565 | #endif | |
566 | return ret; | |
567 | } | |
568 | ||
0ae45f63 TT |
569 | #define EXPIRE_DIRTY_ATIME 0x0001 |
570 | ||
2c136579 | 571 | /* |
0e2f2b23 | 572 | * Move expired (dirtied before work->older_than_this) dirty inodes from |
697e6fed | 573 | * @delaying_queue to @dispatch_queue. |
2c136579 | 574 | */ |
e84d0a4f | 575 | static int move_expired_inodes(struct list_head *delaying_queue, |
2c136579 | 576 | struct list_head *dispatch_queue, |
0ae45f63 | 577 | int flags, |
ad4e38dd | 578 | struct wb_writeback_work *work) |
2c136579 | 579 | { |
0ae45f63 TT |
580 | unsigned long *older_than_this = NULL; |
581 | unsigned long expire_time; | |
5c03449d SL |
582 | LIST_HEAD(tmp); |
583 | struct list_head *pos, *node; | |
cf137307 | 584 | struct super_block *sb = NULL; |
5c03449d | 585 | struct inode *inode; |
cf137307 | 586 | int do_sb_sort = 0; |
e84d0a4f | 587 | int moved = 0; |
5c03449d | 588 | |
0ae45f63 TT |
589 | if ((flags & EXPIRE_DIRTY_ATIME) == 0) |
590 | older_than_this = work->older_than_this; | |
a2f48706 TT |
591 | else if (!work->for_sync) { |
592 | expire_time = jiffies - (dirtytime_expire_interval * HZ); | |
0ae45f63 TT |
593 | older_than_this = &expire_time; |
594 | } | |
2c136579 | 595 | while (!list_empty(delaying_queue)) { |
7ccf19a8 | 596 | inode = wb_inode(delaying_queue->prev); |
0ae45f63 TT |
597 | if (older_than_this && |
598 | inode_dirtied_after(inode, *older_than_this)) | |
2c136579 | 599 | break; |
a8855990 JK |
600 | list_move(&inode->i_wb_list, &tmp); |
601 | moved++; | |
0ae45f63 TT |
602 | if (flags & EXPIRE_DIRTY_ATIME) |
603 | set_bit(__I_DIRTY_TIME_EXPIRED, &inode->i_state); | |
a8855990 JK |
604 | if (sb_is_blkdev_sb(inode->i_sb)) |
605 | continue; | |
cf137307 JA |
606 | if (sb && sb != inode->i_sb) |
607 | do_sb_sort = 1; | |
608 | sb = inode->i_sb; | |
5c03449d SL |
609 | } |
610 | ||
cf137307 JA |
611 | /* just one sb in list, splice to dispatch_queue and we're done */ |
612 | if (!do_sb_sort) { | |
613 | list_splice(&tmp, dispatch_queue); | |
e84d0a4f | 614 | goto out; |
cf137307 JA |
615 | } |
616 | ||
5c03449d SL |
617 | /* Move inodes from one superblock together */ |
618 | while (!list_empty(&tmp)) { | |
7ccf19a8 | 619 | sb = wb_inode(tmp.prev)->i_sb; |
5c03449d | 620 | list_for_each_prev_safe(pos, node, &tmp) { |
7ccf19a8 | 621 | inode = wb_inode(pos); |
5c03449d | 622 | if (inode->i_sb == sb) |
7ccf19a8 | 623 | list_move(&inode->i_wb_list, dispatch_queue); |
5c03449d | 624 | } |
2c136579 | 625 | } |
e84d0a4f WF |
626 | out: |
627 | return moved; | |
2c136579 FW |
628 | } |
629 | ||
630 | /* | |
631 | * Queue all expired dirty inodes for io, eldest first. | |
4ea879b9 WF |
632 | * Before |
633 | * newly dirtied b_dirty b_io b_more_io | |
634 | * =============> gf edc BA | |
635 | * After | |
636 | * newly dirtied b_dirty b_io b_more_io | |
637 | * =============> g fBAedc | |
638 | * | | |
639 | * +--> dequeue for IO | |
2c136579 | 640 | */ |
ad4e38dd | 641 | static void queue_io(struct bdi_writeback *wb, struct wb_writeback_work *work) |
66f3b8e2 | 642 | { |
e84d0a4f | 643 | int moved; |
0ae45f63 | 644 | |
f758eeab | 645 | assert_spin_locked(&wb->list_lock); |
4ea879b9 | 646 | list_splice_init(&wb->b_more_io, &wb->b_io); |
0ae45f63 TT |
647 | moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, 0, work); |
648 | moved += move_expired_inodes(&wb->b_dirty_time, &wb->b_io, | |
649 | EXPIRE_DIRTY_ATIME, work); | |
d6c10f1f TH |
650 | if (moved) |
651 | wb_io_lists_populated(wb); | |
ad4e38dd | 652 | trace_writeback_queue_io(wb, work, moved); |
66f3b8e2 JA |
653 | } |
654 | ||
a9185b41 | 655 | static int write_inode(struct inode *inode, struct writeback_control *wbc) |
08d8e974 | 656 | { |
9fb0a7da TH |
657 | int ret; |
658 | ||
659 | if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) { | |
660 | trace_writeback_write_inode_start(inode, wbc); | |
661 | ret = inode->i_sb->s_op->write_inode(inode, wbc); | |
662 | trace_writeback_write_inode(inode, wbc); | |
663 | return ret; | |
664 | } | |
03ba3782 | 665 | return 0; |
08d8e974 | 666 | } |
08d8e974 | 667 | |
1da177e4 | 668 | /* |
169ebd90 JK |
669 | * Wait for writeback on an inode to complete. Called with i_lock held. |
670 | * Caller must make sure inode cannot go away when we drop i_lock. | |
01c03194 | 671 | */ |
169ebd90 JK |
672 | static void __inode_wait_for_writeback(struct inode *inode) |
673 | __releases(inode->i_lock) | |
674 | __acquires(inode->i_lock) | |
01c03194 CH |
675 | { |
676 | DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); | |
677 | wait_queue_head_t *wqh; | |
678 | ||
679 | wqh = bit_waitqueue(&inode->i_state, __I_SYNC); | |
250df6ed DC |
680 | while (inode->i_state & I_SYNC) { |
681 | spin_unlock(&inode->i_lock); | |
74316201 N |
682 | __wait_on_bit(wqh, &wq, bit_wait, |
683 | TASK_UNINTERRUPTIBLE); | |
250df6ed | 684 | spin_lock(&inode->i_lock); |
58a9d3d8 | 685 | } |
01c03194 CH |
686 | } |
687 | ||
169ebd90 JK |
688 | /* |
689 | * Wait for writeback on an inode to complete. Caller must have inode pinned. | |
690 | */ | |
691 | void inode_wait_for_writeback(struct inode *inode) | |
692 | { | |
693 | spin_lock(&inode->i_lock); | |
694 | __inode_wait_for_writeback(inode); | |
695 | spin_unlock(&inode->i_lock); | |
696 | } | |
697 | ||
698 | /* | |
699 | * Sleep until I_SYNC is cleared. This function must be called with i_lock | |
700 | * held and drops it. It is aimed for callers not holding any inode reference | |
701 | * so once i_lock is dropped, inode can go away. | |
702 | */ | |
703 | static void inode_sleep_on_writeback(struct inode *inode) | |
704 | __releases(inode->i_lock) | |
705 | { | |
706 | DEFINE_WAIT(wait); | |
707 | wait_queue_head_t *wqh = bit_waitqueue(&inode->i_state, __I_SYNC); | |
708 | int sleep; | |
709 | ||
710 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
711 | sleep = inode->i_state & I_SYNC; | |
712 | spin_unlock(&inode->i_lock); | |
713 | if (sleep) | |
714 | schedule(); | |
715 | finish_wait(wqh, &wait); | |
716 | } | |
717 | ||
ccb26b5a JK |
718 | /* |
719 | * Find proper writeback list for the inode depending on its current state and | |
720 | * possibly also change of its state while we were doing writeback. Here we | |
721 | * handle things such as livelock prevention or fairness of writeback among | |
722 | * inodes. This function can be called only by flusher thread - noone else | |
723 | * processes all inodes in writeback lists and requeueing inodes behind flusher | |
724 | * thread's back can have unexpected consequences. | |
725 | */ | |
726 | static void requeue_inode(struct inode *inode, struct bdi_writeback *wb, | |
727 | struct writeback_control *wbc) | |
728 | { | |
729 | if (inode->i_state & I_FREEING) | |
730 | return; | |
731 | ||
732 | /* | |
733 | * Sync livelock prevention. Each inode is tagged and synced in one | |
734 | * shot. If still dirty, it will be redirty_tail()'ed below. Update | |
