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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 *
Francois Camie1f8e872008-10-15 22:01:59 -070011 * 10Apr2002 Andrew Morton
Linus Torvalds1da177e2005-04-16 15:20:36 -070012 * Split out of fs/inode.c
13 * Additions for address_space-based writeback
14 */
15
16#include <linux/kernel.h>
Paul Gortmaker630d9c42011-11-16 23:57:37 -050017#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include <linux/spinlock.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090019#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/sched.h>
21#include <linux/fs.h>
22#include <linux/mm.h>
Wu Fengguangbc31b862012-01-07 20:41:55 -060023#include <linux/pagemap.h>
Jens Axboe03ba3782009-09-09 09:08:54 +020024#include <linux/kthread.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025#include <linux/writeback.h>
26#include <linux/blkdev.h>
27#include <linux/backing-dev.h>
Dave Chinner455b2862010-07-07 13:24:06 +100028#include <linux/tracepoint.h>
Al Viro719ea2f2013-09-29 11:24:49 -040029#include <linux/device.h>
Tejun Heo21c63212015-05-28 14:50:49 -040030#include <linux/memcontrol.h>
David Howells07f3f052006-09-30 20:52:18 +020031#include "internal.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070032
Jens Axboed0bceac2009-05-18 08:20:32 +020033/*
Wu Fengguangbc31b862012-01-07 20:41:55 -060034 * 4MB minimal write chunk size
35 */
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +030036#define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_SHIFT - 10))
Wu Fengguangbc31b862012-01-07 20:41:55 -060037
Tejun Heocc395d72015-05-22 17:13:58 -040038struct wb_completion {
39 atomic_t cnt;
40};
41
Wu Fengguangbc31b862012-01-07 20:41:55 -060042/*
Jens Axboec4a77a62009-09-16 15:18:25 +020043 * Passed into wb_writeback(), essentially a subset of writeback_control
44 */
Christoph Hellwig83ba7b02010-07-06 08:59:53 +020045struct wb_writeback_work {
Jens Axboec4a77a62009-09-16 15:18:25 +020046 long nr_pages;
47 struct super_block *sb;
Jan Kara0dc83bd2014-02-21 11:19:04 +010048 unsigned long *older_than_this;
Jens Axboec4a77a62009-09-16 15:18:25 +020049 enum writeback_sync_modes sync_mode;
Wu Fengguang6e6938b2010-06-06 10:38:15 -060050 unsigned int tagged_writepages:1;
H Hartley Sweeten52957fe2010-04-01 20:36:30 -050051 unsigned int for_kupdate:1;
52 unsigned int range_cyclic:1;
53 unsigned int for_background:1;
Dave Chinner7747bd42013-07-02 22:38:35 +100054 unsigned int for_sync:1; /* sync(2) WB_SYNC_ALL writeback */
Tejun Heoac7b19a2015-05-22 17:13:57 -040055 unsigned int auto_free:1; /* free on completion */
Curt Wohlgemuth0e175a12011-10-07 21:54:10 -060056 enum wb_reason reason; /* why was writeback initiated? */
Jens Axboec4a77a62009-09-16 15:18:25 +020057
Jens Axboe8010c3b2009-09-15 20:04:57 +020058 struct list_head list; /* pending work list */
Tejun Heocc395d72015-05-22 17:13:58 -040059 struct wb_completion *done; /* set if the caller waits */
Jens Axboe03ba3782009-09-09 09:08:54 +020060};
61
Theodore Ts'oa2f48702015-03-17 12:23:19 -040062/*
Tejun Heocc395d72015-05-22 17:13:58 -040063 * If one wants to wait for one or more wb_writeback_works, each work's
64 * ->done should be set to a wb_completion defined using the following
65 * macro. Once all work items are issued with wb_queue_work(), the caller
66 * can wait for the completion of all using wb_wait_for_completion(). Work
67 * items which are waited upon aren't freed automatically on completion.
68 */
69#define DEFINE_WB_COMPLETION_ONSTACK(cmpl) \
70 struct wb_completion cmpl = { \
71 .cnt = ATOMIC_INIT(1), \
72 }
73
74
75/*
Theodore Ts'oa2f48702015-03-17 12:23:19 -040076 * If an inode is constantly having its pages dirtied, but then the
77 * updates stop dirtytime_expire_interval seconds in the past, it's
78 * possible for the worst case time between when an inode has its
79 * timestamps updated and when they finally get written out to be two
80 * dirtytime_expire_intervals. We set the default to 12 hours (in
81 * seconds), which means most of the time inodes will have their
82 * timestamps written to disk after 12 hours, but in the worst case a
83 * few inodes might not their timestamps updated for 24 hours.
84 */
85unsigned int dirtytime_expire_interval = 12 * 60 * 60;
86
Nick Piggin7ccf19a2010-10-21 11:49:30 +110087static inline struct inode *wb_inode(struct list_head *head)
88{
Dave Chinnerc7f54082015-03-04 14:07:22 -050089 return list_entry(head, struct inode, i_io_list);
Nick Piggin7ccf19a2010-10-21 11:49:30 +110090}
91
Wu Fengguang15eb77a2012-01-17 11:18:56 -060092/*
93 * Include the creation of the trace points after defining the
94 * wb_writeback_work structure and inline functions so that the definition
95 * remains local to this file.
96 */
97#define CREATE_TRACE_POINTS
98#include <trace/events/writeback.h>
99
Steven Whitehouse774016b2014-02-06 15:47:47 +0000100EXPORT_TRACEPOINT_SYMBOL_GPL(wbc_writepage);
101
Tejun Heod6c10f12015-05-22 17:13:45 -0400102static bool wb_io_lists_populated(struct bdi_writeback *wb)
103{
104 if (wb_has_dirty_io(wb)) {
105 return false;
106 } else {
107 set_bit(WB_has_dirty_io, &wb->state);
Tejun Heo95a46c62015-05-22 17:13:47 -0400108 WARN_ON_ONCE(!wb->avg_write_bandwidth);
Tejun Heo766a9d62015-05-22 17:13:46 -0400109 atomic_long_add(wb->avg_write_bandwidth,
110 &wb->bdi->tot_write_bandwidth);
Tejun Heod6c10f12015-05-22 17:13:45 -0400111 return true;
112 }
113}
114
115static void wb_io_lists_depopulated(struct bdi_writeback *wb)
116{
117 if (wb_has_dirty_io(wb) && list_empty(&wb->b_dirty) &&
Tejun Heo766a9d62015-05-22 17:13:46 -0400118 list_empty(&wb->b_io) && list_empty(&wb->b_more_io)) {
Tejun Heod6c10f12015-05-22 17:13:45 -0400119 clear_bit(WB_has_dirty_io, &wb->state);
Tejun Heo95a46c62015-05-22 17:13:47 -0400120 WARN_ON_ONCE(atomic_long_sub_return(wb->avg_write_bandwidth,
121 &wb->bdi->tot_write_bandwidth) < 0);
Tejun Heo766a9d62015-05-22 17:13:46 -0400122 }
Tejun Heod6c10f12015-05-22 17:13:45 -0400123}
124
125/**
Dave Chinnerc7f54082015-03-04 14:07:22 -0500126 * inode_io_list_move_locked - move an inode onto a bdi_writeback IO list
Tejun Heod6c10f12015-05-22 17:13:45 -0400127 * @inode: inode to be moved
128 * @wb: target bdi_writeback
Wang Longbbbc3c12017-12-05 07:23:19 -0500129 * @head: one of @wb->b_{dirty|io|more_io|dirty_time}
Tejun Heod6c10f12015-05-22 17:13:45 -0400130 *
Dave Chinnerc7f54082015-03-04 14:07:22 -0500131 * Move @inode->i_io_list to @list of @wb and set %WB_has_dirty_io.
Tejun Heod6c10f12015-05-22 17:13:45 -0400132 * Returns %true if @inode is the first occupant of the !dirty_time IO
133 * lists; otherwise, %false.
134 */
Dave Chinnerc7f54082015-03-04 14:07:22 -0500135static bool inode_io_list_move_locked(struct inode *inode,
Tejun Heod6c10f12015-05-22 17:13:45 -0400136 struct bdi_writeback *wb,
137 struct list_head *head)
138{
139 assert_spin_locked(&wb->list_lock);
140
Dave Chinnerc7f54082015-03-04 14:07:22 -0500141 list_move(&inode->i_io_list, head);
Tejun Heod6c10f12015-05-22 17:13:45 -0400142
143 /* dirty_time doesn't count as dirty_io until expiration */
144 if (head != &wb->b_dirty_time)
145 return wb_io_lists_populated(wb);
146
147 wb_io_lists_depopulated(wb);
148 return false;
149}
150
151/**
Dave Chinnerc7f54082015-03-04 14:07:22 -0500152 * inode_io_list_del_locked - remove an inode from its bdi_writeback IO list
Tejun Heod6c10f12015-05-22 17:13:45 -0400153 * @inode: inode to be removed
154 * @wb: bdi_writeback @inode is being removed from
155 *
156 * Remove @inode which may be on one of @wb->b_{dirty|io|more_io} lists and
157 * clear %WB_has_dirty_io if all are empty afterwards.
158 */
Dave Chinnerc7f54082015-03-04 14:07:22 -0500159static void inode_io_list_del_locked(struct inode *inode,
Tejun Heod6c10f12015-05-22 17:13:45 -0400160 struct bdi_writeback *wb)
161{
162 assert_spin_locked(&wb->list_lock);
163
Dave Chinnerc7f54082015-03-04 14:07:22 -0500164 list_del_init(&inode->i_io_list);
Tejun Heod6c10f12015-05-22 17:13:45 -0400165 wb_io_lists_depopulated(wb);
166}
167
Tejun Heof0054bb2015-05-22 17:13:30 -0400168static void wb_wakeup(struct bdi_writeback *wb)
Jan Kara5acda9d2014-04-03 14:46:23 -0700169{
Tejun Heof0054bb2015-05-22 17:13:30 -0400170 spin_lock_bh(&wb->work_lock);
171 if (test_bit(WB_registered, &wb->state))
172 mod_delayed_work(bdi_wq, &wb->dwork, 0);
173 spin_unlock_bh(&wb->work_lock);
Jan Kara5acda9d2014-04-03 14:46:23 -0700174}
175
Tahsin Erdogan4a3a4852017-03-10 12:09:49 -0800176static void finish_writeback_work(struct bdi_writeback *wb,
177 struct wb_writeback_work *work)
178{
179 struct wb_completion *done = work->done;
180
181 if (work->auto_free)
182 kfree(work);
183 if (done && atomic_dec_and_test(&done->cnt))
184 wake_up_all(&wb->bdi->wb_waitq);
185}
186
Tejun Heof0054bb2015-05-22 17:13:30 -0400187static void wb_queue_work(struct bdi_writeback *wb,
188 struct wb_writeback_work *work)
Jan Kara65850272011-01-13 15:45:44 -0800189{
Tejun Heo5634cc22015-08-18 14:54:56 -0700190 trace_writeback_queue(wb, work);
Jan Kara65850272011-01-13 15:45:44 -0800191
Tejun Heocc395d72015-05-22 17:13:58 -0400192 if (work->done)
193 atomic_inc(&work->done->cnt);
Tahsin Erdogan4a3a4852017-03-10 12:09:49 -0800194
195 spin_lock_bh(&wb->work_lock);
196
197 if (test_bit(WB_registered, &wb->state)) {
198 list_add_tail(&work->list, &wb->work_list);
199 mod_delayed_work(bdi_wq, &wb->dwork, 0);
200 } else
201 finish_writeback_work(wb, work);
202
Tejun Heof0054bb2015-05-22 17:13:30 -0400203 spin_unlock_bh(&wb->work_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204}
205
Tejun Heocc395d72015-05-22 17:13:58 -0400206/**
207 * wb_wait_for_completion - wait for completion of bdi_writeback_works
208 * @bdi: bdi work items were issued to
209 * @done: target wb_completion
210 *
211 * Wait for one or more work items issued to @bdi with their ->done field
212 * set to @done, which should have been defined with
213 * DEFINE_WB_COMPLETION_ONSTACK(). This function returns after all such
214 * work items are completed. Work items which are waited upon aren't freed
215 * automatically on completion.
216 */
217static void wb_wait_for_completion(struct backing_dev_info *bdi,
218 struct wb_completion *done)
219{
220 atomic_dec(&done->cnt); /* put down the initial count */
221 wait_event(bdi->wb_waitq, !atomic_read(&done->cnt));
222}
223
Tejun Heo703c2702015-05-22 17:13:44 -0400224#ifdef CONFIG_CGROUP_WRITEBACK
225
Tejun Heo2a814902015-05-28 14:50:51 -0400226/* parameters for foreign inode detection, see wb_detach_inode() */
227#define WB_FRN_TIME_SHIFT 13 /* 1s = 2^13, upto 8 secs w/ 16bit */
228#define WB_FRN_TIME_AVG_SHIFT 3 /* avg = avg * 7/8 + new * 1/8 */
229#define WB_FRN_TIME_CUT_DIV 2 /* ignore rounds < avg / 2 */
230#define WB_FRN_TIME_PERIOD (2 * (1 << WB_FRN_TIME_SHIFT)) /* 2s */
231
232#define WB_FRN_HIST_SLOTS 16 /* inode->i_wb_frn_history is 16bit */
233#define WB_FRN_HIST_UNIT (WB_FRN_TIME_PERIOD / WB_FRN_HIST_SLOTS)
234 /* each slot's duration is 2s / 16 */
235#define WB_FRN_HIST_THR_SLOTS (WB_FRN_HIST_SLOTS / 2)
236 /* if foreign slots >= 8, switch */
237#define WB_FRN_HIST_MAX_SLOTS (WB_FRN_HIST_THR_SLOTS / 2 + 1)
238 /* one round can affect upto 5 slots */
239
Tejun Heoa1a0e232016-02-29 18:28:53 -0500240static atomic_t isw_nr_in_flight = ATOMIC_INIT(0);
241static struct workqueue_struct *isw_wq;
242
Tejun Heo21c63212015-05-28 14:50:49 -0400243void __inode_attach_wb(struct inode *inode, struct page *page)
244{
245 struct backing_dev_info *bdi = inode_to_bdi(inode);
246 struct bdi_writeback *wb = NULL;
247
248 if (inode_cgwb_enabled(inode)) {
249 struct cgroup_subsys_state *memcg_css;
250
251 if (page) {
252 memcg_css = mem_cgroup_css_from_page(page);
253 wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC);
254 } else {
255 /* must pin memcg_css, see wb_get_create() */
256 memcg_css = task_get_css(current, memory_cgrp_id);
257 wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC);
258 css_put(memcg_css);
259 }
260 }
261
262 if (!wb)
263 wb = &bdi->wb;
264
265 /*
266 * There may be multiple instances of this function racing to
267 * update the same inode. Use cmpxchg() to tell the winner.
268 */
269 if (unlikely(cmpxchg(&inode->i_wb, NULL, wb)))
270 wb_put(wb);
271}
272
Tejun Heo703c2702015-05-22 17:13:44 -0400273/**
Tejun Heo87e1d782015-05-28 14:50:52 -0400274 * locked_inode_to_wb_and_lock_list - determine a locked inode's wb and lock it
275 * @inode: inode of interest with i_lock held
276 *
277 * Returns @inode's wb with its list_lock held. @inode->i_lock must be
278 * held on entry and is released on return. The returned wb is guaranteed
279 * to stay @inode's associated wb until its list_lock is released.
280 */
281static struct bdi_writeback *
282locked_inode_to_wb_and_lock_list(struct inode *inode)
283 __releases(&inode->i_lock)
284 __acquires(&wb->list_lock)
285{
286 while (true) {
287 struct bdi_writeback *wb = inode_to_wb(inode);
288
289 /*
290 * inode_to_wb() association is protected by both
291 * @inode->i_lock and @wb->list_lock but list_lock nests
292 * outside i_lock. Drop i_lock and verify that the
293 * association hasn't changed after acquiring list_lock.
294 */
295 wb_get(wb);
296 spin_unlock(&inode->i_lock);
297 spin_lock(&wb->list_lock);
Tejun Heo87e1d782015-05-28 14:50:52 -0400298
Tejun Heoaaa2cac2015-05-28 14:50:55 -0400299 /* i_wb may have changed inbetween, can't use inode_to_wb() */
Tejun Heo614a4e32016-03-18 13:50:03 -0400300 if (likely(wb == inode->i_wb)) {
301 wb_put(wb); /* @inode already has ref */
302 return wb;
303 }
Tejun Heo87e1d782015-05-28 14:50:52 -0400304
305 spin_unlock(&wb->list_lock);
Tejun Heo614a4e32016-03-18 13:50:03 -0400306 wb_put(wb);
Tejun Heo87e1d782015-05-28 14:50:52 -0400307 cpu_relax();
308 spin_lock(&inode->i_lock);
309 }
310}
311
312/**
313 * inode_to_wb_and_lock_list - determine an inode's wb and lock it
314 * @inode: inode of interest
315 *
316 * Same as locked_inode_to_wb_and_lock_list() but @inode->i_lock isn't held
317 * on entry.
