1457c8996SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-only 21da177e4SLinus Torvalds /* 31da177e4SLinus Torvalds * fs/fs-writeback.c 41da177e4SLinus Torvalds * 51da177e4SLinus Torvalds * Copyright (C) 2002, Linus Torvalds. 61da177e4SLinus Torvalds * 71da177e4SLinus Torvalds * Contains all the functions related to writing back and waiting 81da177e4SLinus Torvalds * upon dirty inodes against superblocks, and writing back dirty 91da177e4SLinus Torvalds * pages against inodes. ie: data writeback. Writeout of the 101da177e4SLinus Torvalds * inode itself is not handled here. 111da177e4SLinus Torvalds * 12e1f8e874SFrancois Cami * 10Apr2002 Andrew Morton 131da177e4SLinus Torvalds * Split out of fs/inode.c 141da177e4SLinus Torvalds * Additions for address_space-based writeback 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/kernel.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 191da177e4SLinus Torvalds #include <linux/spinlock.h> 205a0e3ad6STejun Heo #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/sched.h> 221da177e4SLinus Torvalds #include <linux/fs.h> 231da177e4SLinus Torvalds #include <linux/mm.h> 24bc31b86aSWu Fengguang #include <linux/pagemap.h> 2503ba3782SJens Axboe #include <linux/kthread.h> 261da177e4SLinus Torvalds #include <linux/writeback.h> 271da177e4SLinus Torvalds #include <linux/blkdev.h> 281da177e4SLinus Torvalds #include <linux/backing-dev.h> 29455b2864SDave Chinner #include <linux/tracepoint.h> 30719ea2fbSAl Viro #include <linux/device.h> 3121c6321fSTejun Heo #include <linux/memcontrol.h> 3207f3f05cSDavid Howells #include "internal.h" 331da177e4SLinus Torvalds 34d0bceac7SJens Axboe /* 35bc31b86aSWu Fengguang * 4MB minimal write chunk size 36bc31b86aSWu Fengguang */ 3709cbfeafSKirill A. Shutemov #define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_SHIFT - 10)) 38bc31b86aSWu Fengguang 39bc31b86aSWu Fengguang /* 40c4a77a6cSJens Axboe * Passed into wb_writeback(), essentially a subset of writeback_control 41c4a77a6cSJens Axboe */ 4283ba7b07SChristoph Hellwig struct wb_writeback_work { 43c4a77a6cSJens Axboe long nr_pages; 44c4a77a6cSJens Axboe struct super_block *sb; 45c4a77a6cSJens Axboe enum writeback_sync_modes sync_mode; 466e6938b6SWu Fengguang unsigned int tagged_writepages:1; 4752957fe1SH Hartley Sweeten unsigned int for_kupdate:1; 4852957fe1SH Hartley Sweeten unsigned int range_cyclic:1; 4952957fe1SH Hartley Sweeten unsigned int for_background:1; 507747bd4bSDave Chinner unsigned int for_sync:1; /* sync(2) WB_SYNC_ALL writeback */ 51ac7b19a3STejun Heo unsigned int auto_free:1; /* free on completion */ 520e175a18SCurt Wohlgemuth enum wb_reason reason; /* why was writeback initiated? */ 53c4a77a6cSJens Axboe 548010c3b6SJens Axboe struct list_head list; /* pending work list */ 55cc395d7fSTejun Heo struct wb_completion *done; /* set if the caller waits */ 5603ba3782SJens Axboe }; 5703ba3782SJens Axboe 58a2f48706STheodore Ts'o /* 59a2f48706STheodore Ts'o * If an inode is constantly having its pages dirtied, but then the 60a2f48706STheodore Ts'o * updates stop dirtytime_expire_interval seconds in the past, it's 61a2f48706STheodore Ts'o * possible for the worst case time between when an inode has its 62a2f48706STheodore Ts'o * timestamps updated and when they finally get written out to be two 63a2f48706STheodore Ts'o * dirtytime_expire_intervals. We set the default to 12 hours (in 64a2f48706STheodore Ts'o * seconds), which means most of the time inodes will have their 65a2f48706STheodore Ts'o * timestamps written to disk after 12 hours, but in the worst case a 66a2f48706STheodore Ts'o * few inodes might not their timestamps updated for 24 hours. 67a2f48706STheodore Ts'o */ 68a2f48706STheodore Ts'o unsigned int dirtytime_expire_interval = 12 * 60 * 60; 69a2f48706STheodore Ts'o 707ccf19a8SNick Piggin static inline struct inode *wb_inode(struct list_head *head) 717ccf19a8SNick Piggin { 72c7f54084SDave Chinner return list_entry(head, struct inode, i_io_list); 737ccf19a8SNick Piggin } 747ccf19a8SNick Piggin 7515eb77a0SWu Fengguang /* 7615eb77a0SWu Fengguang * Include the creation of the trace points after defining the 7715eb77a0SWu Fengguang * wb_writeback_work structure and inline functions so that the definition 7815eb77a0SWu Fengguang * remains local to this file. 7915eb77a0SWu Fengguang */ 8015eb77a0SWu Fengguang #define CREATE_TRACE_POINTS 8115eb77a0SWu Fengguang #include <trace/events/writeback.h> 8215eb77a0SWu Fengguang 83774016b2SSteven Whitehouse EXPORT_TRACEPOINT_SYMBOL_GPL(wbc_writepage); 84774016b2SSteven Whitehouse 85d6c10f1fSTejun Heo static bool wb_io_lists_populated(struct bdi_writeback *wb) 86d6c10f1fSTejun Heo { 87d6c10f1fSTejun Heo if (wb_has_dirty_io(wb)) { 88d6c10f1fSTejun Heo return false; 89d6c10f1fSTejun Heo } else { 90d6c10f1fSTejun Heo set_bit(WB_has_dirty_io, &wb->state); 9195a46c65STejun Heo WARN_ON_ONCE(!wb->avg_write_bandwidth); 92766a9d6eSTejun Heo atomic_long_add(wb->avg_write_bandwidth, 93766a9d6eSTejun Heo &wb->bdi->tot_write_bandwidth); 94d6c10f1fSTejun Heo return true; 95d6c10f1fSTejun Heo } 96d6c10f1fSTejun Heo } 97d6c10f1fSTejun Heo 98d6c10f1fSTejun Heo static void wb_io_lists_depopulated(struct bdi_writeback *wb) 99d6c10f1fSTejun Heo { 100d6c10f1fSTejun Heo if (wb_has_dirty_io(wb) && list_empty(&wb->b_dirty) && 101766a9d6eSTejun Heo list_empty(&wb->b_io) && list_empty(&wb->b_more_io)) { 102d6c10f1fSTejun Heo clear_bit(WB_has_dirty_io, &wb->state); 10395a46c65STejun Heo WARN_ON_ONCE(atomic_long_sub_return(wb->avg_write_bandwidth, 10495a46c65STejun Heo &wb->bdi->tot_write_bandwidth) < 0); 105766a9d6eSTejun Heo } 106d6c10f1fSTejun Heo } 107d6c10f1fSTejun Heo 108d6c10f1fSTejun Heo /** 109c7f54084SDave Chinner * inode_io_list_move_locked - move an inode onto a bdi_writeback IO list 110d6c10f1fSTejun Heo * @inode: inode to be moved 111d6c10f1fSTejun Heo * @wb: target bdi_writeback 112bbbc3c1cSWang Long * @head: one of @wb->b_{dirty|io|more_io|dirty_time} 113d6c10f1fSTejun Heo * 114c7f54084SDave Chinner * Move @inode->i_io_list to @list of @wb and set %WB_has_dirty_io. 115d6c10f1fSTejun Heo * Returns %true if @inode is the first occupant of the !dirty_time IO 116d6c10f1fSTejun Heo * lists; otherwise, %false. 117d6c10f1fSTejun Heo */ 118c7f54084SDave Chinner static bool inode_io_list_move_locked(struct inode *inode, 119d6c10f1fSTejun Heo struct bdi_writeback *wb, 120d6c10f1fSTejun Heo struct list_head *head) 121d6c10f1fSTejun Heo { 122d6c10f1fSTejun Heo assert_spin_locked(&wb->list_lock); 123d6c10f1fSTejun Heo 124c7f54084SDave Chinner list_move(&inode->i_io_list, head); 125d6c10f1fSTejun Heo 126d6c10f1fSTejun Heo /* dirty_time doesn't count as dirty_io until expiration */ 127d6c10f1fSTejun Heo if (head != &wb->b_dirty_time) 128d6c10f1fSTejun Heo return wb_io_lists_populated(wb); 129d6c10f1fSTejun Heo 130d6c10f1fSTejun Heo wb_io_lists_depopulated(wb); 131d6c10f1fSTejun Heo return false; 132d6c10f1fSTejun Heo } 133d6c10f1fSTejun Heo 134f0054bb1STejun Heo static void wb_wakeup(struct bdi_writeback *wb) 1355acda9d1SJan Kara { 136f0054bb1STejun Heo spin_lock_bh(&wb->work_lock); 137f0054bb1STejun Heo if (test_bit(WB_registered, &wb->state)) 138f0054bb1STejun Heo mod_delayed_work(bdi_wq, &wb->dwork, 0); 139f0054bb1STejun Heo spin_unlock_bh(&wb->work_lock); 1405acda9d1SJan Kara } 1415acda9d1SJan Kara 1424a3a485bSTahsin Erdogan static void finish_writeback_work(struct bdi_writeback *wb, 1434a3a485bSTahsin Erdogan struct wb_writeback_work *work) 1444a3a485bSTahsin Erdogan { 1454a3a485bSTahsin Erdogan struct wb_completion *done = work->done; 1464a3a485bSTahsin Erdogan 1474a3a485bSTahsin Erdogan if (work->auto_free) 1484a3a485bSTahsin Erdogan kfree(work); 1498e00c4e9STejun Heo if (done) { 1508e00c4e9STejun Heo wait_queue_head_t *waitq = done->waitq; 1518e00c4e9STejun Heo 1528e00c4e9STejun Heo /* @done can't be accessed after the following dec */ 1538e00c4e9STejun Heo if (atomic_dec_and_test(&done->cnt)) 1548e00c4e9STejun Heo wake_up_all(waitq); 1558e00c4e9STejun Heo } 1564a3a485bSTahsin Erdogan } 1574a3a485bSTahsin Erdogan 158f0054bb1STejun Heo static void wb_queue_work(struct bdi_writeback *wb, 1596585027aSJan Kara struct wb_writeback_work *work) 1606585027aSJan Kara { 1615634cc2aSTejun Heo trace_writeback_queue(wb, work); 1626585027aSJan Kara 163cc395d7fSTejun Heo if (work->done) 164cc395d7fSTejun Heo atomic_inc(&work->done->cnt); 1654a3a485bSTahsin Erdogan 1664a3a485bSTahsin Erdogan spin_lock_bh(&wb->work_lock); 1674a3a485bSTahsin Erdogan 1684a3a485bSTahsin Erdogan if (test_bit(WB_registered, &wb->state)) { 169f0054bb1STejun Heo list_add_tail(&work->list, &wb->work_list); 170f0054bb1STejun Heo mod_delayed_work(bdi_wq, &wb->dwork, 0); 1714a3a485bSTahsin Erdogan } else 1724a3a485bSTahsin Erdogan finish_writeback_work(wb, work); 1734a3a485bSTahsin Erdogan 174f0054bb1STejun Heo spin_unlock_bh(&wb->work_lock); 17503ba3782SJens Axboe } 1761da177e4SLinus Torvalds 177cc395d7fSTejun Heo /** 178cc395d7fSTejun Heo * wb_wait_for_completion - wait for completion of bdi_writeback_works 179cc395d7fSTejun Heo * @done: target wb_completion 180cc395d7fSTejun Heo * 181cc395d7fSTejun Heo * Wait for one or more work items issued to @bdi with their ->done field 1825b9cce4cSTejun Heo * set to @done, which should have been initialized with 1835b9cce4cSTejun Heo * DEFINE_WB_COMPLETION(). This function returns after all such work items 1845b9cce4cSTejun Heo * are completed. Work items which are waited upon aren't freed 185cc395d7fSTejun Heo * automatically on completion. 186cc395d7fSTejun Heo */ 1875b9cce4cSTejun Heo void wb_wait_for_completion(struct wb_completion *done) 188cc395d7fSTejun Heo { 189cc395d7fSTejun Heo atomic_dec(&done->cnt); /* put down the initial count */ 1905b9cce4cSTejun Heo wait_event(*done->waitq, !atomic_read(&done->cnt)); 191cc395d7fSTejun Heo } 192cc395d7fSTejun Heo 193703c2708STejun Heo #ifdef CONFIG_CGROUP_WRITEBACK 194703c2708STejun Heo 19555a694dfSTejun Heo /* 19655a694dfSTejun Heo * Parameters for foreign inode detection, see wbc_detach_inode() to see 19755a694dfSTejun Heo * how they're used. 19855a694dfSTejun Heo * 19955a694dfSTejun Heo * These paramters are inherently heuristical as the detection target 20055a694dfSTejun Heo * itself is fuzzy. All we want to do is detaching an inode from the 20155a694dfSTejun Heo * current owner if it's being written to by some other cgroups too much. 20255a694dfSTejun Heo * 20355a694dfSTejun Heo * The current cgroup writeback is built on the assumption that multiple 20455a694dfSTejun Heo * cgroups writing to the same inode concurrently is very rare and a mode 20555a694dfSTejun Heo * of operation which isn't well supported. As such, the goal is not 20655a694dfSTejun Heo * taking too long when a different cgroup takes over an inode while 20755a694dfSTejun Heo * avoiding too aggressive flip-flops from occasional foreign writes. 20855a694dfSTejun Heo * 20955a694dfSTejun Heo * We record, very roughly, 2s worth of IO time history and if more than 21055a694dfSTejun Heo * half of that is foreign, trigger the switch. The recording is quantized 21155a694dfSTejun Heo * to 16 slots. To avoid tiny writes from swinging the decision too much, 21255a694dfSTejun Heo * writes smaller than 1/8 of avg size are ignored. 21355a694dfSTejun Heo */ 2142a814908STejun Heo #define WB_FRN_TIME_SHIFT 13 /* 1s = 2^13, upto 8 secs w/ 16bit */ 2152a814908STejun Heo #define WB_FRN_TIME_AVG_SHIFT 3 /* avg = avg * 7/8 + new * 1/8 */ 21655a694dfSTejun Heo #define WB_FRN_TIME_CUT_DIV 8 /* ignore rounds < avg / 8 */ 2172a814908STejun Heo #define WB_FRN_TIME_PERIOD (2 * (1 << WB_FRN_TIME_SHIFT)) /* 2s */ 2182a814908STejun Heo 2192a814908STejun Heo #define WB_FRN_HIST_SLOTS 16 /* inode->i_wb_frn_history is 16bit */ 2202a814908STejun Heo #define WB_FRN_HIST_UNIT (WB_FRN_TIME_PERIOD / WB_FRN_HIST_SLOTS) 2212a814908STejun Heo /* each slot's duration is 2s / 16 */ 2222a814908STejun Heo #define WB_FRN_HIST_THR_SLOTS (WB_FRN_HIST_SLOTS / 2) 2232a814908STejun Heo /* if foreign slots >= 8, switch */ 2242a814908STejun Heo #define WB_FRN_HIST_MAX_SLOTS (WB_FRN_HIST_THR_SLOTS / 2 + 1) 2252a814908STejun Heo /* one round can affect upto 5 slots */ 2266444f47eSTejun Heo #define WB_FRN_MAX_IN_FLIGHT 1024 /* don't queue too many concurrently */ 2272a814908STejun Heo 228c22d70a1SRoman Gushchin /* 229c22d70a1SRoman Gushchin * Maximum inodes per isw. A specific value has been chosen to make 230c22d70a1SRoman Gushchin * struct inode_switch_wbs_context fit into 1024 bytes kmalloc. 231c22d70a1SRoman Gushchin */ 232c22d70a1SRoman Gushchin #define WB_MAX_INODES_PER_ISW ((1024UL - sizeof(struct inode_switch_wbs_context)) \ 233c22d70a1SRoman Gushchin / sizeof(struct inode *)) 234c22d70a1SRoman Gushchin 235a1a0e23eSTejun Heo static atomic_t isw_nr_in_flight = ATOMIC_INIT(0); 236a1a0e23eSTejun Heo static struct workqueue_struct *isw_wq; 237a1a0e23eSTejun Heo 23821c6321fSTejun Heo void __inode_attach_wb(struct inode *inode, struct page *page) 23921c6321fSTejun Heo { 24021c6321fSTejun Heo struct backing_dev_info *bdi = inode_to_bdi(inode); 24121c6321fSTejun Heo struct bdi_writeback *wb = NULL; 24221c6321fSTejun Heo 24321c6321fSTejun Heo if (inode_cgwb_enabled(inode)) { 24421c6321fSTejun Heo struct cgroup_subsys_state *memcg_css; 24521c6321fSTejun Heo 24621c6321fSTejun Heo if (page) { 24721c6321fSTejun Heo memcg_css = mem_cgroup_css_from_page(page); 24821c6321fSTejun Heo wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); 24921c6321fSTejun Heo } else { 25021c6321fSTejun Heo /* must pin memcg_css, see wb_get_create() */ 25121c6321fSTejun Heo memcg_css = task_get_css(current, memory_cgrp_id); 25221c6321fSTejun Heo wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); 25321c6321fSTejun Heo css_put(memcg_css); 25421c6321fSTejun Heo } 25521c6321fSTejun Heo } 25621c6321fSTejun Heo 25721c6321fSTejun Heo if (!wb) 25821c6321fSTejun Heo wb = &bdi->wb; 25921c6321fSTejun Heo 26021c6321fSTejun Heo /* 26121c6321fSTejun Heo * There may be multiple instances of this function racing to 26221c6321fSTejun Heo * update the same inode. Use cmpxchg() to tell the winner. 