735 | * the dirty time to prevent enqueue and sync it again. | |
736 | */ | |
737 | if ((inode->i_state & I_DIRTY) && | |
738 | (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)) | |
739 | inode->dirtied_when = jiffies; | |
740 | ||
4f8ad655 JK |
741 | if (wbc->pages_skipped) { |
742 | /* | |
743 | * writeback is not making progress due to locked | |
744 | * buffers. Skip this inode for now. | |
745 | */ | |
746 | redirty_tail(inode, wb); | |
747 | return; | |
748 | } | |
749 | ||
ccb26b5a JK |
750 | if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) { |
751 | /* | |
752 | * We didn't write back all the pages. nfs_writepages() | |
753 | * sometimes bales out without doing anything. | |
754 | */ | |
755 | if (wbc->nr_to_write <= 0) { | |
756 | /* Slice used up. Queue for next turn. */ | |
757 | requeue_io(inode, wb); | |
758 | } else { | |
759 | /* | |
760 | * Writeback blocked by something other than | |
761 | * congestion. Delay the inode for some time to | |
762 | * avoid spinning on the CPU (100% iowait) | |
763 | * retrying writeback of the dirty page/inode | |
764 | * that cannot be performed immediately. | |
765 | */ | |
766 | redirty_tail(inode, wb); | |
767 | } | |
768 | } else if (inode->i_state & I_DIRTY) { | |
769 | /* | |
770 | * Filesystems can dirty the inode during writeback operations, | |
771 | * such as delayed allocation during submission or metadata | |
772 | * updates after data IO completion. | |
773 | */ | |
774 | redirty_tail(inode, wb); | |
0ae45f63 | 775 | } else if (inode->i_state & I_DIRTY_TIME) { |
a2f48706 | 776 | inode->dirtied_when = jiffies; |
d6c10f1f | 777 | inode_wb_list_move_locked(inode, wb, &wb->b_dirty_time); |
ccb26b5a JK |
778 | } else { |
779 | /* The inode is clean. Remove from writeback lists. */ | |
d6c10f1f | 780 | inode_wb_list_del_locked(inode, wb); |
ccb26b5a JK |
781 | } |
782 | } | |
783 | ||
01c03194 | 784 | /* |
4f8ad655 JK |
785 | * Write out an inode and its dirty pages. Do not update the writeback list |
786 | * linkage. That is left to the caller. The caller is also responsible for | |
787 | * setting I_SYNC flag and calling inode_sync_complete() to clear it. | |
1da177e4 LT |
788 | */ |
789 | static int | |
cd8ed2a4 | 790 | __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) |
1da177e4 | 791 | { |
1da177e4 | 792 | struct address_space *mapping = inode->i_mapping; |
251d6a47 | 793 | long nr_to_write = wbc->nr_to_write; |
01c03194 | 794 | unsigned dirty; |
1da177e4 LT |
795 | int ret; |
796 | ||
4f8ad655 | 797 | WARN_ON(!(inode->i_state & I_SYNC)); |
1da177e4 | 798 | |
9fb0a7da TH |
799 | trace_writeback_single_inode_start(inode, wbc, nr_to_write); |
800 | ||
1da177e4 LT |
801 | ret = do_writepages(mapping, wbc); |
802 | ||
26821ed4 CH |
803 | /* |
804 | * Make sure to wait on the data before writing out the metadata. | |
805 | * This is important for filesystems that modify metadata on data | |
7747bd4b DC |
806 | * I/O completion. We don't do it for sync(2) writeback because it has a |
807 | * separate, external IO completion path and ->sync_fs for guaranteeing | |
808 | * inode metadata is written back correctly. | |
26821ed4 | 809 | */ |
7747bd4b | 810 | if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync) { |
26821ed4 | 811 | int err = filemap_fdatawait(mapping); |
1da177e4 LT |
812 | if (ret == 0) |
813 | ret = err; | |
814 | } | |
815 | ||
5547e8aa DM |
816 | /* |
817 | * Some filesystems may redirty the inode during the writeback | |
818 | * due to delalloc, clear dirty metadata flags right before | |
819 | * write_inode() | |
820 | */ | |
250df6ed | 821 | spin_lock(&inode->i_lock); |
9c6ac78e | 822 | |
5547e8aa | 823 | dirty = inode->i_state & I_DIRTY; |
a2f48706 TT |
824 | if (inode->i_state & I_DIRTY_TIME) { |
825 | if ((dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) || | |
826 | unlikely(inode->i_state & I_DIRTY_TIME_EXPIRED) || | |
827 | unlikely(time_after(jiffies, | |
828 | (inode->dirtied_time_when + | |
829 | dirtytime_expire_interval * HZ)))) { | |
830 | dirty |= I_DIRTY_TIME | I_DIRTY_TIME_EXPIRED; | |
831 | trace_writeback_lazytime(inode); | |
832 | } | |
833 | } else | |
834 | inode->i_state &= ~I_DIRTY_TIME_EXPIRED; | |
0ae45f63 | 835 | inode->i_state &= ~dirty; |
9c6ac78e TH |
836 | |
837 | /* | |
838 | * Paired with smp_mb() in __mark_inode_dirty(). This allows | |
839 | * __mark_inode_dirty() to test i_state without grabbing i_lock - | |
840 | * either they see the I_DIRTY bits cleared or we see the dirtied | |
841 | * inode. | |
842 | * | |
843 | * I_DIRTY_PAGES is always cleared together above even if @mapping | |
844 | * still has dirty pages. The flag is reinstated after smp_mb() if | |
845 | * necessary. This guarantees that either __mark_inode_dirty() | |
846 | * sees clear I_DIRTY_PAGES or we see PAGECACHE_TAG_DIRTY. | |
847 | */ | |
848 | smp_mb(); | |
849 | ||
850 | if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) | |
851 | inode->i_state |= I_DIRTY_PAGES; | |
852 | ||
250df6ed | 853 | spin_unlock(&inode->i_lock); |
9c6ac78e | 854 | |
0ae45f63 TT |
855 | if (dirty & I_DIRTY_TIME) |
856 | mark_inode_dirty_sync(inode); | |
26821ed4 | 857 | /* Don't write the inode if only I_DIRTY_PAGES was set */ |
0ae45f63 | 858 | if (dirty & ~I_DIRTY_PAGES) { |
a9185b41 | 859 | int err = write_inode(inode, wbc); |
1da177e4 LT |
860 | if (ret == 0) |
861 | ret = err; | |
862 | } | |
4f8ad655 JK |
863 | trace_writeback_single_inode(inode, wbc, nr_to_write); |
864 | return ret; | |
865 | } | |
866 | ||
867 | /* | |
868 | * Write out an inode's dirty pages. Either the caller has an active reference | |
869 | * on the inode or the inode has I_WILL_FREE set. | |
870 | * | |
871 | * This function is designed to be called for writing back one inode which | |
872 | * we go e.g. from filesystem. Flusher thread uses __writeback_single_inode() | |
873 | * and does more profound writeback list handling in writeback_sb_inodes(). | |
874 | */ | |
875 | static int | |
876 | writeback_single_inode(struct inode *inode, struct bdi_writeback *wb, | |
877 | struct writeback_control *wbc) | |
878 | { | |
879 | int ret = 0; | |
880 | ||
881 | spin_lock(&inode->i_lock); | |
882 | if (!atomic_read(&inode->i_count)) | |
883 | WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); | |
884 | else | |
885 | WARN_ON(inode->i_state & I_WILL_FREE); | |
886 | ||
887 | if (inode->i_state & I_SYNC) { | |
888 | if (wbc->sync_mode != WB_SYNC_ALL) | |
889 | goto out; | |
890 | /* | |
169ebd90 JK |
891 | * It's a data-integrity sync. We must wait. Since callers hold |
892 | * inode reference or inode has I_WILL_FREE set, it cannot go | |
893 | * away under us. | |
4f8ad655 | 894 | */ |
169ebd90 | 895 | __inode_wait_for_writeback(inode); |
4f8ad655 JK |
896 | } |
897 | WARN_ON(inode->i_state & I_SYNC); | |
898 | /* | |
f9b0e058 JK |
899 | * Skip inode if it is clean and we have no outstanding writeback in |