318 */
319static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode)
320 __acquires(&wb->list_lock)
321{
322 spin_lock(&inode->i_lock);
323 return locked_inode_to_wb_and_lock_list(inode);
324}
325
Tejun Heo682aa8e2015-05-28 14:50:53 -0400326struct inode_switch_wbs_context {
327 struct inode *inode;
328 struct bdi_writeback *new_wb;
329
330 struct rcu_head rcu_head;
331 struct work_struct work;
332};
333
334static void inode_switch_wbs_work_fn(struct work_struct *work)
335{
336 struct inode_switch_wbs_context *isw =
337 container_of(work, struct inode_switch_wbs_context, work);
338 struct inode *inode = isw->inode;
Tejun Heod10c8092015-05-28 14:50:56 -0400339 struct address_space *mapping = inode->i_mapping;
340 struct bdi_writeback *old_wb = inode->i_wb;
Tejun Heo682aa8e2015-05-28 14:50:53 -0400341 struct bdi_writeback *new_wb = isw->new_wb;
Matthew Wilcox04edf022017-12-04 10:46:23 -0500342 XA_STATE(xas, &mapping->i_pages, 0);
343 struct page *page;
Tejun Heod10c8092015-05-28 14:50:56 -0400344 bool switched = false;
Tejun Heo682aa8e2015-05-28 14:50:53 -0400345
346 /*
347 * By the time control reaches here, RCU grace period has passed
348 * since I_WB_SWITCH assertion and all wb stat update transactions
349 * between unlocked_inode_to_wb_begin/end() are guaranteed to be
Matthew Wilcoxb93b0162018-04-10 16:36:56 -0700350 * synchronizing against the i_pages lock.
Tejun Heod10c8092015-05-28 14:50:56 -0400351 *
Matthew Wilcoxb93b0162018-04-10 16:36:56 -0700352 * Grabbing old_wb->list_lock, inode->i_lock and the i_pages lock
Tejun Heod10c8092015-05-28 14:50:56 -0400353 * gives us exclusion against all wb related operations on @inode
354 * including IO list manipulations and stat updates.
Tejun Heo682aa8e2015-05-28 14:50:53 -0400355 */
Tejun Heod10c8092015-05-28 14:50:56 -0400356 if (old_wb < new_wb) {
357 spin_lock(&old_wb->list_lock);
358 spin_lock_nested(&new_wb->list_lock, SINGLE_DEPTH_NESTING);
359 } else {
360 spin_lock(&new_wb->list_lock);
361 spin_lock_nested(&old_wb->list_lock, SINGLE_DEPTH_NESTING);
362 }
Tejun Heo682aa8e2015-05-28 14:50:53 -0400363 spin_lock(&inode->i_lock);
Matthew Wilcoxb93b0162018-04-10 16:36:56 -0700364 xa_lock_irq(&mapping->i_pages);
Tejun Heo682aa8e2015-05-28 14:50:53 -0400365
Tejun Heod10c8092015-05-28 14:50:56 -0400366 /*
367 * Once I_FREEING is visible under i_lock, the eviction path owns
Dave Chinnerc7f54082015-03-04 14:07:22 -0500368 * the inode and we shouldn't modify ->i_io_list.
Tejun Heod10c8092015-05-28 14:50:56 -0400369 */
370 if (unlikely(inode->i_state & I_FREEING))
371 goto skip_switch;
372
373 /*
374 * Count and transfer stats. Note that PAGECACHE_TAG_DIRTY points
375 * to possibly dirty pages while PAGECACHE_TAG_WRITEBACK points to
Matthew Wilcoxb93b0162018-04-10 16:36:56 -0700376 * pages actually under writeback.
Tejun Heod10c8092015-05-28 14:50:56 -0400377 */
Matthew Wilcox04edf022017-12-04 10:46:23 -0500378 xas_for_each_marked(&xas, page, ULONG_MAX, PAGECACHE_TAG_DIRTY) {
379 if (PageDirty(page)) {
Nikolay Borisov3e8f3992017-07-12 14:37:51 -0700380 dec_wb_stat(old_wb, WB_RECLAIMABLE);
381 inc_wb_stat(new_wb, WB_RECLAIMABLE);
Tejun Heod10c8092015-05-28 14:50:56 -0400382 }
383 }
384
Matthew Wilcox04edf022017-12-04 10:46:23 -0500385 xas_set(&xas, 0);
386 xas_for_each_marked(&xas, page, ULONG_MAX, PAGECACHE_TAG_WRITEBACK) {
387 WARN_ON_ONCE(!PageWriteback(page));
388 dec_wb_stat(old_wb, WB_WRITEBACK);
389 inc_wb_stat(new_wb, WB_WRITEBACK);
Tejun Heod10c8092015-05-28 14:50:56 -0400390 }
391
392 wb_get(new_wb);
393
394 /*
395 * Transfer to @new_wb's IO list if necessary. The specific list
396 * @inode was on is ignored and the inode is put on ->b_dirty which
397 * is always correct including from ->b_dirty_time. The transfer
398 * preserves @inode->dirtied_when ordering.
399 */
Dave Chinnerc7f54082015-03-04 14:07:22 -0500400 if (!list_empty(&inode->i_io_list)) {
Tejun Heod10c8092015-05-28 14:50:56 -0400401 struct inode *pos;
402
Dave Chinnerc7f54082015-03-04 14:07:22 -0500403 inode_io_list_del_locked(inode, old_wb);
Tejun Heod10c8092015-05-28 14:50:56 -0400404 inode->i_wb = new_wb;
Dave Chinnerc7f54082015-03-04 14:07:22 -0500405 list_for_each_entry(pos, &new_wb->b_dirty, i_io_list)
Tejun Heod10c8092015-05-28 14:50:56 -0400406 if (time_after_eq(inode->dirtied_when,
407 pos->dirtied_when))
408 break;
Dave Chinnerc7f54082015-03-04 14:07:22 -0500409 inode_io_list_move_locked(inode, new_wb, pos->i_io_list.prev);
Tejun Heod10c8092015-05-28 14:50:56 -0400410 } else {
411 inode->i_wb = new_wb;
412 }
413
414 /* ->i_wb_frn updates may race wbc_detach_inode() but doesn't matter */
Tejun Heo682aa8e2015-05-28 14:50:53 -0400415 inode->i_wb_frn_winner = 0;
416 inode->i_wb_frn_avg_time = 0;
417 inode->i_wb_frn_history = 0;
Tejun Heod10c8092015-05-28 14:50:56 -0400418 switched = true;
419skip_switch:
Tejun Heo682aa8e2015-05-28 14:50:53 -0400420 /*
421 * Paired with load_acquire in unlocked_inode_to_wb_begin() and
422 * ensures that the new wb is visible if they see !I_WB_SWITCH.
423 */
424 smp_store_release(&inode->i_state, inode->i_state & ~I_WB_SWITCH);
425
Matthew Wilcoxb93b0162018-04-10 16:36:56 -0700426 xa_unlock_irq(&mapping->i_pages);
Tejun Heo682aa8e2015-05-28 14:50:53 -0400427 spin_unlock(&inode->i_lock);
Tejun Heod10c8092015-05-28 14:50:56 -0400428 spin_unlock(&new_wb->list_lock);
429 spin_unlock(&old_wb->list_lock);
430
431 if (switched) {
432 wb_wakeup(new_wb);
433 wb_put(old_wb);
434 }
435 wb_put(new_wb);
Tejun Heo682aa8e2015-05-28 14:50:53 -0400436
437 iput(inode);
Tejun Heo682aa8e2015-05-28 14:50:53 -0400438 kfree(isw);
Tejun Heoa1a0e232016-02-29 18:28:53 -0500439
440 atomic_dec(&isw_nr_in_flight);
Tejun Heo682aa8e2015-05-28 14:50:53 -0400441}
442
443static void inode_switch_wbs_rcu_fn(struct rcu_head *rcu_head)
444{
445 struct inode_switch_wbs_context *isw = container_of(rcu_head,
446 struct inode_switch_wbs_context, rcu_head);
447
448 /* needs to grab bh-unsafe locks, bounce to work item */
449 INIT_WORK(&isw->work, inode_switch_wbs_work_fn);
Tejun Heoa1a0e232016-02-29 18:28:53 -0500450 queue_work(isw_wq, &isw->work);
Tejun Heo682aa8e2015-05-28 14:50:53 -0400451}
452
453/**
454 * inode_switch_wbs - change the wb association of an inode
455 * @inode: target inode
456 * @new_wb_id: ID of the new wb
457 *
458 * Switch @inode's wb association to the wb identified by @new_wb_id. The
459 * switching is performed asynchronously and may fail silently.
460 */
461static void inode_switch_wbs(struct inode *inode, int new_wb_id)
462{
463 struct backing_dev_info *bdi = inode_to_bdi(inode);
464 struct cgroup_subsys_state *memcg_css;
465 struct inode_switch_wbs_context *isw;
466
467 /* noop if seems to be already in progress */
468 if (inode->i_state & I_WB_SWITCH)
469 return;
470
471 isw = kzalloc(sizeof(*isw), GFP_ATOMIC);
472 if (!isw)
473 return;
474
475 /* find and pin the new wb */
476 rcu_read_lock();
477 memcg_css = css_from_id(new_wb_id, &memory_cgrp_subsys);
478 if (memcg_css)
479 isw->new_wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC);
480 rcu_read_unlock();
481 if (!isw->new_wb)
482 goto out_free;
483
484 /* while holding I_WB_SWITCH, no one else can update the association */
485 spin_lock(&inode->i_lock);
Linus Torvalds1751e8a2017-11-27 13:05:09 -0800486 if (!(inode->i_sb->s_flags & SB_ACTIVE) ||
Tejun Heoa1a0e232016-02-29 18:28:53 -0500487 inode->i_state & (I_WB_SWITCH | I_FREEING) ||
488 inode_to_wb(inode) == isw->new_wb) {
489 spin_unlock(&inode->i_lock);
490 goto out_free;
491 }
Tejun Heo682aa8e2015-05-28 14:50:53 -0400492 inode->i_state |= I_WB_SWITCH;
Tahsin Erdogan74524952016-06-16 05:15:33 -0700493 __iget(inode);
Tejun Heo682aa8e2015-05-28 14:50:53 -0400494 spin_unlock(&inode->i_lock);
495
Tejun Heo682aa8e2015-05-28 14:50:53 -0400496 isw->inode = inode;
497
Tejun Heoa1a0e232016-02-29 18:28:53 -0500498 atomic_inc(&isw_nr_in_flight);
499
Tejun Heo682aa8e2015-05-28 14:50:53 -0400500 /*
501 * In addition to synchronizing among switchers, I_WB_SWITCH tells
Matthew Wilcoxb93b0162018-04-10 16:36:56 -0700502 * the RCU protected stat update paths to grab the i_page
503 * lock so that stat transfer can synchronize against them.
Tejun Heo682aa8e2015-05-28 14:50:53 -0400504 * Let's continue after I_WB_SWITCH is guaranteed to be visible.
505 */
506 call_rcu(&isw->rcu_head, inode_switch_wbs_rcu_fn);
507 return;
508
509out_free:
510 if (isw->new_wb)
511 wb_put(isw->new_wb);
512 kfree(isw);
513}
514
Tejun Heo87e1d782015-05-28 14:50:52 -0400515/**
Tejun Heob16b1de2015-06-02 08:39:48 -0600516 * wbc_attach_and_unlock_inode - associate wbc with target inode and unlock it
517 * @wbc: writeback_control of interest
518 * @inode: target inode
519 *
520 * @inode is locked and about to be written back under the control of @wbc.
521 * Record @inode's writeback context into @wbc and unlock the i_lock. On
522 * writeback completion, wbc_detach_inode() should be called. This is used
523 * to track the cgroup writeback context.
524 */
525void wbc_attach_and_unlock_inode(struct writeback_control *wbc,
526 struct inode *inode)
527{
Tejun Heodd73e4b2015-06-16 18:48:30 -0400528 if (!inode_cgwb_enabled(inode)) {
529 spin_unlock(&inode->i_lock);
530 return;
531 }
532
Tejun Heob16b1de2015-06-02 08:39:48 -0600533 wbc->wb = inode_to_wb(inode);
Tejun Heo2a814902015-05-28 14:50:51 -0400534 wbc->inode = inode;
535
536 wbc->wb_id = wbc->wb->memcg_css->id;
537 wbc->wb_lcand_id = inode->i_wb_frn_winner;
538 wbc->wb_tcand_id = 0;
539 wbc->wb_bytes = 0;
540 wbc->wb_lcand_bytes = 0;
541 wbc->wb_tcand_bytes = 0;
542
Tejun Heob16b1de2015-06-02 08:39:48 -0600543 wb_get(wbc->wb);
544 spin_unlock(&inode->i_lock);
Tejun Heoe8a7abf2015-05-28 14:50:57 -0400545
546 /*
547 * A dying wb indicates that the memcg-blkcg mapping has changed
548 * and a new wb is already serving the memcg. Switch immediately.
549 */
550 if (unlikely(wb_dying(wbc->wb)))
551 inode_switch_wbs(inode, wbc->wb_id);
Tejun Heob16b1de2015-06-02 08:39:48 -0600552}
553
554/**
Tejun Heo2a814902015-05-28 14:50:51 -0400555 * wbc_detach_inode - disassociate wbc from inode and perform foreign detection
556 * @wbc: writeback_control of the just finished writeback
Tejun Heob16b1de2015-06-02 08:39:48 -0600557 *
558 * To be called after a writeback attempt of an inode finishes and undoes
559 * wbc_attach_and_unlock_inode(). Can be called under any context.
Tejun Heo2a814902015-05-28 14:50:51 -0400560 *
561 * As concurrent write sharing of an inode is expected to be very rare and
562 * memcg only tracks page ownership on first-use basis severely confining
563 * the usefulness of such sharing, cgroup writeback tracks ownership
564 * per-inode. While the support for concurrent write sharing of an inode
565 * is deemed unnecessary, an inode being written to by different cgroups at
566 * different points in time is a lot more common, and, more importantly,
567 * charging only by first-use can too readily lead to grossly incorrect
568 * behaviors (single foreign page can lead to gigabytes of writeback to be
569 * incorrectly attributed).
570 *
571 * To resolve this issue, cgroup writeback detects the majority dirtier of
572 * an inode and transfers the ownership to it. To avoid unnnecessary
573 * oscillation, the detection mechanism keeps track of history and gives
574 * out the switch verdict only if the foreign usage pattern is stable over
575 * a certain amount of time and/or writeback attempts.
576 *
577 * On each writeback attempt, @wbc tries to detect the majority writer
578 * using Boyer-Moore majority vote algorithm. In addition to the byte
579 * count from the majority voting, it also counts the bytes written for the
580 * current wb and the last round's winner wb (max of last round's current
581 * wb, the winner from two rounds ago, and the last round's majority
582 * candidate). Keeping track of the historical winner helps the algorithm
583 * to semi-reliably detect the most active writer even when it's not the
584 * absolute majority.
585 *
586 * Once the winner of the round is determined, whether the winner is
587 * foreign or not and how much IO time the round consumed is recorded in
588 * inode->i_wb_frn_history. If the amount of recorded foreign IO time is
589 * over a certain threshold, the switch verdict is given.
Tejun Heob16b1de2015-06-02 08:39:48 -0600590 */
591void wbc_detach_inode(struct writeback_control *wbc)
592{
Tejun Heo2a814902015-05-28 14:50:51 -0400593 struct bdi_writeback *wb = wbc->wb;
594 struct inode *inode = wbc->inode;
Tejun Heodd73e4b2015-06-16 18:48:30 -0400595 unsigned long avg_time, max_bytes, max_time;
596 u16 history;
Tejun Heo2a814902015-05-28 14:50:51 -0400597 int max_id;
598
Tejun Heodd73e4b2015-06-16 18:48:30 -0400599 if (!wb)
600 return;
601
602 history = inode->i_wb_frn_history;
603 avg_time = inode->i_wb_frn_avg_time;
604
Tejun Heo2a814902015-05-28 14:50:51 -0400605 /* pick the winner of this round */
606 if (wbc->wb_bytes >= wbc->wb_lcand_bytes &&
607 wbc->wb_bytes >= wbc->wb_tcand_bytes) {
608 max_id = wbc->wb_id;
609 max_bytes = wbc->wb_bytes;
610 } else if (wbc->wb_lcand_bytes >= wbc->wb_tcand_bytes) {
611 max_id = wbc->wb_lcand_id;
612 max_bytes = wbc->wb_lcand_bytes;
613 } else {
614 max_id = wbc->wb_tcand_id;
615 max_bytes = wbc->wb_tcand_bytes;
616 }
617
618 /*
619 * Calculate the amount of IO time the winner consumed and fold it
620 * into the running average kept per inode. If the consumed IO
621 * time is lower than avag / WB_FRN_TIME_CUT_DIV, ignore it for
622 * deciding whether to switch or not. This is to prevent one-off
623 * small dirtiers from skewing the verdict.
624 */
625 max_time = DIV_ROUND_UP((max_bytes >> PAGE_SHIFT) << WB_FRN_TIME_SHIFT,
626 wb->avg_write_bandwidth);
627 if (avg_time)
628 avg_time += (max_time >> WB_FRN_TIME_AVG_SHIFT) -
629 (avg_time >> WB_FRN_TIME_AVG_SHIFT);
630 else
631 avg_time = max_time; /* immediate catch up on first run */
632
633 if (max_time >= avg_time / WB_FRN_TIME_CUT_DIV) {
634 int slots;
635
636 /*
637 * The switch verdict is reached if foreign wb's consume
638 * more than a certain proportion of IO time in a
639 * WB_FRN_TIME_PERIOD. This is loosely tracked by 16 slot
640 * history mask where each bit represents one sixteenth of
641 * the period. Determine the number of slots to shift into
642 * history from @max_time.
643 */
644 slots = min(DIV_ROUND_UP(max_time, WB_FRN_HIST_UNIT),
645 (unsigned long)WB_FRN_HIST_MAX_SLOTS);
646 history <<= slots;
647 if (wbc->wb_id != max_id)
648 history |= (1U << slots) - 1;
649
650 /*
651 * Switch if the current wb isn't the consistent winner.
652 * If there are multiple closely competing dirtiers, the
653 * inode may switch across them repeatedly over time, which
654 * is okay. The main goal is avoiding keeping an inode on
655 * the wrong wb for an extended period of time.
656 */
Tejun Heo682aa8e2015-05-28 14:50:53 -0400657 if (hweight32(history) > WB_FRN_HIST_THR_SLOTS)
658 inode_switch_wbs(inode, max_id);
Tejun Heo2a814902015-05-28 14:50:51 -0400659 }
660
661 /*
662 * Multiple instances of this function may race to update the
663 * following fields but we don't mind occassional inaccuracies.