26321c6321fSTejun Heo */ 26421c6321fSTejun Heo if (unlikely(cmpxchg(&inode->i_wb, NULL, wb))) 26521c6321fSTejun Heo wb_put(wb); 26621c6321fSTejun Heo } 2679b0eb69bSTejun Heo EXPORT_SYMBOL_GPL(__inode_attach_wb); 26821c6321fSTejun Heo 269703c2708STejun Heo /** 270f3b6a6dfSRoman Gushchin * inode_cgwb_move_to_attached - put the inode onto wb->b_attached list 271f3b6a6dfSRoman Gushchin * @inode: inode of interest with i_lock held 272f3b6a6dfSRoman Gushchin * @wb: target bdi_writeback 273f3b6a6dfSRoman Gushchin * 274f3b6a6dfSRoman Gushchin * Remove the inode from wb's io lists and if necessarily put onto b_attached 275f3b6a6dfSRoman Gushchin * list. Only inodes attached to cgwb's are kept on this list. 276f3b6a6dfSRoman Gushchin */ 277f3b6a6dfSRoman Gushchin static void inode_cgwb_move_to_attached(struct inode *inode, 278f3b6a6dfSRoman Gushchin struct bdi_writeback *wb) 279f3b6a6dfSRoman Gushchin { 280f3b6a6dfSRoman Gushchin assert_spin_locked(&wb->list_lock); 281f3b6a6dfSRoman Gushchin assert_spin_locked(&inode->i_lock); 282f3b6a6dfSRoman Gushchin 283f3b6a6dfSRoman Gushchin inode->i_state &= ~I_SYNC_QUEUED; 284f3b6a6dfSRoman Gushchin if (wb != &wb->bdi->wb) 285f3b6a6dfSRoman Gushchin list_move(&inode->i_io_list, &wb->b_attached); 286f3b6a6dfSRoman Gushchin else 287f3b6a6dfSRoman Gushchin list_del_init(&inode->i_io_list); 288f3b6a6dfSRoman Gushchin wb_io_lists_depopulated(wb); 289f3b6a6dfSRoman Gushchin } 290f3b6a6dfSRoman Gushchin 291f3b6a6dfSRoman Gushchin /** 29287e1d789STejun Heo * locked_inode_to_wb_and_lock_list - determine a locked inode's wb and lock it 29387e1d789STejun Heo * @inode: inode of interest with i_lock held 29487e1d789STejun Heo * 29587e1d789STejun Heo * Returns @inode's wb with its list_lock held. @inode->i_lock must be 29687e1d789STejun Heo * held on entry and is released on return. The returned wb is guaranteed 29787e1d789STejun Heo * to stay @inode's associated wb until its list_lock is released. 29887e1d789STejun Heo */ 29987e1d789STejun Heo static struct bdi_writeback * 30087e1d789STejun Heo locked_inode_to_wb_and_lock_list(struct inode *inode) 30187e1d789STejun Heo __releases(&inode->i_lock) 30287e1d789STejun Heo __acquires(&wb->list_lock) 30387e1d789STejun Heo { 30487e1d789STejun Heo while (true) { 30587e1d789STejun Heo struct bdi_writeback *wb = inode_to_wb(inode); 30687e1d789STejun Heo 30787e1d789STejun Heo /* 30887e1d789STejun Heo * inode_to_wb() association is protected by both 30987e1d789STejun Heo * @inode->i_lock and @wb->list_lock but list_lock nests 31087e1d789STejun Heo * outside i_lock. Drop i_lock and verify that the 31187e1d789STejun Heo * association hasn't changed after acquiring list_lock. 31287e1d789STejun Heo */ 31387e1d789STejun Heo wb_get(wb); 31487e1d789STejun Heo spin_unlock(&inode->i_lock); 31587e1d789STejun Heo spin_lock(&wb->list_lock); 31687e1d789STejun Heo 317aaa2cacfSTejun Heo /* i_wb may have changed inbetween, can't use inode_to_wb() */ 318614a4e37STejun Heo if (likely(wb == inode->i_wb)) { 319614a4e37STejun Heo wb_put(wb); /* @inode already has ref */ 320614a4e37STejun Heo return wb; 321614a4e37STejun Heo } 32287e1d789STejun Heo 32387e1d789STejun Heo spin_unlock(&wb->list_lock); 324614a4e37STejun Heo wb_put(wb); 32587e1d789STejun Heo cpu_relax(); 32687e1d789STejun Heo spin_lock(&inode->i_lock); 32787e1d789STejun Heo } 32887e1d789STejun Heo } 32987e1d789STejun Heo 33087e1d789STejun Heo /** 33187e1d789STejun Heo * inode_to_wb_and_lock_list - determine an inode's wb and lock it 33287e1d789STejun Heo * @inode: inode of interest 33387e1d789STejun Heo * 33487e1d789STejun Heo * Same as locked_inode_to_wb_and_lock_list() but @inode->i_lock isn't held 33587e1d789STejun Heo * on entry. 33687e1d789STejun Heo */ 33787e1d789STejun Heo static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode) 33887e1d789STejun Heo __acquires(&wb->list_lock) 33987e1d789STejun Heo { 34087e1d789STejun Heo spin_lock(&inode->i_lock); 34187e1d789STejun Heo return locked_inode_to_wb_and_lock_list(inode); 34287e1d789STejun Heo } 34387e1d789STejun Heo 344682aa8e1STejun Heo struct inode_switch_wbs_context { 34529264d92SRoman Gushchin struct rcu_work work; 346f5fbe6b7SRoman Gushchin 347f5fbe6b7SRoman Gushchin /* 348f5fbe6b7SRoman Gushchin * Multiple inodes can be switched at once. The switching procedure 349f5fbe6b7SRoman Gushchin * consists of two parts, separated by a RCU grace period. To make 350f5fbe6b7SRoman Gushchin * sure that the second part is executed for each inode gone through 351f5fbe6b7SRoman Gushchin * the first part, all inode pointers are placed into a NULL-terminated 352f5fbe6b7SRoman Gushchin * array embedded into struct inode_switch_wbs_context. Otherwise 353f5fbe6b7SRoman Gushchin * an inode could be left in a non-consistent state. 354f5fbe6b7SRoman Gushchin */ 355f5fbe6b7SRoman Gushchin struct bdi_writeback *new_wb; 356f5fbe6b7SRoman Gushchin struct inode *inodes[]; 357682aa8e1STejun Heo }; 358682aa8e1STejun Heo 3597fc5854fSTejun Heo static void bdi_down_write_wb_switch_rwsem(struct backing_dev_info *bdi) 3607fc5854fSTejun Heo { 3617fc5854fSTejun Heo down_write(&bdi->wb_switch_rwsem); 3627fc5854fSTejun Heo } 3637fc5854fSTejun Heo 3647fc5854fSTejun Heo static void bdi_up_write_wb_switch_rwsem(struct backing_dev_info *bdi) 3657fc5854fSTejun Heo { 3667fc5854fSTejun Heo up_write(&bdi->wb_switch_rwsem); 3677fc5854fSTejun Heo } 3687fc5854fSTejun Heo 369f5fbe6b7SRoman Gushchin static bool inode_do_switch_wbs(struct inode *inode, 370f5fbe6b7SRoman Gushchin struct bdi_writeback *old_wb, 37172d4512eSRoman Gushchin struct bdi_writeback *new_wb) 372682aa8e1STejun Heo { 373d10c8095STejun Heo struct address_space *mapping = inode->i_mapping; 37404edf02cSMatthew Wilcox XA_STATE(xas, &mapping->i_pages, 0); 37504edf02cSMatthew Wilcox struct page *page; 376d10c8095STejun Heo bool switched = false; 377682aa8e1STejun Heo 378682aa8e1STejun Heo spin_lock(&inode->i_lock); 379b93b0163SMatthew Wilcox xa_lock_irq(&mapping->i_pages); 380682aa8e1STejun Heo 381d10c8095STejun Heo /* 3824ade5867SRoman Gushchin * Once I_FREEING or I_WILL_FREE are visible under i_lock, the eviction 3834ade5867SRoman Gushchin * path owns the inode and we shouldn't modify ->i_io_list. 384d10c8095STejun Heo */ 3854ade5867SRoman Gushchin if (unlikely(inode->i_state & (I_FREEING | I_WILL_FREE))) 386d10c8095STejun Heo goto skip_switch; 387d10c8095STejun Heo 3883a8e9ac8STejun Heo trace_inode_switch_wbs(inode, old_wb, new_wb); 3893a8e9ac8STejun Heo 390d10c8095STejun Heo /* 391d10c8095STejun Heo * Count and transfer stats. Note that PAGECACHE_TAG_DIRTY points 392d10c8095STejun Heo * to possibly dirty pages while PAGECACHE_TAG_WRITEBACK points to 393b93b0163SMatthew Wilcox * pages actually under writeback. 394d10c8095STejun Heo */ 39504edf02cSMatthew Wilcox xas_for_each_marked(&xas, page, ULONG_MAX, PAGECACHE_TAG_DIRTY) { 39604edf02cSMatthew Wilcox if (PageDirty(page)) { 3973e8f399dSNikolay Borisov dec_wb_stat(old_wb, WB_RECLAIMABLE); 3983e8f399dSNikolay Borisov inc_wb_stat(new_wb, WB_RECLAIMABLE); 399d10c8095STejun Heo } 400d10c8095STejun Heo } 401d10c8095STejun Heo 40204edf02cSMatthew Wilcox xas_set(&xas, 0); 40304edf02cSMatthew Wilcox xas_for_each_marked(&xas, page, ULONG_MAX, PAGECACHE_TAG_WRITEBACK) { 404d10c8095STejun Heo WARN_ON_ONCE(!PageWriteback(page)); 4053e8f399dSNikolay Borisov dec_wb_stat(old_wb, WB_WRITEBACK); 4063e8f399dSNikolay Borisov inc_wb_stat(new_wb, WB_WRITEBACK); 407d10c8095STejun Heo } 408d10c8095STejun Heo 409*633a2abbSJan Kara if (mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK)) { 410*633a2abbSJan Kara atomic_dec(&old_wb->writeback_inodes); 411*633a2abbSJan Kara atomic_inc(&new_wb->writeback_inodes); 412*633a2abbSJan Kara } 413*633a2abbSJan Kara 414d10c8095STejun Heo wb_get(new_wb); 415d10c8095STejun Heo 416d10c8095STejun Heo /* 417f3b6a6dfSRoman Gushchin * Transfer to @new_wb's IO list if necessary. If the @inode is dirty, 418f3b6a6dfSRoman Gushchin * the specific list @inode was on is ignored and the @inode is put on 419f3b6a6dfSRoman Gushchin * ->b_dirty which is always correct including from ->b_dirty_time. 420f3b6a6dfSRoman Gushchin * The transfer preserves @inode->dirtied_when ordering. If the @inode 421f3b6a6dfSRoman Gushchin * was clean, it means it was on the b_attached list, so move it onto 422f3b6a6dfSRoman Gushchin * the b_attached list of @new_wb. 423d10c8095STejun Heo */ 424c7f54084SDave Chinner if (!list_empty(&inode->i_io_list)) { 425f3b6a6dfSRoman Gushchin inode->i_wb = new_wb; 426f3b6a6dfSRoman Gushchin 427f3b6a6dfSRoman Gushchin if (inode->i_state & I_DIRTY_ALL) { 428d10c8095STejun Heo struct inode *pos; 429d10c8095STejun Heo 430c7f54084SDave Chinner list_for_each_entry(pos, &new_wb->b_dirty, i_io_list) 431d10c8095STejun Heo if (time_after_eq(inode->dirtied_when, 432d10c8095STejun Heo pos->dirtied_when)) 433d10c8095STejun Heo break; 434f3b6a6dfSRoman Gushchin inode_io_list_move_locked(inode, new_wb, 435f3b6a6dfSRoman Gushchin pos->i_io_list.prev); 436f3b6a6dfSRoman Gushchin } else { 437f3b6a6dfSRoman Gushchin inode_cgwb_move_to_attached(inode, new_wb); 438f3b6a6dfSRoman Gushchin } 439d10c8095STejun Heo } else { 440d10c8095STejun Heo inode->i_wb = new_wb; 441d10c8095STejun Heo } 442d10c8095STejun Heo 443d10c8095STejun Heo /* ->i_wb_frn updates may race wbc_detach_inode() but doesn't matter */ 444682aa8e1STejun Heo inode->i_wb_frn_winner = 0; 445682aa8e1STejun Heo inode->i_wb_frn_avg_time = 0; 446682aa8e1STejun Heo inode->i_wb_frn_history = 0; 447d10c8095STejun Heo switched = true; 448d10c8095STejun Heo skip_switch: 449682aa8e1STejun Heo /* 450682aa8e1STejun Heo * Paired with load_acquire in unlocked_inode_to_wb_begin() and 451682aa8e1STejun Heo * ensures that the new wb is visible if they see !I_WB_SWITCH. 452682aa8e1STejun Heo */ 453682aa8e1STejun Heo smp_store_release(&inode->i_state, inode->i_state & ~I_WB_SWITCH); 454682aa8e1STejun Heo 455b93b0163SMatthew Wilcox xa_unlock_irq(&mapping->i_pages); 456682aa8e1STejun Heo spin_unlock(&inode->i_lock); 457d10c8095STejun Heo 458f5fbe6b7SRoman Gushchin return switched; 45972d4512eSRoman Gushchin } 460682aa8e1STejun Heo 46172d4512eSRoman Gushchin static void inode_switch_wbs_work_fn(struct work_struct *work) 46272d4512eSRoman Gushchin { 46372d4512eSRoman Gushchin struct inode_switch_wbs_context *isw = 46472d4512eSRoman Gushchin container_of(to_rcu_work(work), struct inode_switch_wbs_context, work); 465f5fbe6b7SRoman Gushchin struct backing_dev_info *bdi = inode_to_bdi(isw->inodes[0]); 466f5fbe6b7SRoman Gushchin struct bdi_writeback *old_wb = isw->inodes[0]->i_wb; 467f5fbe6b7SRoman Gushchin struct bdi_writeback *new_wb = isw->new_wb; 468f5fbe6b7SRoman Gushchin unsigned long nr_switched = 0; 469f5fbe6b7SRoman Gushchin struct inode **inodep; 47072d4512eSRoman Gushchin 471f5fbe6b7SRoman Gushchin /* 472f5fbe6b7SRoman Gushchin * If @inode switches cgwb membership while sync_inodes_sb() is 473f5fbe6b7SRoman Gushchin * being issued, sync_inodes_sb() might miss it. Synchronize. 474f5fbe6b7SRoman Gushchin */ 475f5fbe6b7SRoman Gushchin down_read(&bdi->wb_switch_rwsem); 476f5fbe6b7SRoman Gushchin 477f5fbe6b7SRoman Gushchin /* 478f5fbe6b7SRoman Gushchin * By the time control reaches here, RCU grace period has passed 479f5fbe6b7SRoman Gushchin * since I_WB_SWITCH assertion and all wb stat update transactions 480f5fbe6b7SRoman Gushchin * between unlocked_inode_to_wb_begin/end() are guaranteed to be 481f5fbe6b7SRoman Gushchin * synchronizing against the i_pages lock. 482f5fbe6b7SRoman Gushchin * 483f5fbe6b7SRoman Gushchin * Grabbing old_wb->list_lock, inode->i_lock and the i_pages lock 484f5fbe6b7SRoman Gushchin * gives us exclusion against all wb related operations on @inode 485f5fbe6b7SRoman Gushchin * including IO list manipulations and stat updates. 486f5fbe6b7SRoman Gushchin */ 487f5fbe6b7SRoman Gushchin if (old_wb < new_wb) { 488f5fbe6b7SRoman Gushchin spin_lock(&old_wb->list_lock); 489f5fbe6b7SRoman Gushchin spin_lock_nested(&new_wb->list_lock, SINGLE_DEPTH_NESTING); 490f5fbe6b7SRoman Gushchin } else { 491f5fbe6b7SRoman Gushchin spin_lock(&new_wb->list_lock); 492f5fbe6b7SRoman Gushchin spin_lock_nested(&old_wb->list_lock, SINGLE_DEPTH_NESTING); 493f5fbe6b7SRoman Gushchin } 494f5fbe6b7SRoman Gushchin 495f5fbe6b7SRoman Gushchin for (inodep = isw->inodes; *inodep; inodep++) { 496f5fbe6b7SRoman Gushchin WARN_ON_ONCE((*inodep)->i_wb != old_wb); 497f5fbe6b7SRoman Gushchin if (inode_do_switch_wbs(*inodep, old_wb, new_wb)) 498f5fbe6b7SRoman Gushchin nr_switched++; 499f5fbe6b7SRoman Gushchin } 500f5fbe6b7SRoman Gushchin 501f5fbe6b7SRoman Gushchin spin_unlock(&new_wb->list_lock); 502f5fbe6b7SRoman Gushchin spin_unlock(&old_wb->list_lock); 503f5fbe6b7SRoman Gushchin 504f5fbe6b7SRoman Gushchin up_read(&bdi->wb_switch_rwsem); 505f5fbe6b7SRoman Gushchin 506f5fbe6b7SRoman Gushchin if (nr_switched) { 507f5fbe6b7SRoman Gushchin wb_wakeup(new_wb); 508f5fbe6b7SRoman Gushchin wb_put_many(old_wb, nr_switched); 509f5fbe6b7SRoman Gushchin } 510f5fbe6b7SRoman Gushchin 511f5fbe6b7SRoman Gushchin for (inodep = isw->inodes; *inodep; inodep++) 512f5fbe6b7SRoman Gushchin iput(*inodep); 513f5fbe6b7SRoman Gushchin wb_put(new_wb); 514682aa8e1STejun Heo kfree(isw); 515a1a0e23eSTejun Heo atomic_dec(&isw_nr_in_flight); 516682aa8e1STejun Heo } 517682aa8e1STejun Heo 518c22d70a1SRoman Gushchin static bool inode_prepare_wbs_switch(struct inode *inode, 519c22d70a1SRoman Gushchin struct bdi_writeback *new_wb) 520c22d70a1SRoman Gushchin { 521c22d70a1SRoman Gushchin /* 522c22d70a1SRoman Gushchin * Paired with smp_mb() in cgroup_writeback_umount(). 523c22d70a1SRoman Gushchin * isw_nr_in_flight must be increased before checking SB_ACTIVE and 524c22d70a1SRoman Gushchin * grabbing an inode, otherwise isw_nr_in_flight can be observed as 0 525c22d70a1SRoman Gushchin * in cgroup_writeback_umount() and the isw_wq will be not flushed. 526c22d70a1SRoman Gushchin */ 527c22d70a1SRoman Gushchin smp_mb(); 528c22d70a1SRoman Gushchin 529593311e8SRoman Gushchin if (IS_DAX(inode)) 530593311e8SRoman Gushchin return false; 531593311e8SRoman Gushchin 532c22d70a1SRoman Gushchin /* while holding I_WB_SWITCH, no one else can update the association */ 533c22d70a1SRoman Gushchin spin_lock(&inode->i_lock); 534c22d70a1SRoman Gushchin if (!(inode->i_sb->s_flags & SB_ACTIVE) || 535c22d70a1SRoman Gushchin inode->i_state & (I_WB_SWITCH | I_FREEING | I_WILL_FREE) || 536c22d70a1SRoman Gushchin inode_to_wb(inode) == new_wb) { 537c22d70a1SRoman Gushchin spin_unlock(&inode->i_lock); 538c22d70a1SRoman Gushchin return false; 539c22d70a1SRoman Gushchin } 540c22d70a1SRoman Gushchin inode->i_state |= I_WB_SWITCH; 541c22d70a1SRoman Gushchin __iget(inode); 542c22d70a1SRoman Gushchin spin_unlock(&inode->i_lock); 543c22d70a1SRoman Gushchin 544c22d70a1SRoman Gushchin return true; 545c22d70a1SRoman Gushchin } 546c22d70a1SRoman Gushchin 547682aa8e1STejun Heo /** 548682aa8e1STejun Heo * inode_switch_wbs - change the wb association of an inode 549682aa8e1STejun Heo * @inode: target inode 550682aa8e1STejun Heo * @new_wb_id: ID of the new wb 551682aa8e1STejun Heo * 552682aa8e1STejun Heo * Switch @inode's wb association to the wb identified by @new_wb_id. The 553682aa8e1STejun Heo * switching is performed asynchronously and may fail silently. 