900 | * WB_SYNC_ALL mode. We don't want to mess with writeback lists in this | |
901 | * function since flusher thread may be doing for example sync in | |
902 | * parallel and if we move the inode, it could get skipped. So here we | |
903 | * make sure inode is on some writeback list and leave it there unless | |
904 | * we have completely cleaned the inode. | |
4f8ad655 | 905 | */ |
0ae45f63 | 906 | if (!(inode->i_state & I_DIRTY_ALL) && |
f9b0e058 JK |
907 | (wbc->sync_mode != WB_SYNC_ALL || |
908 | !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))) | |
4f8ad655 JK |
909 | goto out; |
910 | inode->i_state |= I_SYNC; | |
b16b1deb | 911 | wbc_attach_and_unlock_inode(wbc, inode); |
4f8ad655 | 912 | |
cd8ed2a4 | 913 | ret = __writeback_single_inode(inode, wbc); |
1da177e4 | 914 | |
b16b1deb | 915 | wbc_detach_inode(wbc); |
f758eeab | 916 | spin_lock(&wb->list_lock); |
250df6ed | 917 | spin_lock(&inode->i_lock); |
4f8ad655 JK |
918 | /* |
919 | * If inode is clean, remove it from writeback lists. Otherwise don't | |
920 | * touch it. See comment above for explanation. | |
921 | */ | |
0ae45f63 | 922 | if (!(inode->i_state & I_DIRTY_ALL)) |
d6c10f1f | 923 | inode_wb_list_del_locked(inode, wb); |
4f8ad655 | 924 | spin_unlock(&wb->list_lock); |
1c0eeaf5 | 925 | inode_sync_complete(inode); |
4f8ad655 JK |
926 | out: |
927 | spin_unlock(&inode->i_lock); | |
1da177e4 LT |
928 | return ret; |
929 | } | |
930 | ||
a88a341a | 931 | static long writeback_chunk_size(struct bdi_writeback *wb, |
1a12d8bd | 932 | struct wb_writeback_work *work) |
d46db3d5 WF |
933 | { |
934 | long pages; | |
935 | ||
936 | /* | |
937 | * WB_SYNC_ALL mode does livelock avoidance by syncing dirty | |
938 | * inodes/pages in one big loop. Setting wbc.nr_to_write=LONG_MAX | |
939 | * here avoids calling into writeback_inodes_wb() more than once. | |
940 | * | |
941 | * The intended call sequence for WB_SYNC_ALL writeback is: | |
942 | * | |
943 | * wb_writeback() | |
944 | * writeback_sb_inodes() <== called only once | |
945 | * write_cache_pages() <== called once for each inode | |
946 | * (quickly) tag currently dirty pages | |
947 | * (maybe slowly) sync all tagged pages | |
948 | */ | |
949 | if (work->sync_mode == WB_SYNC_ALL || work->tagged_writepages) | |
950 | pages = LONG_MAX; | |
1a12d8bd | 951 | else { |
a88a341a | 952 | pages = min(wb->avg_write_bandwidth / 2, |
dcc25ae7 | 953 | global_wb_domain.dirty_limit / DIRTY_SCOPE); |
1a12d8bd WF |
954 | pages = min(pages, work->nr_pages); |
955 | pages = round_down(pages + MIN_WRITEBACK_PAGES, | |
956 | MIN_WRITEBACK_PAGES); | |
957 | } | |
d46db3d5 WF |
958 | |
959 | return pages; | |
960 | } | |
961 | ||
f11c9c5c ES |
962 | /* |
963 | * Write a portion of b_io inodes which belong to @sb. | |
edadfb10 | 964 | * |
d46db3d5 | 965 | * Return the number of pages and/or inodes written. |
f11c9c5c | 966 | */ |
d46db3d5 WF |
967 | static long writeback_sb_inodes(struct super_block *sb, |
968 | struct bdi_writeback *wb, | |
969 | struct wb_writeback_work *work) | |
1da177e4 | 970 | { |
d46db3d5 WF |
971 | struct writeback_control wbc = { |
972 | .sync_mode = work->sync_mode, | |
973 | .tagged_writepages = work->tagged_writepages, | |
974 | .for_kupdate = work->for_kupdate, | |
975 | .for_background = work->for_background, | |
7747bd4b | 976 | .for_sync = work->for_sync, |
d46db3d5 WF |
977 | .range_cyclic = work->range_cyclic, |
978 | .range_start = 0, | |
979 | .range_end = LLONG_MAX, | |
980 | }; | |
981 | unsigned long start_time = jiffies; | |
982 | long write_chunk; | |
983 | long wrote = 0; /* count both pages and inodes */ | |
984 | ||
03ba3782 | 985 | while (!list_empty(&wb->b_io)) { |
7ccf19a8 | 986 | struct inode *inode = wb_inode(wb->b_io.prev); |
edadfb10 CH |
987 | |
988 | if (inode->i_sb != sb) { | |
d46db3d5 | 989 | if (work->sb) { |
edadfb10 CH |
990 | /* |
991 | * We only want to write back data for this | |
992 | * superblock, move all inodes not belonging | |
993 | * to it back onto the dirty list. | |
994 | */ | |
f758eeab | 995 | redirty_tail(inode, wb); |
edadfb10 CH |
996 | continue; |
997 | } | |
998 | ||
999 | /* | |
1000 | * The inode belongs to a different superblock. | |
1001 | * Bounce back to the caller to unpin this and | |
1002 | * pin the next superblock. | |
1003 | */ | |
d46db3d5 | 1004 | break; |
edadfb10 CH |
1005 | } |
1006 | ||
9843b76a | 1007 | /* |
331cbdee WL |
1008 | * Don't bother with new inodes or inodes being freed, first |
1009 | * kind does not need periodic writeout yet, and for the latter | |
9843b76a CH |
1010 | * kind writeout is handled by the freer. |
1011 | */ | |
250df6ed | 1012 | spin_lock(&inode->i_lock); |
9843b76a | 1013 | if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { |
250df6ed | 1014 | spin_unlock(&inode->i_lock); |
fcc5c222 | 1015 | redirty_tail(inode, wb); |
7ef0d737 NP |
1016 | continue; |
1017 | } | |
cc1676d9 JK |
1018 | if ((inode->i_state & I_SYNC) && wbc.sync_mode != WB_SYNC_ALL) { |
1019 | /* | |
1020 | * If this inode is locked for writeback and we are not | |
1021 | * doing writeback-for-data-integrity, move it to | |
1022 | * b_more_io so that writeback can proceed with the | |
1023 | * other inodes on s_io. | |
1024 | * | |
1025 | * We'll have another go at writing back this inode | |
1026 | * when we completed a full scan of b_io. | |
1027 | */ | |
1028 | spin_unlock(&inode->i_lock); | |
1029 | requeue_io(inode, wb); | |
1030 | trace_writeback_sb_inodes_requeue(inode); | |
1031 | continue; | |
1032 | } | |
f0d07b7f JK |
1033 | spin_unlock(&wb->list_lock); |
1034 | ||
4f8ad655 JK |
1035 | /* |
1036 | * We already requeued the inode if it had I_SYNC set and we | |
1037 | * are doing WB_SYNC_NONE writeback. So this catches only the | |
1038 | * WB_SYNC_ALL case. | |
1039 | */ | |
169ebd90 JK |
1040 | if (inode->i_state & I_SYNC) { |
1041 | /* Wait for I_SYNC. This function drops i_lock... */ | |
1042 | inode_sleep_on_writeback(inode); | |
1043 | /* Inode may be gone, start again */ | |
ead188f9 | 1044 | spin_lock(&wb->list_lock); |
169ebd90 JK |
1045 | continue; |
1046 | } | |
4f8ad655 | 1047 | inode->i_state |= I_SYNC; |
b16b1deb | 1048 | wbc_attach_and_unlock_inode(&wbc, inode); |
169ebd90 | 1049 | |
a88a341a | 1050 | write_chunk = writeback_chunk_size(wb, work); |
d46db3d5 WF |
1051 | wbc.nr_to_write = write_chunk; |
1052 | wbc.pages_skipped = 0; | |
250df6ed | 1053 | |
169ebd90 JK |
1054 | /* |
1055 | * We use I_SYNC to pin the inode in memory. While it is set | |
1056 | * evict_inode() will wait so the inode cannot be freed. | |
1057 | */ | |
cd8ed2a4 | 1058 | __writeback_single_inode(inode, &wbc); |
250df6ed | 1059 | |
b16b1deb | 1060 | wbc_detach_inode(&wbc); |
d46db3d5 WF |
1061 | work->nr_pages -= write_chunk - wbc.nr_to_write; |
1062 | wrote += write_chunk - wbc.nr_to_write; | |
4f8ad655 JK |
1063 | spin_lock(&wb->list_lock); |
1064 | spin_lock(&inode->i_lock); | |