664 */
665 inode->i_wb_frn_winner = max_id;
666 inode->i_wb_frn_avg_time = min(avg_time, (unsigned long)U16_MAX);
667 inode->i_wb_frn_history = history;
668
Tejun Heob16b1de2015-06-02 08:39:48 -0600669 wb_put(wbc->wb);
670 wbc->wb = NULL;
671}
672
673/**
Tejun Heo2a814902015-05-28 14:50:51 -0400674 * wbc_account_io - account IO issued during writeback
675 * @wbc: writeback_control of the writeback in progress
676 * @page: page being written out
677 * @bytes: number of bytes being written out
678 *
679 * @bytes from @page are about to written out during the writeback
680 * controlled by @wbc. Keep the book for foreign inode detection. See
681 * wbc_detach_inode().
682 */
683void wbc_account_io(struct writeback_control *wbc, struct page *page,
684 size_t bytes)
685{
686 int id;
687
688 /*
689 * pageout() path doesn't attach @wbc to the inode being written
690 * out. This is intentional as we don't want the function to block
691 * behind a slow cgroup. Ultimately, we want pageout() to kick off
692 * regular writeback instead of writing things out itself.
693 */
694 if (!wbc->wb)
695 return;
696
Tejun Heo2a814902015-05-28 14:50:51 -0400697 id = mem_cgroup_css_from_page(page)->id;
Tejun Heo2a814902015-05-28 14:50:51 -0400698
699 if (id == wbc->wb_id) {
700 wbc->wb_bytes += bytes;
701 return;
702 }
703
704 if (id == wbc->wb_lcand_id)
705 wbc->wb_lcand_bytes += bytes;
706
707 /* Boyer-Moore majority vote algorithm */
708 if (!wbc->wb_tcand_bytes)
709 wbc->wb_tcand_id = id;
710 if (id == wbc->wb_tcand_id)
711 wbc->wb_tcand_bytes += bytes;
712 else
713 wbc->wb_tcand_bytes -= min(bytes, wbc->wb_tcand_bytes);
714}
Tejun Heo5aa2a962015-07-23 14:27:09 -0400715EXPORT_SYMBOL_GPL(wbc_account_io);
Tejun Heo2a814902015-05-28 14:50:51 -0400716
717/**
Tejun Heo703c2702015-05-22 17:13:44 -0400718 * inode_congested - test whether an inode is congested
Tejun Heo60292bc2015-08-18 14:54:54 -0700719 * @inode: inode to test for congestion (may be NULL)
Tejun Heo703c2702015-05-22 17:13:44 -0400720 * @cong_bits: mask of WB_[a]sync_congested bits to test
721 *
722 * Tests whether @inode is congested. @cong_bits is the mask of congestion
723 * bits to test and the return value is the mask of set bits.
724 *
725 * If cgroup writeback is enabled for @inode, the congestion state is
726 * determined by whether the cgwb (cgroup bdi_writeback) for the blkcg
727 * associated with @inode is congested; otherwise, the root wb's congestion
728 * state is used.
Tejun Heo60292bc2015-08-18 14:54:54 -0700729 *
730 * @inode is allowed to be NULL as this function is often called on
731 * mapping->host which is NULL for the swapper space.
Tejun Heo703c2702015-05-22 17:13:44 -0400732 */
733int inode_congested(struct inode *inode, int cong_bits)
734{
Tejun Heo5cb8b822015-05-28 14:50:54 -0400735 /*
736 * Once set, ->i_wb never becomes NULL while the inode is alive.
737 * Start transaction iff ->i_wb is visible.
738 */
Tejun Heoaaa2cac2015-05-28 14:50:55 -0400739 if (inode && inode_to_wb_is_valid(inode)) {
Tejun Heo5cb8b822015-05-28 14:50:54 -0400740 struct bdi_writeback *wb;
Greg Thelen2e898e42018-04-20 14:55:42 -0700741 struct wb_lock_cookie lock_cookie = {};
742 bool congested;
Tejun Heo5cb8b822015-05-28 14:50:54 -0400743
Greg Thelen2e898e42018-04-20 14:55:42 -0700744 wb = unlocked_inode_to_wb_begin(inode, &lock_cookie);
Tejun Heo5cb8b822015-05-28 14:50:54 -0400745 congested = wb_congested(wb, cong_bits);
Greg Thelen2e898e42018-04-20 14:55:42 -0700746 unlocked_inode_to_wb_end(inode, &lock_cookie);
Tejun Heo5cb8b822015-05-28 14:50:54 -0400747 return congested;
Tejun Heo703c2702015-05-22 17:13:44 -0400748 }
749
750 return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);
751}
752EXPORT_SYMBOL_GPL(inode_congested);
753
Tejun Heof2b65122015-05-22 17:13:55 -0400754/**
755 * wb_split_bdi_pages - split nr_pages to write according to bandwidth
756 * @wb: target bdi_writeback to split @nr_pages to
757 * @nr_pages: number of pages to write for the whole bdi
758 *
759 * Split @wb's portion of @nr_pages according to @wb's write bandwidth in
760 * relation to the total write bandwidth of all wb's w/ dirty inodes on
761 * @wb->bdi.
762 */
763static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages)
764{
765 unsigned long this_bw = wb->avg_write_bandwidth;
766 unsigned long tot_bw = atomic_long_read(&wb->bdi->tot_write_bandwidth);
767
768 if (nr_pages == LONG_MAX)
769 return LONG_MAX;
770
771 /*
772 * This may be called on clean wb's and proportional distribution
773 * may not make sense, just use the original @nr_pages in those
774 * cases. In general, we wanna err on the side of writing more.
775 */
776 if (!tot_bw || this_bw >= tot_bw)
777 return nr_pages;
778 else
779 return DIV_ROUND_UP_ULL((u64)nr_pages * this_bw, tot_bw);
780}
781
Tejun Heodb125362015-05-22 17:14:01 -0400782/**
Tejun Heodb125362015-05-22 17:14:01 -0400783 * bdi_split_work_to_wbs - split a wb_writeback_work to all wb's of a bdi
784 * @bdi: target backing_dev_info
785 * @base_work: wb_writeback_work to issue
786 * @skip_if_busy: skip wb's which already have writeback in progress
787 *
788 * Split and issue @base_work to all wb's (bdi_writeback's) of @bdi which
789 * have dirty inodes. If @base_work->nr_page isn't %LONG_MAX, it's
790 * distributed to the busy wbs according to each wb's proportion in the
791 * total active write bandwidth of @bdi.
792 */
793static void bdi_split_work_to_wbs(struct backing_dev_info *bdi,
794 struct wb_writeback_work *base_work,
795 bool skip_if_busy)
796{
Tejun Heob8175252015-10-02 14:47:05 -0400797 struct bdi_writeback *last_wb = NULL;
Tejun Heob33e18f2015-10-27 14:19:39 +0900798 struct bdi_writeback *wb = list_entry(&bdi->wb_list,
799 struct bdi_writeback, bdi_node);
Tejun Heodb125362015-05-22 17:14:01 -0400800
801 might_sleep();
Tejun Heodb125362015-05-22 17:14:01 -0400802restart:
803 rcu_read_lock();
Tejun Heob8175252015-10-02 14:47:05 -0400804 list_for_each_entry_continue_rcu(wb, &bdi->wb_list, bdi_node) {
Tejun Heo8a1270c2015-08-18 14:54:53 -0700805 DEFINE_WB_COMPLETION_ONSTACK(fallback_work_done);
806 struct wb_writeback_work fallback_work;
807 struct wb_writeback_work *work;
808 long nr_pages;
809
Tejun Heob8175252015-10-02 14:47:05 -0400810 if (last_wb) {
811 wb_put(last_wb);
812 last_wb = NULL;
813 }
814
Tejun Heo006a0972015-08-25 14:11:52 -0400815 /* SYNC_ALL writes out I_DIRTY_TIME too */
816 if (!wb_has_dirty_io(wb) &&
817 (base_work->sync_mode == WB_SYNC_NONE ||
818 list_empty(&wb->b_dirty_time)))
819 continue;
820 if (skip_if_busy && writeback_in_progress(wb))
Tejun Heodb125362015-05-22 17:14:01 -0400821 continue;
822
Tejun Heo8a1270c2015-08-18 14:54:53 -0700823 nr_pages = wb_split_bdi_pages(wb, base_work->nr_pages);
824
825 work = kmalloc(sizeof(*work), GFP_ATOMIC);
826 if (work) {
827 *work = *base_work;
828 work->nr_pages = nr_pages;
829 work->auto_free = 1;
830 wb_queue_work(wb, work);
831 continue;
Tejun Heodb125362015-05-22 17:14:01 -0400832 }
Tejun Heo8a1270c2015-08-18 14:54:53 -0700833
834 /* alloc failed, execute synchronously using on-stack fallback */
835 work = &fallback_work;
836 *work = *base_work;
837 work->nr_pages = nr_pages;
838 work->auto_free = 0;
839 work->done = &fallback_work_done;
840
841 wb_queue_work(wb, work);
842
Tejun Heob8175252015-10-02 14:47:05 -0400843 /*
844 * Pin @wb so that it stays on @bdi->wb_list. This allows
845 * continuing iteration from @wb after dropping and
846 * regrabbing rcu read lock.
847 */
848 wb_get(wb);
849 last_wb = wb;
850
Tejun Heo8a1270c2015-08-18 14:54:53 -0700851 rcu_read_unlock();
852 wb_wait_for_completion(bdi, &fallback_work_done);
853 goto restart;
Tejun Heodb125362015-05-22 17:14:01 -0400854 }
855 rcu_read_unlock();
Tejun Heob8175252015-10-02 14:47:05 -0400856
857 if (last_wb)
858 wb_put(last_wb);
Tejun Heodb125362015-05-22 17:14:01 -0400859}
860
Tejun Heoa1a0e232016-02-29 18:28:53 -0500861/**
862 * cgroup_writeback_umount - flush inode wb switches for umount
863 *
864 * This function is called when a super_block is about to be destroyed and
865 * flushes in-flight inode wb switches. An inode wb switch goes through
866 * RCU and then workqueue, so the two need to be flushed in order to ensure
867 * that all previously scheduled switches are finished. As wb switches are
868 * rare occurrences and synchronize_rcu() can take a while, perform
869 * flushing iff wb switches are in flight.
870 */
871void cgroup_writeback_umount(void)
872{
873 if (atomic_read(&isw_nr_in_flight)) {
874 synchronize_rcu();
875 flush_workqueue(isw_wq);
876 }
877}
878
879static int __init cgroup_writeback_init(void)
880{
881 isw_wq = alloc_workqueue("inode_switch_wbs", 0, 0);
882 if (!isw_wq)
883 return -ENOMEM;
884 return 0;
885}
886fs_initcall(cgroup_writeback_init);
887
Tejun Heof2b65122015-05-22 17:13:55 -0400888#else /* CONFIG_CGROUP_WRITEBACK */
889
Tejun Heo87e1d782015-05-28 14:50:52 -0400890static struct bdi_writeback *
891locked_inode_to_wb_and_lock_list(struct inode *inode)
892 __releases(&inode->i_lock)
893 __acquires(&wb->list_lock)
894{
895 struct bdi_writeback *wb = inode_to_wb(inode);
896
897 spin_unlock(&inode->i_lock);
898 spin_lock(&wb->list_lock);
899 return wb;
900}
901
902static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode)
903 __acquires(&wb->list_lock)
904{
905 struct bdi_writeback *wb = inode_to_wb(inode);
906
907 spin_lock(&wb->list_lock);
908 return wb;
909}
910
Tejun Heof2b65122015-05-22 17:13:55 -0400911static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages)
912{
913 return nr_pages;
914}
915
Tejun Heodb125362015-05-22 17:14:01 -0400916static void bdi_split_work_to_wbs(struct backing_dev_info *bdi,
917 struct wb_writeback_work *base_work,
918 bool skip_if_busy)
919{
920 might_sleep();
921
Tejun Heo006a0972015-08-25 14:11:52 -0400922 if (!skip_if_busy || !writeback_in_progress(&bdi->wb)) {
Tejun Heodb125362015-05-22 17:14:01 -0400923 base_work->auto_free = 0;
Tejun Heodb125362015-05-22 17:14:01 -0400924 wb_queue_work(&bdi->wb, base_work);
925 }
926}
927
Tejun Heo703c2702015-05-22 17:13:44 -0400928#endif /* CONFIG_CGROUP_WRITEBACK */
929
Jens Axboee8e8a0c2017-09-28 11:31:22 -0600930/*
931 * Add in the number of potentially dirty inodes, because each inode
932 * write can dirty pagecache in the underlying blockdev.
933 */
934static unsigned long get_nr_dirty_pages(void)
935{
936 return global_node_page_state(NR_FILE_DIRTY) +
937 global_node_page_state(NR_UNSTABLE_NFS) +
938 get_nr_dirty_inodes();
939}
940
941static void wb_start_writeback(struct bdi_writeback *wb, enum wb_reason reason)
Jens Axboeb6e51312009-09-16 15:13:54 +0200942{
Tejun Heoc00ddad2015-05-22 17:13:51 -0400943 if (!wb_has_dirty_io(wb))
944 return;
945
946 /*
Jens Axboeaac8d412017-09-28 11:31:55 -0600947 * All callers of this function want to start writeback of all
948 * dirty pages. Places like vmscan can call this at a very
949 * high frequency, causing pointless allocations of tons of
950 * work items and keeping the flusher threads busy retrieving
951 * that work. Ensure that we only allow one of them pending and
Jens Axboe85009b42017-09-30 02:09:06 -0600952 * inflight at the time.
Jens Axboeaac8d412017-09-28 11:31:55 -0600953 */
Jens Axboe85009b42017-09-30 02:09:06 -0600954 if (test_bit(WB_start_all, &wb->state) ||
955 test_and_set_bit(WB_start_all, &wb->state))
Jens Axboeaac8d412017-09-28 11:31:55 -0600956 return;
957
Jens Axboe85009b42017-09-30 02:09:06 -0600958 wb->start_all_reason = reason;
959 wb_wakeup(wb);
Christoph Hellwigc5444192010-06-08 18:15:15 +0200960}
Wu Fengguangd3ddec72009-09-23 20:33:40 +0800961
Christoph Hellwigc5444192010-06-08 18:15:15 +0200962/**
Tejun Heo9ecf48662015-05-22 17:13:54 -0400963 * wb_start_background_writeback - start background writeback
964 * @wb: bdi_writback to write from
Christoph Hellwigc5444192010-06-08 18:15:15 +0200965 *
966 * Description:
Jan Kara65850272011-01-13 15:45:44 -0800967 * This makes sure WB_SYNC_NONE background writeback happens. When
Tejun Heo9ecf48662015-05-22 17:13:54 -0400968 * this function returns, it is only guaranteed that for given wb
Jan Kara65850272011-01-13 15:45:44 -0800969 * some IO is happening if we are over background dirty threshold.
970 * Caller need not hold sb s_umount semaphore.
Christoph Hellwigc5444192010-06-08 18:15:15 +0200971 */
Tejun Heo9ecf48662015-05-22 17:13:54 -0400972void wb_start_background_writeback(struct bdi_writeback *wb)
Christoph Hellwigc5444192010-06-08 18:15:15 +0200973{
Jan Kara65850272011-01-13 15:45:44 -0800974 /*
975 * We just wake up the flusher thread. It will perform background
976 * writeback as soon as there is no other work to do.
977 */
Tejun Heo5634cc22015-08-18 14:54:56 -0700978 trace_writeback_wake_background(wb);
Tejun Heo9ecf48662015-05-22 17:13:54 -0400979 wb_wakeup(wb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980}
981
982/*
Dave Chinnera66979a2011-03-22 22:23:41 +1100983 * Remove the inode from the writeback list it is on.
984 */
Dave Chinnerc7f54082015-03-04 14:07:22 -0500985void inode_io_list_del(struct inode *inode)
Dave Chinnera66979a2011-03-22 22:23:41 +1100986{
Tejun Heo87e1d782015-05-28 14:50:52 -0400987 struct bdi_writeback *wb;
Dave Chinnera66979a2011-03-22 22:23:41 +1100988
Tejun Heo87e1d782015-05-28 14:50:52 -0400989 wb = inode_to_wb_and_lock_list(inode);
Dave Chinnerc7f54082015-03-04 14:07:22 -0500990 inode_io_list_del_locked(inode, wb);
Tejun Heo52ebea72015-05-22 17:13:37 -0400991 spin_unlock(&wb->list_lock);
Christoph Hellwigf758eea2011-04-21 18:19:44 -0600992}
Dave Chinnera66979a2011-03-22 22:23:41 +1100993
994/*
Dave Chinner6c60d2b2016-07-26 15:21:50 -0700995 * mark an inode as under writeback on the sb
996 */
997void sb_mark_inode_writeback(struct inode *inode)
998{
999 struct super_block *sb = inode->i_sb;
1000 unsigned long flags;
1001
1002 if (list_empty(&inode->i_wb_list)) {
1003 spin_lock_irqsave(&sb->s_inode_wblist_lock, flags);
Brian Foster9a46b04f2016-07-26 15:21:53 -07001004 if (list_empty(&inode->i_wb_list)) {
Dave Chinner6c60d2b2016-07-26 15:21:50 -07001005 list_add_tail(&inode->i_wb_list, &sb->s_inodes_wb);
Brian Foster9a46b04f2016-07-26 15:21:53 -07001006 trace_sb_mark_inode_writeback(inode);
1007 }
Dave Chinner6c60d2b2016-07-26 15:21:50 -07001008 spin_unlock_irqrestore(&sb->s_inode_wblist_lock, flags);
1009 }
1010}
1011
1012/*
1013 * clear an inode as under writeback on the sb
1014 */
1015void sb_clear_inode_writeback(struct inode *inode)
1016{
1017 struct super_block *sb = inode->i_sb;
1018 unsigned long flags;
1019
1020 if (!list_empty(&inode->i_wb_list)) {
1021 spin_lock_irqsave(&sb->s_inode_wblist_lock, flags);
Brian Foster9a46b04f2016-07-26 15:21:53 -07001022 if (!list_empty(&inode->i_wb_list)) {
1023 list_del_init(&inode->i_wb_list);
1024 trace_sb_clear_inode_writeback(inode);
1025 }
Dave Chinner6c60d2b2016-07-26 15:21:50 -07001026 spin_unlock_irqrestore(&sb->s_inode_wblist_lock, flags);
1027 }
1028}
1029
1030/*
Andrew Morton6610a0b2007-10-16 23:30:32 -07001031 * Redirty an inode: set its when-it-was dirtied timestamp and move it to the
1032 * furthest end of its superblock's dirty-inode list.