554682aa8e1STejun Heo */ 555682aa8e1STejun Heo static void inode_switch_wbs(struct inode *inode, int new_wb_id) 556682aa8e1STejun Heo { 557682aa8e1STejun Heo struct backing_dev_info *bdi = inode_to_bdi(inode); 558682aa8e1STejun Heo struct cgroup_subsys_state *memcg_css; 559682aa8e1STejun Heo struct inode_switch_wbs_context *isw; 560682aa8e1STejun Heo 561682aa8e1STejun Heo /* noop if seems to be already in progress */ 562682aa8e1STejun Heo if (inode->i_state & I_WB_SWITCH) 563682aa8e1STejun Heo return; 564682aa8e1STejun Heo 5656444f47eSTejun Heo /* avoid queueing a new switch if too many are already in flight */ 5666444f47eSTejun Heo if (atomic_read(&isw_nr_in_flight) > WB_FRN_MAX_IN_FLIGHT) 5677fc5854fSTejun Heo return; 5687fc5854fSTejun Heo 569f5fbe6b7SRoman Gushchin isw = kzalloc(sizeof(*isw) + 2 * sizeof(struct inode *), GFP_ATOMIC); 570682aa8e1STejun Heo if (!isw) 5716444f47eSTejun Heo return; 572682aa8e1STejun Heo 5738826ee4fSRoman Gushchin atomic_inc(&isw_nr_in_flight); 5748826ee4fSRoman Gushchin 575682aa8e1STejun Heo /* find and pin the new wb */ 576682aa8e1STejun Heo rcu_read_lock(); 577682aa8e1STejun Heo memcg_css = css_from_id(new_wb_id, &memory_cgrp_subsys); 5788b0ed844SMuchun Song if (memcg_css && !css_tryget(memcg_css)) 5798b0ed844SMuchun Song memcg_css = NULL; 580682aa8e1STejun Heo rcu_read_unlock(); 5818b0ed844SMuchun Song if (!memcg_css) 5828b0ed844SMuchun Song goto out_free; 5838b0ed844SMuchun Song 5848b0ed844SMuchun Song isw->new_wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); 5858b0ed844SMuchun Song css_put(memcg_css); 586682aa8e1STejun Heo if (!isw->new_wb) 587682aa8e1STejun Heo goto out_free; 588682aa8e1STejun Heo 589c22d70a1SRoman Gushchin if (!inode_prepare_wbs_switch(inode, isw->new_wb)) 590a1a0e23eSTejun Heo goto out_free; 591682aa8e1STejun Heo 592f5fbe6b7SRoman Gushchin isw->inodes[0] = inode; 593682aa8e1STejun Heo 594682aa8e1STejun Heo /* 595682aa8e1STejun Heo * In addition to synchronizing among switchers, I_WB_SWITCH tells 596b93b0163SMatthew Wilcox * the RCU protected stat update paths to grab the i_page 597b93b0163SMatthew Wilcox * lock so that stat transfer can synchronize against them. 598682aa8e1STejun Heo * Let's continue after I_WB_SWITCH is guaranteed to be visible. 599682aa8e1STejun Heo */ 60029264d92SRoman Gushchin INIT_RCU_WORK(&isw->work, inode_switch_wbs_work_fn); 60129264d92SRoman Gushchin queue_rcu_work(isw_wq, &isw->work); 6026444f47eSTejun Heo return; 603682aa8e1STejun Heo 604682aa8e1STejun Heo out_free: 6058826ee4fSRoman Gushchin atomic_dec(&isw_nr_in_flight); 606682aa8e1STejun Heo if (isw->new_wb) 607682aa8e1STejun Heo wb_put(isw->new_wb); 608682aa8e1STejun Heo kfree(isw); 609682aa8e1STejun Heo } 610682aa8e1STejun Heo 61187e1d789STejun Heo /** 612c22d70a1SRoman Gushchin * cleanup_offline_cgwb - detach associated inodes 613c22d70a1SRoman Gushchin * @wb: target wb 614c22d70a1SRoman Gushchin * 615c22d70a1SRoman Gushchin * Switch all inodes attached to @wb to a nearest living ancestor's wb in order 616c22d70a1SRoman Gushchin * to eventually release the dying @wb. Returns %true if not all inodes were 617c22d70a1SRoman Gushchin * switched and the function has to be restarted. 618c22d70a1SRoman Gushchin */ 619c22d70a1SRoman Gushchin bool cleanup_offline_cgwb(struct bdi_writeback *wb) 620c22d70a1SRoman Gushchin { 621c22d70a1SRoman Gushchin struct cgroup_subsys_state *memcg_css; 622c22d70a1SRoman Gushchin struct inode_switch_wbs_context *isw; 623c22d70a1SRoman Gushchin struct inode *inode; 624c22d70a1SRoman Gushchin int nr; 625c22d70a1SRoman Gushchin bool restart = false; 626c22d70a1SRoman Gushchin 627c22d70a1SRoman Gushchin isw = kzalloc(sizeof(*isw) + WB_MAX_INODES_PER_ISW * 628c22d70a1SRoman Gushchin sizeof(struct inode *), GFP_KERNEL); 629c22d70a1SRoman Gushchin if (!isw) 630c22d70a1SRoman Gushchin return restart; 631c22d70a1SRoman Gushchin 632c22d70a1SRoman Gushchin atomic_inc(&isw_nr_in_flight); 633c22d70a1SRoman Gushchin 634c22d70a1SRoman Gushchin for (memcg_css = wb->memcg_css->parent; memcg_css; 635c22d70a1SRoman Gushchin memcg_css = memcg_css->parent) { 636c22d70a1SRoman Gushchin isw->new_wb = wb_get_create(wb->bdi, memcg_css, GFP_KERNEL); 637c22d70a1SRoman Gushchin if (isw->new_wb) 638c22d70a1SRoman Gushchin break; 639c22d70a1SRoman Gushchin } 640c22d70a1SRoman Gushchin if (unlikely(!isw->new_wb)) 641c22d70a1SRoman Gushchin isw->new_wb = &wb->bdi->wb; /* wb_get() is noop for bdi's wb */ 642c22d70a1SRoman Gushchin 643c22d70a1SRoman Gushchin nr = 0; 644c22d70a1SRoman Gushchin spin_lock(&wb->list_lock); 645c22d70a1SRoman Gushchin list_for_each_entry(inode, &wb->b_attached, i_io_list) { 646c22d70a1SRoman Gushchin if (!inode_prepare_wbs_switch(inode, isw->new_wb)) 647c22d70a1SRoman Gushchin continue; 648c22d70a1SRoman Gushchin 649c22d70a1SRoman Gushchin isw->inodes[nr++] = inode; 650c22d70a1SRoman Gushchin 651c22d70a1SRoman Gushchin if (nr >= WB_MAX_INODES_PER_ISW - 1) { 652c22d70a1SRoman Gushchin restart = true; 653c22d70a1SRoman Gushchin break; 654c22d70a1SRoman Gushchin } 655c22d70a1SRoman Gushchin } 656c22d70a1SRoman Gushchin spin_unlock(&wb->list_lock); 657c22d70a1SRoman Gushchin 658c22d70a1SRoman Gushchin /* no attached inodes? bail out */ 659c22d70a1SRoman Gushchin if (nr == 0) { 660c22d70a1SRoman Gushchin atomic_dec(&isw_nr_in_flight); 661c22d70a1SRoman Gushchin wb_put(isw->new_wb); 662c22d70a1SRoman Gushchin kfree(isw); 663c22d70a1SRoman Gushchin return restart; 664c22d70a1SRoman Gushchin } 665c22d70a1SRoman Gushchin 666c22d70a1SRoman Gushchin /* 667c22d70a1SRoman Gushchin * In addition to synchronizing among switchers, I_WB_SWITCH tells 668c22d70a1SRoman Gushchin * the RCU protected stat update paths to grab the i_page 669c22d70a1SRoman Gushchin * lock so that stat transfer can synchronize against them. 670c22d70a1SRoman Gushchin * Let's continue after I_WB_SWITCH is guaranteed to be visible. 671c22d70a1SRoman Gushchin */ 672c22d70a1SRoman Gushchin INIT_RCU_WORK(&isw->work, inode_switch_wbs_work_fn); 673c22d70a1SRoman Gushchin queue_rcu_work(isw_wq, &isw->work); 674c22d70a1SRoman Gushchin 675c22d70a1SRoman Gushchin return restart; 676c22d70a1SRoman Gushchin } 677c22d70a1SRoman Gushchin 678c22d70a1SRoman Gushchin /** 679b16b1debSTejun Heo * wbc_attach_and_unlock_inode - associate wbc with target inode and unlock it 680b16b1debSTejun Heo * @wbc: writeback_control of interest 681b16b1debSTejun Heo * @inode: target inode 682b16b1debSTejun Heo * 683b16b1debSTejun Heo * @inode is locked and about to be written back under the control of @wbc. 684b16b1debSTejun Heo * Record @inode's writeback context into @wbc and unlock the i_lock. On 685b16b1debSTejun Heo * writeback completion, wbc_detach_inode() should be called. This is used 686b16b1debSTejun Heo * to track the cgroup writeback context. 687b16b1debSTejun Heo */ 688b16b1debSTejun Heo void wbc_attach_and_unlock_inode(struct writeback_control *wbc, 689b16b1debSTejun Heo struct inode *inode) 690b16b1debSTejun Heo { 691dd73e4b7STejun Heo if (!inode_cgwb_enabled(inode)) { 692dd73e4b7STejun Heo spin_unlock(&inode->i_lock); 693dd73e4b7STejun Heo return; 694dd73e4b7STejun Heo } 695dd73e4b7STejun Heo 696b16b1debSTejun Heo wbc->wb = inode_to_wb(inode); 6972a814908STejun Heo wbc->inode = inode; 6982a814908STejun Heo 6992a814908STejun Heo wbc->wb_id = wbc->wb->memcg_css->id; 7002a814908STejun Heo wbc->wb_lcand_id = inode->i_wb_frn_winner; 7012a814908STejun Heo wbc->wb_tcand_id = 0; 7022a814908STejun Heo wbc->wb_bytes = 0; 7032a814908STejun Heo wbc->wb_lcand_bytes = 0; 7042a814908STejun Heo wbc->wb_tcand_bytes = 0; 7052a814908STejun Heo 706b16b1debSTejun Heo wb_get(wbc->wb); 707b16b1debSTejun Heo spin_unlock(&inode->i_lock); 708e8a7abf5STejun Heo 709e8a7abf5STejun Heo /* 71065de03e2STejun Heo * A dying wb indicates that either the blkcg associated with the 71165de03e2STejun Heo * memcg changed or the associated memcg is dying. In the first 71265de03e2STejun Heo * case, a replacement wb should already be available and we should 71365de03e2STejun Heo * refresh the wb immediately. In the second case, trying to 71465de03e2STejun Heo * refresh will keep failing. 715e8a7abf5STejun Heo */ 71665de03e2STejun Heo if (unlikely(wb_dying(wbc->wb) && !css_is_dying(wbc->wb->memcg_css))) 717e8a7abf5STejun Heo inode_switch_wbs(inode, wbc->wb_id); 718b16b1debSTejun Heo } 7199b0eb69bSTejun Heo EXPORT_SYMBOL_GPL(wbc_attach_and_unlock_inode); 720b16b1debSTejun Heo 721b16b1debSTejun Heo /** 7222a814908STejun Heo * wbc_detach_inode - disassociate wbc from inode and perform foreign detection 7232a814908STejun Heo * @wbc: writeback_control of the just finished writeback 724b16b1debSTejun Heo * 725b16b1debSTejun Heo * To be called after a writeback attempt of an inode finishes and undoes 726b16b1debSTejun Heo * wbc_attach_and_unlock_inode(). Can be called under any context. 7272a814908STejun Heo * 7282a814908STejun Heo * As concurrent write sharing of an inode is expected to be very rare and 7292a814908STejun Heo * memcg only tracks page ownership on first-use basis severely confining 7302a814908STejun Heo * the usefulness of such sharing, cgroup writeback tracks ownership 7312a814908STejun Heo * per-inode. While the support for concurrent write sharing of an inode 7322a814908STejun Heo * is deemed unnecessary, an inode being written to by different cgroups at 7332a814908STejun Heo * different points in time is a lot more common, and, more importantly, 7342a814908STejun Heo * charging only by first-use can too readily lead to grossly incorrect 7352a814908STejun Heo * behaviors (single foreign page can lead to gigabytes of writeback to be 7362a814908STejun Heo * incorrectly attributed). 7372a814908STejun Heo * 7382a814908STejun Heo * To resolve this issue, cgroup writeback detects the majority dirtier of 7392a814908STejun Heo * an inode and transfers the ownership to it. To avoid unnnecessary 7402a814908STejun Heo * oscillation, the detection mechanism keeps track of history and gives 7412a814908STejun Heo * out the switch verdict only if the foreign usage pattern is stable over 7422a814908STejun Heo * a certain amount of time and/or writeback attempts. 7432a814908STejun Heo * 7442a814908STejun Heo * On each writeback attempt, @wbc tries to detect the majority writer 7452a814908STejun Heo * using Boyer-Moore majority vote algorithm. In addition to the byte 7462a814908STejun Heo * count from the majority voting, it also counts the bytes written for the 7472a814908STejun Heo * current wb and the last round's winner wb (max of last round's current 7482a814908STejun Heo * wb, the winner from two rounds ago, and the last round's majority 7492a814908STejun Heo * candidate). Keeping track of the historical winner helps the algorithm 7502a814908STejun Heo * to semi-reliably detect the most active writer even when it's not the 7512a814908STejun Heo * absolute majority. 7522a814908STejun Heo * 7532a814908STejun Heo * Once the winner of the round is determined, whether the winner is 7542a814908STejun Heo * foreign or not and how much IO time the round consumed is recorded in 7552a814908STejun Heo * inode->i_wb_frn_history. If the amount of recorded foreign IO time is 7562a814908STejun Heo * over a certain threshold, the switch verdict is given. 757b16b1debSTejun Heo */ 758b16b1debSTejun Heo void wbc_detach_inode(struct writeback_control *wbc) 759b16b1debSTejun Heo { 7602a814908STejun Heo struct bdi_writeback *wb = wbc->wb; 7612a814908STejun Heo struct inode *inode = wbc->inode; 762dd73e4b7STejun Heo unsigned long avg_time, max_bytes, max_time; 763dd73e4b7STejun Heo u16 history; 7642a814908STejun Heo int max_id; 7652a814908STejun Heo 766dd73e4b7STejun Heo if (!wb) 767dd73e4b7STejun Heo return; 768dd73e4b7STejun Heo 769dd73e4b7STejun Heo history = inode->i_wb_frn_history; 770dd73e4b7STejun Heo avg_time = inode->i_wb_frn_avg_time; 771dd73e4b7STejun Heo 7722a814908STejun Heo /* pick the winner of this round */ 7732a814908STejun Heo if (wbc->wb_bytes >= wbc->wb_lcand_bytes && 7742a814908STejun Heo wbc->wb_bytes >= wbc->wb_tcand_bytes) { 7752a814908STejun Heo max_id = wbc->wb_id; 7762a814908STejun Heo max_bytes = wbc->wb_bytes; 7772a814908STejun Heo } else if (wbc->wb_lcand_bytes >= wbc->wb_tcand_bytes) { 7782a814908STejun Heo max_id = wbc->wb_lcand_id; 7792a814908STejun Heo max_bytes = wbc->wb_lcand_bytes; 7802a814908STejun Heo } else { 7812a814908STejun Heo max_id = wbc->wb_tcand_id; 7822a814908STejun Heo max_bytes = wbc->wb_tcand_bytes; 7832a814908STejun Heo } 7842a814908STejun Heo 7852a814908STejun Heo /* 7862a814908STejun Heo * Calculate the amount of IO time the winner consumed and fold it 7872a814908STejun Heo * into the running average kept per inode. If the consumed IO 7882a814908STejun Heo * time is lower than avag / WB_FRN_TIME_CUT_DIV, ignore it for 7892a814908STejun Heo * deciding whether to switch or not. This is to prevent one-off 7902a814908STejun Heo * small dirtiers from skewing the verdict. 7912a814908STejun Heo */ 7922a814908STejun Heo max_time = DIV_ROUND_UP((max_bytes >> PAGE_SHIFT) << WB_FRN_TIME_SHIFT, 7932a814908STejun Heo wb->avg_write_bandwidth); 7942a814908STejun Heo if (avg_time) 7952a814908STejun Heo avg_time += (max_time >> WB_FRN_TIME_AVG_SHIFT) - 7962a814908STejun Heo (avg_time >> WB_FRN_TIME_AVG_SHIFT); 7972a814908STejun Heo else 7982a814908STejun Heo avg_time = max_time; /* immediate catch up on first run */ 7992a814908STejun Heo 8002a814908STejun Heo if (max_time >= avg_time / WB_FRN_TIME_CUT_DIV) { 8012a814908STejun Heo int slots; 8022a814908STejun Heo 8032a814908STejun Heo /* 8042a814908STejun Heo * The switch verdict is reached if foreign wb's consume 8052a814908STejun Heo * more than a certain proportion of IO time in a 8062a814908STejun Heo * WB_FRN_TIME_PERIOD. This is loosely tracked by 16 slot 8072a814908STejun Heo * history mask where each bit represents one sixteenth of 8082a814908STejun Heo * the period. Determine the number of slots to shift into 8092a814908STejun Heo * history from @max_time. 8102a814908STejun Heo */ 8112a814908STejun Heo slots = min(DIV_ROUND_UP(max_time, WB_FRN_HIST_UNIT), 8122a814908STejun Heo (unsigned long)WB_FRN_HIST_MAX_SLOTS); 8132a814908STejun Heo history <<= slots; 8142a814908STejun Heo if (wbc->wb_id != max_id) 8152a814908STejun Heo history |= (1U << slots) - 1; 8162a814908STejun Heo 8173a8e9ac8STejun Heo if (history) 8183a8e9ac8STejun Heo trace_inode_foreign_history(inode, wbc, history); 8193a8e9ac8STejun Heo 8202a814908STejun Heo /* 8212a814908STejun Heo * Switch if the current wb isn't the consistent winner. 