0ae45f63 | 1065 | if (!(inode->i_state & I_DIRTY_ALL)) |
d46db3d5 | 1066 | wrote++; |
4f8ad655 JK |
1067 | requeue_inode(inode, wb, &wbc); |
1068 | inode_sync_complete(inode); | |
0f1b1fd8 | 1069 | spin_unlock(&inode->i_lock); |
169ebd90 | 1070 | cond_resched_lock(&wb->list_lock); |
d46db3d5 WF |
1071 | /* |
1072 | * bail out to wb_writeback() often enough to check | |
1073 | * background threshold and other termination conditions. | |
1074 | */ | |
1075 | if (wrote) { | |
1076 | if (time_is_before_jiffies(start_time + HZ / 10UL)) | |
1077 | break; | |
1078 | if (work->nr_pages <= 0) | |
1079 | break; | |
8bc3be27 | 1080 | } |
1da177e4 | 1081 | } |
d46db3d5 | 1082 | return wrote; |
f11c9c5c ES |
1083 | } |
1084 | ||
d46db3d5 WF |
1085 | static long __writeback_inodes_wb(struct bdi_writeback *wb, |
1086 | struct wb_writeback_work *work) | |
f11c9c5c | 1087 | { |
d46db3d5 WF |
1088 | unsigned long start_time = jiffies; |
1089 | long wrote = 0; | |
38f21977 | 1090 | |
f11c9c5c | 1091 | while (!list_empty(&wb->b_io)) { |
7ccf19a8 | 1092 | struct inode *inode = wb_inode(wb->b_io.prev); |
f11c9c5c | 1093 | struct super_block *sb = inode->i_sb; |
9ecc2738 | 1094 | |
eb6ef3df | 1095 | if (!trylock_super(sb)) { |
0e995816 | 1096 | /* |
eb6ef3df | 1097 | * trylock_super() may fail consistently due to |
0e995816 WF |
1098 | * s_umount being grabbed by someone else. Don't use |
1099 | * requeue_io() to avoid busy retrying the inode/sb. | |
1100 | */ | |
1101 | redirty_tail(inode, wb); | |
edadfb10 | 1102 | continue; |
f11c9c5c | 1103 | } |
d46db3d5 | 1104 | wrote += writeback_sb_inodes(sb, wb, work); |
eb6ef3df | 1105 | up_read(&sb->s_umount); |
f11c9c5c | 1106 | |
d46db3d5 WF |
1107 | /* refer to the same tests at the end of writeback_sb_inodes */ |
1108 | if (wrote) { | |
1109 | if (time_is_before_jiffies(start_time + HZ / 10UL)) | |
1110 | break; | |
1111 | if (work->nr_pages <= 0) | |
1112 | break; | |
1113 | } | |
f11c9c5c | 1114 | } |
66f3b8e2 | 1115 | /* Leave any unwritten inodes on b_io */ |
d46db3d5 | 1116 | return wrote; |
66f3b8e2 JA |
1117 | } |
1118 | ||
7d9f073b | 1119 | static long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, |
0e175a18 | 1120 | enum wb_reason reason) |
edadfb10 | 1121 | { |
d46db3d5 WF |
1122 | struct wb_writeback_work work = { |
1123 | .nr_pages = nr_pages, | |
1124 | .sync_mode = WB_SYNC_NONE, | |
1125 | .range_cyclic = 1, | |
0e175a18 | 1126 | .reason = reason, |
d46db3d5 | 1127 | }; |
edadfb10 | 1128 | |
f758eeab | 1129 | spin_lock(&wb->list_lock); |
424b351f | 1130 | if (list_empty(&wb->b_io)) |
ad4e38dd | 1131 | queue_io(wb, &work); |
d46db3d5 | 1132 | __writeback_inodes_wb(wb, &work); |
f758eeab | 1133 | spin_unlock(&wb->list_lock); |
edadfb10 | 1134 | |
d46db3d5 WF |
1135 | return nr_pages - work.nr_pages; |
1136 | } | |
03ba3782 | 1137 | |
03ba3782 JA |
1138 | /* |
1139 | * Explicit flushing or periodic writeback of "old" data. | |
66f3b8e2 | 1140 | * |
03ba3782 JA |
1141 | * Define "old": the first time one of an inode's pages is dirtied, we mark the |
1142 | * dirtying-time in the inode's address_space. So this periodic writeback code | |
1143 | * just walks the superblock inode list, writing back any inodes which are | |
1144 | * older than a specific point in time. | |
66f3b8e2 | 1145 | * |
03ba3782 JA |
1146 | * Try to run once per dirty_writeback_interval. But if a writeback event |
1147 | * takes longer than a dirty_writeback_interval interval, then leave a | |
1148 | * one-second gap. | |
66f3b8e2 | 1149 | * |
03ba3782 JA |
1150 | * older_than_this takes precedence over nr_to_write. So we'll only write back |
1151 | * all dirty pages if they are all attached to "old" mappings. | |
66f3b8e2 | 1152 | */ |
c4a77a6c | 1153 | static long wb_writeback(struct bdi_writeback *wb, |
83ba7b07 | 1154 | struct wb_writeback_work *work) |
66f3b8e2 | 1155 | { |
e98be2d5 | 1156 | unsigned long wb_start = jiffies; |
d46db3d5 | 1157 | long nr_pages = work->nr_pages; |
0dc83bd3 | 1158 | unsigned long oldest_jif; |
a5989bdc | 1159 | struct inode *inode; |
d46db3d5 | 1160 | long progress; |
66f3b8e2 | 1161 | |
0dc83bd3 JK |
1162 | oldest_jif = jiffies; |
1163 | work->older_than_this = &oldest_jif; | |
38f21977 | 1164 | |
e8dfc305 | 1165 | spin_lock(&wb->list_lock); |
03ba3782 JA |
1166 | for (;;) { |
1167 | /* | |
d3ddec76 | 1168 | * Stop writeback when nr_pages has been consumed |
03ba3782 | 1169 | */ |
83ba7b07 | 1170 | if (work->nr_pages <= 0) |
03ba3782 | 1171 | break; |
66f3b8e2 | 1172 | |
aa373cf5 JK |
1173 | /* |
1174 | * Background writeout and kupdate-style writeback may | |
1175 | * run forever. Stop them if there is other work to do | |
1176 | * so that e.g. sync can proceed. They'll be restarted | |
1177 | * after the other works are all done. | |
1178 | */ | |
1179 | if ((work->for_background || work->for_kupdate) && | |
f0054bb1 | 1180 | !list_empty(&wb->work_list)) |
aa373cf5 JK |
1181 | break; |
1182 | ||
38f21977 | 1183 | /* |
d3ddec76 WF |
1184 | * For background writeout, stop when we are below the |
1185 | * background dirty threshold | |
38f21977 | 1186 | */ |
aa661bbe | 1187 | if (work->for_background && !wb_over_bg_thresh(wb)) |
03ba3782 | 1188 | break; |
38f21977 | 1189 | |
1bc36b64 JK |
1190 | /* |
1191 | * Kupdate and background works are special and we want to | |
1192 | * include all inodes that need writing. Livelock avoidance is | |
1193 | * handled by these works yielding to any other work so we are | |
1194 | * safe. | |
1195 | */ | |
ba9aa839 | 1196 | if (work->for_kupdate) { |
0dc83bd3 | 1197 | oldest_jif = jiffies - |
ba9aa839 | 1198 | msecs_to_jiffies(dirty_expire_interval * 10); |
1bc36b64 | 1199 | } else if (work->for_background) |
0dc83bd3 | 1200 | oldest_jif = jiffies; |
028c2dd1 | 1201 | |
d46db3d5 | 1202 | trace_writeback_start(wb->bdi, work); |
e8dfc305 | 1203 | if (list_empty(&wb->b_io)) |
ad4e38dd | 1204 | queue_io(wb, work); |
83ba7b07 | 1205 | if (work->sb) |
d46db3d5 | 1206 | progress = writeback_sb_inodes(work->sb, wb, work); |
edadfb10 | 1207 | else |
d46db3d5 WF |
1208 | progress = __writeback_inodes_wb(wb, work); |
1209 | trace_writeback_written(wb->bdi, work); | |
028c2dd1 | 1210 | |
e98be2d5 | 1211 | wb_update_bandwidth(wb, wb_start); |
03ba3782 JA |
1212 | |
1213 | /* | |
e6fb6da2 WF |
1214 | * Did we write something? Try for more |
1215 | * | |
1216 | * Dirty inodes are moved to b_io for writeback in batches. | |
1217 | * The completion of the current batch does not necessarily | |
1218 | * mean the overall work is done. So we keep looping as long | |
1219 | * as made some progress on cleaning pages or inodes. | |
03ba3782 | 1220 | */ |
d46db3d5 | 1221 | if (progress) |
71fd05a8 JA |
1222 | continue; |
1223 | /* | |
e6fb6da2 | 1224 | * No more inodes for IO, bail |
71fd05a8 | 1225 | */ |
b7a2441f | 1226 | if (list_empty(&wb->b_more_io)) |
03ba3782 | 1227 | break; |
71fd05a8 JA |
1228 | /* |