1033 *
1034 * Before stamping the inode's ->dirtied_when, we check to see whether it is
Jens Axboe66f3b8e2009-09-02 09:19:46 +02001035 * already the most-recently-dirtied inode on the b_dirty list. If that is
Andrew Morton6610a0b2007-10-16 23:30:32 -07001036 * the case then the inode must have been redirtied while it was being written
1037 * out and we don't reset its dirtied_when.
1038 */
Christoph Hellwigf758eea2011-04-21 18:19:44 -06001039static void redirty_tail(struct inode *inode, struct bdi_writeback *wb)
Andrew Morton6610a0b2007-10-16 23:30:32 -07001040{
Jens Axboe03ba3782009-09-09 09:08:54 +02001041 if (!list_empty(&wb->b_dirty)) {
Jens Axboe66f3b8e2009-09-02 09:19:46 +02001042 struct inode *tail;
Andrew Morton6610a0b2007-10-16 23:30:32 -07001043
Nick Piggin7ccf19a2010-10-21 11:49:30 +11001044 tail = wb_inode(wb->b_dirty.next);
Jens Axboe66f3b8e2009-09-02 09:19:46 +02001045 if (time_before(inode->dirtied_when, tail->dirtied_when))
Andrew Morton6610a0b2007-10-16 23:30:32 -07001046 inode->dirtied_when = jiffies;
1047 }
Dave Chinnerc7f54082015-03-04 14:07:22 -05001048 inode_io_list_move_locked(inode, wb, &wb->b_dirty);
Andrew Morton6610a0b2007-10-16 23:30:32 -07001049}
1050
1051/*
Jens Axboe66f3b8e2009-09-02 09:19:46 +02001052 * requeue inode for re-scanning after bdi->b_io list is exhausted.
Andrew Mortonc986d1e2007-10-16 23:30:34 -07001053 */
Christoph Hellwigf758eea2011-04-21 18:19:44 -06001054static void requeue_io(struct inode *inode, struct bdi_writeback *wb)
Andrew Mortonc986d1e2007-10-16 23:30:34 -07001055{
Dave Chinnerc7f54082015-03-04 14:07:22 -05001056 inode_io_list_move_locked(inode, wb, &wb->b_more_io);
Andrew Mortonc986d1e2007-10-16 23:30:34 -07001057}
1058
Joern Engel1c0eeaf2007-10-16 23:30:44 -07001059static void inode_sync_complete(struct inode *inode)
1060{
Jan Kara365b94ae2012-05-03 14:47:55 +02001061 inode->i_state &= ~I_SYNC;
Jan Kara4eff96d2012-11-26 16:29:51 -08001062 /* If inode is clean an unused, put it into LRU now... */
1063 inode_add_lru(inode);
Jan Kara365b94ae2012-05-03 14:47:55 +02001064 /* Waiters must see I_SYNC cleared before being woken up */
Joern Engel1c0eeaf2007-10-16 23:30:44 -07001065 smp_mb();
1066 wake_up_bit(&inode->i_state, __I_SYNC);
1067}
1068
Jeff Laytond2caa3c52009-04-02 16:56:37 -07001069static bool inode_dirtied_after(struct inode *inode, unsigned long t)
1070{
1071 bool ret = time_after(inode->dirtied_when, t);
1072#ifndef CONFIG_64BIT
1073 /*
1074 * For inodes being constantly redirtied, dirtied_when can get stuck.
1075 * It _appears_ to be in the future, but is actually in distant past.
1076 * This test is necessary to prevent such wrapped-around relative times
Jens Axboe5b0830c2009-09-23 19:37:09 +02001077 * from permanently stopping the whole bdi writeback.
Jeff Laytond2caa3c52009-04-02 16:56:37 -07001078 */
1079 ret = ret && time_before_eq(inode->dirtied_when, jiffies);
1080#endif
1081 return ret;
1082}
1083
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05001084#define EXPIRE_DIRTY_ATIME 0x0001
1085
Andrew Mortonc986d1e2007-10-16 23:30:34 -07001086/*
Wang Sheng-Hui0e2f2b22012-09-11 08:28:18 +08001087 * Move expired (dirtied before work->older_than_this) dirty inodes from
Jan Kara697e6fe2012-03-09 07:26:22 -08001088 * @delaying_queue to @dispatch_queue.
Fengguang Wu2c136572007-10-16 23:30:39 -07001089 */
Wu Fengguange84d0a42011-04-23 12:27:27 -06001090static int move_expired_inodes(struct list_head *delaying_queue,
Fengguang Wu2c136572007-10-16 23:30:39 -07001091 struct list_head *dispatch_queue,
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05001092 int flags,
Curt Wohlgemuthad4e38d2011-10-07 21:51:56 -06001093 struct wb_writeback_work *work)
Fengguang Wu2c136572007-10-16 23:30:39 -07001094{
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05001095 unsigned long *older_than_this = NULL;
1096 unsigned long expire_time;
Shaohua Li5c034492009-09-24 14:42:33 +02001097 LIST_HEAD(tmp);
1098 struct list_head *pos, *node;
Jens Axboecf137302009-09-24 15:12:57 +02001099 struct super_block *sb = NULL;
Shaohua Li5c034492009-09-24 14:42:33 +02001100 struct inode *inode;
Jens Axboecf137302009-09-24 15:12:57 +02001101 int do_sb_sort = 0;
Wu Fengguange84d0a42011-04-23 12:27:27 -06001102 int moved = 0;
Shaohua Li5c034492009-09-24 14:42:33 +02001103
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05001104 if ((flags & EXPIRE_DIRTY_ATIME) == 0)
1105 older_than_this = work->older_than_this;
Theodore Ts'oa2f48702015-03-17 12:23:19 -04001106 else if (!work->for_sync) {
1107 expire_time = jiffies - (dirtytime_expire_interval * HZ);
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05001108 older_than_this = &expire_time;
1109 }
Fengguang Wu2c136572007-10-16 23:30:39 -07001110 while (!list_empty(delaying_queue)) {
Nick Piggin7ccf19a2010-10-21 11:49:30 +11001111 inode = wb_inode(delaying_queue->prev);
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05001112 if (older_than_this &&
1113 inode_dirtied_after(inode, *older_than_this))
Fengguang Wu2c136572007-10-16 23:30:39 -07001114 break;
Dave Chinnerc7f54082015-03-04 14:07:22 -05001115 list_move(&inode->i_io_list, &tmp);
Jan Karaa8855992013-07-09 22:36:45 +08001116 moved++;
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05001117 if (flags & EXPIRE_DIRTY_ATIME)
1118 set_bit(__I_DIRTY_TIME_EXPIRED, &inode->i_state);
Jan Karaa8855992013-07-09 22:36:45 +08001119 if (sb_is_blkdev_sb(inode->i_sb))
1120 continue;
Jens Axboecf137302009-09-24 15:12:57 +02001121 if (sb && sb != inode->i_sb)
1122 do_sb_sort = 1;
1123 sb = inode->i_sb;
Shaohua Li5c034492009-09-24 14:42:33 +02001124 }
1125
Jens Axboecf137302009-09-24 15:12:57 +02001126 /* just one sb in list, splice to dispatch_queue and we're done */
1127 if (!do_sb_sort) {
1128 list_splice(&tmp, dispatch_queue);
Wu Fengguange84d0a42011-04-23 12:27:27 -06001129 goto out;
Jens Axboecf137302009-09-24 15:12:57 +02001130 }
1131
Shaohua Li5c034492009-09-24 14:42:33 +02001132 /* Move inodes from one superblock together */
1133 while (!list_empty(&tmp)) {
Nick Piggin7ccf19a2010-10-21 11:49:30 +11001134 sb = wb_inode(tmp.prev)->i_sb;
Shaohua Li5c034492009-09-24 14:42:33 +02001135 list_for_each_prev_safe(pos, node, &tmp) {
Nick Piggin7ccf19a2010-10-21 11:49:30 +11001136 inode = wb_inode(pos);
Shaohua Li5c034492009-09-24 14:42:33 +02001137 if (inode->i_sb == sb)
Dave Chinnerc7f54082015-03-04 14:07:22 -05001138 list_move(&inode->i_io_list, dispatch_queue);
Shaohua Li5c034492009-09-24 14:42:33 +02001139 }
Fengguang Wu2c136572007-10-16 23:30:39 -07001140 }
Wu Fengguange84d0a42011-04-23 12:27:27 -06001141out:
1142 return moved;
Fengguang Wu2c136572007-10-16 23:30:39 -07001143}
1144
1145/*
1146 * Queue all expired dirty inodes for io, eldest first.
Wu Fengguang4ea879b2010-08-11 14:17:42 -07001147 * Before
1148 * newly dirtied b_dirty b_io b_more_io
1149 * =============> gf edc BA
1150 * After
1151 * newly dirtied b_dirty b_io b_more_io
1152 * =============> g fBAedc
1153 * |
1154 * +--> dequeue for IO
Fengguang Wu2c136572007-10-16 23:30:39 -07001155 */
Curt Wohlgemuthad4e38d2011-10-07 21:51:56 -06001156static void queue_io(struct bdi_writeback *wb, struct wb_writeback_work *work)
Fengguang Wu2c136572007-10-16 23:30:39 -07001157{
Wu Fengguange84d0a42011-04-23 12:27:27 -06001158 int moved;
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05001159
Christoph Hellwigf758eea2011-04-21 18:19:44 -06001160 assert_spin_locked(&wb->list_lock);
Wu Fengguang4ea879b2010-08-11 14:17:42 -07001161 list_splice_init(&wb->b_more_io, &wb->b_io);
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05001162 moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, 0, work);
1163 moved += move_expired_inodes(&wb->b_dirty_time, &wb->b_io,
1164 EXPIRE_DIRTY_ATIME, work);
Tejun Heod6c10f12015-05-22 17:13:45 -04001165 if (moved)
1166 wb_io_lists_populated(wb);
Curt Wohlgemuthad4e38d2011-10-07 21:51:56 -06001167 trace_writeback_queue_io(wb, work, moved);
Jens Axboe66f3b8e2009-09-02 09:19:46 +02001168}
1169
Christoph Hellwiga9185b42010-03-05 09:21:37 +01001170static int write_inode(struct inode *inode, struct writeback_control *wbc)
Jens Axboe66f3b8e2009-09-02 09:19:46 +02001171{
Tejun Heo9fb0a7d2013-01-11 13:06:37 -08001172 int ret;
1173
1174 if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) {
1175 trace_writeback_write_inode_start(inode, wbc);
1176 ret = inode->i_sb->s_op->write_inode(inode, wbc);
1177 trace_writeback_write_inode(inode, wbc);
1178 return ret;
1179 }
Jens Axboe03ba3782009-09-09 09:08:54 +02001180 return 0;
Fengguang Wu2c136572007-10-16 23:30:39 -07001181}
1182
1183/*
Jan Kara169ebd92012-05-03 14:48:03 +02001184 * Wait for writeback on an inode to complete. Called with i_lock held.
1185 * Caller must make sure inode cannot go away when we drop i_lock.
Christoph Hellwig01c03192009-06-08 13:35:40 +02001186 */
Jan Kara169ebd92012-05-03 14:48:03 +02001187static void __inode_wait_for_writeback(struct inode *inode)
1188 __releases(inode->i_lock)
1189 __acquires(inode->i_lock)
Christoph Hellwig01c03192009-06-08 13:35:40 +02001190{
1191 DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC);
1192 wait_queue_head_t *wqh;
1193
1194 wqh = bit_waitqueue(&inode->i_state, __I_SYNC);
Dave Chinner250df6e2011-03-22 22:23:36 +11001195 while (inode->i_state & I_SYNC) {
1196 spin_unlock(&inode->i_lock);
NeilBrown74316202014-07-07 15:16:04 +10001197 __wait_on_bit(wqh, &wq, bit_wait,
1198 TASK_UNINTERRUPTIBLE);
Dave Chinner250df6e2011-03-22 22:23:36 +11001199 spin_lock(&inode->i_lock);
Richard Kennedy58a9d3d82010-05-24 14:32:38 -07001200 }
Christoph Hellwig01c03192009-06-08 13:35:40 +02001201}
1202
1203/*
Jan Kara169ebd92012-05-03 14:48:03 +02001204 * Wait for writeback on an inode to complete. Caller must have inode pinned.
1205 */
1206void inode_wait_for_writeback(struct inode *inode)
1207{
1208 spin_lock(&inode->i_lock);
1209 __inode_wait_for_writeback(inode);
1210 spin_unlock(&inode->i_lock);
1211}
1212
1213/*
1214 * Sleep until I_SYNC is cleared. This function must be called with i_lock
1215 * held and drops it. It is aimed for callers not holding any inode reference
1216 * so once i_lock is dropped, inode can go away.
1217 */
1218static void inode_sleep_on_writeback(struct inode *inode)
1219 __releases(inode->i_lock)
1220{
1221 DEFINE_WAIT(wait);
1222 wait_queue_head_t *wqh = bit_waitqueue(&inode->i_state, __I_SYNC);
1223 int sleep;
1224
1225 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
1226 sleep = inode->i_state & I_SYNC;
1227 spin_unlock(&inode->i_lock);
1228 if (sleep)
1229 schedule();
1230 finish_wait(wqh, &wait);
1231}
1232
1233/*
Jan Karaccb26b52012-05-03 14:47:58 +02001234 * Find proper writeback list for the inode depending on its current state and
1235 * possibly also change of its state while we were doing writeback. Here we
1236 * handle things such as livelock prevention or fairness of writeback among
1237 * inodes. This function can be called only by flusher thread - noone else
1238 * processes all inodes in writeback lists and requeueing inodes behind flusher
1239 * thread's back can have unexpected consequences.
1240 */
1241static void requeue_inode(struct inode *inode, struct bdi_writeback *wb,
1242 struct writeback_control *wbc)
1243{
1244 if (inode->i_state & I_FREEING)
1245 return;
1246
1247 /*
1248 * Sync livelock prevention. Each inode is tagged and synced in one
1249 * shot. If still dirty, it will be redirty_tail()'ed below. Update
1250 * the dirty time to prevent enqueue and sync it again.
1251 */
1252 if ((inode->i_state & I_DIRTY) &&
1253 (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages))
1254 inode->dirtied_when = jiffies;
1255
Jan Kara4f8ad652012-05-03 14:48:00 +02001256 if (wbc->pages_skipped) {
1257 /*
1258 * writeback is not making progress due to locked
1259 * buffers. Skip this inode for now.
1260 */
1261 redirty_tail(inode, wb);
1262 return;
1263 }
1264
Jan Karaccb26b52012-05-03 14:47:58 +02001265 if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) {
1266 /*
1267 * We didn't write back all the pages. nfs_writepages()
1268 * sometimes bales out without doing anything.
1269 */
1270 if (wbc->nr_to_write <= 0) {
1271 /* Slice used up. Queue for next turn. */
1272 requeue_io(inode, wb);
1273 } else {
1274 /*
1275 * Writeback blocked by something other than
1276 * congestion. Delay the inode for some time to
1277 * avoid spinning on the CPU (100% iowait)
1278 * retrying writeback of the dirty page/inode
1279 * that cannot be performed immediately.
1280 */
1281 redirty_tail(inode, wb);
1282 }
1283 } else if (inode->i_state & I_DIRTY) {
1284 /*
1285 * Filesystems can dirty the inode during writeback operations,
1286 * such as delayed allocation during submission or metadata
1287 * updates after data IO completion.
1288 */
1289 redirty_tail(inode, wb);
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05001290 } else if (inode->i_state & I_DIRTY_TIME) {
Theodore Ts'oa2f48702015-03-17 12:23:19 -04001291 inode->dirtied_when = jiffies;
Dave Chinnerc7f54082015-03-04 14:07:22 -05001292 inode_io_list_move_locked(inode, wb, &wb->b_dirty_time);
Jan Karaccb26b52012-05-03 14:47:58 +02001293 } else {
1294 /* The inode is clean. Remove from writeback lists. */
Dave Chinnerc7f54082015-03-04 14:07:22 -05001295 inode_io_list_del_locked(inode, wb);
Jan Karaccb26b52012-05-03 14:47:58 +02001296 }
1297}
1298
1299/*
Jan Kara4f8ad652012-05-03 14:48:00 +02001300 * Write out an inode and its dirty pages. Do not update the writeback list
1301 * linkage. That is left to the caller. The caller is also responsible for
1302 * setting I_SYNC flag and calling inode_sync_complete() to clear it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001303 */
1304static int
Yan Hongcd8ed2a2012-10-08 16:33:45 -07001305__writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001306{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307 struct address_space *mapping = inode->i_mapping;
Wu Fengguang251d6a42010-12-01 17:33:37 -06001308 long nr_to_write = wbc->nr_to_write;
Christoph Hellwig01c03192009-06-08 13:35:40 +02001309 unsigned dirty;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001310 int ret;
1311
Jan Kara4f8ad652012-05-03 14:48:00 +02001312 WARN_ON(!(inode->i_state & I_SYNC));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001313
Tejun Heo9fb0a7d2013-01-11 13:06:37 -08001314 trace_writeback_single_inode_start(inode, wbc, nr_to_write);
1315
Linus Torvalds1da177e2005-04-16 15:20:36 -07001316 ret = do_writepages(mapping, wbc);
1317
Christoph Hellwig26821ed2010-03-05 09:21:21 +01001318 /*
1319 * Make sure to wait on the data before writing out the metadata.