8222a814908STejun Heo * If there are multiple closely competing dirtiers, the 8232a814908STejun Heo * inode may switch across them repeatedly over time, which 8242a814908STejun Heo * is okay. The main goal is avoiding keeping an inode on 8252a814908STejun Heo * the wrong wb for an extended period of time. 8262a814908STejun Heo */ 827682aa8e1STejun Heo if (hweight32(history) > WB_FRN_HIST_THR_SLOTS) 828682aa8e1STejun Heo inode_switch_wbs(inode, max_id); 8292a814908STejun Heo } 8302a814908STejun Heo 8312a814908STejun Heo /* 8322a814908STejun Heo * Multiple instances of this function may race to update the 8332a814908STejun Heo * following fields but we don't mind occassional inaccuracies. 8342a814908STejun Heo */ 8352a814908STejun Heo inode->i_wb_frn_winner = max_id; 8362a814908STejun Heo inode->i_wb_frn_avg_time = min(avg_time, (unsigned long)U16_MAX); 8372a814908STejun Heo inode->i_wb_frn_history = history; 8382a814908STejun Heo 839b16b1debSTejun Heo wb_put(wbc->wb); 840b16b1debSTejun Heo wbc->wb = NULL; 841b16b1debSTejun Heo } 8429b0eb69bSTejun Heo EXPORT_SYMBOL_GPL(wbc_detach_inode); 843b16b1debSTejun Heo 844b16b1debSTejun Heo /** 84534e51a5eSTejun Heo * wbc_account_cgroup_owner - account writeback to update inode cgroup ownership 8462a814908STejun Heo * @wbc: writeback_control of the writeback in progress 8472a814908STejun Heo * @page: page being written out 8482a814908STejun Heo * @bytes: number of bytes being written out 8492a814908STejun Heo * 8502a814908STejun Heo * @bytes from @page are about to written out during the writeback 8512a814908STejun Heo * controlled by @wbc. Keep the book for foreign inode detection. See 8522a814908STejun Heo * wbc_detach_inode(). 8532a814908STejun Heo */ 85434e51a5eSTejun Heo void wbc_account_cgroup_owner(struct writeback_control *wbc, struct page *page, 8552a814908STejun Heo size_t bytes) 8562a814908STejun Heo { 85766311422STejun Heo struct cgroup_subsys_state *css; 8582a814908STejun Heo int id; 8592a814908STejun Heo 8602a814908STejun Heo /* 8612a814908STejun Heo * pageout() path doesn't attach @wbc to the inode being written 8622a814908STejun Heo * out. This is intentional as we don't want the function to block 8632a814908STejun Heo * behind a slow cgroup. Ultimately, we want pageout() to kick off 8642a814908STejun Heo * regular writeback instead of writing things out itself. 8652a814908STejun Heo */ 86627b36d8fSTejun Heo if (!wbc->wb || wbc->no_cgroup_owner) 8672a814908STejun Heo return; 8682a814908STejun Heo 86966311422STejun Heo css = mem_cgroup_css_from_page(page); 87066311422STejun Heo /* dead cgroups shouldn't contribute to inode ownership arbitration */ 87166311422STejun Heo if (!(css->flags & CSS_ONLINE)) 87266311422STejun Heo return; 87366311422STejun Heo 87466311422STejun Heo id = css->id; 8752a814908STejun Heo 8762a814908STejun Heo if (id == wbc->wb_id) { 8772a814908STejun Heo wbc->wb_bytes += bytes; 8782a814908STejun Heo return; 8792a814908STejun Heo } 8802a814908STejun Heo 8812a814908STejun Heo if (id == wbc->wb_lcand_id) 8822a814908STejun Heo wbc->wb_lcand_bytes += bytes; 8832a814908STejun Heo 8842a814908STejun Heo /* Boyer-Moore majority vote algorithm */ 8852a814908STejun Heo if (!wbc->wb_tcand_bytes) 8862a814908STejun Heo wbc->wb_tcand_id = id; 8872a814908STejun Heo if (id == wbc->wb_tcand_id) 8882a814908STejun Heo wbc->wb_tcand_bytes += bytes; 8892a814908STejun Heo else 8902a814908STejun Heo wbc->wb_tcand_bytes -= min(bytes, wbc->wb_tcand_bytes); 8912a814908STejun Heo } 89234e51a5eSTejun Heo EXPORT_SYMBOL_GPL(wbc_account_cgroup_owner); 8932a814908STejun Heo 8942a814908STejun Heo /** 895703c2708STejun Heo * inode_congested - test whether an inode is congested 89660292bccSTejun Heo * @inode: inode to test for congestion (may be NULL) 897703c2708STejun Heo * @cong_bits: mask of WB_[a]sync_congested bits to test 898703c2708STejun Heo * 899703c2708STejun Heo * Tests whether @inode is congested. @cong_bits is the mask of congestion 900703c2708STejun Heo * bits to test and the return value is the mask of set bits. 901703c2708STejun Heo * 902703c2708STejun Heo * If cgroup writeback is enabled for @inode, the congestion state is 903703c2708STejun Heo * determined by whether the cgwb (cgroup bdi_writeback) for the blkcg 904703c2708STejun Heo * associated with @inode is congested; otherwise, the root wb's congestion 905703c2708STejun Heo * state is used. 90660292bccSTejun Heo * 90760292bccSTejun Heo * @inode is allowed to be NULL as this function is often called on 90860292bccSTejun Heo * mapping->host which is NULL for the swapper space. 909703c2708STejun Heo */ 910703c2708STejun Heo int inode_congested(struct inode *inode, int cong_bits) 911703c2708STejun Heo { 9125cb8b824STejun Heo /* 9135cb8b824STejun Heo * Once set, ->i_wb never becomes NULL while the inode is alive. 9145cb8b824STejun Heo * Start transaction iff ->i_wb is visible. 9155cb8b824STejun Heo */ 916aaa2cacfSTejun Heo if (inode && inode_to_wb_is_valid(inode)) { 9175cb8b824STejun Heo struct bdi_writeback *wb; 9182e898e4cSGreg Thelen struct wb_lock_cookie lock_cookie = {}; 9192e898e4cSGreg Thelen bool congested; 9205cb8b824STejun Heo 9212e898e4cSGreg Thelen wb = unlocked_inode_to_wb_begin(inode, &lock_cookie); 9225cb8b824STejun Heo congested = wb_congested(wb, cong_bits); 9232e898e4cSGreg Thelen unlocked_inode_to_wb_end(inode, &lock_cookie); 9245cb8b824STejun Heo return congested; 925703c2708STejun Heo } 926703c2708STejun Heo 927703c2708STejun Heo return wb_congested(&inode_to_bdi(inode)->wb, cong_bits); 928703c2708STejun Heo } 929703c2708STejun Heo EXPORT_SYMBOL_GPL(inode_congested); 930703c2708STejun Heo 931f2b65121STejun Heo /** 932f2b65121STejun Heo * wb_split_bdi_pages - split nr_pages to write according to bandwidth 933f2b65121STejun Heo * @wb: target bdi_writeback to split @nr_pages to 934f2b65121STejun Heo * @nr_pages: number of pages to write for the whole bdi 935f2b65121STejun Heo * 936f2b65121STejun Heo * Split @wb's portion of @nr_pages according to @wb's write bandwidth in 937f2b65121STejun Heo * relation to the total write bandwidth of all wb's w/ dirty inodes on 938f2b65121STejun Heo * @wb->bdi. 939f2b65121STejun Heo */ 940f2b65121STejun Heo static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages) 941f2b65121STejun Heo { 942f2b65121STejun Heo unsigned long this_bw = wb->avg_write_bandwidth; 943f2b65121STejun Heo unsigned long tot_bw = atomic_long_read(&wb->bdi->tot_write_bandwidth); 944f2b65121STejun Heo 945f2b65121STejun Heo if (nr_pages == LONG_MAX) 946f2b65121STejun Heo return LONG_MAX; 947f2b65121STejun Heo 948f2b65121STejun Heo /* 949f2b65121STejun Heo * This may be called on clean wb's and proportional distribution 950f2b65121STejun Heo * may not make sense, just use the original @nr_pages in those 951f2b65121STejun Heo * cases. In general, we wanna err on the side of writing more. 952f2b65121STejun Heo */ 953f2b65121STejun Heo if (!tot_bw || this_bw >= tot_bw) 954f2b65121STejun Heo return nr_pages; 955f2b65121STejun Heo else 956f2b65121STejun Heo return DIV_ROUND_UP_ULL((u64)nr_pages * this_bw, tot_bw); 957f2b65121STejun Heo } 958f2b65121STejun Heo 959db125360STejun Heo /** 960db125360STejun Heo * bdi_split_work_to_wbs - split a wb_writeback_work to all wb's of a bdi 961db125360STejun Heo * @bdi: target backing_dev_info 962db125360STejun Heo * @base_work: wb_writeback_work to issue 963db125360STejun Heo * @skip_if_busy: skip wb's which already have writeback in progress 964db125360STejun Heo * 965db125360STejun Heo * Split and issue @base_work to all wb's (bdi_writeback's) of @bdi which 966db125360STejun Heo * have dirty inodes. If @base_work->nr_page isn't %LONG_MAX, it's 967db125360STejun Heo * distributed to the busy wbs according to each wb's proportion in the 968db125360STejun Heo * total active write bandwidth of @bdi. 969db125360STejun Heo */ 970db125360STejun Heo static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, 971db125360STejun Heo struct wb_writeback_work *base_work, 972db125360STejun Heo bool skip_if_busy) 973db125360STejun Heo { 974b817525aSTejun Heo struct bdi_writeback *last_wb = NULL; 975b33e18f6STejun Heo struct bdi_writeback *wb = list_entry(&bdi->wb_list, 976b817525aSTejun Heo struct bdi_writeback, bdi_node); 977db125360STejun Heo 978db125360STejun Heo might_sleep(); 979db125360STejun Heo restart: 980db125360STejun Heo rcu_read_lock(); 981b817525aSTejun Heo list_for_each_entry_continue_rcu(wb, &bdi->wb_list, bdi_node) { 9825b9cce4cSTejun Heo DEFINE_WB_COMPLETION(fallback_work_done, bdi); 9838a1270cdSTejun Heo struct wb_writeback_work fallback_work; 9848a1270cdSTejun Heo struct wb_writeback_work *work; 9858a1270cdSTejun Heo long nr_pages; 9868a1270cdSTejun Heo 987b817525aSTejun Heo if (last_wb) { 988b817525aSTejun Heo wb_put(last_wb); 989b817525aSTejun Heo last_wb = NULL; 990b817525aSTejun Heo } 991b817525aSTejun Heo 992006a0973STejun Heo /* SYNC_ALL writes out I_DIRTY_TIME too */ 993006a0973STejun Heo if (!wb_has_dirty_io(wb) && 994006a0973STejun Heo (base_work->sync_mode == WB_SYNC_NONE || 995006a0973STejun Heo list_empty(&wb->b_dirty_time))) 996006a0973STejun Heo continue; 997006a0973STejun Heo if (skip_if_busy && writeback_in_progress(wb)) 998db125360STejun Heo continue; 999db125360STejun Heo 10008a1270cdSTejun Heo nr_pages = wb_split_bdi_pages(wb, base_work->nr_pages); 10018a1270cdSTejun Heo 10028a1270cdSTejun Heo work = kmalloc(sizeof(*work), GFP_ATOMIC); 10038a1270cdSTejun Heo if (work) { 10048a1270cdSTejun Heo *work = *base_work; 10058a1270cdSTejun Heo work->nr_pages = nr_pages; 10068a1270cdSTejun Heo work->auto_free = 1; 10078a1270cdSTejun Heo wb_queue_work(wb, work); 10088a1270cdSTejun Heo continue; 1009db125360STejun Heo } 10108a1270cdSTejun Heo 10118a1270cdSTejun Heo /* alloc failed, execute synchronously using on-stack fallback */ 10128a1270cdSTejun Heo work = &fallback_work; 10138a1270cdSTejun Heo *work = *base_work; 10148a1270cdSTejun Heo work->nr_pages = nr_pages; 10158a1270cdSTejun Heo work->auto_free = 0; 10168a1270cdSTejun Heo work->done = &fallback_work_done; 10178a1270cdSTejun Heo 10188a1270cdSTejun Heo wb_queue_work(wb, work); 10198a1270cdSTejun Heo 1020b817525aSTejun Heo /* 1021b817525aSTejun Heo * Pin @wb so that it stays on @bdi->wb_list. This allows 1022b817525aSTejun Heo * continuing iteration from @wb after dropping and 1023b817525aSTejun Heo * regrabbing rcu read lock. 1024b817525aSTejun Heo */ 1025b817525aSTejun Heo wb_get(wb); 1026b817525aSTejun Heo last_wb = wb; 1027b817525aSTejun Heo 1028db125360STejun Heo rcu_read_unlock(); 10295b9cce4cSTejun Heo wb_wait_for_completion(&fallback_work_done); 1030db125360STejun Heo goto restart; 1031db125360STejun Heo } 1032db125360STejun Heo rcu_read_unlock(); 1033b817525aSTejun Heo 1034b817525aSTejun Heo if (last_wb) 1035b817525aSTejun Heo wb_put(last_wb); 1036db125360STejun Heo } 1037db125360STejun Heo 1038a1a0e23eSTejun Heo /** 1039d62241c7STejun Heo * cgroup_writeback_by_id - initiate cgroup writeback from bdi and memcg IDs 1040d62241c7STejun Heo * @bdi_id: target bdi id 1041d62241c7STejun Heo * @memcg_id: target memcg css id 1042b46ec1daSRandy Dunlap * @nr: number of pages to write, 0 for best-effort dirty flushing 1043d62241c7STejun Heo * @reason: reason why some writeback work initiated 1044d62241c7STejun Heo * @done: target wb_completion 1045d62241c7STejun Heo * 1046d62241c7STejun Heo * Initiate flush of the bdi_writeback identified by @bdi_id and @memcg_id 1047d62241c7STejun Heo * with the specified parameters. 1048d62241c7STejun Heo */ 1049d62241c7STejun Heo int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, unsigned long nr, 1050d62241c7STejun Heo enum wb_reason reason, struct wb_completion *done) 1051d62241c7STejun Heo { 1052d62241c7STejun Heo struct backing_dev_info *bdi; 1053d62241c7STejun Heo struct cgroup_subsys_state *memcg_css; 1054d62241c7STejun Heo struct bdi_writeback *wb; 1055d62241c7STejun Heo struct wb_writeback_work *work; 1056d62241c7STejun Heo int ret; 1057d62241c7STejun Heo 1058d62241c7STejun Heo /* lookup bdi and memcg */ 1059d62241c7STejun Heo bdi = bdi_get_by_id(bdi_id); 1060d62241c7STejun Heo if (!bdi) 1061d62241c7STejun Heo return -ENOENT; 1062d62241c7STejun Heo 1063d62241c7STejun Heo rcu_read_lock(); 1064d62241c7STejun Heo memcg_css = css_from_id(memcg_id, &memory_cgrp_subsys); 1065d62241c7STejun Heo if (memcg_css && !css_tryget(memcg_css)) 1066d62241c7STejun Heo memcg_css = NULL; 1067d62241c7STejun Heo rcu_read_unlock(); 1068d62241c7STejun Heo if (!memcg_css) { 1069d62241c7STejun Heo ret = -ENOENT; 1070d62241c7STejun Heo goto out_bdi_put; 1071d62241c7STejun Heo } 1072d62241c7STejun Heo 1073d62241c7STejun Heo /* 1074d62241c7STejun Heo * And find the associated wb. If the wb isn't there already 1075d62241c7STejun Heo * there's nothing to flush, don't create one. 1076d62241c7STejun Heo */ 1077d62241c7STejun Heo wb = wb_get_lookup(bdi, memcg_css); 1078d62241c7STejun Heo if (!wb) { 1079d62241c7STejun Heo ret = -ENOENT; 1080d62241c7STejun Heo goto out_css_put; 1081d62241c7STejun Heo } 1082d62241c7STejun Heo 1083d62241c7STejun Heo /* 1084d62241c7STejun Heo * If @nr is zero, the caller is attempting to write out most of 1085d62241c7STejun Heo * the currently dirty pages. Let's take the current dirty page 1086d62241c7STejun Heo * count and inflate it by 25% which should be large enough to 1087d62241c7STejun Heo * flush out most dirty pages while avoiding getting livelocked by 1088d62241c7STejun Heo * concurrent dirtiers. 1089d62241c7STejun Heo */ 1090d62241c7STejun Heo if (!nr) { 1091d62241c7STejun Heo unsigned long filepages, headroom, dirty, writeback; 1092d62241c7STejun Heo 1093d62241c7STejun Heo mem_cgroup_wb_stats(wb, &filepages, &headroom, &dirty, 1094d62241c7STejun Heo &writeback); 1095d62241c7STejun Heo nr = dirty * 10 / 8; 1096d62241c7STejun Heo } 1097d62241c7STejun Heo 1098d62241c7STejun Heo /* issue the writeback work */ 1099d62241c7STejun Heo work = kzalloc(sizeof(*work), GFP_NOWAIT | __GFP_NOWARN); 1100d62241c7STejun Heo if (work) { 1101d62241c7STejun Heo work->nr_pages = nr; 1102d62241c7STejun Heo work->sync_mode = WB_SYNC_NONE; 1103d62241c7STejun Heo work->range_cyclic = 1; 1104d62241c7STejun Heo work->reason = reason; 1105d62241c7STejun Heo work->done = done; 1106d62241c7STejun Heo work->auto_free = 1; 1107d62241c7STejun Heo wb_queue_work(wb, work); 1108d62241c7STejun Heo ret = 0; 1109d62241c7STejun Heo } else { 1110d62241c7STejun Heo ret = -ENOMEM; 1111d62241c7STejun Heo } 1112d62241c7STejun Heo 1113d62241c7STejun Heo wb_put(wb); 1114d62241c7STejun Heo out_css_put: 1115d62241c7STejun Heo css_put(memcg_css); 1116d62241c7STejun Heo out_bdi_put: 1117d62241c7STejun Heo bdi_put(bdi); 1118d62241c7STejun Heo return ret; 1119d62241c7STejun Heo } 1120d62241c7STejun Heo 1121d62241c7STejun Heo /** 1122a1a0e23eSTejun Heo * cgroup_writeback_umount - flush inode wb switches for umount 1123a1a0e23eSTejun Heo * 1124a1a0e23eSTejun Heo * This function is called when a super_block is about to be destroyed and 1125a1a0e23eSTejun Heo * flushes in-flight inode wb switches. An inode wb switch goes through 1126a1a0e23eSTejun Heo * RCU and then workqueue, so the two need to be flushed in order to ensure 1127a1a0e23eSTejun Heo * that all previously scheduled switches are finished. As wb switches are 1128a1a0e23eSTejun Heo * rare occurrences and synchronize_rcu() can take a while, perform 1129a1a0e23eSTejun Heo * flushing iff wb switches are in flight. 