1229 | * Nothing written. Wait for some inode to | |
1230 | * become available for writeback. Otherwise | |
1231 | * we'll just busyloop. | |
1232 | */ | |
71fd05a8 | 1233 | if (!list_empty(&wb->b_more_io)) { |
d46db3d5 | 1234 | trace_writeback_wait(wb->bdi, work); |
7ccf19a8 | 1235 | inode = wb_inode(wb->b_more_io.prev); |
250df6ed | 1236 | spin_lock(&inode->i_lock); |
f0d07b7f | 1237 | spin_unlock(&wb->list_lock); |
169ebd90 JK |
1238 | /* This function drops i_lock... */ |
1239 | inode_sleep_on_writeback(inode); | |
f0d07b7f | 1240 | spin_lock(&wb->list_lock); |
03ba3782 JA |
1241 | } |
1242 | } | |
e8dfc305 | 1243 | spin_unlock(&wb->list_lock); |
03ba3782 | 1244 | |
d46db3d5 | 1245 | return nr_pages - work->nr_pages; |
03ba3782 JA |
1246 | } |
1247 | ||
1248 | /* | |
83ba7b07 | 1249 | * Return the next wb_writeback_work struct that hasn't been processed yet. |
03ba3782 | 1250 | */ |
f0054bb1 | 1251 | static struct wb_writeback_work *get_next_work_item(struct bdi_writeback *wb) |
03ba3782 | 1252 | { |
83ba7b07 | 1253 | struct wb_writeback_work *work = NULL; |
03ba3782 | 1254 | |
f0054bb1 TH |
1255 | spin_lock_bh(&wb->work_lock); |
1256 | if (!list_empty(&wb->work_list)) { | |
1257 | work = list_entry(wb->work_list.next, | |
83ba7b07 CH |
1258 | struct wb_writeback_work, list); |
1259 | list_del_init(&work->list); | |
03ba3782 | 1260 | } |
f0054bb1 | 1261 | spin_unlock_bh(&wb->work_lock); |
83ba7b07 | 1262 | return work; |
03ba3782 JA |
1263 | } |
1264 | ||
cdf01dd5 LT |
1265 | /* |
1266 | * Add in the number of potentially dirty inodes, because each inode | |
1267 | * write can dirty pagecache in the underlying blockdev. | |
1268 | */ | |
1269 | static unsigned long get_nr_dirty_pages(void) | |
1270 | { | |
1271 | return global_page_state(NR_FILE_DIRTY) + | |
1272 | global_page_state(NR_UNSTABLE_NFS) + | |
1273 | get_nr_dirty_inodes(); | |
1274 | } | |
1275 | ||
6585027a JK |
1276 | static long wb_check_background_flush(struct bdi_writeback *wb) |
1277 | { | |
aa661bbe | 1278 | if (wb_over_bg_thresh(wb)) { |
6585027a JK |
1279 | |
1280 | struct wb_writeback_work work = { | |
1281 | .nr_pages = LONG_MAX, | |
1282 | .sync_mode = WB_SYNC_NONE, | |
1283 | .for_background = 1, | |
1284 | .range_cyclic = 1, | |
0e175a18 | 1285 | .reason = WB_REASON_BACKGROUND, |
6585027a JK |
1286 | }; |
1287 | ||
1288 | return wb_writeback(wb, &work); | |
1289 | } | |
1290 | ||
1291 | return 0; | |
1292 | } | |
1293 | ||
03ba3782 JA |
1294 | static long wb_check_old_data_flush(struct bdi_writeback *wb) |
1295 | { | |
1296 | unsigned long expired; | |
1297 | long nr_pages; | |
1298 | ||
69b62d01 JA |
1299 | /* |
1300 | * When set to zero, disable periodic writeback | |
1301 | */ | |
1302 | if (!dirty_writeback_interval) | |
1303 | return 0; | |
1304 | ||
03ba3782 JA |
1305 | expired = wb->last_old_flush + |
1306 | msecs_to_jiffies(dirty_writeback_interval * 10); | |
1307 | if (time_before(jiffies, expired)) | |
1308 | return 0; | |
1309 | ||
1310 | wb->last_old_flush = jiffies; | |
cdf01dd5 | 1311 | nr_pages = get_nr_dirty_pages(); |
03ba3782 | 1312 | |
c4a77a6c | 1313 | if (nr_pages) { |
83ba7b07 | 1314 | struct wb_writeback_work work = { |
c4a77a6c JA |
1315 | .nr_pages = nr_pages, |
1316 | .sync_mode = WB_SYNC_NONE, | |
1317 | .for_kupdate = 1, | |
1318 | .range_cyclic = 1, | |
0e175a18 | 1319 | .reason = WB_REASON_PERIODIC, |
c4a77a6c JA |
1320 | }; |
1321 | ||
83ba7b07 | 1322 | return wb_writeback(wb, &work); |
c4a77a6c | 1323 | } |
03ba3782 JA |
1324 | |
1325 | return 0; | |
1326 | } | |
1327 | ||
1328 | /* | |
1329 | * Retrieve work items and do the writeback they describe | |
1330 | */ | |
25d130ba | 1331 | static long wb_do_writeback(struct bdi_writeback *wb) |
03ba3782 | 1332 | { |
83ba7b07 | 1333 | struct wb_writeback_work *work; |
c4a77a6c | 1334 | long wrote = 0; |
03ba3782 | 1335 | |
4452226e | 1336 | set_bit(WB_writeback_running, &wb->state); |
f0054bb1 | 1337 | while ((work = get_next_work_item(wb)) != NULL) { |
cc395d7f | 1338 | struct wb_completion *done = work->done; |
98754bf7 | 1339 | bool need_wake_up = false; |
03ba3782 | 1340 | |
f0054bb1 | 1341 | trace_writeback_exec(wb->bdi, work); |
455b2864 | 1342 | |
83ba7b07 | 1343 | wrote += wb_writeback(wb, work); |
03ba3782 | 1344 | |
98754bf7 TH |
1345 | if (work->single_wait) { |
1346 | WARN_ON_ONCE(work->auto_free); | |
1347 | /* paired w/ rmb in wb_wait_for_single_work() */ | |
1348 | smp_wmb(); | |
1349 | work->single_done = 1; | |
1350 | need_wake_up = true; | |
1351 | } else if (work->auto_free) { | |
83ba7b07 | 1352 | kfree(work); |
98754bf7 TH |
1353 | } |
1354 | ||
cc395d7f | 1355 | if (done && atomic_dec_and_test(&done->cnt)) |
98754bf7 TH |
1356 | need_wake_up = true; |
1357 | ||
1358 | if (need_wake_up) | |
cc395d7f | 1359 | wake_up_all(&wb->bdi->wb_waitq); |
03ba3782 JA |
1360 | } |
1361 | ||
1362 | /* | |
1363 | * Check for periodic writeback, kupdated() style | |
1364 | */ | |
1365 | wrote += wb_check_old_data_flush(wb); | |
6585027a | 1366 | wrote += wb_check_background_flush(wb); |
4452226e | 1367 | clear_bit(WB_writeback_running, &wb->state); |
03ba3782 JA |
1368 | |
1369 | return wrote; | |
1370 | } | |
1371 | ||
1372 | /* | |
1373 | * Handle writeback of dirty data for the device backed by this bdi. Also | |
839a8e86 | 1374 | * reschedules periodically and does kupdated style flushing. |
03ba3782 | 1375 | */ |
f0054bb1 | 1376 | void wb_workfn(struct work_struct *work) |
03ba3782 | 1377 | { |
839a8e86 TH |
1378 | struct bdi_writeback *wb = container_of(to_delayed_work(work), |
1379 | struct bdi_writeback, dwork); | |
03ba3782 JA |
1380 | long pages_written; |
1381 | ||
f0054bb1 | 1382 | set_worker_desc("flush-%s", dev_name(wb->bdi->dev)); |
766f9164 | 1383 | current->flags |= PF_SWAPWRITE; |
455b2864 | 1384 | |
839a8e86 | 1385 | if (likely(!current_is_workqueue_rescuer() || |
4452226e | 1386 | !test_bit(WB_registered, &wb->state))) { |
6467716a | 1387 | /* |
f0054bb1 | 1388 | * The normal path. Keep writing back @wb until its |
839a8e86 | 1389 | * work_list is empty. Note that this path is also taken |
f0054bb1 | 1390 | * if @wb is shutting down even when we're running off the |
839a8e86 | 1391 | * rescuer as work_list needs to be drained. |
6467716a | 1392 | */ |
839a8e86 | 1393 | do { |
25d130ba | 1394 | pages_written = wb_do_writeback(wb); |
839a8e86 | 1395 | trace_writeback_pages_written(pages_written); |
f0054bb1 | 1396 | } while (!list_empty(&wb->work_list)); |
839a8e86 TH |
1397 | } else { |
1398 | /* | |
1399 | * bdi_wq can't get enough workers and we're running off | |
1400 | * the emergency worker. Don't hog it. Hopefully, 1024 is | |
1401 | * enough for efficient IO. | |
1402 | */ | |
f0054bb1 | 1403 | pages_written = writeback_inodes_wb(wb, 1024, |
839a8e86 | 1404 | WB_REASON_FORKER_THREAD); |
455b2864 | 1405 | trace_writeback_pages_written(pages_written); |
03ba3782 JA |
1406 | } |
1407 | ||