1320 * This is important for filesystems that modify metadata on data
Dave Chinner7747bd42013-07-02 22:38:35 +10001321 * I/O completion. We don't do it for sync(2) writeback because it has a
1322 * separate, external IO completion path and ->sync_fs for guaranteeing
1323 * inode metadata is written back correctly.
Christoph Hellwig26821ed2010-03-05 09:21:21 +01001324 */
Dave Chinner7747bd42013-07-02 22:38:35 +10001325 if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync) {
Christoph Hellwig26821ed2010-03-05 09:21:21 +01001326 int err = filemap_fdatawait(mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001327 if (ret == 0)
1328 ret = err;
1329 }
1330
Dmitry Monakhov5547e8a2010-05-07 13:35:44 +04001331 /*
1332 * Some filesystems may redirty the inode during the writeback
1333 * due to delalloc, clear dirty metadata flags right before
1334 * write_inode()
1335 */
Dave Chinner250df6e2011-03-22 22:23:36 +11001336 spin_lock(&inode->i_lock);
Tejun Heo9c6ac782014-10-24 15:38:21 -04001337
Dmitry Monakhov5547e8a2010-05-07 13:35:44 +04001338 dirty = inode->i_state & I_DIRTY;
Theodore Ts'oa2f48702015-03-17 12:23:19 -04001339 if (inode->i_state & I_DIRTY_TIME) {
Christoph Hellwig0e11f642018-02-21 07:54:49 -08001340 if ((dirty & I_DIRTY_INODE) ||
Jan Karadc5ff2b2016-07-26 11:38:20 +02001341 wbc->sync_mode == WB_SYNC_ALL ||
Theodore Ts'oa2f48702015-03-17 12:23:19 -04001342 unlikely(inode->i_state & I_DIRTY_TIME_EXPIRED) ||
1343 unlikely(time_after(jiffies,
1344 (inode->dirtied_time_when +
1345 dirtytime_expire_interval * HZ)))) {
1346 dirty |= I_DIRTY_TIME | I_DIRTY_TIME_EXPIRED;
1347 trace_writeback_lazytime(inode);
1348 }
1349 } else
1350 inode->i_state &= ~I_DIRTY_TIME_EXPIRED;
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05001351 inode->i_state &= ~dirty;
Tejun Heo9c6ac782014-10-24 15:38:21 -04001352
1353 /*
1354 * Paired with smp_mb() in __mark_inode_dirty(). This allows
1355 * __mark_inode_dirty() to test i_state without grabbing i_lock -
1356 * either they see the I_DIRTY bits cleared or we see the dirtied
1357 * inode.
1358 *
1359 * I_DIRTY_PAGES is always cleared together above even if @mapping
1360 * still has dirty pages. The flag is reinstated after smp_mb() if
1361 * necessary. This guarantees that either __mark_inode_dirty()
1362 * sees clear I_DIRTY_PAGES or we see PAGECACHE_TAG_DIRTY.
1363 */
1364 smp_mb();
1365
1366 if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
1367 inode->i_state |= I_DIRTY_PAGES;
1368
Dave Chinner250df6e2011-03-22 22:23:36 +11001369 spin_unlock(&inode->i_lock);
Tejun Heo9c6ac782014-10-24 15:38:21 -04001370
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05001371 if (dirty & I_DIRTY_TIME)
1372 mark_inode_dirty_sync(inode);
Christoph Hellwig26821ed2010-03-05 09:21:21 +01001373 /* Don't write the inode if only I_DIRTY_PAGES was set */
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05001374 if (dirty & ~I_DIRTY_PAGES) {
Christoph Hellwiga9185b42010-03-05 09:21:37 +01001375 int err = write_inode(inode, wbc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376 if (ret == 0)
1377 ret = err;
1378 }
Jan Kara4f8ad652012-05-03 14:48:00 +02001379 trace_writeback_single_inode(inode, wbc, nr_to_write);
1380 return ret;
1381}
1382
1383/*
1384 * Write out an inode's dirty pages. Either the caller has an active reference
1385 * on the inode or the inode has I_WILL_FREE set.
1386 *
1387 * This function is designed to be called for writing back one inode which
1388 * we go e.g. from filesystem. Flusher thread uses __writeback_single_inode()
1389 * and does more profound writeback list handling in writeback_sb_inodes().
1390 */
Tejun Heoaaf25592016-03-18 13:52:04 -04001391static int writeback_single_inode(struct inode *inode,
1392 struct writeback_control *wbc)
Jan Kara4f8ad652012-05-03 14:48:00 +02001393{
Tejun Heoaaf25592016-03-18 13:52:04 -04001394 struct bdi_writeback *wb;
Jan Kara4f8ad652012-05-03 14:48:00 +02001395 int ret = 0;
1396
1397 spin_lock(&inode->i_lock);
1398 if (!atomic_read(&inode->i_count))
1399 WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING)));
1400 else
1401 WARN_ON(inode->i_state & I_WILL_FREE);
1402
1403 if (inode->i_state & I_SYNC) {
1404 if (wbc->sync_mode != WB_SYNC_ALL)
1405 goto out;
1406 /*
Jan Kara169ebd92012-05-03 14:48:03 +02001407 * It's a data-integrity sync. We must wait. Since callers hold
1408 * inode reference or inode has I_WILL_FREE set, it cannot go
1409 * away under us.
Jan Kara4f8ad652012-05-03 14:48:00 +02001410 */
Jan Kara169ebd92012-05-03 14:48:03 +02001411 __inode_wait_for_writeback(inode);
Jan Kara4f8ad652012-05-03 14:48:00 +02001412 }
1413 WARN_ON(inode->i_state & I_SYNC);
1414 /*
Jan Karaf9b0e052013-12-14 04:21:26 +08001415 * Skip inode if it is clean and we have no outstanding writeback in
1416 * WB_SYNC_ALL mode. We don't want to mess with writeback lists in this
1417 * function since flusher thread may be doing for example sync in
1418 * parallel and if we move the inode, it could get skipped. So here we
1419 * make sure inode is on some writeback list and leave it there unless
1420 * we have completely cleaned the inode.
Jan Kara4f8ad652012-05-03 14:48:00 +02001421 */
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05001422 if (!(inode->i_state & I_DIRTY_ALL) &&
Jan Karaf9b0e052013-12-14 04:21:26 +08001423 (wbc->sync_mode != WB_SYNC_ALL ||
1424 !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK)))
Jan Kara4f8ad652012-05-03 14:48:00 +02001425 goto out;
1426 inode->i_state |= I_SYNC;
Tejun Heob16b1de2015-06-02 08:39:48 -06001427 wbc_attach_and_unlock_inode(wbc, inode);
Jan Kara4f8ad652012-05-03 14:48:00 +02001428
Yan Hongcd8ed2a2012-10-08 16:33:45 -07001429 ret = __writeback_single_inode(inode, wbc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001430
Tejun Heob16b1de2015-06-02 08:39:48 -06001431 wbc_detach_inode(wbc);
Tejun Heoaaf25592016-03-18 13:52:04 -04001432
1433 wb = inode_to_wb_and_lock_list(inode);
Dave Chinner250df6e2011-03-22 22:23:36 +11001434 spin_lock(&inode->i_lock);
Jan Kara4f8ad652012-05-03 14:48:00 +02001435 /*
1436 * If inode is clean, remove it from writeback lists. Otherwise don't
1437 * touch it. See comment above for explanation.
1438 */
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05001439 if (!(inode->i_state & I_DIRTY_ALL))
Dave Chinnerc7f54082015-03-04 14:07:22 -05001440 inode_io_list_del_locked(inode, wb);
Jan Kara4f8ad652012-05-03 14:48:00 +02001441 spin_unlock(&wb->list_lock);
Joern Engel1c0eeaf2007-10-16 23:30:44 -07001442 inode_sync_complete(inode);
Jan Kara4f8ad652012-05-03 14:48:00 +02001443out:
1444 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445 return ret;
1446}
1447
Tejun Heoa88a3412015-05-22 17:13:28 -04001448static long writeback_chunk_size(struct bdi_writeback *wb,
Wu Fengguang1a12d8b2010-08-29 13:28:09 -06001449 struct wb_writeback_work *work)
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001450{
1451 long pages;
1452
1453 /*
1454 * WB_SYNC_ALL mode does livelock avoidance by syncing dirty
1455 * inodes/pages in one big loop. Setting wbc.nr_to_write=LONG_MAX
1456 * here avoids calling into writeback_inodes_wb() more than once.
1457 *
1458 * The intended call sequence for WB_SYNC_ALL writeback is:
1459 *
1460 * wb_writeback()
1461 * writeback_sb_inodes() <== called only once
1462 * write_cache_pages() <== called once for each inode
1463 * (quickly) tag currently dirty pages
1464 * (maybe slowly) sync all tagged pages
1465 */
1466 if (work->sync_mode == WB_SYNC_ALL || work->tagged_writepages)
1467 pages = LONG_MAX;
Wu Fengguang1a12d8b2010-08-29 13:28:09 -06001468 else {
Tejun Heoa88a3412015-05-22 17:13:28 -04001469 pages = min(wb->avg_write_bandwidth / 2,
Tejun Heodcc25ae2015-05-22 18:23:22 -04001470 global_wb_domain.dirty_limit / DIRTY_SCOPE);
Wu Fengguang1a12d8b2010-08-29 13:28:09 -06001471 pages = min(pages, work->nr_pages);
1472 pages = round_down(pages + MIN_WRITEBACK_PAGES,
1473 MIN_WRITEBACK_PAGES);
1474 }
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001475
1476 return pages;
1477}
1478
Jens Axboe03ba3782009-09-09 09:08:54 +02001479/*
Edward Shishkinf11c9c52010-03-11 14:09:47 -08001480 * Write a portion of b_io inodes which belong to @sb.
Christoph Hellwigedadfb12010-06-10 12:07:54 +02001481 *
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001482 * Return the number of pages and/or inodes written.
Linus Torvalds0ba13fd2015-09-11 13:26:39 -07001483 *
1484 * NOTE! This is called with wb->list_lock held, and will
1485 * unlock and relock that for each inode it ends up doing
1486 * IO for.
Edward Shishkinf11c9c52010-03-11 14:09:47 -08001487 */
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001488static long writeback_sb_inodes(struct super_block *sb,
1489 struct bdi_writeback *wb,
1490 struct wb_writeback_work *work)
Jens Axboe03ba3782009-09-09 09:08:54 +02001491{
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001492 struct writeback_control wbc = {
1493 .sync_mode = work->sync_mode,
1494 .tagged_writepages = work->tagged_writepages,
1495 .for_kupdate = work->for_kupdate,
1496 .for_background = work->for_background,
Dave Chinner7747bd42013-07-02 22:38:35 +10001497 .for_sync = work->for_sync,
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001498 .range_cyclic = work->range_cyclic,
1499 .range_start = 0,
1500 .range_end = LLONG_MAX,
1501 };
1502 unsigned long start_time = jiffies;
1503 long write_chunk;
1504 long wrote = 0; /* count both pages and inodes */
1505
Jens Axboe03ba3782009-09-09 09:08:54 +02001506 while (!list_empty(&wb->b_io)) {
Nick Piggin7ccf19a2010-10-21 11:49:30 +11001507 struct inode *inode = wb_inode(wb->b_io.prev);
Tejun Heoaaf25592016-03-18 13:52:04 -04001508 struct bdi_writeback *tmp_wb;
Christoph Hellwigedadfb12010-06-10 12:07:54 +02001509
1510 if (inode->i_sb != sb) {
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001511 if (work->sb) {
Christoph Hellwigedadfb12010-06-10 12:07:54 +02001512 /*
1513 * We only want to write back data for this
1514 * superblock, move all inodes not belonging
1515 * to it back onto the dirty list.
1516 */
Christoph Hellwigf758eea2011-04-21 18:19:44 -06001517 redirty_tail(inode, wb);
Christoph Hellwigedadfb12010-06-10 12:07:54 +02001518 continue;
1519 }
1520
1521 /*
1522 * The inode belongs to a different superblock.
1523 * Bounce back to the caller to unpin this and
1524 * pin the next superblock.
1525 */
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001526 break;
Christoph Hellwigedadfb12010-06-10 12:07:54 +02001527 }
1528
Christoph Hellwig9843b762010-10-24 19:40:46 +02001529 /*
Wanpeng Li331cbde2012-06-09 11:10:55 +08001530 * Don't bother with new inodes or inodes being freed, first
1531 * kind does not need periodic writeout yet, and for the latter
Christoph Hellwig9843b762010-10-24 19:40:46 +02001532 * kind writeout is handled by the freer.
1533 */
Dave Chinner250df6e2011-03-22 22:23:36 +11001534 spin_lock(&inode->i_lock);
Christoph Hellwig9843b762010-10-24 19:40:46 +02001535 if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
Dave Chinner250df6e2011-03-22 22:23:36 +11001536 spin_unlock(&inode->i_lock);
Wu Fengguangfcc5c222011-07-11 23:08:50 -07001537 redirty_tail(inode, wb);
Nick Piggin7ef0d732009-03-12 14:31:38 -07001538 continue;
1539 }
Jan Karacc1676d2012-05-03 14:47:56 +02001540 if ((inode->i_state & I_SYNC) && wbc.sync_mode != WB_SYNC_ALL) {
1541 /*
1542 * If this inode is locked for writeback and we are not
1543 * doing writeback-for-data-integrity, move it to
1544 * b_more_io so that writeback can proceed with the
1545 * other inodes on s_io.
1546 *
1547 * We'll have another go at writing back this inode
1548 * when we completed a full scan of b_io.
1549 */
1550 spin_unlock(&inode->i_lock);
1551 requeue_io(inode, wb);
1552 trace_writeback_sb_inodes_requeue(inode);
1553 continue;
1554 }
Jan Karaf0d07b72012-05-03 14:47:59 +02001555 spin_unlock(&wb->list_lock);
1556
Jan Kara4f8ad652012-05-03 14:48:00 +02001557 /*
1558 * We already requeued the inode if it had I_SYNC set and we
1559 * are doing WB_SYNC_NONE writeback. So this catches only the
1560 * WB_SYNC_ALL case.
1561 */
Jan Kara169ebd92012-05-03 14:48:03 +02001562 if (inode->i_state & I_SYNC) {
1563 /* Wait for I_SYNC. This function drops i_lock... */
1564 inode_sleep_on_writeback(inode);
1565 /* Inode may be gone, start again */
Jan Karaead188f2012-06-08 17:07:36 +02001566 spin_lock(&wb->list_lock);
Jan Kara169ebd92012-05-03 14:48:03 +02001567 continue;
1568 }
Jan Kara4f8ad652012-05-03 14:48:00 +02001569 inode->i_state |= I_SYNC;
Tejun Heob16b1de2015-06-02 08:39:48 -06001570 wbc_attach_and_unlock_inode(&wbc, inode);
Jan Kara169ebd92012-05-03 14:48:03 +02001571
Tejun Heoa88a3412015-05-22 17:13:28 -04001572 write_chunk = writeback_chunk_size(wb, work);
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001573 wbc.nr_to_write = write_chunk;
1574 wbc.pages_skipped = 0;
Dave Chinner250df6e2011-03-22 22:23:36 +11001575
Jan Kara169ebd92012-05-03 14:48:03 +02001576 /*
1577 * We use I_SYNC to pin the inode in memory. While it is set
1578 * evict_inode() will wait so the inode cannot be freed.
1579 */
Yan Hongcd8ed2a2012-10-08 16:33:45 -07001580 __writeback_single_inode(inode, &wbc);
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001581
Tejun Heob16b1de2015-06-02 08:39:48 -06001582 wbc_detach_inode(&wbc);
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001583 work->nr_pages -= write_chunk - wbc.nr_to_write;
1584 wrote += write_chunk - wbc.nr_to_write;
Chris Mason590dca32015-09-18 13:35:08 -04001585
1586 if (need_resched()) {
1587 /*
1588 * We're trying to balance between building up a nice
1589 * long list of IOs to improve our merge rate, and
1590 * getting those IOs out quickly for anyone throttling
1591 * in balance_dirty_pages(). cond_resched() doesn't
1592 * unplug, so get our IOs out the door before we
1593 * give up the CPU.
1594 */
1595 blk_flush_plug(current);
1596 cond_resched();
1597 }
1598
Tejun Heoaaf25592016-03-18 13:52:04 -04001599 /*
1600 * Requeue @inode if still dirty. Be careful as @inode may
1601 * have been switched to another wb in the meantime.
1602 */
1603 tmp_wb = inode_to_wb_and_lock_list(inode);
Jan Kara4f8ad652012-05-03 14:48:00 +02001604 spin_lock(&inode->i_lock);
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05001605 if (!(inode->i_state & I_DIRTY_ALL))
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001606 wrote++;
Tejun Heoaaf25592016-03-18 13:52:04 -04001607 requeue_inode(inode, tmp_wb, &wbc);
Jan Kara4f8ad652012-05-03 14:48:00 +02001608 inode_sync_complete(inode);
Dave Chinner0f1b1fd2011-03-22 22:23:43 +11001609 spin_unlock(&inode->i_lock);
Chris Mason590dca32015-09-18 13:35:08 -04001610
Tejun Heoaaf25592016-03-18 13:52:04 -04001611 if (unlikely(tmp_wb != wb)) {
1612 spin_unlock(&tmp_wb->list_lock);
1613 spin_lock(&wb->list_lock);
1614 }
1615
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001616 /*
1617 * bail out to wb_writeback() often enough to check
1618 * background threshold and other termination conditions.