1130a1a0e23eSTejun Heo */ 1131a1a0e23eSTejun Heo void cgroup_writeback_umount(void) 1132a1a0e23eSTejun Heo { 1133592fa002SRoman Gushchin /* 1134592fa002SRoman Gushchin * SB_ACTIVE should be reliably cleared before checking 1135592fa002SRoman Gushchin * isw_nr_in_flight, see generic_shutdown_super(). 1136592fa002SRoman Gushchin */ 1137592fa002SRoman Gushchin smp_mb(); 1138592fa002SRoman Gushchin 1139a1a0e23eSTejun Heo if (atomic_read(&isw_nr_in_flight)) { 1140ec084de9SJiufei Xue /* 1141ec084de9SJiufei Xue * Use rcu_barrier() to wait for all pending callbacks to 1142ec084de9SJiufei Xue * ensure that all in-flight wb switches are in the workqueue. 1143ec084de9SJiufei Xue */ 1144ec084de9SJiufei Xue rcu_barrier(); 1145a1a0e23eSTejun Heo flush_workqueue(isw_wq); 1146a1a0e23eSTejun Heo } 1147a1a0e23eSTejun Heo } 1148a1a0e23eSTejun Heo 1149a1a0e23eSTejun Heo static int __init cgroup_writeback_init(void) 1150a1a0e23eSTejun Heo { 1151a1a0e23eSTejun Heo isw_wq = alloc_workqueue("inode_switch_wbs", 0, 0); 1152a1a0e23eSTejun Heo if (!isw_wq) 1153a1a0e23eSTejun Heo return -ENOMEM; 1154a1a0e23eSTejun Heo return 0; 1155a1a0e23eSTejun Heo } 1156a1a0e23eSTejun Heo fs_initcall(cgroup_writeback_init); 1157a1a0e23eSTejun Heo 1158f2b65121STejun Heo #else /* CONFIG_CGROUP_WRITEBACK */ 1159f2b65121STejun Heo 11607fc5854fSTejun Heo static void bdi_down_write_wb_switch_rwsem(struct backing_dev_info *bdi) { } 11617fc5854fSTejun Heo static void bdi_up_write_wb_switch_rwsem(struct backing_dev_info *bdi) { } 11627fc5854fSTejun Heo 1163f3b6a6dfSRoman Gushchin static void inode_cgwb_move_to_attached(struct inode *inode, 1164f3b6a6dfSRoman Gushchin struct bdi_writeback *wb) 1165f3b6a6dfSRoman Gushchin { 1166f3b6a6dfSRoman Gushchin assert_spin_locked(&wb->list_lock); 1167f3b6a6dfSRoman Gushchin assert_spin_locked(&inode->i_lock); 1168f3b6a6dfSRoman Gushchin 1169f3b6a6dfSRoman Gushchin inode->i_state &= ~I_SYNC_QUEUED; 1170f3b6a6dfSRoman Gushchin list_del_init(&inode->i_io_list); 1171f3b6a6dfSRoman Gushchin wb_io_lists_depopulated(wb); 1172f3b6a6dfSRoman Gushchin } 1173f3b6a6dfSRoman Gushchin 117487e1d789STejun Heo static struct bdi_writeback * 117587e1d789STejun Heo locked_inode_to_wb_and_lock_list(struct inode *inode) 117687e1d789STejun Heo __releases(&inode->i_lock) 117787e1d789STejun Heo __acquires(&wb->list_lock) 117887e1d789STejun Heo { 117987e1d789STejun Heo struct bdi_writeback *wb = inode_to_wb(inode); 118087e1d789STejun Heo 118187e1d789STejun Heo spin_unlock(&inode->i_lock); 118287e1d789STejun Heo spin_lock(&wb->list_lock); 118387e1d789STejun Heo return wb; 118487e1d789STejun Heo } 118587e1d789STejun Heo 118687e1d789STejun Heo static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode) 118787e1d789STejun Heo __acquires(&wb->list_lock) 118887e1d789STejun Heo { 118987e1d789STejun Heo struct bdi_writeback *wb = inode_to_wb(inode); 119087e1d789STejun Heo 119187e1d789STejun Heo spin_lock(&wb->list_lock); 119287e1d789STejun Heo return wb; 119387e1d789STejun Heo } 119487e1d789STejun Heo 1195f2b65121STejun Heo static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages) 1196f2b65121STejun Heo { 1197f2b65121STejun Heo return nr_pages; 1198f2b65121STejun Heo } 1199f2b65121STejun Heo 1200db125360STejun Heo static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, 1201db125360STejun Heo struct wb_writeback_work *base_work, 1202db125360STejun Heo bool skip_if_busy) 1203db125360STejun Heo { 1204db125360STejun Heo might_sleep(); 1205db125360STejun Heo 1206006a0973STejun Heo if (!skip_if_busy || !writeback_in_progress(&bdi->wb)) { 1207db125360STejun Heo base_work->auto_free = 0; 1208db125360STejun Heo wb_queue_work(&bdi->wb, base_work); 1209db125360STejun Heo } 1210db125360STejun Heo } 1211db125360STejun Heo 1212703c2708STejun Heo #endif /* CONFIG_CGROUP_WRITEBACK */ 1213703c2708STejun Heo 1214e8e8a0c6SJens Axboe /* 1215e8e8a0c6SJens Axboe * Add in the number of potentially dirty inodes, because each inode 1216e8e8a0c6SJens Axboe * write can dirty pagecache in the underlying blockdev. 1217e8e8a0c6SJens Axboe */ 1218e8e8a0c6SJens Axboe static unsigned long get_nr_dirty_pages(void) 1219e8e8a0c6SJens Axboe { 1220e8e8a0c6SJens Axboe return global_node_page_state(NR_FILE_DIRTY) + 1221e8e8a0c6SJens Axboe get_nr_dirty_inodes(); 1222e8e8a0c6SJens Axboe } 1223e8e8a0c6SJens Axboe 1224e8e8a0c6SJens Axboe static void wb_start_writeback(struct bdi_writeback *wb, enum wb_reason reason) 1225b6e51316SJens Axboe { 1226c00ddad3STejun Heo if (!wb_has_dirty_io(wb)) 1227c00ddad3STejun Heo return; 1228c00ddad3STejun Heo 1229c00ddad3STejun Heo /* 1230aac8d41cSJens Axboe * All callers of this function want to start writeback of all 1231aac8d41cSJens Axboe * dirty pages. Places like vmscan can call this at a very 1232aac8d41cSJens Axboe * high frequency, causing pointless allocations of tons of 1233aac8d41cSJens Axboe * work items and keeping the flusher threads busy retrieving 1234aac8d41cSJens Axboe * that work. Ensure that we only allow one of them pending and 123585009b4fSJens Axboe * inflight at the time. 1236aac8d41cSJens Axboe */ 123785009b4fSJens Axboe if (test_bit(WB_start_all, &wb->state) || 123885009b4fSJens Axboe test_and_set_bit(WB_start_all, &wb->state)) 1239aac8d41cSJens Axboe return; 1240aac8d41cSJens Axboe 124185009b4fSJens Axboe wb->start_all_reason = reason; 1242c00ddad3STejun Heo wb_wakeup(wb); 1243d3ddec76SWu Fengguang } 1244d3ddec76SWu Fengguang 1245c5444198SChristoph Hellwig /** 12469ecf4866STejun Heo * wb_start_background_writeback - start background writeback 12479ecf4866STejun Heo * @wb: bdi_writback to write from 1248c5444198SChristoph Hellwig * 1249c5444198SChristoph Hellwig * Description: 12506585027aSJan Kara * This makes sure WB_SYNC_NONE background writeback happens. When 12519ecf4866STejun Heo * this function returns, it is only guaranteed that for given wb 12526585027aSJan Kara * some IO is happening if we are over background dirty threshold. 12536585027aSJan Kara * Caller need not hold sb s_umount semaphore. 1254c5444198SChristoph Hellwig */ 12559ecf4866STejun Heo void wb_start_background_writeback(struct bdi_writeback *wb) 1256c5444198SChristoph Hellwig { 12576585027aSJan Kara /* 12586585027aSJan Kara * We just wake up the flusher thread. It will perform background 12596585027aSJan Kara * writeback as soon as there is no other work to do. 12606585027aSJan Kara */ 12615634cc2aSTejun Heo trace_writeback_wake_background(wb); 12629ecf4866STejun Heo wb_wakeup(wb); 12631da177e4SLinus Torvalds } 12641da177e4SLinus Torvalds 12651da177e4SLinus Torvalds /* 1266a66979abSDave Chinner * Remove the inode from the writeback list it is on. 1267a66979abSDave Chinner */ 1268c7f54084SDave Chinner void inode_io_list_del(struct inode *inode) 1269a66979abSDave Chinner { 127087e1d789STejun Heo struct bdi_writeback *wb; 1271a66979abSDave Chinner 127287e1d789STejun Heo wb = inode_to_wb_and_lock_list(inode); 1273b35250c0SJan Kara spin_lock(&inode->i_lock); 1274f3b6a6dfSRoman Gushchin 1275f3b6a6dfSRoman Gushchin inode->i_state &= ~I_SYNC_QUEUED; 1276f3b6a6dfSRoman Gushchin list_del_init(&inode->i_io_list); 1277f3b6a6dfSRoman Gushchin wb_io_lists_depopulated(wb); 1278f3b6a6dfSRoman Gushchin 1279b35250c0SJan Kara spin_unlock(&inode->i_lock); 128052ebea74STejun Heo spin_unlock(&wb->list_lock); 1281f758eeabSChristoph Hellwig } 12824301efa4SJan Kara EXPORT_SYMBOL(inode_io_list_del); 1283a66979abSDave Chinner 1284a66979abSDave Chinner /* 12856c60d2b5SDave Chinner * mark an inode as under writeback on the sb 12866c60d2b5SDave Chinner */ 12876c60d2b5SDave Chinner void sb_mark_inode_writeback(struct inode *inode) 12886c60d2b5SDave Chinner { 12896c60d2b5SDave Chinner struct super_block *sb = inode->i_sb; 12906c60d2b5SDave Chinner unsigned long flags; 12916c60d2b5SDave Chinner 12926c60d2b5SDave Chinner if (list_empty(&inode->i_wb_list)) { 12936c60d2b5SDave Chinner spin_lock_irqsave(&sb->s_inode_wblist_lock, flags); 12949a46b04fSBrian Foster if (list_empty(&inode->i_wb_list)) { 12956c60d2b5SDave Chinner list_add_tail(&inode->i_wb_list, &sb->s_inodes_wb); 12969a46b04fSBrian Foster trace_sb_mark_inode_writeback(inode); 12979a46b04fSBrian Foster } 12986c60d2b5SDave Chinner spin_unlock_irqrestore(&sb->s_inode_wblist_lock, flags); 12996c60d2b5SDave Chinner } 13006c60d2b5SDave Chinner } 13016c60d2b5SDave Chinner 13026c60d2b5SDave Chinner /* 13036c60d2b5SDave Chinner * clear an inode as under writeback on the sb 13046c60d2b5SDave Chinner */ 13056c60d2b5SDave Chinner void sb_clear_inode_writeback(struct inode *inode) 13066c60d2b5SDave Chinner { 13076c60d2b5SDave Chinner struct super_block *sb = inode->i_sb; 13086c60d2b5SDave Chinner unsigned long flags; 13096c60d2b5SDave Chinner 13106c60d2b5SDave Chinner if (!list_empty(&inode->i_wb_list)) { 13116c60d2b5SDave Chinner spin_lock_irqsave(&sb->s_inode_wblist_lock, flags); 13129a46b04fSBrian Foster if (!list_empty(&inode->i_wb_list)) { 13136c60d2b5SDave Chinner list_del_init(&inode->i_wb_list); 13149a46b04fSBrian Foster trace_sb_clear_inode_writeback(inode); 13159a46b04fSBrian Foster } 13166c60d2b5SDave Chinner spin_unlock_irqrestore(&sb->s_inode_wblist_lock, flags); 13176c60d2b5SDave Chinner } 13186c60d2b5SDave Chinner } 13196c60d2b5SDave Chinner 13206c60d2b5SDave Chinner /* 13216610a0bcSAndrew Morton * Redirty an inode: set its when-it-was dirtied timestamp and move it to the 13226610a0bcSAndrew Morton * furthest end of its superblock's dirty-inode list. 13236610a0bcSAndrew Morton * 13246610a0bcSAndrew Morton * Before stamping the inode's ->dirtied_when, we check to see whether it is 132566f3b8e2SJens Axboe * already the most-recently-dirtied inode on the b_dirty list. If that is 13266610a0bcSAndrew Morton * the case then the inode must have been redirtied while it was being written 13276610a0bcSAndrew Morton * out and we don't reset its dirtied_when. 13286610a0bcSAndrew Morton */ 1329b35250c0SJan Kara static void redirty_tail_locked(struct inode *inode, struct bdi_writeback *wb) 13306610a0bcSAndrew Morton { 1331b35250c0SJan Kara assert_spin_locked(&inode->i_lock); 1332b35250c0SJan Kara 133303ba3782SJens Axboe if (!list_empty(&wb->b_dirty)) { 133466f3b8e2SJens Axboe struct inode *tail; 13356610a0bcSAndrew Morton 13367ccf19a8SNick Piggin tail = wb_inode(wb->b_dirty.next); 133766f3b8e2SJens Axboe if (time_before(inode->dirtied_when, tail->dirtied_when)) 13386610a0bcSAndrew Morton inode->dirtied_when = jiffies; 13396610a0bcSAndrew Morton } 1340c7f54084SDave Chinner inode_io_list_move_locked(inode, wb, &wb->b_dirty); 13415afced3bSJan Kara inode->i_state &= ~I_SYNC_QUEUED; 13426610a0bcSAndrew Morton } 13436610a0bcSAndrew Morton 1344b35250c0SJan Kara static void redirty_tail(struct inode *inode, struct bdi_writeback *wb) 1345b35250c0SJan Kara { 1346b35250c0SJan Kara spin_lock(&inode->i_lock); 1347b35250c0SJan Kara redirty_tail_locked(inode, wb); 1348b35250c0SJan Kara spin_unlock(&inode->i_lock); 1349b35250c0SJan Kara } 1350b35250c0SJan Kara 13516610a0bcSAndrew Morton /* 135266f3b8e2SJens Axboe * requeue inode for re-scanning after bdi->b_io list is exhausted. 1353c986d1e2SAndrew Morton */ 1354f758eeabSChristoph Hellwig static void requeue_io(struct inode *inode, struct bdi_writeback *wb) 1355c986d1e2SAndrew Morton { 1356c7f54084SDave Chinner inode_io_list_move_locked(inode, wb, &wb->b_more_io); 1357c986d1e2SAndrew Morton } 1358c986d1e2SAndrew Morton 13591c0eeaf5SJoern Engel static void inode_sync_complete(struct inode *inode) 13601c0eeaf5SJoern Engel { 1361365b94aeSJan Kara inode->i_state &= ~I_SYNC; 13624eff96ddSJan Kara /* If inode is clean an unused, put it into LRU now... */ 13634eff96ddSJan Kara inode_add_lru(inode); 1364365b94aeSJan Kara /* Waiters must see I_SYNC cleared before being woken up */ 13651c0eeaf5SJoern Engel smp_mb(); 13661c0eeaf5SJoern Engel wake_up_bit(&inode->i_state, __I_SYNC); 13671c0eeaf5SJoern Engel } 13681c0eeaf5SJoern Engel 1369d2caa3c5SJeff Layton static bool inode_dirtied_after(struct inode *inode, unsigned long t) 1370d2caa3c5SJeff Layton { 1371d2caa3c5SJeff Layton bool ret = time_after(inode->dirtied_when, t); 1372d2caa3c5SJeff Layton #ifndef CONFIG_64BIT 1373d2caa3c5SJeff Layton /* 1374d2caa3c5SJeff Layton * For inodes being constantly redirtied, dirtied_when can get stuck. 1375d2caa3c5SJeff Layton * It _appears_ to be in the future, but is actually in distant past. 1376d2caa3c5SJeff Layton * This test is necessary to prevent such wrapped-around relative times 13775b0830cbSJens Axboe * from permanently stopping the whole bdi writeback. 1378d2caa3c5SJeff Layton */ 1379d2caa3c5SJeff Layton ret = ret && time_before_eq(inode->dirtied_when, jiffies); 1380d2caa3c5SJeff Layton #endif 1381d2caa3c5SJeff Layton return ret; 1382d2caa3c5SJeff Layton } 1383d2caa3c5SJeff Layton 13840ae45f63STheodore Ts'o #define EXPIRE_DIRTY_ATIME 0x0001 13850ae45f63STheodore Ts'o 1386c986d1e2SAndrew Morton /* 1387f9cae926SJan Kara * Move expired (dirtied before dirtied_before) dirty inodes from 1388697e6fedSJan Kara * @delaying_queue to @dispatch_queue. 