f0054bb1 | 1408 | if (!list_empty(&wb->work_list)) |
6ca738d6 DB |
1409 | mod_delayed_work(bdi_wq, &wb->dwork, 0); |
1410 | else if (wb_has_dirty_io(wb) && dirty_writeback_interval) | |
f0054bb1 | 1411 | wb_wakeup_delayed(wb); |
455b2864 | 1412 | |
839a8e86 | 1413 | current->flags &= ~PF_SWAPWRITE; |
03ba3782 JA |
1414 | } |
1415 | ||
1416 | /* | |
b8c2f347 CH |
1417 | * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back |
1418 | * the whole world. | |
03ba3782 | 1419 | */ |
0e175a18 | 1420 | void wakeup_flusher_threads(long nr_pages, enum wb_reason reason) |
03ba3782 | 1421 | { |
b8c2f347 | 1422 | struct backing_dev_info *bdi; |
03ba3782 | 1423 | |
47df3dde JK |
1424 | if (!nr_pages) |
1425 | nr_pages = get_nr_dirty_pages(); | |
03ba3782 | 1426 | |
b8c2f347 | 1427 | rcu_read_lock(); |
f2b65121 TH |
1428 | list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { |
1429 | struct bdi_writeback *wb; | |
1430 | struct wb_iter iter; | |
1431 | ||
1432 | if (!bdi_has_dirty_io(bdi)) | |
1433 | continue; | |
1434 | ||
1435 | bdi_for_each_wb(wb, bdi, &iter, 0) | |
1436 | wb_start_writeback(wb, wb_split_bdi_pages(wb, nr_pages), | |
1437 | false, reason); | |
1438 | } | |
cfc4ba53 | 1439 | rcu_read_unlock(); |
1da177e4 LT |
1440 | } |
1441 | ||
a2f48706 TT |
1442 | /* |
1443 | * Wake up bdi's periodically to make sure dirtytime inodes gets | |
1444 | * written back periodically. We deliberately do *not* check the | |
1445 | * b_dirtytime list in wb_has_dirty_io(), since this would cause the | |
1446 | * kernel to be constantly waking up once there are any dirtytime | |
1447 | * inodes on the system. So instead we define a separate delayed work | |
1448 | * function which gets called much more rarely. (By default, only | |
1449 | * once every 12 hours.) | |
1450 | * | |
1451 | * If there is any other write activity going on in the file system, | |
1452 | * this function won't be necessary. But if the only thing that has | |
1453 | * happened on the file system is a dirtytime inode caused by an atime | |
1454 | * update, we need this infrastructure below to make sure that inode | |
1455 | * eventually gets pushed out to disk. | |
1456 | */ | |
1457 | static void wakeup_dirtytime_writeback(struct work_struct *w); | |
1458 | static DECLARE_DELAYED_WORK(dirtytime_work, wakeup_dirtytime_writeback); | |
1459 | ||
1460 | static void wakeup_dirtytime_writeback(struct work_struct *w) | |
1461 | { | |
1462 | struct backing_dev_info *bdi; | |
1463 | ||
1464 | rcu_read_lock(); | |
1465 | list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { | |
001fe6f6 TH |
1466 | struct bdi_writeback *wb; |
1467 | struct wb_iter iter; | |
1468 | ||
1469 | bdi_for_each_wb(wb, bdi, &iter, 0) | |
1470 | if (!list_empty(&bdi->wb.b_dirty_time)) | |
1471 | wb_wakeup(&bdi->wb); | |
a2f48706 TT |
1472 | } |
1473 | rcu_read_unlock(); | |
1474 | schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ); | |
1475 | } | |
1476 | ||
1477 | static int __init start_dirtytime_writeback(void) | |
1478 | { | |
1479 | schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ); | |
1480 | return 0; | |
1481 | } | |
1482 | __initcall(start_dirtytime_writeback); | |
1483 | ||
1efff914 TT |
1484 | int dirtytime_interval_handler(struct ctl_table *table, int write, |
1485 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
1486 | { | |
1487 | int ret; | |
1488 | ||
1489 | ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); | |
1490 | if (ret == 0 && write) | |
1491 | mod_delayed_work(system_wq, &dirtytime_work, 0); | |
1492 | return ret; | |
1493 | } | |
1494 | ||
03ba3782 JA |
1495 | static noinline void block_dump___mark_inode_dirty(struct inode *inode) |
1496 | { | |
1497 | if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { | |
1498 | struct dentry *dentry; | |
1499 | const char *name = "?"; | |
1500 | ||
1501 | dentry = d_find_alias(inode); | |
1502 | if (dentry) { | |
1503 | spin_lock(&dentry->d_lock); | |
1504 | name = (const char *) dentry->d_name.name; | |
1505 | } | |
1506 | printk(KERN_DEBUG | |
1507 | "%s(%d): dirtied inode %lu (%s) on %s\n", | |
1508 | current->comm, task_pid_nr(current), inode->i_ino, | |
1509 | name, inode->i_sb->s_id); | |
1510 | if (dentry) { | |
1511 | spin_unlock(&dentry->d_lock); | |
1512 | dput(dentry); | |
1513 | } | |
1514 | } | |
1515 | } | |
1516 | ||
1517 | /** | |
1518 | * __mark_inode_dirty - internal function | |
1519 | * @inode: inode to mark | |
1520 | * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) | |
1521 | * Mark an inode as dirty. Callers should use mark_inode_dirty or | |
1522 | * mark_inode_dirty_sync. | |
1da177e4 | 1523 | * |
03ba3782 JA |
1524 | * Put the inode on the super block's dirty list. |
1525 | * | |
1526 | * CAREFUL! We mark it dirty unconditionally, but move it onto the | |
1527 | * dirty list only if it is hashed or if it refers to a blockdev. | |
1528 | * If it was not hashed, it will never be added to the dirty list | |
1529 | * even if it is later hashed, as it will have been marked dirty already. | |
1530 | * | |
1531 | * In short, make sure you hash any inodes _before_ you start marking | |
1532 | * them dirty. | |
1da177e4 | 1533 | * |
03ba3782 JA |
1534 | * Note that for blockdevs, inode->dirtied_when represents the dirtying time of |
1535 | * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of | |
1536 | * the kernel-internal blockdev inode represents the dirtying time of the | |
1537 | * blockdev's pages. This is why for I_DIRTY_PAGES we always use | |
1538 | * page->mapping->host, so the page-dirtying time is recorded in the internal | |
1539 | * blockdev inode. | |
1da177e4 | 1540 | */ |
0ae45f63 | 1541 | #define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC) |
03ba3782 | 1542 | void __mark_inode_dirty(struct inode *inode, int flags) |
1da177e4 | 1543 | { |
03ba3782 | 1544 | struct super_block *sb = inode->i_sb; |
0ae45f63 TT |
1545 | int dirtytime; |
1546 | ||
1547 | trace_writeback_mark_inode_dirty(inode, flags); | |
1da177e4 | 1548 | |
03ba3782 JA |
1549 | /* |
1550 | * Don't do this for I_DIRTY_PAGES - that doesn't actually | |
1551 | * dirty the inode itself | |
1552 | */ | |
0ae45f63 | 1553 | if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC | I_DIRTY_TIME)) { |
9fb0a7da TH |
1554 | trace_writeback_dirty_inode_start(inode, flags); |
1555 | ||
03ba3782 | 1556 | if (sb->s_op->dirty_inode) |
aa385729 | 1557 | sb->s_op->dirty_inode(inode, flags); |
9fb0a7da TH |
1558 | |
1559 | trace_writeback_dirty_inode(inode, flags); | |
03ba3782 | 1560 | } |
0ae45f63 TT |
1561 | if (flags & I_DIRTY_INODE) |
1562 | flags &= ~I_DIRTY_TIME; | |
1563 | dirtytime = flags & I_DIRTY_TIME; | |
03ba3782 JA |
1564 | |
1565 | /* | |
9c6ac78e TH |
1566 | * Paired with smp_mb() in __writeback_single_inode() for the |
1567 | * following lockless i_state test. See there for details. | |
03ba3782 JA |
1568 | */ |
1569 | smp_mb(); | |
1570 | ||
0ae45f63 TT |