1619 */
1620 if (wrote) {
1621 if (time_is_before_jiffies(start_time + HZ / 10UL))
1622 break;
1623 if (work->nr_pages <= 0)
1624 break;
Fengguang Wu8bc3be22008-02-04 22:29:36 -08001625 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001626 }
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001627 return wrote;
Edward Shishkinf11c9c52010-03-11 14:09:47 -08001628}
Nick Piggin38f21972009-01-06 14:40:25 -08001629
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001630static long __writeback_inodes_wb(struct bdi_writeback *wb,
1631 struct wb_writeback_work *work)
Edward Shishkinf11c9c52010-03-11 14:09:47 -08001632{
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001633 unsigned long start_time = jiffies;
1634 long wrote = 0;
Edward Shishkinf11c9c52010-03-11 14:09:47 -08001635
1636 while (!list_empty(&wb->b_io)) {
Nick Piggin7ccf19a2010-10-21 11:49:30 +11001637 struct inode *inode = wb_inode(wb->b_io.prev);
Edward Shishkinf11c9c52010-03-11 14:09:47 -08001638 struct super_block *sb = inode->i_sb;
Edward Shishkinf11c9c52010-03-11 14:09:47 -08001639
Konstantin Khlebnikoveb6ef3d2015-02-19 20:19:35 +03001640 if (!trylock_super(sb)) {
Wu Fengguang0e995812011-07-29 22:14:35 -06001641 /*
Konstantin Khlebnikoveb6ef3d2015-02-19 20:19:35 +03001642 * trylock_super() may fail consistently due to
Wu Fengguang0e995812011-07-29 22:14:35 -06001643 * s_umount being grabbed by someone else. Don't use
1644 * requeue_io() to avoid busy retrying the inode/sb.
1645 */
1646 redirty_tail(inode, wb);
Christoph Hellwigedadfb12010-06-10 12:07:54 +02001647 continue;
Edward Shishkinf11c9c52010-03-11 14:09:47 -08001648 }
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001649 wrote += writeback_sb_inodes(sb, wb, work);
Konstantin Khlebnikoveb6ef3d2015-02-19 20:19:35 +03001650 up_read(&sb->s_umount);
Edward Shishkinf11c9c52010-03-11 14:09:47 -08001651
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001652 /* refer to the same tests at the end of writeback_sb_inodes */
1653 if (wrote) {
1654 if (time_is_before_jiffies(start_time + HZ / 10UL))
1655 break;
1656 if (work->nr_pages <= 0)
1657 break;
1658 }
Edward Shishkinf11c9c52010-03-11 14:09:47 -08001659 }
Jens Axboe66f3b8e2009-09-02 09:19:46 +02001660 /* Leave any unwritten inodes on b_io */
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001661 return wrote;
Jens Axboe66f3b8e2009-09-02 09:19:46 +02001662}
1663
Wanpeng Li7d9f0732013-09-11 14:22:40 -07001664static long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages,
Curt Wohlgemuth0e175a12011-10-07 21:54:10 -06001665 enum wb_reason reason)
Christoph Hellwigedadfb12010-06-10 12:07:54 +02001666{
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001667 struct wb_writeback_work work = {
1668 .nr_pages = nr_pages,
1669 .sync_mode = WB_SYNC_NONE,
1670 .range_cyclic = 1,
Curt Wohlgemuth0e175a12011-10-07 21:54:10 -06001671 .reason = reason,
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001672 };
Linus Torvalds505a6662015-09-11 13:37:19 -07001673 struct blk_plug plug;
Christoph Hellwigedadfb12010-06-10 12:07:54 +02001674
Linus Torvalds505a6662015-09-11 13:37:19 -07001675 blk_start_plug(&plug);
Christoph Hellwigf758eea2011-04-21 18:19:44 -06001676 spin_lock(&wb->list_lock);
Wu Fengguang424b3512010-07-21 20:11:53 -06001677 if (list_empty(&wb->b_io))
Curt Wohlgemuthad4e38d2011-10-07 21:51:56 -06001678 queue_io(wb, &work);
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001679 __writeback_inodes_wb(wb, &work);
Christoph Hellwigf758eea2011-04-21 18:19:44 -06001680 spin_unlock(&wb->list_lock);
Linus Torvalds505a6662015-09-11 13:37:19 -07001681 blk_finish_plug(&plug);
Christoph Hellwigedadfb12010-06-10 12:07:54 +02001682
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001683 return nr_pages - work.nr_pages;
Jens Axboe66f3b8e2009-09-02 09:19:46 +02001684}
1685
Jens Axboe03ba3782009-09-09 09:08:54 +02001686/*
1687 * Explicit flushing or periodic writeback of "old" data.
1688 *
1689 * Define "old": the first time one of an inode's pages is dirtied, we mark the
1690 * dirtying-time in the inode's address_space. So this periodic writeback code
1691 * just walks the superblock inode list, writing back any inodes which are
1692 * older than a specific point in time.
1693 *
1694 * Try to run once per dirty_writeback_interval. But if a writeback event
1695 * takes longer than a dirty_writeback_interval interval, then leave a
1696 * one-second gap.
1697 *
1698 * older_than_this takes precedence over nr_to_write. So we'll only write back
1699 * all dirty pages if they are all attached to "old" mappings.
1700 */
Jens Axboec4a77a62009-09-16 15:18:25 +02001701static long wb_writeback(struct bdi_writeback *wb,
Christoph Hellwig83ba7b02010-07-06 08:59:53 +02001702 struct wb_writeback_work *work)
Jens Axboe03ba3782009-09-09 09:08:54 +02001703{
Wu Fengguange98be2d2010-08-29 11:22:30 -06001704 unsigned long wb_start = jiffies;
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001705 long nr_pages = work->nr_pages;
Jan Kara0dc83bd2014-02-21 11:19:04 +01001706 unsigned long oldest_jif;
Jan Karaa5989bd2009-09-16 19:22:48 +02001707 struct inode *inode;
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001708 long progress;
Linus Torvalds505a6662015-09-11 13:37:19 -07001709 struct blk_plug plug;
Jens Axboe03ba3782009-09-09 09:08:54 +02001710
Jan Kara0dc83bd2014-02-21 11:19:04 +01001711 oldest_jif = jiffies;
1712 work->older_than_this = &oldest_jif;
Jens Axboe03ba3782009-09-09 09:08:54 +02001713
Linus Torvalds505a6662015-09-11 13:37:19 -07001714 blk_start_plug(&plug);
Wu Fengguange8dfc302011-04-21 12:06:32 -06001715 spin_lock(&wb->list_lock);
Jens Axboe03ba3782009-09-09 09:08:54 +02001716 for (;;) {
1717 /*
Wu Fengguangd3ddec72009-09-23 20:33:40 +08001718 * Stop writeback when nr_pages has been consumed
Jens Axboe03ba3782009-09-09 09:08:54 +02001719 */
Christoph Hellwig83ba7b02010-07-06 08:59:53 +02001720 if (work->nr_pages <= 0)
Jens Axboe03ba3782009-09-09 09:08:54 +02001721 break;
1722
1723 /*
Jan Karaaa373cf2011-01-13 15:45:47 -08001724 * Background writeout and kupdate-style writeback may
1725 * run forever. Stop them if there is other work to do
1726 * so that e.g. sync can proceed. They'll be restarted
1727 * after the other works are all done.
1728 */
1729 if ((work->for_background || work->for_kupdate) &&
Tejun Heof0054bb2015-05-22 17:13:30 -04001730 !list_empty(&wb->work_list))
Jan Karaaa373cf2011-01-13 15:45:47 -08001731 break;
1732
1733 /*
Wu Fengguangd3ddec72009-09-23 20:33:40 +08001734 * For background writeout, stop when we are below the
1735 * background dirty threshold
Jens Axboe03ba3782009-09-09 09:08:54 +02001736 */
Tejun Heoaa661bb2015-05-22 18:23:31 -04001737 if (work->for_background && !wb_over_bg_thresh(wb))
Jens Axboe03ba3782009-09-09 09:08:54 +02001738 break;
1739
Jan Kara1bc36b62011-10-19 11:44:41 +02001740 /*
1741 * Kupdate and background works are special and we want to
1742 * include all inodes that need writing. Livelock avoidance is
1743 * handled by these works yielding to any other work so we are
1744 * safe.
1745 */
Wu Fengguangba9aa832010-07-21 20:32:30 -06001746 if (work->for_kupdate) {
Jan Kara0dc83bd2014-02-21 11:19:04 +01001747 oldest_jif = jiffies -
Wu Fengguangba9aa832010-07-21 20:32:30 -06001748 msecs_to_jiffies(dirty_expire_interval * 10);
Jan Kara1bc36b62011-10-19 11:44:41 +02001749 } else if (work->for_background)
Jan Kara0dc83bd2014-02-21 11:19:04 +01001750 oldest_jif = jiffies;
Dave Chinner028c2dd2010-07-07 13:24:07 +10001751
Tejun Heo5634cc22015-08-18 14:54:56 -07001752 trace_writeback_start(wb, work);
Wu Fengguange8dfc302011-04-21 12:06:32 -06001753 if (list_empty(&wb->b_io))
Curt Wohlgemuthad4e38d2011-10-07 21:51:56 -06001754 queue_io(wb, work);
Christoph Hellwig83ba7b02010-07-06 08:59:53 +02001755 if (work->sb)
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001756 progress = writeback_sb_inodes(work->sb, wb, work);
Christoph Hellwigedadfb12010-06-10 12:07:54 +02001757 else
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001758 progress = __writeback_inodes_wb(wb, work);
Tejun Heo5634cc22015-08-18 14:54:56 -07001759 trace_writeback_written(wb, work);
Dave Chinner028c2dd2010-07-07 13:24:07 +10001760
Wu Fengguange98be2d2010-08-29 11:22:30 -06001761 wb_update_bandwidth(wb, wb_start);
Jens Axboe03ba3782009-09-09 09:08:54 +02001762
1763 /*
Jens Axboe71fd05a2009-09-23 19:32:26 +02001764 * Did we write something? Try for more
Wu Fengguange6fb6da2010-07-22 10:23:44 -06001765 *
1766 * Dirty inodes are moved to b_io for writeback in batches.
1767 * The completion of the current batch does not necessarily
1768 * mean the overall work is done. So we keep looping as long
1769 * as made some progress on cleaning pages or inodes.
Jens Axboe71fd05a2009-09-23 19:32:26 +02001770 */
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001771 if (progress)
Jens Axboe71fd05a2009-09-23 19:32:26 +02001772 continue;
1773 /*
Wu Fengguange6fb6da2010-07-22 10:23:44 -06001774 * No more inodes for IO, bail
Jens Axboe71fd05a2009-09-23 19:32:26 +02001775 */
Wu Fengguangb7a24412010-07-21 22:19:51 -06001776 if (list_empty(&wb->b_more_io))
Jens Axboe03ba3782009-09-09 09:08:54 +02001777 break;
1778 /*
Jens Axboe8010c3b2009-09-15 20:04:57 +02001779 * Nothing written. Wait for some inode to
1780 * become available for writeback. Otherwise
1781 * we'll just busyloop.
Jens Axboe03ba3782009-09-09 09:08:54 +02001782 */
Tahsin Erdoganbace9242016-12-12 16:43:20 -08001783 trace_writeback_wait(wb, work);
1784 inode = wb_inode(wb->b_more_io.prev);
1785 spin_lock(&inode->i_lock);
1786 spin_unlock(&wb->list_lock);
1787 /* This function drops i_lock... */
1788 inode_sleep_on_writeback(inode);
1789 spin_lock(&wb->list_lock);
Jens Axboe03ba3782009-09-09 09:08:54 +02001790 }
Wu Fengguange8dfc302011-04-21 12:06:32 -06001791 spin_unlock(&wb->list_lock);
Linus Torvalds505a6662015-09-11 13:37:19 -07001792 blk_finish_plug(&plug);
Jens Axboe03ba3782009-09-09 09:08:54 +02001793
Wu Fengguangd46db3d2011-05-04 19:54:37 -06001794 return nr_pages - work->nr_pages;
Jens Axboe03ba3782009-09-09 09:08:54 +02001795}
1796
1797/*
Christoph Hellwig83ba7b02010-07-06 08:59:53 +02001798 * Return the next wb_writeback_work struct that hasn't been processed yet.
Jens Axboe03ba3782009-09-09 09:08:54 +02001799 */
Tejun Heof0054bb2015-05-22 17:13:30 -04001800static struct wb_writeback_work *get_next_work_item(struct bdi_writeback *wb)
Jens Axboe03ba3782009-09-09 09:08:54 +02001801{
Christoph Hellwig83ba7b02010-07-06 08:59:53 +02001802 struct wb_writeback_work *work = NULL;
Jens Axboe03ba3782009-09-09 09:08:54 +02001803
Tejun Heof0054bb2015-05-22 17:13:30 -04001804 spin_lock_bh(&wb->work_lock);
1805 if (!list_empty(&wb->work_list)) {
1806 work = list_entry(wb->work_list.next,
Christoph Hellwig83ba7b02010-07-06 08:59:53 +02001807 struct wb_writeback_work, list);
1808 list_del_init(&work->list);
Jens Axboe03ba3782009-09-09 09:08:54 +02001809 }
Tejun Heof0054bb2015-05-22 17:13:30 -04001810 spin_unlock_bh(&wb->work_lock);
Christoph Hellwig83ba7b02010-07-06 08:59:53 +02001811 return work;
Jens Axboe03ba3782009-09-09 09:08:54 +02001812}
1813
Jan Kara65850272011-01-13 15:45:44 -08001814static long wb_check_background_flush(struct bdi_writeback *wb)
1815{
Tejun Heoaa661bb2015-05-22 18:23:31 -04001816 if (wb_over_bg_thresh(wb)) {
Jan Kara65850272011-01-13 15:45:44 -08001817
1818 struct wb_writeback_work work = {
1819 .nr_pages = LONG_MAX,
1820 .sync_mode = WB_SYNC_NONE,
1821 .for_background = 1,
1822 .range_cyclic = 1,
Curt Wohlgemuth0e175a12011-10-07 21:54:10 -06001823 .reason = WB_REASON_BACKGROUND,
Jan Kara65850272011-01-13 15:45:44 -08001824 };
1825
1826 return wb_writeback(wb, &work);
1827 }
1828
1829 return 0;
1830}
1831
Jens Axboe03ba3782009-09-09 09:08:54 +02001832static long wb_check_old_data_flush(struct bdi_writeback *wb)
1833{
1834 unsigned long expired;
1835 long nr_pages;
1836
Jens Axboe69b62d02010-05-17 12:51:03 +02001837 /*
1838 * When set to zero, disable periodic writeback
1839 */
1840 if (!dirty_writeback_interval)
1841 return 0;
1842
Jens Axboe03ba3782009-09-09 09:08:54 +02001843 expired = wb->last_old_flush +
1844 msecs_to_jiffies(dirty_writeback_interval * 10);
1845 if (time_before(jiffies, expired))
1846 return 0;
1847
1848 wb->last_old_flush = jiffies;
Linus Torvaldscdf01dd2010-10-30 08:55:52 -07001849 nr_pages = get_nr_dirty_pages();
Jens Axboe03ba3782009-09-09 09:08:54 +02001850
Jens Axboec4a77a62009-09-16 15:18:25 +02001851 if (nr_pages) {
Christoph Hellwig83ba7b02010-07-06 08:59:53 +02001852 struct wb_writeback_work work = {
Jens Axboec4a77a62009-09-16 15:18:25 +02001853 .nr_pages = nr_pages,
1854 .sync_mode = WB_SYNC_NONE,
1855 .for_kupdate = 1,
1856 .range_cyclic = 1,
Curt Wohlgemuth0e175a12011-10-07 21:54:10 -06001857 .reason = WB_REASON_PERIODIC,
Jens Axboec4a77a62009-09-16 15:18:25 +02001858 };
1859
Christoph Hellwig83ba7b02010-07-06 08:59:53 +02001860 return wb_writeback(wb, &work);
Jens Axboec4a77a62009-09-16 15:18:25 +02001861 }
Jens Axboe03ba3782009-09-09 09:08:54 +02001862
1863 return 0;
1864}
1865
Jens Axboe85009b42017-09-30 02:09:06 -06001866static long wb_check_start_all(struct bdi_writeback *wb)
1867{
1868 long nr_pages;
1869
1870 if (!test_bit(WB_start_all, &wb->state))
1871 return 0;
1872
1873 nr_pages = get_nr_dirty_pages();
1874 if (nr_pages) {
1875 struct wb_writeback_work work = {
1876 .nr_pages = wb_split_bdi_pages(wb, nr_pages),
1877 .sync_mode = WB_SYNC_NONE,
1878 .range_cyclic = 1,
1879 .reason = wb->start_all_reason,
1880 };
1881
1882 nr_pages = wb_writeback(wb, &work);
1883 }
1884
1885 clear_bit(WB_start_all, &wb->state);
1886 return nr_pages;
1887}
1888
1889
Jens Axboe03ba3782009-09-09 09:08:54 +02001890/*
1891 * Retrieve work items and do the writeback they describe
1892 */
Wanpeng Li25d130b2013-07-08 16:00:14 -07001893static long wb_do_writeback(struct bdi_writeback *wb)
Jens Axboe03ba3782009-09-09 09:08:54 +02001894{
Christoph Hellwig83ba7b02010-07-06 08:59:53 +02001895 struct wb_writeback_work *work;
Jens Axboec4a77a62009-09-16 15:18:25 +02001896 long wrote = 0;
Jens Axboe03ba3782009-09-09 09:08:54 +02001897
Tejun Heo44522262015-05-22 17:13:26 -04001898 set_bit(WB_writeback_running, &wb->state);
Tejun Heof0054bb2015-05-22 17:13:30 -04001899 while ((work = get_next_work_item(wb)) != NULL) {
Tejun Heo5634cc22015-08-18 14:54:56 -07001900 trace_writeback_exec(wb, work);
Christoph Hellwig83ba7b02010-07-06 08:59:53 +02001901 wrote += wb_writeback(wb, work);
Tahsin Erdogan4a3a4852017-03-10 12:09:49 -08001902 finish_writeback_work(wb, work);
Jens Axboe03ba3782009-09-09 09:08:54 +02001903 }
1904
1905 /*
Jens Axboe85009b42017-09-30 02:09:06 -06001906 * Check for a flush-everything request
1907 */
1908 wrote += wb_check_start_all(wb);
1909
1910 /*
Jens Axboe03ba3782009-09-09 09:08:54 +02001911 * Check for periodic writeback, kupdated() style
1912 */
1913 wrote += wb_check_old_data_flush(wb);
Jan Kara65850272011-01-13 15:45:44 -08001914 wrote += wb_check_background_flush(wb);
Tejun Heo44522262015-05-22 17:13:26 -04001915 clear_bit(WB_writeback_running, &wb->state);
Jens Axboe03ba3782009-09-09 09:08:54 +02001916
1917 return wrote;
1918}
1919
1920/*
1921 * Handle writeback of dirty data for the device backed by this bdi. Also
Tejun Heo839a8e82013-04-01 19:08:06 -07001922 * reschedules periodically and does kupdated style flushing.