13892c136579SFengguang Wu */ 1390e84d0a4fSWu Fengguang static int move_expired_inodes(struct list_head *delaying_queue, 13912c136579SFengguang Wu struct list_head *dispatch_queue, 13925fcd5750SJan Kara unsigned long dirtied_before) 13932c136579SFengguang Wu { 13945c03449dSShaohua Li LIST_HEAD(tmp); 13955c03449dSShaohua Li struct list_head *pos, *node; 1396cf137307SJens Axboe struct super_block *sb = NULL; 13975c03449dSShaohua Li struct inode *inode; 1398cf137307SJens Axboe int do_sb_sort = 0; 1399e84d0a4fSWu Fengguang int moved = 0; 14005c03449dSShaohua Li 14012c136579SFengguang Wu while (!list_empty(delaying_queue)) { 14027ccf19a8SNick Piggin inode = wb_inode(delaying_queue->prev); 1403f9cae926SJan Kara if (inode_dirtied_after(inode, dirtied_before)) 14042c136579SFengguang Wu break; 1405c7f54084SDave Chinner list_move(&inode->i_io_list, &tmp); 1406a8855990SJan Kara moved++; 14075afced3bSJan Kara spin_lock(&inode->i_lock); 14085afced3bSJan Kara inode->i_state |= I_SYNC_QUEUED; 14095afced3bSJan Kara spin_unlock(&inode->i_lock); 1410a8855990SJan Kara if (sb_is_blkdev_sb(inode->i_sb)) 1411a8855990SJan Kara continue; 1412cf137307SJens Axboe if (sb && sb != inode->i_sb) 1413cf137307SJens Axboe do_sb_sort = 1; 1414cf137307SJens Axboe sb = inode->i_sb; 14155c03449dSShaohua Li } 14165c03449dSShaohua Li 1417cf137307SJens Axboe /* just one sb in list, splice to dispatch_queue and we're done */ 1418cf137307SJens Axboe if (!do_sb_sort) { 1419cf137307SJens Axboe list_splice(&tmp, dispatch_queue); 1420e84d0a4fSWu Fengguang goto out; 1421cf137307SJens Axboe } 1422cf137307SJens Axboe 14235c03449dSShaohua Li /* Move inodes from one superblock together */ 14245c03449dSShaohua Li while (!list_empty(&tmp)) { 14257ccf19a8SNick Piggin sb = wb_inode(tmp.prev)->i_sb; 14265c03449dSShaohua Li list_for_each_prev_safe(pos, node, &tmp) { 14277ccf19a8SNick Piggin inode = wb_inode(pos); 14285c03449dSShaohua Li if (inode->i_sb == sb) 1429c7f54084SDave Chinner list_move(&inode->i_io_list, dispatch_queue); 14302c136579SFengguang Wu } 14312c136579SFengguang Wu } 1432e84d0a4fSWu Fengguang out: 1433e84d0a4fSWu Fengguang return moved; 14345c03449dSShaohua Li } 14352c136579SFengguang Wu 14362c136579SFengguang Wu /* 14372c136579SFengguang Wu * Queue all expired dirty inodes for io, eldest first. 14384ea879b9SWu Fengguang * Before 14394ea879b9SWu Fengguang * newly dirtied b_dirty b_io b_more_io 14404ea879b9SWu Fengguang * =============> gf edc BA 14414ea879b9SWu Fengguang * After 14424ea879b9SWu Fengguang * newly dirtied b_dirty b_io b_more_io 14434ea879b9SWu Fengguang * =============> g fBAedc 14444ea879b9SWu Fengguang * | 14454ea879b9SWu Fengguang * +--> dequeue for IO 14462c136579SFengguang Wu */ 1447f9cae926SJan Kara static void queue_io(struct bdi_writeback *wb, struct wb_writeback_work *work, 1448f9cae926SJan Kara unsigned long dirtied_before) 14492c136579SFengguang Wu { 1450e84d0a4fSWu Fengguang int moved; 1451f9cae926SJan Kara unsigned long time_expire_jif = dirtied_before; 14520ae45f63STheodore Ts'o 1453f758eeabSChristoph Hellwig assert_spin_locked(&wb->list_lock); 14544ea879b9SWu Fengguang list_splice_init(&wb->b_more_io, &wb->b_io); 14555fcd5750SJan Kara moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, dirtied_before); 1456f9cae926SJan Kara if (!work->for_sync) 1457f9cae926SJan Kara time_expire_jif = jiffies - dirtytime_expire_interval * HZ; 14580ae45f63STheodore Ts'o moved += move_expired_inodes(&wb->b_dirty_time, &wb->b_io, 14595fcd5750SJan Kara time_expire_jif); 1460d6c10f1fSTejun Heo if (moved) 1461d6c10f1fSTejun Heo wb_io_lists_populated(wb); 1462f9cae926SJan Kara trace_writeback_queue_io(wb, work, dirtied_before, moved); 146366f3b8e2SJens Axboe } 146466f3b8e2SJens Axboe 1465a9185b41SChristoph Hellwig static int write_inode(struct inode *inode, struct writeback_control *wbc) 146666f3b8e2SJens Axboe { 14679fb0a7daSTejun Heo int ret; 14689fb0a7daSTejun Heo 14699fb0a7daSTejun Heo if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) { 14709fb0a7daSTejun Heo trace_writeback_write_inode_start(inode, wbc); 14719fb0a7daSTejun Heo ret = inode->i_sb->s_op->write_inode(inode, wbc); 14729fb0a7daSTejun Heo trace_writeback_write_inode(inode, wbc); 14739fb0a7daSTejun Heo return ret; 14749fb0a7daSTejun Heo } 147503ba3782SJens Axboe return 0; 147666f3b8e2SJens Axboe } 147708d8e974SFengguang Wu 14782c136579SFengguang Wu /* 1479169ebd90SJan Kara * Wait for writeback on an inode to complete. Called with i_lock held. 1480169ebd90SJan Kara * Caller must make sure inode cannot go away when we drop i_lock. 148101c03194SChristoph Hellwig */ 1482169ebd90SJan Kara static void __inode_wait_for_writeback(struct inode *inode) 1483169ebd90SJan Kara __releases(inode->i_lock) 1484169ebd90SJan Kara __acquires(inode->i_lock) 148501c03194SChristoph Hellwig { 148601c03194SChristoph Hellwig DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); 148701c03194SChristoph Hellwig wait_queue_head_t *wqh; 148801c03194SChristoph Hellwig 148901c03194SChristoph Hellwig wqh = bit_waitqueue(&inode->i_state, __I_SYNC); 149058a9d3d8SRichard Kennedy while (inode->i_state & I_SYNC) { 1491250df6edSDave Chinner spin_unlock(&inode->i_lock); 149274316201SNeilBrown __wait_on_bit(wqh, &wq, bit_wait, 149374316201SNeilBrown TASK_UNINTERRUPTIBLE); 1494250df6edSDave Chinner spin_lock(&inode->i_lock); 149558a9d3d8SRichard Kennedy } 149601c03194SChristoph Hellwig } 149701c03194SChristoph Hellwig 149801c03194SChristoph Hellwig /* 1499169ebd90SJan Kara * Wait for writeback on an inode to complete. Caller must have inode pinned. 1500169ebd90SJan Kara */ 1501169ebd90SJan Kara void inode_wait_for_writeback(struct inode *inode) 1502169ebd90SJan Kara { 1503169ebd90SJan Kara spin_lock(&inode->i_lock); 1504169ebd90SJan Kara __inode_wait_for_writeback(inode); 1505169ebd90SJan Kara spin_unlock(&inode->i_lock); 1506169ebd90SJan Kara } 1507169ebd90SJan Kara 1508169ebd90SJan Kara /* 1509169ebd90SJan Kara * Sleep until I_SYNC is cleared. This function must be called with i_lock 1510169ebd90SJan Kara * held and drops it. It is aimed for callers not holding any inode reference 1511169ebd90SJan Kara * so once i_lock is dropped, inode can go away. 1512169ebd90SJan Kara */ 1513169ebd90SJan Kara static void inode_sleep_on_writeback(struct inode *inode) 1514169ebd90SJan Kara __releases(inode->i_lock) 1515169ebd90SJan Kara { 1516169ebd90SJan Kara DEFINE_WAIT(wait); 1517169ebd90SJan Kara wait_queue_head_t *wqh = bit_waitqueue(&inode->i_state, __I_SYNC); 1518169ebd90SJan Kara int sleep; 1519169ebd90SJan Kara 1520169ebd90SJan Kara prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); 1521169ebd90SJan Kara sleep = inode->i_state & I_SYNC; 1522169ebd90SJan Kara spin_unlock(&inode->i_lock); 1523169ebd90SJan Kara if (sleep) 1524169ebd90SJan Kara schedule(); 1525169ebd90SJan Kara finish_wait(wqh, &wait); 1526169ebd90SJan Kara } 1527169ebd90SJan Kara 1528169ebd90SJan Kara /* 1529ccb26b5aSJan Kara * Find proper writeback list for the inode depending on its current state and 1530ccb26b5aSJan Kara * possibly also change of its state while we were doing writeback. Here we 1531ccb26b5aSJan Kara * handle things such as livelock prevention or fairness of writeback among 1532ccb26b5aSJan Kara * inodes. This function can be called only by flusher thread - noone else 1533ccb26b5aSJan Kara * processes all inodes in writeback lists and requeueing inodes behind flusher 1534ccb26b5aSJan Kara * thread's back can have unexpected consequences. 1535ccb26b5aSJan Kara */ 1536ccb26b5aSJan Kara static void requeue_inode(struct inode *inode, struct bdi_writeback *wb, 1537ccb26b5aSJan Kara struct writeback_control *wbc) 1538ccb26b5aSJan Kara { 1539ccb26b5aSJan Kara if (inode->i_state & I_FREEING) 1540ccb26b5aSJan Kara return; 1541ccb26b5aSJan Kara 1542ccb26b5aSJan Kara /* 1543ccb26b5aSJan Kara * Sync livelock prevention. Each inode is tagged and synced in one 1544ccb26b5aSJan Kara * shot. If still dirty, it will be redirty_tail()'ed below. Update 1545ccb26b5aSJan Kara * the dirty time to prevent enqueue and sync it again. 1546ccb26b5aSJan Kara */ 1547ccb26b5aSJan Kara if ((inode->i_state & I_DIRTY) && 1548ccb26b5aSJan Kara (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)) 1549ccb26b5aSJan Kara inode->dirtied_when = jiffies; 1550ccb26b5aSJan Kara 15514f8ad655SJan Kara if (wbc->pages_skipped) { 15524f8ad655SJan Kara /* 15534f8ad655SJan Kara * writeback is not making progress due to locked 15544f8ad655SJan Kara * buffers. Skip this inode for now. 15554f8ad655SJan Kara */ 1556b35250c0SJan Kara redirty_tail_locked(inode, wb); 15574f8ad655SJan Kara return; 15584f8ad655SJan Kara } 15594f8ad655SJan Kara 1560ccb26b5aSJan Kara if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) { 1561ccb26b5aSJan Kara /* 1562ccb26b5aSJan Kara * We didn't write back all the pages. nfs_writepages() 1563ccb26b5aSJan Kara * sometimes bales out without doing anything. 1564ccb26b5aSJan Kara */ 1565ccb26b5aSJan Kara if (wbc->nr_to_write <= 0) { 1566ccb26b5aSJan Kara /* Slice used up. Queue for next turn. */ 1567ccb26b5aSJan Kara requeue_io(inode, wb); 1568ccb26b5aSJan Kara } else { 1569ccb26b5aSJan Kara /* 1570ccb26b5aSJan Kara * Writeback blocked by something other than 1571ccb26b5aSJan Kara * congestion. Delay the inode for some time to 1572ccb26b5aSJan Kara * avoid spinning on the CPU (100% iowait) 1573ccb26b5aSJan Kara * retrying writeback of the dirty page/inode 1574ccb26b5aSJan Kara * that cannot be performed immediately. 1575ccb26b5aSJan Kara */ 1576b35250c0SJan Kara redirty_tail_locked(inode, wb); 1577ccb26b5aSJan Kara } 1578ccb26b5aSJan Kara } else if (inode->i_state & I_DIRTY) { 1579ccb26b5aSJan Kara /* 1580ccb26b5aSJan Kara * Filesystems can dirty the inode during writeback operations, 1581ccb26b5aSJan Kara * such as delayed allocation during submission or metadata 1582ccb26b5aSJan Kara * updates after data IO completion. 1583ccb26b5aSJan Kara */ 1584b35250c0SJan Kara redirty_tail_locked(inode, wb); 15850ae45f63STheodore Ts'o } else if (inode->i_state & I_DIRTY_TIME) { 1586a2f48706STheodore Ts'o inode->dirtied_when = jiffies; 1587c7f54084SDave Chinner inode_io_list_move_locked(inode, wb, &wb->b_dirty_time); 15885afced3bSJan Kara inode->i_state &= ~I_SYNC_QUEUED; 1589ccb26b5aSJan Kara } else { 1590ccb26b5aSJan Kara /* The inode is clean. Remove from writeback lists. */ 1591f3b6a6dfSRoman Gushchin inode_cgwb_move_to_attached(inode, wb); 1592ccb26b5aSJan Kara } 1593ccb26b5aSJan Kara } 1594ccb26b5aSJan Kara 1595ccb26b5aSJan Kara /* 1596da0c4c60SEric Biggers * Write out an inode and its dirty pages (or some of its dirty pages, depending 1597da0c4c60SEric Biggers * on @wbc->nr_to_write), and clear the relevant dirty flags from i_state. 1598da0c4c60SEric Biggers * 1599da0c4c60SEric Biggers * This doesn't remove the inode from the writeback list it is on, except 1600da0c4c60SEric Biggers * potentially to move it from b_dirty_time to b_dirty due to timestamp 1601da0c4c60SEric Biggers * expiration. The caller is otherwise responsible for writeback list handling. 1602da0c4c60SEric Biggers * 1603da0c4c60SEric Biggers * The caller is also responsible for setting the I_SYNC flag beforehand and 1604da0c4c60SEric Biggers * calling inode_sync_complete() to clear it afterwards. 16051da177e4SLinus Torvalds */ 16061da177e4SLinus Torvalds static int 1607cd8ed2a4SYan Hong __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) 16081da177e4SLinus Torvalds { 16091da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 1610251d6a47SWu Fengguang long nr_to_write = wbc->nr_to_write; 161101c03194SChristoph Hellwig unsigned dirty; 16121da177e4SLinus Torvalds int ret; 16131da177e4SLinus Torvalds 16144f8ad655SJan Kara WARN_ON(!(inode->i_state & I_SYNC)); 16151da177e4SLinus Torvalds 16169fb0a7daSTejun Heo trace_writeback_single_inode_start(inode, wbc, nr_to_write); 16179fb0a7daSTejun Heo 16181da177e4SLinus Torvalds ret = do_writepages(mapping, wbc); 16191da177e4SLinus Torvalds 162026821ed4SChristoph Hellwig /* 162126821ed4SChristoph Hellwig * Make sure to wait on the data before writing out the metadata. 162226821ed4SChristoph Hellwig * This is important for filesystems that modify metadata on data 16237747bd4bSDave Chinner * I/O completion. We don't do it for sync(2) writeback because it has a 16247747bd4bSDave Chinner * separate, external IO completion path and ->sync_fs for guaranteeing 16257747bd4bSDave Chinner * inode metadata is written back correctly. 162626821ed4SChristoph Hellwig */ 16277747bd4bSDave Chinner if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync) { 162826821ed4SChristoph Hellwig int err = filemap_fdatawait(mapping); 16291da177e4SLinus Torvalds if (ret == 0) 16301da177e4SLinus Torvalds ret = err; 16311da177e4SLinus Torvalds } 16321da177e4SLinus Torvalds 16335547e8aaSDmitry Monakhov /* 16341e249cb5SEric Biggers * If the inode has dirty timestamps and we need to write them, call 16351e249cb5SEric Biggers * mark_inode_dirty_sync() to notify the filesystem about it and to 16361e249cb5SEric Biggers * change I_DIRTY_TIME into I_DIRTY_SYNC. 16371e249cb5SEric Biggers */ 16381e249cb5SEric Biggers if ((inode->i_state & I_DIRTY_TIME) && 163983dc881dSEric Biggers (wbc->sync_mode == WB_SYNC_ALL || 16401e249cb5SEric Biggers time_after(jiffies, inode->dirtied_time_when + 16411e249cb5SEric Biggers dirtytime_expire_interval * HZ))) { 16421e249cb5SEric Biggers trace_writeback_lazytime(inode); 16431e249cb5SEric Biggers mark_inode_dirty_sync(inode); 16441e249cb5SEric Biggers } 16451e249cb5SEric Biggers 16461e249cb5SEric Biggers /* 1647da0c4c60SEric Biggers * Get and clear the dirty flags from i_state. This needs to be done 1648da0c4c60SEric Biggers * after calling writepages because some filesystems may redirty the 1649da0c4c60SEric Biggers * inode during writepages due to delalloc. It also needs to be done 1650da0c4c60SEric Biggers * after handling timestamp expiration, as that may dirty the inode too. 16515547e8aaSDmitry Monakhov */ 1652250df6edSDave Chinner spin_lock(&inode->i_lock); 16535547e8aaSDmitry Monakhov dirty = inode->i_state & I_DIRTY; 16540ae45f63STheodore Ts'o inode->i_state &= ~dirty; 16559c6ac78eSTejun Heo 16569c6ac78eSTejun Heo /* 16579c6ac78eSTejun Heo * Paired with smp_mb() in __mark_inode_dirty(). This allows 16589c6ac78eSTejun Heo * __mark_inode_dirty() to test i_state without grabbing i_lock - 16599c6ac78eSTejun Heo * either they see the I_DIRTY bits cleared or we see the dirtied 16609c6ac78eSTejun Heo * inode. 16619c6ac78eSTejun Heo * 16629c6ac78eSTejun Heo * I_DIRTY_PAGES is always cleared together above even if @mapping 16639c6ac78eSTejun Heo * still has dirty pages. The flag is reinstated after smp_mb() if 16649c6ac78eSTejun Heo * necessary. This guarantees that either __mark_inode_dirty() 16659c6ac78eSTejun Heo * sees clear I_DIRTY_PAGES or we see PAGECACHE_TAG_DIRTY. 