1571 | if (((inode->i_state & flags) == flags) || |
1572 | (dirtytime && (inode->i_state & I_DIRTY_INODE))) | |
03ba3782 JA |
1573 | return; |
1574 | ||
1575 | if (unlikely(block_dump)) | |
1576 | block_dump___mark_inode_dirty(inode); | |
1577 | ||
250df6ed | 1578 | spin_lock(&inode->i_lock); |
0ae45f63 TT |
1579 | if (dirtytime && (inode->i_state & I_DIRTY_INODE)) |
1580 | goto out_unlock_inode; | |
03ba3782 JA |
1581 | if ((inode->i_state & flags) != flags) { |
1582 | const int was_dirty = inode->i_state & I_DIRTY; | |
1583 | ||
52ebea74 TH |
1584 | inode_attach_wb(inode, NULL); |
1585 | ||
0ae45f63 TT |
1586 | if (flags & I_DIRTY_INODE) |
1587 | inode->i_state &= ~I_DIRTY_TIME; | |
03ba3782 JA |
1588 | inode->i_state |= flags; |
1589 | ||
1590 | /* | |
1591 | * If the inode is being synced, just update its dirty state. | |
1592 | * The unlocker will place the inode on the appropriate | |
1593 | * superblock list, based upon its state. | |
1594 | */ | |
1595 | if (inode->i_state & I_SYNC) | |
250df6ed | 1596 | goto out_unlock_inode; |
03ba3782 JA |
1597 | |
1598 | /* | |
1599 | * Only add valid (hashed) inodes to the superblock's | |
1600 | * dirty list. Add blockdev inodes as well. | |
1601 | */ | |
1602 | if (!S_ISBLK(inode->i_mode)) { | |
1d3382cb | 1603 | if (inode_unhashed(inode)) |
250df6ed | 1604 | goto out_unlock_inode; |
03ba3782 | 1605 | } |
a4ffdde6 | 1606 | if (inode->i_state & I_FREEING) |
250df6ed | 1607 | goto out_unlock_inode; |
03ba3782 JA |
1608 | |
1609 | /* | |
1610 | * If the inode was already on b_dirty/b_io/b_more_io, don't | |
1611 | * reposition it (that would break b_dirty time-ordering). | |
1612 | */ | |
1613 | if (!was_dirty) { | |
0747259d | 1614 | struct bdi_writeback *wb = inode_to_wb(inode); |
d6c10f1f | 1615 | struct list_head *dirty_list; |
a66979ab | 1616 | bool wakeup_bdi = false; |
253c34e9 | 1617 | |
146d7009 | 1618 | spin_unlock(&inode->i_lock); |
0747259d | 1619 | spin_lock(&wb->list_lock); |
253c34e9 | 1620 | |
0747259d TH |
1621 | WARN(bdi_cap_writeback_dirty(wb->bdi) && |
1622 | !test_bit(WB_registered, &wb->state), | |
1623 | "bdi-%s not registered\n", wb->bdi->name); | |
03ba3782 JA |
1624 | |
1625 | inode->dirtied_when = jiffies; | |
a2f48706 TT |
1626 | if (dirtytime) |
1627 | inode->dirtied_time_when = jiffies; | |
d6c10f1f | 1628 | |
a2f48706 | 1629 | if (inode->i_state & (I_DIRTY_INODE | I_DIRTY_PAGES)) |
0747259d | 1630 | dirty_list = &wb->b_dirty; |
a2f48706 | 1631 | else |
0747259d | 1632 | dirty_list = &wb->b_dirty_time; |
d6c10f1f | 1633 | |
0747259d | 1634 | wakeup_bdi = inode_wb_list_move_locked(inode, wb, |
d6c10f1f TH |
1635 | dirty_list); |
1636 | ||
0747259d | 1637 | spin_unlock(&wb->list_lock); |
0ae45f63 | 1638 | trace_writeback_dirty_inode_enqueue(inode); |
a66979ab | 1639 | |
d6c10f1f TH |
1640 | /* |
1641 | * If this is the first dirty inode for this bdi, | |
1642 | * we have to wake-up the corresponding bdi thread | |
1643 | * to make sure background write-back happens | |
1644 | * later. | |
1645 | */ | |
0747259d TH |
1646 | if (bdi_cap_writeback_dirty(wb->bdi) && wakeup_bdi) |
1647 | wb_wakeup_delayed(wb); | |
a66979ab | 1648 | return; |
1da177e4 | 1649 | } |
1da177e4 | 1650 | } |
250df6ed DC |
1651 | out_unlock_inode: |
1652 | spin_unlock(&inode->i_lock); | |
253c34e9 | 1653 | |
03ba3782 JA |
1654 | } |
1655 | EXPORT_SYMBOL(__mark_inode_dirty); | |
1656 | ||
b6e51316 | 1657 | static void wait_sb_inodes(struct super_block *sb) |
03ba3782 JA |
1658 | { |
1659 | struct inode *inode, *old_inode = NULL; | |
1660 | ||
1661 | /* | |
1662 | * We need to be protected against the filesystem going from | |
1663 | * r/o to r/w or vice versa. | |
1664 | */ | |
b6e51316 | 1665 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
03ba3782 | 1666 | |
55fa6091 | 1667 | spin_lock(&inode_sb_list_lock); |
03ba3782 JA |
1668 | |
1669 | /* | |
1670 | * Data integrity sync. Must wait for all pages under writeback, | |
1671 | * because there may have been pages dirtied before our sync | |
1672 | * call, but which had writeout started before we write it out. | |
1673 | * In which case, the inode may not be on the dirty list, but | |
1674 | * we still have to wait for that writeout. | |
1675 | */ | |
b6e51316 | 1676 | list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { |
250df6ed | 1677 | struct address_space *mapping = inode->i_mapping; |
03ba3782 | 1678 | |
250df6ed DC |
1679 | spin_lock(&inode->i_lock); |
1680 | if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || | |
1681 | (mapping->nrpages == 0)) { | |
1682 | spin_unlock(&inode->i_lock); | |
03ba3782 | 1683 | continue; |
250df6ed | 1684 | } |
03ba3782 | 1685 | __iget(inode); |
250df6ed | 1686 | spin_unlock(&inode->i_lock); |
55fa6091 DC |
1687 | spin_unlock(&inode_sb_list_lock); |
1688 | ||
03ba3782 | 1689 | /* |
55fa6091 DC |
1690 | * We hold a reference to 'inode' so it couldn't have been |
1691 | * removed from s_inodes list while we dropped the | |
1692 | * inode_sb_list_lock. We cannot iput the inode now as we can | |
1693 | * be holding the last reference and we cannot iput it under | |
1694 | * inode_sb_list_lock. So we keep the reference and iput it | |
1695 | * later. | |
03ba3782 JA |
1696 | */ |
1697 | iput(old_inode); | |
1698 | old_inode = inode; | |
1699 | ||
1700 | filemap_fdatawait(mapping); | |
1701 | ||
1702 | cond_resched(); | |
1703 | ||
55fa6091 | 1704 | spin_lock(&inode_sb_list_lock); |
03ba3782 | 1705 | } |
55fa6091 | 1706 | spin_unlock(&inode_sb_list_lock); |
03ba3782 | 1707 | iput(old_inode); |
1da177e4 LT |
1708 | } |
1709 | ||
f30a7d0c TH |
1710 | static void __writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr, |
1711 | enum wb_reason reason, bool skip_if_busy) | |
1da177e4 | 1712 | { |
cc395d7f | 1713 | DEFINE_WB_COMPLETION_ONSTACK(done); |
83ba7b07 | 1714 | struct wb_writeback_work work = { |
6e6938b6 WF |
1715 | .sb = sb, |
1716 | .sync_mode = WB_SYNC_NONE, | |
1717 | .tagged_writepages = 1, | |
1718 | .done = &done, | |
1719 | .nr_pages = nr, | |
0e175a18 | 1720 | .reason = reason, |
3c4d7165 | 1721 | }; |
e7972912 | 1722 | struct backing_dev_info *bdi = sb->s_bdi; |
d8a8559c | 1723 | |
e7972912 | 1724 | if (!bdi_has_dirty_io(bdi) || bdi == &noop_backing_dev_info) |
6eedc701 | 1725 | return; |
cf37e972 | 1726 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
f30a7d0c | 1727 | |
db125360 | 1728 | bdi_split_work_to_wbs(sb->s_bdi, &work, skip_if_busy); |
cc395d7f | 1729 | wb_wait_for_completion(bdi, &done); |
e913fc82 | 1730 | } |
f30a7d0c TH |
1731 | |
1732 | /** | |
1733 | * writeback_inodes_sb_nr - writeback dirty inodes from given super_block | |
1734 | * @sb: the superblock | |
1735 | * @nr: the number of pages to write | |
1736 | * @reason: reason why some writeback work initiated | |
1737 | * | |
1738 | * Start writeback on some inodes on this super_block. No guarantees are made | |