Jens Axboe03ba3782009-09-09 09:08:54 +02001923 */
Tejun Heof0054bb2015-05-22 17:13:30 -04001924void wb_workfn(struct work_struct *work)
Jens Axboe03ba3782009-09-09 09:08:54 +02001925{
Tejun Heo839a8e82013-04-01 19:08:06 -07001926 struct bdi_writeback *wb = container_of(to_delayed_work(work),
1927 struct bdi_writeback, dwork);
Jens Axboe03ba3782009-09-09 09:08:54 +02001928 long pages_written;
1929
Tejun Heof0054bb2015-05-22 17:13:30 -04001930 set_worker_desc("flush-%s", dev_name(wb->bdi->dev));
Peter Zijlstra766f9162010-10-26 14:22:45 -07001931 current->flags |= PF_SWAPWRITE;
Christoph Hellwig08243902010-06-19 23:08:22 +02001932
Tejun Heo839a8e82013-04-01 19:08:06 -07001933 if (likely(!current_is_workqueue_rescuer() ||
Tejun Heo44522262015-05-22 17:13:26 -04001934 !test_bit(WB_registered, &wb->state))) {
Artem Bityutskiy64677162010-07-25 14:29:22 +03001935 /*
Tejun Heof0054bb2015-05-22 17:13:30 -04001936 * The normal path. Keep writing back @wb until its
Tejun Heo839a8e82013-04-01 19:08:06 -07001937 * work_list is empty. Note that this path is also taken
Tejun Heof0054bb2015-05-22 17:13:30 -04001938 * if @wb is shutting down even when we're running off the
Tejun Heo839a8e82013-04-01 19:08:06 -07001939 * rescuer as work_list needs to be drained.
Artem Bityutskiy64677162010-07-25 14:29:22 +03001940 */
Tejun Heo839a8e82013-04-01 19:08:06 -07001941 do {
Wanpeng Li25d130b2013-07-08 16:00:14 -07001942 pages_written = wb_do_writeback(wb);
Tejun Heo839a8e82013-04-01 19:08:06 -07001943 trace_writeback_pages_written(pages_written);
Tejun Heof0054bb2015-05-22 17:13:30 -04001944 } while (!list_empty(&wb->work_list));
Tejun Heo839a8e82013-04-01 19:08:06 -07001945 } else {
1946 /*
1947 * bdi_wq can't get enough workers and we're running off
1948 * the emergency worker. Don't hog it. Hopefully, 1024 is
1949 * enough for efficient IO.
1950 */
Tejun Heof0054bb2015-05-22 17:13:30 -04001951 pages_written = writeback_inodes_wb(wb, 1024,
Tejun Heo839a8e82013-04-01 19:08:06 -07001952 WB_REASON_FORKER_THREAD);
Dave Chinner455b2862010-07-07 13:24:06 +10001953 trace_writeback_pages_written(pages_written);
Jens Axboe03ba3782009-09-09 09:08:54 +02001954 }
1955
Tejun Heof0054bb2015-05-22 17:13:30 -04001956 if (!list_empty(&wb->work_list))
Jan Karab8b78492018-05-03 18:26:26 +02001957 wb_wakeup(wb);
Derek Basehore6ca738d2014-04-03 14:46:22 -07001958 else if (wb_has_dirty_io(wb) && dirty_writeback_interval)
Tejun Heof0054bb2015-05-22 17:13:30 -04001959 wb_wakeup_delayed(wb);
Dave Chinner455b2862010-07-07 13:24:06 +10001960
Tejun Heo839a8e82013-04-01 19:08:06 -07001961 current->flags &= ~PF_SWAPWRITE;
Jens Axboe03ba3782009-09-09 09:08:54 +02001962}
1963
1964/*
Jens Axboe595043e2017-09-28 11:26:59 -06001965 * Start writeback of `nr_pages' pages on this bdi. If `nr_pages' is zero,
1966 * write back the whole world.
1967 */
1968static void __wakeup_flusher_threads_bdi(struct backing_dev_info *bdi,
Jens Axboee8e8a0c2017-09-28 11:31:22 -06001969 enum wb_reason reason)
Jens Axboe595043e2017-09-28 11:26:59 -06001970{
1971 struct bdi_writeback *wb;
1972
1973 if (!bdi_has_dirty_io(bdi))
1974 return;
1975
1976 list_for_each_entry_rcu(wb, &bdi->wb_list, bdi_node)
Jens Axboee8e8a0c2017-09-28 11:31:22 -06001977 wb_start_writeback(wb, reason);
Jens Axboe595043e2017-09-28 11:26:59 -06001978}
1979
1980void wakeup_flusher_threads_bdi(struct backing_dev_info *bdi,
1981 enum wb_reason reason)
1982{
Jens Axboe595043e2017-09-28 11:26:59 -06001983 rcu_read_lock();
Jens Axboee8e8a0c2017-09-28 11:31:22 -06001984 __wakeup_flusher_threads_bdi(bdi, reason);
Jens Axboe595043e2017-09-28 11:26:59 -06001985 rcu_read_unlock();
1986}
1987
1988/*
Jens Axboe9ba4b2d2017-09-20 08:58:25 -06001989 * Wakeup the flusher threads to start writeback of all currently dirty pages
Jens Axboe03ba3782009-09-09 09:08:54 +02001990 */
Jens Axboe9ba4b2d2017-09-20 08:58:25 -06001991void wakeup_flusher_threads(enum wb_reason reason)
Jens Axboe03ba3782009-09-09 09:08:54 +02001992{
Christoph Hellwigb8c2f342010-06-08 18:15:07 +02001993 struct backing_dev_info *bdi;
Christoph Hellwigb8c2f342010-06-08 18:15:07 +02001994
Konstantin Khlebnikov51350ea2016-08-04 21:36:05 +03001995 /*
1996 * If we are expecting writeback progress we must submit plugged IO.
1997 */
1998 if (blk_needs_flush_plug(current))
1999 blk_schedule_flush_plug(current);
2000
Christoph Hellwigb8c2f342010-06-08 18:15:07 +02002001 rcu_read_lock();
Jens Axboe595043e2017-09-28 11:26:59 -06002002 list_for_each_entry_rcu(bdi, &bdi_list, bdi_list)
Jens Axboee8e8a0c2017-09-28 11:31:22 -06002003 __wakeup_flusher_threads_bdi(bdi, reason);
Christoph Hellwigb8c2f342010-06-08 18:15:07 +02002004 rcu_read_unlock();
Jens Axboe03ba3782009-09-09 09:08:54 +02002005}
2006
Theodore Ts'oa2f48702015-03-17 12:23:19 -04002007/*
2008 * Wake up bdi's periodically to make sure dirtytime inodes gets
2009 * written back periodically. We deliberately do *not* check the
2010 * b_dirtytime list in wb_has_dirty_io(), since this would cause the
2011 * kernel to be constantly waking up once there are any dirtytime
2012 * inodes on the system. So instead we define a separate delayed work
2013 * function which gets called much more rarely. (By default, only
2014 * once every 12 hours.)
2015 *
2016 * If there is any other write activity going on in the file system,
2017 * this function won't be necessary. But if the only thing that has
2018 * happened on the file system is a dirtytime inode caused by an atime
2019 * update, we need this infrastructure below to make sure that inode
2020 * eventually gets pushed out to disk.
2021 */
2022static void wakeup_dirtytime_writeback(struct work_struct *w);
2023static DECLARE_DELAYED_WORK(dirtytime_work, wakeup_dirtytime_writeback);
2024
2025static void wakeup_dirtytime_writeback(struct work_struct *w)
2026{
2027 struct backing_dev_info *bdi;
2028
2029 rcu_read_lock();
2030 list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) {
Tejun Heo001fe6f2015-05-22 17:13:56 -04002031 struct bdi_writeback *wb;
Tejun Heo001fe6f2015-05-22 17:13:56 -04002032
Tejun Heob8175252015-10-02 14:47:05 -04002033 list_for_each_entry_rcu(wb, &bdi->wb_list, bdi_node)
Tejun Heo6fdf8602015-09-29 12:47:51 -04002034 if (!list_empty(&wb->b_dirty_time))
2035 wb_wakeup(wb);
Theodore Ts'oa2f48702015-03-17 12:23:19 -04002036 }
2037 rcu_read_unlock();
2038 schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ);
2039}
2040
2041static int __init start_dirtytime_writeback(void)
2042{
2043 schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ);
2044 return 0;
2045}
2046__initcall(start_dirtytime_writeback);
2047
Theodore Ts'o1efff912015-03-17 12:23:32 -04002048int dirtytime_interval_handler(struct ctl_table *table, int write,
2049 void __user *buffer, size_t *lenp, loff_t *ppos)
2050{
2051 int ret;
2052
2053 ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
2054 if (ret == 0 && write)
2055 mod_delayed_work(system_wq, &dirtytime_work, 0);
2056 return ret;
2057}
2058
Jens Axboe03ba3782009-09-09 09:08:54 +02002059static noinline void block_dump___mark_inode_dirty(struct inode *inode)
2060{
2061 if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) {
2062 struct dentry *dentry;
2063 const char *name = "?";
2064
2065 dentry = d_find_alias(inode);
2066 if (dentry) {
2067 spin_lock(&dentry->d_lock);
2068 name = (const char *) dentry->d_name.name;
2069 }
2070 printk(KERN_DEBUG
2071 "%s(%d): dirtied inode %lu (%s) on %s\n",
2072 current->comm, task_pid_nr(current), inode->i_ino,
2073 name, inode->i_sb->s_id);
2074 if (dentry) {
2075 spin_unlock(&dentry->d_lock);
2076 dput(dentry);
2077 }
2078 }
2079}
2080
2081/**
Mauro Carvalho Chehab0117d422017-05-12 07:45:42 -03002082 * __mark_inode_dirty - internal function
2083 *
2084 * @inode: inode to mark
2085 * @flags: what kind of dirty (i.e. I_DIRTY_SYNC)
2086 *
2087 * Mark an inode as dirty. Callers should use mark_inode_dirty or
2088 * mark_inode_dirty_sync.
Jens Axboe03ba3782009-09-09 09:08:54 +02002089 *
2090 * Put the inode on the super block's dirty list.
2091 *
2092 * CAREFUL! We mark it dirty unconditionally, but move it onto the
2093 * dirty list only if it is hashed or if it refers to a blockdev.
2094 * If it was not hashed, it will never be added to the dirty list
2095 * even if it is later hashed, as it will have been marked dirty already.
2096 *
2097 * In short, make sure you hash any inodes _before_ you start marking
2098 * them dirty.
2099 *
Jens Axboe03ba3782009-09-09 09:08:54 +02002100 * Note that for blockdevs, inode->dirtied_when represents the dirtying time of
2101 * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of
2102 * the kernel-internal blockdev inode represents the dirtying time of the
2103 * blockdev's pages. This is why for I_DIRTY_PAGES we always use
2104 * page->mapping->host, so the page-dirtying time is recorded in the internal
2105 * blockdev inode.
2106 */
2107void __mark_inode_dirty(struct inode *inode, int flags)
2108{
2109 struct super_block *sb = inode->i_sb;
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05002110 int dirtytime;
2111
2112 trace_writeback_mark_inode_dirty(inode, flags);
Jens Axboe03ba3782009-09-09 09:08:54 +02002113
2114 /*
2115 * Don't do this for I_DIRTY_PAGES - that doesn't actually
2116 * dirty the inode itself
2117 */
Christoph Hellwig0e11f642018-02-21 07:54:49 -08002118 if (flags & (I_DIRTY_INODE | I_DIRTY_TIME)) {
Tejun Heo9fb0a7d2013-01-11 13:06:37 -08002119 trace_writeback_dirty_inode_start(inode, flags);
2120
Jens Axboe03ba3782009-09-09 09:08:54 +02002121 if (sb->s_op->dirty_inode)
Christoph Hellwigaa385722011-05-27 06:53:02 -04002122 sb->s_op->dirty_inode(inode, flags);
Tejun Heo9fb0a7d2013-01-11 13:06:37 -08002123
2124 trace_writeback_dirty_inode(inode, flags);
Jens Axboe03ba3782009-09-09 09:08:54 +02002125 }
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05002126 if (flags & I_DIRTY_INODE)
2127 flags &= ~I_DIRTY_TIME;
2128 dirtytime = flags & I_DIRTY_TIME;
Jens Axboe03ba3782009-09-09 09:08:54 +02002129
2130 /*
Tejun Heo9c6ac782014-10-24 15:38:21 -04002131 * Paired with smp_mb() in __writeback_single_inode() for the
2132 * following lockless i_state test. See there for details.
Jens Axboe03ba3782009-09-09 09:08:54 +02002133 */
2134 smp_mb();
2135
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05002136 if (((inode->i_state & flags) == flags) ||
2137 (dirtytime && (inode->i_state & I_DIRTY_INODE)))
Jens Axboe03ba3782009-09-09 09:08:54 +02002138 return;
2139
2140 if (unlikely(block_dump))
2141 block_dump___mark_inode_dirty(inode);
2142
Dave Chinner250df6e2011-03-22 22:23:36 +11002143 spin_lock(&inode->i_lock);
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05002144 if (dirtytime && (inode->i_state & I_DIRTY_INODE))
2145 goto out_unlock_inode;
Jens Axboe03ba3782009-09-09 09:08:54 +02002146 if ((inode->i_state & flags) != flags) {
2147 const int was_dirty = inode->i_state & I_DIRTY;
2148
Tejun Heo52ebea72015-05-22 17:13:37 -04002149 inode_attach_wb(inode, NULL);
2150
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05002151 if (flags & I_DIRTY_INODE)
2152 inode->i_state &= ~I_DIRTY_TIME;
Jens Axboe03ba3782009-09-09 09:08:54 +02002153 inode->i_state |= flags;
2154
2155 /*
2156 * If the inode is being synced, just update its dirty state.
2157 * The unlocker will place the inode on the appropriate
2158 * superblock list, based upon its state.
2159 */
2160 if (inode->i_state & I_SYNC)
Dave Chinner250df6e2011-03-22 22:23:36 +11002161 goto out_unlock_inode;
Jens Axboe03ba3782009-09-09 09:08:54 +02002162
2163 /*
2164 * Only add valid (hashed) inodes to the superblock's
2165 * dirty list. Add blockdev inodes as well.
2166 */
2167 if (!S_ISBLK(inode->i_mode)) {
Al Viro1d3382cb2010-10-23 15:19:20 -04002168 if (inode_unhashed(inode))
Dave Chinner250df6e2011-03-22 22:23:36 +11002169 goto out_unlock_inode;
Jens Axboe03ba3782009-09-09 09:08:54 +02002170 }
Al Viroa4ffdde2010-06-02 17:38:30 -04002171 if (inode->i_state & I_FREEING)
Dave Chinner250df6e2011-03-22 22:23:36 +11002172 goto out_unlock_inode;
Jens Axboe03ba3782009-09-09 09:08:54 +02002173
2174 /*
2175 * If the inode was already on b_dirty/b_io/b_more_io, don't
2176 * reposition it (that would break b_dirty time-ordering).
2177 */
2178 if (!was_dirty) {
Tejun Heo87e1d782015-05-28 14:50:52 -04002179 struct bdi_writeback *wb;
Tejun Heod6c10f12015-05-22 17:13:45 -04002180 struct list_head *dirty_list;
Dave Chinnera66979a2011-03-22 22:23:41 +11002181 bool wakeup_bdi = false;
Jens Axboe500b0672009-09-09 09:10:25 +02002182
Tejun Heo87e1d782015-05-28 14:50:52 -04002183 wb = locked_inode_to_wb_and_lock_list(inode);
Artem Bityutskiy253c34e2010-07-25 14:29:21 +03002184
Tejun Heo07472592015-05-22 17:14:02 -04002185 WARN(bdi_cap_writeback_dirty(wb->bdi) &&
2186 !test_bit(WB_registered, &wb->state),
2187 "bdi-%s not registered\n", wb->bdi->name);
Jens Axboe03ba3782009-09-09 09:08:54 +02002188
2189 inode->dirtied_when = jiffies;
Theodore Ts'oa2f48702015-03-17 12:23:19 -04002190 if (dirtytime)
2191 inode->dirtied_time_when = jiffies;
Tejun Heod6c10f12015-05-22 17:13:45 -04002192
Christoph Hellwig0e11f642018-02-21 07:54:49 -08002193 if (inode->i_state & I_DIRTY)
Tejun Heo07472592015-05-22 17:14:02 -04002194 dirty_list = &wb->b_dirty;
Theodore Ts'oa2f48702015-03-17 12:23:19 -04002195 else
Tejun Heo07472592015-05-22 17:14:02 -04002196 dirty_list = &wb->b_dirty_time;
Tejun Heod6c10f12015-05-22 17:13:45 -04002197
Dave Chinnerc7f54082015-03-04 14:07:22 -05002198 wakeup_bdi = inode_io_list_move_locked(inode, wb,
Tejun Heod6c10f12015-05-22 17:13:45 -04002199 dirty_list);
2200
Tejun Heo07472592015-05-22 17:14:02 -04002201 spin_unlock(&wb->list_lock);
Theodore Ts'o0ae45f62015-02-02 00:37:00 -05002202 trace_writeback_dirty_inode_enqueue(inode);
Dave Chinnera66979a2011-03-22 22:23:41 +11002203
Tejun Heod6c10f12015-05-22 17:13:45 -04002204 /*
2205 * If this is the first dirty inode for this bdi,
2206 * we have to wake-up the corresponding bdi thread
2207 * to make sure background write-back happens
2208 * later.