16669c6ac78eSTejun Heo */ 16679c6ac78eSTejun Heo smp_mb(); 16689c6ac78eSTejun Heo 16699c6ac78eSTejun Heo if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) 16709c6ac78eSTejun Heo inode->i_state |= I_DIRTY_PAGES; 16719c6ac78eSTejun Heo 1672250df6edSDave Chinner spin_unlock(&inode->i_lock); 16739c6ac78eSTejun Heo 167426821ed4SChristoph Hellwig /* Don't write the inode if only I_DIRTY_PAGES was set */ 16750ae45f63STheodore Ts'o if (dirty & ~I_DIRTY_PAGES) { 1676a9185b41SChristoph Hellwig int err = write_inode(inode, wbc); 16771da177e4SLinus Torvalds if (ret == 0) 16781da177e4SLinus Torvalds ret = err; 16791da177e4SLinus Torvalds } 16804f8ad655SJan Kara trace_writeback_single_inode(inode, wbc, nr_to_write); 16814f8ad655SJan Kara return ret; 16824f8ad655SJan Kara } 16834f8ad655SJan Kara 16844f8ad655SJan Kara /* 1685da0c4c60SEric Biggers * Write out an inode's dirty data and metadata on-demand, i.e. separately from 1686da0c4c60SEric Biggers * the regular batched writeback done by the flusher threads in 1687da0c4c60SEric Biggers * writeback_sb_inodes(). @wbc controls various aspects of the write, such as 1688da0c4c60SEric Biggers * whether it is a data-integrity sync (%WB_SYNC_ALL) or not (%WB_SYNC_NONE). 16894f8ad655SJan Kara * 1690da0c4c60SEric Biggers * To prevent the inode from going away, either the caller must have a reference 1691da0c4c60SEric Biggers * to the inode, or the inode must have I_WILL_FREE or I_FREEING set. 16924f8ad655SJan Kara */ 1693aaf25593STejun Heo static int writeback_single_inode(struct inode *inode, 16944f8ad655SJan Kara struct writeback_control *wbc) 16954f8ad655SJan Kara { 1696aaf25593STejun Heo struct bdi_writeback *wb; 16974f8ad655SJan Kara int ret = 0; 16984f8ad655SJan Kara 16994f8ad655SJan Kara spin_lock(&inode->i_lock); 17004f8ad655SJan Kara if (!atomic_read(&inode->i_count)) 17014f8ad655SJan Kara WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); 17024f8ad655SJan Kara else 17034f8ad655SJan Kara WARN_ON(inode->i_state & I_WILL_FREE); 17044f8ad655SJan Kara 17054f8ad655SJan Kara if (inode->i_state & I_SYNC) { 1706da0c4c60SEric Biggers /* 1707da0c4c60SEric Biggers * Writeback is already running on the inode. For WB_SYNC_NONE, 1708da0c4c60SEric Biggers * that's enough and we can just return. For WB_SYNC_ALL, we 1709da0c4c60SEric Biggers * must wait for the existing writeback to complete, then do 1710da0c4c60SEric Biggers * writeback again if there's anything left. 1711da0c4c60SEric Biggers */ 17124f8ad655SJan Kara if (wbc->sync_mode != WB_SYNC_ALL) 17134f8ad655SJan Kara goto out; 1714169ebd90SJan Kara __inode_wait_for_writeback(inode); 17154f8ad655SJan Kara } 17164f8ad655SJan Kara WARN_ON(inode->i_state & I_SYNC); 17174f8ad655SJan Kara /* 1718da0c4c60SEric Biggers * If the inode is already fully clean, then there's nothing to do. 1719da0c4c60SEric Biggers * 1720da0c4c60SEric Biggers * For data-integrity syncs we also need to check whether any pages are 1721da0c4c60SEric Biggers * still under writeback, e.g. due to prior WB_SYNC_NONE writeback. If 1722da0c4c60SEric Biggers * there are any such pages, we'll need to wait for them. 17234f8ad655SJan Kara */ 17240ae45f63STheodore Ts'o if (!(inode->i_state & I_DIRTY_ALL) && 1725f9b0e058SJan Kara (wbc->sync_mode != WB_SYNC_ALL || 1726f9b0e058SJan Kara !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))) 17274f8ad655SJan Kara goto out; 17284f8ad655SJan Kara inode->i_state |= I_SYNC; 1729b16b1debSTejun Heo wbc_attach_and_unlock_inode(wbc, inode); 17304f8ad655SJan Kara 1731cd8ed2a4SYan Hong ret = __writeback_single_inode(inode, wbc); 17321da177e4SLinus Torvalds 1733b16b1debSTejun Heo wbc_detach_inode(wbc); 1734aaf25593STejun Heo 1735aaf25593STejun Heo wb = inode_to_wb_and_lock_list(inode); 1736250df6edSDave Chinner spin_lock(&inode->i_lock); 17374f8ad655SJan Kara /* 1738da0c4c60SEric Biggers * If the inode is now fully clean, then it can be safely removed from 1739da0c4c60SEric Biggers * its writeback list (if any). Otherwise the flusher threads are 1740da0c4c60SEric Biggers * responsible for the writeback lists. 17414f8ad655SJan Kara */ 17420ae45f63STheodore Ts'o if (!(inode->i_state & I_DIRTY_ALL)) 1743f3b6a6dfSRoman Gushchin inode_cgwb_move_to_attached(inode, wb); 17444f8ad655SJan Kara spin_unlock(&wb->list_lock); 17451c0eeaf5SJoern Engel inode_sync_complete(inode); 17464f8ad655SJan Kara out: 17474f8ad655SJan Kara spin_unlock(&inode->i_lock); 17481da177e4SLinus Torvalds return ret; 17491da177e4SLinus Torvalds } 17501da177e4SLinus Torvalds 1751a88a341aSTejun Heo static long writeback_chunk_size(struct bdi_writeback *wb, 17521a12d8bdSWu Fengguang struct wb_writeback_work *work) 1753d46db3d5SWu Fengguang { 1754d46db3d5SWu Fengguang long pages; 1755d46db3d5SWu Fengguang 1756d46db3d5SWu Fengguang /* 1757d46db3d5SWu Fengguang * WB_SYNC_ALL mode does livelock avoidance by syncing dirty 1758d46db3d5SWu Fengguang * inodes/pages in one big loop. Setting wbc.nr_to_write=LONG_MAX 1759d46db3d5SWu Fengguang * here avoids calling into writeback_inodes_wb() more than once. 1760d46db3d5SWu Fengguang * 1761d46db3d5SWu Fengguang * The intended call sequence for WB_SYNC_ALL writeback is: 1762d46db3d5SWu Fengguang * 1763d46db3d5SWu Fengguang * wb_writeback() 1764d46db3d5SWu Fengguang * writeback_sb_inodes() <== called only once 1765d46db3d5SWu Fengguang * write_cache_pages() <== called once for each inode 1766d46db3d5SWu Fengguang * (quickly) tag currently dirty pages 1767d46db3d5SWu Fengguang * (maybe slowly) sync all tagged pages 1768d46db3d5SWu Fengguang */ 1769d46db3d5SWu Fengguang if (work->sync_mode == WB_SYNC_ALL || work->tagged_writepages) 1770d46db3d5SWu Fengguang pages = LONG_MAX; 17711a12d8bdSWu Fengguang else { 1772a88a341aSTejun Heo pages = min(wb->avg_write_bandwidth / 2, 1773dcc25ae7STejun Heo global_wb_domain.dirty_limit / DIRTY_SCOPE); 17741a12d8bdSWu Fengguang pages = min(pages, work->nr_pages); 17751a12d8bdSWu Fengguang pages = round_down(pages + MIN_WRITEBACK_PAGES, 17761a12d8bdSWu Fengguang MIN_WRITEBACK_PAGES); 17771a12d8bdSWu Fengguang } 1778d46db3d5SWu Fengguang 1779d46db3d5SWu Fengguang return pages; 1780d46db3d5SWu Fengguang } 1781d46db3d5SWu Fengguang 178203ba3782SJens Axboe /* 1783f11c9c5cSEdward Shishkin * Write a portion of b_io inodes which belong to @sb. 1784edadfb10SChristoph Hellwig * 1785d46db3d5SWu Fengguang * Return the number of pages and/or inodes written. 17860ba13fd1SLinus Torvalds * 17870ba13fd1SLinus Torvalds * NOTE! This is called with wb->list_lock held, and will 17880ba13fd1SLinus Torvalds * unlock and relock that for each inode it ends up doing 17890ba13fd1SLinus Torvalds * IO for. 1790f11c9c5cSEdward Shishkin */ 1791d46db3d5SWu Fengguang static long writeback_sb_inodes(struct super_block *sb, 1792d46db3d5SWu Fengguang struct bdi_writeback *wb, 1793d46db3d5SWu Fengguang struct wb_writeback_work *work) 179403ba3782SJens Axboe { 1795d46db3d5SWu Fengguang struct writeback_control wbc = { 1796d46db3d5SWu Fengguang .sync_mode = work->sync_mode, 1797d46db3d5SWu Fengguang .tagged_writepages = work->tagged_writepages, 1798d46db3d5SWu Fengguang .for_kupdate = work->for_kupdate, 1799d46db3d5SWu Fengguang .for_background = work->for_background, 18007747bd4bSDave Chinner .for_sync = work->for_sync, 1801d46db3d5SWu Fengguang .range_cyclic = work->range_cyclic, 1802d46db3d5SWu Fengguang .range_start = 0, 1803d46db3d5SWu Fengguang .range_end = LLONG_MAX, 1804d46db3d5SWu Fengguang }; 1805d46db3d5SWu Fengguang unsigned long start_time = jiffies; 1806d46db3d5SWu Fengguang long write_chunk; 1807d46db3d5SWu Fengguang long wrote = 0; /* count both pages and inodes */ 1808d46db3d5SWu Fengguang 180903ba3782SJens Axboe while (!list_empty(&wb->b_io)) { 18107ccf19a8SNick Piggin struct inode *inode = wb_inode(wb->b_io.prev); 1811aaf25593STejun Heo struct bdi_writeback *tmp_wb; 1812edadfb10SChristoph Hellwig 1813edadfb10SChristoph Hellwig if (inode->i_sb != sb) { 1814d46db3d5SWu Fengguang if (work->sb) { 1815edadfb10SChristoph Hellwig /* 1816edadfb10SChristoph Hellwig * We only want to write back data for this 1817edadfb10SChristoph Hellwig * superblock, move all inodes not belonging 1818edadfb10SChristoph Hellwig * to it back onto the dirty list. 1819edadfb10SChristoph Hellwig */ 1820f758eeabSChristoph Hellwig redirty_tail(inode, wb); 182166f3b8e2SJens Axboe continue; 182266f3b8e2SJens Axboe } 1823edadfb10SChristoph Hellwig 1824edadfb10SChristoph Hellwig /* 1825edadfb10SChristoph Hellwig * The inode belongs to a different superblock. 1826edadfb10SChristoph Hellwig * Bounce back to the caller to unpin this and 1827edadfb10SChristoph Hellwig * pin the next superblock. 1828edadfb10SChristoph Hellwig */ 1829d46db3d5SWu Fengguang break; 1830edadfb10SChristoph Hellwig } 1831edadfb10SChristoph Hellwig 18329843b76aSChristoph Hellwig /* 1833331cbdeeSWanpeng Li * Don't bother with new inodes or inodes being freed, first 1834331cbdeeSWanpeng Li * kind does not need periodic writeout yet, and for the latter 18359843b76aSChristoph Hellwig * kind writeout is handled by the freer. 18369843b76aSChristoph Hellwig */ 1837250df6edSDave Chinner spin_lock(&inode->i_lock); 18389843b76aSChristoph Hellwig if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { 1839b35250c0SJan Kara redirty_tail_locked(inode, wb); 1840250df6edSDave Chinner spin_unlock(&inode->i_lock); 18417ef0d737SNick Piggin continue; 18427ef0d737SNick Piggin } 1843cc1676d9SJan Kara if ((inode->i_state & I_SYNC) && wbc.sync_mode != WB_SYNC_ALL) { 1844cc1676d9SJan Kara /* 1845cc1676d9SJan Kara * If this inode is locked for writeback and we are not 1846cc1676d9SJan Kara * doing writeback-for-data-integrity, move it to 1847cc1676d9SJan Kara * b_more_io so that writeback can proceed with the 1848cc1676d9SJan Kara * other inodes on s_io. 1849cc1676d9SJan Kara * 1850cc1676d9SJan Kara * We'll have another go at writing back this inode 1851cc1676d9SJan Kara * when we completed a full scan of b_io. 1852cc1676d9SJan Kara */ 1853cc1676d9SJan Kara spin_unlock(&inode->i_lock); 1854cc1676d9SJan Kara requeue_io(inode, wb); 1855cc1676d9SJan Kara trace_writeback_sb_inodes_requeue(inode); 1856cc1676d9SJan Kara continue; 1857cc1676d9SJan Kara } 1858f0d07b7fSJan Kara spin_unlock(&wb->list_lock); 1859f0d07b7fSJan Kara 18604f8ad655SJan Kara /* 18614f8ad655SJan Kara * We already requeued the inode if it had I_SYNC set and we 18624f8ad655SJan Kara * are doing WB_SYNC_NONE writeback. So this catches only the 18634f8ad655SJan Kara * WB_SYNC_ALL case. 18644f8ad655SJan Kara */ 1865169ebd90SJan Kara if (inode->i_state & I_SYNC) { 1866169ebd90SJan Kara /* Wait for I_SYNC. This function drops i_lock... */ 1867169ebd90SJan Kara inode_sleep_on_writeback(inode); 1868169ebd90SJan Kara /* Inode may be gone, start again */ 1869ead188f9SJan Kara spin_lock(&wb->list_lock); 1870169ebd90SJan Kara continue; 1871169ebd90SJan Kara } 18724f8ad655SJan Kara inode->i_state |= I_SYNC; 1873b16b1debSTejun Heo wbc_attach_and_unlock_inode(&wbc, inode); 1874169ebd90SJan Kara 1875a88a341aSTejun Heo write_chunk = writeback_chunk_size(wb, work); 1876d46db3d5SWu Fengguang wbc.nr_to_write = write_chunk; 1877d46db3d5SWu Fengguang wbc.pages_skipped = 0; 1878250df6edSDave Chinner 1879169ebd90SJan Kara /* 1880169ebd90SJan Kara * We use I_SYNC to pin the inode in memory. While it is set 1881169ebd90SJan Kara * evict_inode() will wait so the inode cannot be freed. 1882169ebd90SJan Kara */ 1883cd8ed2a4SYan Hong __writeback_single_inode(inode, &wbc); 1884d46db3d5SWu Fengguang 1885b16b1debSTejun Heo wbc_detach_inode(&wbc); 1886d46db3d5SWu Fengguang work->nr_pages -= write_chunk - wbc.nr_to_write; 1887d46db3d5SWu Fengguang wrote += write_chunk - wbc.nr_to_write; 1888590dca3aSChris Mason 1889590dca3aSChris Mason if (need_resched()) { 1890590dca3aSChris Mason /* 1891590dca3aSChris Mason * We're trying to balance between building up a nice 1892590dca3aSChris Mason * long list of IOs to improve our merge rate, and 1893590dca3aSChris Mason * getting those IOs out quickly for anyone throttling 1894590dca3aSChris Mason * in balance_dirty_pages(). cond_resched() doesn't 1895590dca3aSChris Mason * unplug, so get our IOs out the door before we 1896590dca3aSChris Mason * give up the CPU. 1897590dca3aSChris Mason */ 1898590dca3aSChris Mason blk_flush_plug(current); 1899590dca3aSChris Mason cond_resched(); 1900590dca3aSChris Mason } 1901590dca3aSChris Mason 1902aaf25593STejun Heo /* 1903aaf25593STejun Heo * Requeue @inode if still dirty. Be careful as @inode may 1904aaf25593STejun Heo * have been switched to another wb in the meantime. 1905aaf25593STejun Heo */ 1906aaf25593STejun Heo tmp_wb = inode_to_wb_and_lock_list(inode); 19074f8ad655SJan Kara spin_lock(&inode->i_lock); 19080ae45f63STheodore Ts'o if (!(inode->i_state & I_DIRTY_ALL)) 1909d46db3d5SWu Fengguang wrote++; 1910aaf25593STejun Heo requeue_inode(inode, tmp_wb, &wbc); 19114f8ad655SJan Kara inode_sync_complete(inode); 19120f1b1fd8SDave Chinner spin_unlock(&inode->i_lock); 1913590dca3aSChris Mason 1914aaf25593STejun Heo if (unlikely(tmp_wb != wb)) { 1915aaf25593STejun Heo spin_unlock(&tmp_wb->list_lock); 1916aaf25593STejun Heo spin_lock(&wb->list_lock); 1917aaf25593STejun Heo } 1918aaf25593STejun Heo 1919d46db3d5SWu Fengguang /* 1920d46db3d5SWu Fengguang * bail out to wb_writeback() often enough to check 1921d46db3d5SWu Fengguang * background threshold and other termination conditions. 