1739 | * on how many (if any) will be written, and this function does not wait | |
1740 | * for IO completion of submitted IO. | |
1741 | */ | |
1742 | void writeback_inodes_sb_nr(struct super_block *sb, | |
1743 | unsigned long nr, | |
1744 | enum wb_reason reason) | |
1745 | { | |
1746 | __writeback_inodes_sb_nr(sb, nr, reason, false); | |
1747 | } | |
3259f8be CM |
1748 | EXPORT_SYMBOL(writeback_inodes_sb_nr); |
1749 | ||
1750 | /** | |
1751 | * writeback_inodes_sb - writeback dirty inodes from given super_block | |
1752 | * @sb: the superblock | |
786228ab | 1753 | * @reason: reason why some writeback work was initiated |
3259f8be CM |
1754 | * |
1755 | * Start writeback on some inodes on this super_block. No guarantees are made | |
1756 | * on how many (if any) will be written, and this function does not wait | |
1757 | * for IO completion of submitted IO. | |
1758 | */ | |
0e175a18 | 1759 | void writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) |
3259f8be | 1760 | { |
0e175a18 | 1761 | return writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); |
3259f8be | 1762 | } |
0e3c9a22 | 1763 | EXPORT_SYMBOL(writeback_inodes_sb); |
e913fc82 | 1764 | |
17bd55d0 | 1765 | /** |
10ee27a0 | 1766 | * try_to_writeback_inodes_sb_nr - try to start writeback if none underway |
17bd55d0 | 1767 | * @sb: the superblock |
10ee27a0 MX |
1768 | * @nr: the number of pages to write |
1769 | * @reason: the reason of writeback | |
17bd55d0 | 1770 | * |
10ee27a0 | 1771 | * Invoke writeback_inodes_sb_nr if no writeback is currently underway. |
17bd55d0 ES |
1772 | * Returns 1 if writeback was started, 0 if not. |
1773 | */ | |
f30a7d0c TH |
1774 | bool try_to_writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr, |
1775 | enum wb_reason reason) | |
17bd55d0 | 1776 | { |
10ee27a0 | 1777 | if (!down_read_trylock(&sb->s_umount)) |
f30a7d0c | 1778 | return false; |
10ee27a0 | 1779 | |
f30a7d0c | 1780 | __writeback_inodes_sb_nr(sb, nr, reason, true); |
10ee27a0 | 1781 | up_read(&sb->s_umount); |
f30a7d0c | 1782 | return true; |
17bd55d0 | 1783 | } |
10ee27a0 | 1784 | EXPORT_SYMBOL(try_to_writeback_inodes_sb_nr); |
17bd55d0 | 1785 | |
3259f8be | 1786 | /** |
10ee27a0 | 1787 | * try_to_writeback_inodes_sb - try to start writeback if none underway |
3259f8be | 1788 | * @sb: the superblock |
786228ab | 1789 | * @reason: reason why some writeback work was initiated |
3259f8be | 1790 | * |
10ee27a0 | 1791 | * Implement by try_to_writeback_inodes_sb_nr() |
3259f8be CM |
1792 | * Returns 1 if writeback was started, 0 if not. |
1793 | */ | |
f30a7d0c | 1794 | bool try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) |
3259f8be | 1795 | { |
10ee27a0 | 1796 | return try_to_writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); |
3259f8be | 1797 | } |
10ee27a0 | 1798 | EXPORT_SYMBOL(try_to_writeback_inodes_sb); |
3259f8be | 1799 | |
d8a8559c JA |
1800 | /** |
1801 | * sync_inodes_sb - sync sb inode pages | |
0dc83bd3 | 1802 | * @sb: the superblock |
d8a8559c JA |
1803 | * |
1804 | * This function writes and waits on any dirty inode belonging to this | |
0dc83bd3 | 1805 | * super_block. |
d8a8559c | 1806 | */ |
0dc83bd3 | 1807 | void sync_inodes_sb(struct super_block *sb) |
d8a8559c | 1808 | { |
cc395d7f | 1809 | DEFINE_WB_COMPLETION_ONSTACK(done); |
83ba7b07 | 1810 | struct wb_writeback_work work = { |
3c4d7165 CH |
1811 | .sb = sb, |
1812 | .sync_mode = WB_SYNC_ALL, | |
1813 | .nr_pages = LONG_MAX, | |
1814 | .range_cyclic = 0, | |
83ba7b07 | 1815 | .done = &done, |
0e175a18 | 1816 | .reason = WB_REASON_SYNC, |
7747bd4b | 1817 | .for_sync = 1, |
3c4d7165 | 1818 | }; |
e7972912 | 1819 | struct backing_dev_info *bdi = sb->s_bdi; |
3c4d7165 | 1820 | |
6eedc701 | 1821 | /* Nothing to do? */ |
e7972912 | 1822 | if (!bdi_has_dirty_io(bdi) || bdi == &noop_backing_dev_info) |
6eedc701 | 1823 | return; |
cf37e972 CH |
1824 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
1825 | ||
db125360 | 1826 | bdi_split_work_to_wbs(bdi, &work, false); |
cc395d7f | 1827 | wb_wait_for_completion(bdi, &done); |
83ba7b07 | 1828 | |
b6e51316 | 1829 | wait_sb_inodes(sb); |
1da177e4 | 1830 | } |
d8a8559c | 1831 | EXPORT_SYMBOL(sync_inodes_sb); |
1da177e4 | 1832 | |
1da177e4 | 1833 | /** |
7f04c26d AA |
1834 | * write_inode_now - write an inode to disk |
1835 | * @inode: inode to write to disk | |
1836 | * @sync: whether the write should be synchronous or not | |
1837 | * | |
1838 | * This function commits an inode to disk immediately if it is dirty. This is | |
1839 | * primarily needed by knfsd. | |
1da177e4 | 1840 | * |
7f04c26d | 1841 | * The caller must either have a ref on the inode or must have set I_WILL_FREE. |
1da177e4 | 1842 | */ |
1da177e4 LT |
1843 | int write_inode_now(struct inode *inode, int sync) |
1844 | { | |
f758eeab | 1845 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; |
1da177e4 LT |
1846 | struct writeback_control wbc = { |
1847 | .nr_to_write = LONG_MAX, | |
18914b18 | 1848 | .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, |
111ebb6e OH |
1849 | .range_start = 0, |
1850 | .range_end = LLONG_MAX, | |
1da177e4 LT |
1851 | }; |
1852 | ||
1853 | if (!mapping_cap_writeback_dirty(inode->i_mapping)) | |
49364ce2 | 1854 | wbc.nr_to_write = 0; |
1da177e4 LT |
1855 | |
1856 | might_sleep(); | |
4f8ad655 | 1857 | return writeback_single_inode(inode, wb, &wbc); |
1da177e4 LT |
1858 | } |
1859 | EXPORT_SYMBOL(write_inode_now); | |
1860 | ||
1861 | /** | |
1862 | * sync_inode - write an inode and its pages to disk. | |
1863 | * @inode: the inode to sync | |
1864 | * @wbc: controls the writeback mode | |
1865 | * | |
1866 | * sync_inode() will write an inode and its pages to disk. It will also | |
1867 | * correctly update the inode on its superblock's dirty inode lists and will | |
1868 | * update inode->i_state. | |
1869 | * | |
1870 | * The caller must have a ref on the inode. | |
1871 | */ | |
1872 | int sync_inode(struct inode *inode, struct writeback_control *wbc) | |
1873 | { | |
4f8ad655 | 1874 | return writeback_single_inode(inode, &inode_to_bdi(inode)->wb, wbc); |
1da177e4 LT |
1875 | } |
1876 | EXPORT_SYMBOL(sync_inode); | |
c3765016 CH |
1877 | |
1878 | /** | |
c691b9d9 | 1879 | * sync_inode_metadata - write an inode to disk |
c3765016 CH |
1880 | * @inode: the inode to sync |
1881 | * @wait: wait for I/O to complete. | |
1882 | * | |
c691b9d9 | 1883 | * Write an inode to disk and adjust its dirty state after completion. |
c3765016 CH |
1884 | * |
1885 | * Note: only writes the actual inode, no associated data or other metadata. | |
1886 | */ | |
1887 | int sync_inode_metadata(struct inode *inode, int wait) | |
1888 | { | |
1889 | struct writeback_control wbc = { | |
1890 | .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_NONE, | |
1891 | .nr_to_write = 0, /* metadata-only */ | |
1892 | }; | |
1893 | ||
1894 | return sync_inode(inode, &wbc); | |
1895 | } | |
1896 | EXPORT_SYMBOL(sync_inode_metadata); |