2209 */
Tejun Heo07472592015-05-22 17:14:02 -04002210 if (bdi_cap_writeback_dirty(wb->bdi) && wakeup_bdi)
2211 wb_wakeup_delayed(wb);
Dave Chinnera66979a2011-03-22 22:23:41 +11002212 return;
Jens Axboe03ba3782009-09-09 09:08:54 +02002213 }
2214 }
Dave Chinner250df6e2011-03-22 22:23:36 +11002215out_unlock_inode:
2216 spin_unlock(&inode->i_lock);
Jens Axboe03ba3782009-09-09 09:08:54 +02002217}
2218EXPORT_SYMBOL(__mark_inode_dirty);
2219
Dave Chinnere97fedb2015-03-04 13:40:00 -05002220/*
2221 * The @s_sync_lock is used to serialise concurrent sync operations
2222 * to avoid lock contention problems with concurrent wait_sb_inodes() calls.
2223 * Concurrent callers will block on the s_sync_lock rather than doing contending
2224 * walks. The queueing maintains sync(2) required behaviour as all the IO that
2225 * has been issued up to the time this function is enter is guaranteed to be
2226 * completed by the time we have gained the lock and waited for all IO that is
2227 * in progress regardless of the order callers are granted the lock.
2228 */
Jens Axboeb6e51312009-09-16 15:13:54 +02002229static void wait_sb_inodes(struct super_block *sb)
Jens Axboe66f3b8e2009-09-02 09:19:46 +02002230{
Dave Chinner6c60d2b2016-07-26 15:21:50 -07002231 LIST_HEAD(sync_list);
Jens Axboe66f3b8e2009-09-02 09:19:46 +02002232
Jens Axboe03ba3782009-09-09 09:08:54 +02002233 /*
2234 * We need to be protected against the filesystem going from
2235 * r/o to r/w or vice versa.
2236 */
Jens Axboeb6e51312009-09-16 15:13:54 +02002237 WARN_ON(!rwsem_is_locked(&sb->s_umount));
Jens Axboe66f3b8e2009-09-02 09:19:46 +02002238
Dave Chinnere97fedb2015-03-04 13:40:00 -05002239 mutex_lock(&sb->s_sync_lock);
Jens Axboe03ba3782009-09-09 09:08:54 +02002240
2241 /*
Dave Chinner6c60d2b2016-07-26 15:21:50 -07002242 * Splice the writeback list onto a temporary list to avoid waiting on
2243 * inodes that have started writeback after this point.
2244 *
2245 * Use rcu_read_lock() to keep the inodes around until we have a
2246 * reference. s_inode_wblist_lock protects sb->s_inodes_wb as well as
2247 * the local list because inodes can be dropped from either by writeback
2248 * completion.
Jens Axboe03ba3782009-09-09 09:08:54 +02002249 */
Dave Chinner6c60d2b2016-07-26 15:21:50 -07002250 rcu_read_lock();
2251 spin_lock_irq(&sb->s_inode_wblist_lock);
2252 list_splice_init(&sb->s_inodes_wb, &sync_list);
2253
2254 /*
2255 * Data integrity sync. Must wait for all pages under writeback, because
2256 * there may have been pages dirtied before our sync call, but which had
2257 * writeout started before we write it out. In which case, the inode
2258 * may not be on the dirty list, but we still have to wait for that
2259 * writeout.
2260 */
2261 while (!list_empty(&sync_list)) {
2262 struct inode *inode = list_first_entry(&sync_list, struct inode,
2263 i_wb_list);
Dave Chinner250df6e2011-03-22 22:23:36 +11002264 struct address_space *mapping = inode->i_mapping;
Jens Axboe03ba3782009-09-09 09:08:54 +02002265
Dave Chinner6c60d2b2016-07-26 15:21:50 -07002266 /*
2267 * Move each inode back to the wb list before we drop the lock
2268 * to preserve consistency between i_wb_list and the mapping
2269 * writeback tag. Writeback completion is responsible to remove
2270 * the inode from either list once the writeback tag is cleared.
2271 */
2272 list_move_tail(&inode->i_wb_list, &sb->s_inodes_wb);
2273
2274 /*
2275 * The mapping can appear untagged while still on-list since we
2276 * do not have the mapping lock. Skip it here, wb completion
2277 * will remove it.
2278 */
2279 if (!mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK))
2280 continue;
2281
2282 spin_unlock_irq(&sb->s_inode_wblist_lock);
2283
Dave Chinner250df6e2011-03-22 22:23:36 +11002284 spin_lock(&inode->i_lock);
Dave Chinner6c60d2b2016-07-26 15:21:50 -07002285 if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) {
Dave Chinner250df6e2011-03-22 22:23:36 +11002286 spin_unlock(&inode->i_lock);
Dave Chinner6c60d2b2016-07-26 15:21:50 -07002287
2288 spin_lock_irq(&sb->s_inode_wblist_lock);
Jens Axboe03ba3782009-09-09 09:08:54 +02002289 continue;
Dave Chinner250df6e2011-03-22 22:23:36 +11002290 }
Jens Axboe03ba3782009-09-09 09:08:54 +02002291 __iget(inode);
Dave Chinner250df6e2011-03-22 22:23:36 +11002292 spin_unlock(&inode->i_lock);
Dave Chinner6c60d2b2016-07-26 15:21:50 -07002293 rcu_read_unlock();
Jens Axboe03ba3782009-09-09 09:08:54 +02002294
Junichi Nomuraaa750fd2015-11-05 18:47:23 -08002295 /*
2296 * We keep the error status of individual mapping so that
2297 * applications can catch the writeback error using fsync(2).
2298 * See filemap_fdatawait_keep_errors() for details.
2299 */
2300 filemap_fdatawait_keep_errors(mapping);
Jens Axboe03ba3782009-09-09 09:08:54 +02002301
2302 cond_resched();
Nick Piggin38f21972009-01-06 14:40:25 -08002303
Dave Chinner6c60d2b2016-07-26 15:21:50 -07002304 iput(inode);
2305
2306 rcu_read_lock();
2307 spin_lock_irq(&sb->s_inode_wblist_lock);
Jens Axboe66f3b8e2009-09-02 09:19:46 +02002308 }
Dave Chinner6c60d2b2016-07-26 15:21:50 -07002309 spin_unlock_irq(&sb->s_inode_wblist_lock);
2310 rcu_read_unlock();
Dave Chinnere97fedb2015-03-04 13:40:00 -05002311 mutex_unlock(&sb->s_sync_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002312}
2313
Tejun Heof30a7d02015-05-22 17:14:00 -04002314static void __writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr,
2315 enum wb_reason reason, bool skip_if_busy)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002316{
Tejun Heocc395d72015-05-22 17:13:58 -04002317 DEFINE_WB_COMPLETION_ONSTACK(done);
Christoph Hellwig83ba7b02010-07-06 08:59:53 +02002318 struct wb_writeback_work work = {
Wu Fengguang6e6938b2010-06-06 10:38:15 -06002319 .sb = sb,
2320 .sync_mode = WB_SYNC_NONE,
2321 .tagged_writepages = 1,
2322 .done = &done,
2323 .nr_pages = nr,
Curt Wohlgemuth0e175a12011-10-07 21:54:10 -06002324 .reason = reason,
Christoph Hellwig3c4d7162010-06-08 18:14:43 +02002325 };
Tejun Heoe7972912015-05-22 17:13:48 -04002326 struct backing_dev_info *bdi = sb->s_bdi;
Jens Axboe0e3c9a22010-06-01 11:08:43 +02002327
Tejun Heoe7972912015-05-22 17:13:48 -04002328 if (!bdi_has_dirty_io(bdi) || bdi == &noop_backing_dev_info)
Jan Kara6eedc702012-07-03 16:45:27 +02002329 return;
Christoph Hellwigcf37e972010-06-08 18:14:51 +02002330 WARN_ON(!rwsem_is_locked(&sb->s_umount));
Tejun Heof30a7d02015-05-22 17:14:00 -04002331
Tejun Heodb125362015-05-22 17:14:01 -04002332 bdi_split_work_to_wbs(sb->s_bdi, &work, skip_if_busy);
Tejun Heocc395d72015-05-22 17:13:58 -04002333 wb_wait_for_completion(bdi, &done);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002334}
Tejun Heof30a7d02015-05-22 17:14:00 -04002335
2336/**
2337 * writeback_inodes_sb_nr - writeback dirty inodes from given super_block
2338 * @sb: the superblock
2339 * @nr: the number of pages to write
2340 * @reason: reason why some writeback work initiated
2341 *
2342 * Start writeback on some inodes on this super_block. No guarantees are made
2343 * on how many (if any) will be written, and this function does not wait
2344 * for IO completion of submitted IO.
2345 */
2346void writeback_inodes_sb_nr(struct super_block *sb,
2347 unsigned long nr,
2348 enum wb_reason reason)
2349{
2350 __writeback_inodes_sb_nr(sb, nr, reason, false);
2351}
Chris Mason3259f8b2010-10-29 11:16:17 -04002352EXPORT_SYMBOL(writeback_inodes_sb_nr);
2353
2354/**
2355 * writeback_inodes_sb - writeback dirty inodes from given super_block
2356 * @sb: the superblock
Marcos Paulo de Souza786228a2011-11-23 20:56:45 +08002357 * @reason: reason why some writeback work was initiated
Chris Mason3259f8b2010-10-29 11:16:17 -04002358 *
2359 * Start writeback on some inodes on this super_block. No guarantees are made
2360 * on how many (if any) will be written, and this function does not wait
2361 * for IO completion of submitted IO.
2362 */
Curt Wohlgemuth0e175a12011-10-07 21:54:10 -06002363void writeback_inodes_sb(struct super_block *sb, enum wb_reason reason)
Chris Mason3259f8b2010-10-29 11:16:17 -04002364{
Curt Wohlgemuth0e175a12011-10-07 21:54:10 -06002365 return writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason);
Chris Mason3259f8b2010-10-29 11:16:17 -04002366}
Jens Axboed8a85592009-09-02 12:34:32 +02002367EXPORT_SYMBOL(writeback_inodes_sb);
2368
2369/**
Miao Xie10ee27a2013-01-10 13:47:57 +08002370 * try_to_writeback_inodes_sb - try to start writeback if none underway
2371 * @sb: the superblock
2372 * @reason: reason why some writeback work was initiated
2373 *
Rakesh Pandit8264c322017-10-09 13:34:41 +03002374 * Invoke __writeback_inodes_sb_nr if no writeback is currently underway.
Miao Xie10ee27a2013-01-10 13:47:57 +08002375 */
Rakesh Pandit8264c322017-10-09 13:34:41 +03002376void try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason)
Miao Xie10ee27a2013-01-10 13:47:57 +08002377{
Rakesh Pandit8264c322017-10-09 13:34:41 +03002378 if (!down_read_trylock(&sb->s_umount))
2379 return;
2380
2381 __writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason, true);
2382 up_read(&sb->s_umount);
Miao Xie10ee27a2013-01-10 13:47:57 +08002383}
2384EXPORT_SYMBOL(try_to_writeback_inodes_sb);
Chris Mason3259f8b2010-10-29 11:16:17 -04002385
2386/**
Jens Axboed8a85592009-09-02 12:34:32 +02002387 * sync_inodes_sb - sync sb inode pages
Jan Kara0dc83bd2014-02-21 11:19:04 +01002388 * @sb: the superblock
Jens Axboed8a85592009-09-02 12:34:32 +02002389 *
2390 * This function writes and waits on any dirty inode belonging to this
Jan Kara0dc83bd2014-02-21 11:19:04 +01002391 * super_block.
Jens Axboed8a85592009-09-02 12:34:32 +02002392 */
Jan Kara0dc83bd2014-02-21 11:19:04 +01002393void sync_inodes_sb(struct super_block *sb)
Jens Axboed8a85592009-09-02 12:34:32 +02002394{
Tejun Heocc395d72015-05-22 17:13:58 -04002395 DEFINE_WB_COMPLETION_ONSTACK(done);
Christoph Hellwig83ba7b02010-07-06 08:59:53 +02002396 struct wb_writeback_work work = {
Christoph Hellwig3c4d7162010-06-08 18:14:43 +02002397 .sb = sb,
2398 .sync_mode = WB_SYNC_ALL,
2399 .nr_pages = LONG_MAX,
2400 .range_cyclic = 0,
Christoph Hellwig83ba7b02010-07-06 08:59:53 +02002401 .done = &done,
Curt Wohlgemuth0e175a12011-10-07 21:54:10 -06002402 .reason = WB_REASON_SYNC,
Dave Chinner7747bd42013-07-02 22:38:35 +10002403 .for_sync = 1,
Christoph Hellwig3c4d7162010-06-08 18:14:43 +02002404 };
Tejun Heoe7972912015-05-22 17:13:48 -04002405 struct backing_dev_info *bdi = sb->s_bdi;
Christoph Hellwig3c4d7162010-06-08 18:14:43 +02002406
Tejun Heo006a0972015-08-25 14:11:52 -04002407 /*
2408 * Can't skip on !bdi_has_dirty() because we should wait for !dirty
2409 * inodes under writeback and I_DIRTY_TIME inodes ignored by
2410 * bdi_has_dirty() need to be written out too.
2411 */
2412 if (bdi == &noop_backing_dev_info)
Jan Kara6eedc702012-07-03 16:45:27 +02002413 return;
Christoph Hellwigcf37e972010-06-08 18:14:51 +02002414 WARN_ON(!rwsem_is_locked(&sb->s_umount));
2415
Tejun Heodb125362015-05-22 17:14:01 -04002416 bdi_split_work_to_wbs(bdi, &work, false);
Tejun Heocc395d72015-05-22 17:13:58 -04002417 wb_wait_for_completion(bdi, &done);
Christoph Hellwig83ba7b02010-07-06 08:59:53 +02002418
Jens Axboeb6e51312009-09-16 15:13:54 +02002419 wait_sb_inodes(sb);
Jens Axboed8a85592009-09-02 12:34:32 +02002420}
2421EXPORT_SYMBOL(sync_inodes_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002422
Linus Torvalds1da177e2005-04-16 15:20:36 -07002423/**
Andrea Arcangeli7f04c262005-10-30 15:03:05 -08002424 * write_inode_now - write an inode to disk
2425 * @inode: inode to write to disk
2426 * @sync: whether the write should be synchronous or not
Linus Torvalds1da177e2005-04-16 15:20:36 -07002427 *
Andrea Arcangeli7f04c262005-10-30 15:03:05 -08002428 * This function commits an inode to disk immediately if it is dirty. This is
2429 * primarily needed by knfsd.
2430 *
2431 * The caller must either have a ref on the inode or must have set I_WILL_FREE.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002432 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002433int write_inode_now(struct inode *inode, int sync)
2434{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002435 struct writeback_control wbc = {
2436 .nr_to_write = LONG_MAX,
Mike Galbraith18914b12008-02-08 04:20:23 -08002437 .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -07002438 .range_start = 0,
2439 .range_end = LLONG_MAX,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002440 };
2441
2442 if (!mapping_cap_writeback_dirty(inode->i_mapping))
Andrew Morton49364ce2005-11-07 00:59:15 -08002443 wbc.nr_to_write = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002444
2445 might_sleep();
Tejun Heoaaf25592016-03-18 13:52:04 -04002446 return writeback_single_inode(inode, &wbc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002447}
2448EXPORT_SYMBOL(write_inode_now);
2449
2450/**
2451 * sync_inode - write an inode and its pages to disk.
2452 * @inode: the inode to sync
2453 * @wbc: controls the writeback mode
2454 *
2455 * sync_inode() will write an inode and its pages to disk. It will also
2456 * correctly update the inode on its superblock's dirty inode lists and will
2457 * update inode->i_state.
2458 *
2459 * The caller must have a ref on the inode.
2460 */
2461int sync_inode(struct inode *inode, struct writeback_control *wbc)
2462{
Tejun Heoaaf25592016-03-18 13:52:04 -04002463 return writeback_single_inode(inode, wbc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002464}
2465EXPORT_SYMBOL(sync_inode);
Christoph Hellwigc37650162010-10-06 10:48:20 +02002466
2467/**
Andrew Mortonc691b9d2011-01-13 15:45:48 -08002468 * sync_inode_metadata - write an inode to disk
Christoph Hellwigc37650162010-10-06 10:48:20 +02002469 * @inode: the inode to sync
2470 * @wait: wait for I/O to complete.
2471 *
Andrew Mortonc691b9d2011-01-13 15:45:48 -08002472 * Write an inode to disk and adjust its dirty state after completion.
Christoph Hellwigc37650162010-10-06 10:48:20 +02002473 *
2474 * Note: only writes the actual inode, no associated data or other metadata.
2475 */
2476int sync_inode_metadata(struct inode *inode, int wait)
2477{
2478 struct writeback_control wbc = {
2479 .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_NONE,
2480 .nr_to_write = 0, /* metadata-only */
2481 };
2482
2483 return sync_inode(inode, &wbc);
2484}
2485EXPORT_SYMBOL(sync_inode_metadata);