1922d46db3d5SWu Fengguang */ 1923d46db3d5SWu Fengguang if (wrote) { 1924d46db3d5SWu Fengguang if (time_is_before_jiffies(start_time + HZ / 10UL)) 1925d46db3d5SWu Fengguang break; 1926d46db3d5SWu Fengguang if (work->nr_pages <= 0) 1927d46db3d5SWu Fengguang break; 19281da177e4SLinus Torvalds } 19298bc3be27SFengguang Wu } 1930d46db3d5SWu Fengguang return wrote; 1931f11c9c5cSEdward Shishkin } 193238f21977SNick Piggin 1933d46db3d5SWu Fengguang static long __writeback_inodes_wb(struct bdi_writeback *wb, 1934d46db3d5SWu Fengguang struct wb_writeback_work *work) 1935f11c9c5cSEdward Shishkin { 1936d46db3d5SWu Fengguang unsigned long start_time = jiffies; 1937d46db3d5SWu Fengguang long wrote = 0; 1938f11c9c5cSEdward Shishkin 1939f11c9c5cSEdward Shishkin while (!list_empty(&wb->b_io)) { 19407ccf19a8SNick Piggin struct inode *inode = wb_inode(wb->b_io.prev); 1941f11c9c5cSEdward Shishkin struct super_block *sb = inode->i_sb; 1942f11c9c5cSEdward Shishkin 1943eb6ef3dfSKonstantin Khlebnikov if (!trylock_super(sb)) { 19440e995816SWu Fengguang /* 1945eb6ef3dfSKonstantin Khlebnikov * trylock_super() may fail consistently due to 19460e995816SWu Fengguang * s_umount being grabbed by someone else. Don't use 19470e995816SWu Fengguang * requeue_io() to avoid busy retrying the inode/sb. 19480e995816SWu Fengguang */ 19490e995816SWu Fengguang redirty_tail(inode, wb); 1950d19de7edSChristoph Hellwig continue; 1951334132aeSChristoph Hellwig } 1952d46db3d5SWu Fengguang wrote += writeback_sb_inodes(sb, wb, work); 1953eb6ef3dfSKonstantin Khlebnikov up_read(&sb->s_umount); 1954f11c9c5cSEdward Shishkin 1955d46db3d5SWu Fengguang /* refer to the same tests at the end of writeback_sb_inodes */ 1956d46db3d5SWu Fengguang if (wrote) { 1957d46db3d5SWu Fengguang if (time_is_before_jiffies(start_time + HZ / 10UL)) 1958d46db3d5SWu Fengguang break; 1959d46db3d5SWu Fengguang if (work->nr_pages <= 0) 1960f11c9c5cSEdward Shishkin break; 1961f11c9c5cSEdward Shishkin } 1962d46db3d5SWu Fengguang } 196366f3b8e2SJens Axboe /* Leave any unwritten inodes on b_io */ 1964d46db3d5SWu Fengguang return wrote; 196566f3b8e2SJens Axboe } 196666f3b8e2SJens Axboe 19677d9f073bSWanpeng Li static long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, 19680e175a18SCurt Wohlgemuth enum wb_reason reason) 1969edadfb10SChristoph Hellwig { 1970d46db3d5SWu Fengguang struct wb_writeback_work work = { 1971d46db3d5SWu Fengguang .nr_pages = nr_pages, 1972d46db3d5SWu Fengguang .sync_mode = WB_SYNC_NONE, 1973d46db3d5SWu Fengguang .range_cyclic = 1, 19740e175a18SCurt Wohlgemuth .reason = reason, 1975d46db3d5SWu Fengguang }; 1976505a666eSLinus Torvalds struct blk_plug plug; 1977edadfb10SChristoph Hellwig 1978505a666eSLinus Torvalds blk_start_plug(&plug); 1979f758eeabSChristoph Hellwig spin_lock(&wb->list_lock); 1980424b351fSWu Fengguang if (list_empty(&wb->b_io)) 1981f9cae926SJan Kara queue_io(wb, &work, jiffies); 1982d46db3d5SWu Fengguang __writeback_inodes_wb(wb, &work); 1983f758eeabSChristoph Hellwig spin_unlock(&wb->list_lock); 1984505a666eSLinus Torvalds blk_finish_plug(&plug); 1985edadfb10SChristoph Hellwig 1986d46db3d5SWu Fengguang return nr_pages - work.nr_pages; 198766f3b8e2SJens Axboe } 198866f3b8e2SJens Axboe 198903ba3782SJens Axboe /* 199003ba3782SJens Axboe * Explicit flushing or periodic writeback of "old" data. 199103ba3782SJens Axboe * 199203ba3782SJens Axboe * Define "old": the first time one of an inode's pages is dirtied, we mark the 199303ba3782SJens Axboe * dirtying-time in the inode's address_space. So this periodic writeback code 199403ba3782SJens Axboe * just walks the superblock inode list, writing back any inodes which are 199503ba3782SJens Axboe * older than a specific point in time. 199603ba3782SJens Axboe * 199703ba3782SJens Axboe * Try to run once per dirty_writeback_interval. But if a writeback event 199803ba3782SJens Axboe * takes longer than a dirty_writeback_interval interval, then leave a 199903ba3782SJens Axboe * one-second gap. 200003ba3782SJens Axboe * 2001f9cae926SJan Kara * dirtied_before takes precedence over nr_to_write. So we'll only write back 200203ba3782SJens Axboe * all dirty pages if they are all attached to "old" mappings. 200303ba3782SJens Axboe */ 2004c4a77a6cSJens Axboe static long wb_writeback(struct bdi_writeback *wb, 200583ba7b07SChristoph Hellwig struct wb_writeback_work *work) 200603ba3782SJens Axboe { 2007e98be2d5SWu Fengguang unsigned long wb_start = jiffies; 2008d46db3d5SWu Fengguang long nr_pages = work->nr_pages; 2009f9cae926SJan Kara unsigned long dirtied_before = jiffies; 2010a5989bdcSJan Kara struct inode *inode; 2011d46db3d5SWu Fengguang long progress; 2012505a666eSLinus Torvalds struct blk_plug plug; 201303ba3782SJens Axboe 2014505a666eSLinus Torvalds blk_start_plug(&plug); 2015e8dfc305SWu Fengguang spin_lock(&wb->list_lock); 201603ba3782SJens Axboe for (;;) { 201703ba3782SJens Axboe /* 2018d3ddec76SWu Fengguang * Stop writeback when nr_pages has been consumed 201903ba3782SJens Axboe */ 202083ba7b07SChristoph Hellwig if (work->nr_pages <= 0) 202103ba3782SJens Axboe break; 202203ba3782SJens Axboe 202303ba3782SJens Axboe /* 2024aa373cf5SJan Kara * Background writeout and kupdate-style writeback may 2025aa373cf5SJan Kara * run forever. Stop them if there is other work to do 2026aa373cf5SJan Kara * so that e.g. sync can proceed. They'll be restarted 2027aa373cf5SJan Kara * after the other works are all done. 2028aa373cf5SJan Kara */ 2029aa373cf5SJan Kara if ((work->for_background || work->for_kupdate) && 2030f0054bb1STejun Heo !list_empty(&wb->work_list)) 2031aa373cf5SJan Kara break; 2032aa373cf5SJan Kara 2033aa373cf5SJan Kara /* 2034d3ddec76SWu Fengguang * For background writeout, stop when we are below the 2035d3ddec76SWu Fengguang * background dirty threshold 203603ba3782SJens Axboe */ 2037aa661bbeSTejun Heo if (work->for_background && !wb_over_bg_thresh(wb)) 203803ba3782SJens Axboe break; 203903ba3782SJens Axboe 20401bc36b64SJan Kara /* 20411bc36b64SJan Kara * Kupdate and background works are special and we want to 20421bc36b64SJan Kara * include all inodes that need writing. Livelock avoidance is 20431bc36b64SJan Kara * handled by these works yielding to any other work so we are 20441bc36b64SJan Kara * safe. 20451bc36b64SJan Kara */ 2046ba9aa839SWu Fengguang if (work->for_kupdate) { 2047f9cae926SJan Kara dirtied_before = jiffies - 2048ba9aa839SWu Fengguang msecs_to_jiffies(dirty_expire_interval * 10); 20491bc36b64SJan Kara } else if (work->for_background) 2050f9cae926SJan Kara dirtied_before = jiffies; 2051028c2dd1SDave Chinner 20525634cc2aSTejun Heo trace_writeback_start(wb, work); 2053e8dfc305SWu Fengguang if (list_empty(&wb->b_io)) 2054f9cae926SJan Kara queue_io(wb, work, dirtied_before); 205583ba7b07SChristoph Hellwig if (work->sb) 2056d46db3d5SWu Fengguang progress = writeback_sb_inodes(work->sb, wb, work); 2057edadfb10SChristoph Hellwig else 2058d46db3d5SWu Fengguang progress = __writeback_inodes_wb(wb, work); 20595634cc2aSTejun Heo trace_writeback_written(wb, work); 2060028c2dd1SDave Chinner 2061e98be2d5SWu Fengguang wb_update_bandwidth(wb, wb_start); 206203ba3782SJens Axboe 206303ba3782SJens Axboe /* 206471fd05a8SJens Axboe * Did we write something? Try for more 2065e6fb6da2SWu Fengguang * 2066e6fb6da2SWu Fengguang * Dirty inodes are moved to b_io for writeback in batches. 2067e6fb6da2SWu Fengguang * The completion of the current batch does not necessarily 2068e6fb6da2SWu Fengguang * mean the overall work is done. So we keep looping as long 2069e6fb6da2SWu Fengguang * as made some progress on cleaning pages or inodes. 207071fd05a8SJens Axboe */ 2071d46db3d5SWu Fengguang if (progress) 207203ba3782SJens Axboe continue; 2073a5989bdcSJan Kara /* 2074e6fb6da2SWu Fengguang * No more inodes for IO, bail 2075a5989bdcSJan Kara */ 2076b7a2441fSWu Fengguang if (list_empty(&wb->b_more_io)) 207703ba3782SJens Axboe break; 207803ba3782SJens Axboe /* 20798010c3b6SJens Axboe * Nothing written. Wait for some inode to 20808010c3b6SJens Axboe * become available for writeback. Otherwise 20818010c3b6SJens Axboe * we'll just busyloop. 208203ba3782SJens Axboe */ 20835634cc2aSTejun Heo trace_writeback_wait(wb, work); 208403ba3782SJens Axboe inode = wb_inode(wb->b_more_io.prev); 2085250df6edSDave Chinner spin_lock(&inode->i_lock); 2086f0d07b7fSJan Kara spin_unlock(&wb->list_lock); 2087169ebd90SJan Kara /* This function drops i_lock... */ 2088169ebd90SJan Kara inode_sleep_on_writeback(inode); 2089f0d07b7fSJan Kara spin_lock(&wb->list_lock); 209003ba3782SJens Axboe } 2091e8dfc305SWu Fengguang spin_unlock(&wb->list_lock); 2092505a666eSLinus Torvalds blk_finish_plug(&plug); 209303ba3782SJens Axboe 2094d46db3d5SWu Fengguang return nr_pages - work->nr_pages; 209503ba3782SJens Axboe } 209603ba3782SJens Axboe 209703ba3782SJens Axboe /* 209883ba7b07SChristoph Hellwig * Return the next wb_writeback_work struct that hasn't been processed yet. 209903ba3782SJens Axboe */ 2100f0054bb1STejun Heo static struct wb_writeback_work *get_next_work_item(struct bdi_writeback *wb) 210103ba3782SJens Axboe { 210283ba7b07SChristoph Hellwig struct wb_writeback_work *work = NULL; 210303ba3782SJens Axboe 2104f0054bb1STejun Heo spin_lock_bh(&wb->work_lock); 2105f0054bb1STejun Heo if (!list_empty(&wb->work_list)) { 2106f0054bb1STejun Heo work = list_entry(wb->work_list.next, 210783ba7b07SChristoph Hellwig struct wb_writeback_work, list); 210883ba7b07SChristoph Hellwig list_del_init(&work->list); 210903ba3782SJens Axboe } 2110f0054bb1STejun Heo spin_unlock_bh(&wb->work_lock); 211183ba7b07SChristoph Hellwig return work; 211203ba3782SJens Axboe } 211303ba3782SJens Axboe 21146585027aSJan Kara static long wb_check_background_flush(struct bdi_writeback *wb) 21156585027aSJan Kara { 2116aa661bbeSTejun Heo if (wb_over_bg_thresh(wb)) { 21176585027aSJan Kara 21186585027aSJan Kara struct wb_writeback_work work = { 21196585027aSJan Kara .nr_pages = LONG_MAX, 21206585027aSJan Kara .sync_mode = WB_SYNC_NONE, 21216585027aSJan Kara .for_background = 1, 21226585027aSJan Kara .range_cyclic = 1, 21230e175a18SCurt Wohlgemuth .reason = WB_REASON_BACKGROUND, 21246585027aSJan Kara }; 21256585027aSJan Kara 21266585027aSJan Kara return wb_writeback(wb, &work); 21276585027aSJan Kara } 21286585027aSJan Kara 21296585027aSJan Kara return 0; 21306585027aSJan Kara } 21316585027aSJan Kara 213203ba3782SJens Axboe static long wb_check_old_data_flush(struct bdi_writeback *wb) 213303ba3782SJens Axboe { 213403ba3782SJens Axboe unsigned long expired; 213503ba3782SJens Axboe long nr_pages; 213603ba3782SJens Axboe 213769b62d01SJens Axboe /* 213869b62d01SJens Axboe * When set to zero, disable periodic writeback 213969b62d01SJens Axboe */ 214069b62d01SJens Axboe if (!dirty_writeback_interval) 214169b62d01SJens Axboe return 0; 214269b62d01SJens Axboe 214303ba3782SJens Axboe expired = wb->last_old_flush + 214403ba3782SJens Axboe msecs_to_jiffies(dirty_writeback_interval * 10); 214503ba3782SJens Axboe if (time_before(jiffies, expired)) 214603ba3782SJens Axboe return 0; 214703ba3782SJens Axboe 214803ba3782SJens Axboe wb->last_old_flush = jiffies; 2149cdf01dd5SLinus Torvalds nr_pages = get_nr_dirty_pages(); 215003ba3782SJens Axboe 2151c4a77a6cSJens Axboe if (nr_pages) { 215283ba7b07SChristoph Hellwig struct wb_writeback_work work = { 2153c4a77a6cSJens Axboe .nr_pages = nr_pages, 2154c4a77a6cSJens Axboe .sync_mode = WB_SYNC_NONE, 2155c4a77a6cSJens Axboe .for_kupdate = 1, 2156c4a77a6cSJens Axboe .range_cyclic = 1, 21570e175a18SCurt Wohlgemuth .reason = WB_REASON_PERIODIC, 2158c4a77a6cSJens Axboe }; 2159c4a77a6cSJens Axboe 216083ba7b07SChristoph Hellwig return wb_writeback(wb, &work); 2161c4a77a6cSJens Axboe } 216203ba3782SJens Axboe 216303ba3782SJens Axboe return 0; 216403ba3782SJens Axboe } 216503ba3782SJens Axboe 216685009b4fSJens Axboe static long wb_check_start_all(struct bdi_writeback *wb) 216785009b4fSJens Axboe { 216885009b4fSJens Axboe long nr_pages; 216985009b4fSJens Axboe 217085009b4fSJens Axboe if (!test_bit(WB_start_all, &wb->state)) 217185009b4fSJens Axboe return 0; 217285009b4fSJens Axboe 217385009b4fSJens Axboe nr_pages = get_nr_dirty_pages(); 217485009b4fSJens Axboe if (nr_pages) { 217585009b4fSJens Axboe struct wb_writeback_work work = { 217685009b4fSJens Axboe .nr_pages = wb_split_bdi_pages(wb, nr_pages), 217785009b4fSJens Axboe .sync_mode = WB_SYNC_NONE, 217885009b4fSJens Axboe .range_cyclic = 1, 217985009b4fSJens Axboe .reason = wb->start_all_reason, 218085009b4fSJens Axboe }; 218185009b4fSJens Axboe 218285009b4fSJens Axboe nr_pages = wb_writeback(wb, &work); 218385009b4fSJens Axboe } 218485009b4fSJens Axboe 218585009b4fSJens Axboe clear_bit(WB_start_all, &wb->state); 218685009b4fSJens Axboe return nr_pages; 218785009b4fSJens Axboe } 218885009b4fSJens Axboe 218985009b4fSJens Axboe 219003ba3782SJens Axboe /* 219103ba3782SJens Axboe * Retrieve work items and do the writeback they describe 219203ba3782SJens Axboe */ 219325d130baSWanpeng Li static long wb_do_writeback(struct bdi_writeback *wb) 219403ba3782SJens Axboe { 219583ba7b07SChristoph Hellwig struct wb_writeback_work *work; 2196c4a77a6cSJens Axboe long wrote = 0; 219703ba3782SJens Axboe 21984452226eSTejun Heo set_bit(WB_writeback_running, &wb->state); 2199f0054bb1STejun Heo while ((work = get_next_work_item(wb)) != NULL) { 22005634cc2aSTejun Heo trace_writeback_exec(wb, work); 220183ba7b07SChristoph Hellwig wrote += wb_writeback(wb, work); 22024a3a485bSTahsin Erdogan finish_writeback_work(wb, work); 220303ba3782SJens Axboe } 220403ba3782SJens Axboe 220503ba3782SJens Axboe /* 220685009b4fSJens Axboe * Check for a flush-everything request 220785009b4fSJens Axboe */ 220885009b4fSJens Axboe wrote += wb_check_start_all(wb); 220985009b4fSJens Axboe 221085009b4fSJens Axboe /* 221103ba3782SJens Axboe * Check for periodic writeback, kupdated() style 221203ba3782SJens Axboe */ 221303ba3782SJens Axboe wrote += wb_check_old_data_flush(wb); 22146585027aSJan Kara wrote += wb_check_background_flush(wb); 22154452226eSTejun Heo clear_bit(WB_writeback_running, &wb->state); 221603ba3782SJens Axboe 221703ba3782SJens Axboe return wrote; 221803ba3782SJens Axboe } 221903ba3782SJens Axboe 222003ba3782SJens Axboe /* 222103ba3782SJens Axboe * Handle writeback of dirty data for the device backed by this bdi. Also 2222839a8e86STejun Heo * reschedules periodically and does kupdated style flushing. 222303ba3782SJens Axboe */ 2224f0054bb1STejun Heo void wb_workfn(struct work_struct *work) 222503ba3782SJens Axboe { 2226839a8e86STejun Heo struct bdi_writeback *wb = container_of(to_delayed_work(work), 2227839a8e86STejun Heo struct bdi_writeback, dwork); 222803ba3782SJens Axboe long pages_written; 222903ba3782SJens Axboe 223068f23b89STheodore Ts'o set_worker_desc("flush-%s", bdi_dev_name(wb->bdi)); 2231766f9164SPeter Zijlstra current->flags |= PF_SWAPWRITE; 223203ba3782SJens Axboe 2233839a8e86STejun Heo if (likely(!current_is_workqueue_rescuer() || 22344452226eSTejun Heo !test_bit(WB_registered, &wb->state))) { 223503ba3782SJens Axboe /* 2236f0054bb1STejun Heo * The normal path. Keep writing back @wb until its 2237839a8e86STejun Heo * work_list is empty. Note that this path is also taken 2238f0054bb1STejun Heo * if @wb is shutting down even when we're running off the 2239839a8e86STejun Heo * rescuer as work_list needs to be drained. 224003ba3782SJens Axboe */ 2241839a8e86STejun Heo do { 224225d130baSWanpeng Li pages_written = wb_do_writeback(wb); 2243455b2864SDave Chinner trace_writeback_pages_written(pages_written); 2244f0054bb1STejun Heo } while (!list_empty(&wb->work_list)); 2245839a8e86STejun Heo } else { 2246253c34e9SArtem Bityutskiy /* 2247839a8e86STejun Heo * bdi_wq can't get enough workers and we're running off 2248839a8e86STejun Heo * the emergency worker. Don't hog it. Hopefully, 1024 is 2249839a8e86STejun Heo * enough for efficient IO. 2250253c34e9SArtem Bityutskiy */ 2251f0054bb1STejun Heo pages_written = writeback_inodes_wb(wb, 1024, 2252839a8e86STejun Heo WB_REASON_FORKER_THREAD); 2253839a8e86STejun Heo trace_writeback_pages_written(pages_written); 225403ba3782SJens Axboe } 225503ba3782SJens Axboe 2256f0054bb1STejun Heo if (!list_empty(&wb->work_list)) 2257b8b78495SJan Kara wb_wakeup(wb); 22586ca738d6SDerek Basehore else if (wb_has_dirty_io(wb) && dirty_writeback_interval) 2259f0054bb1STejun Heo wb_wakeup_delayed(wb); 2260455b2864SDave Chinner 2261839a8e86STejun Heo current->flags &= ~PF_SWAPWRITE; 226203ba3782SJens Axboe } 226303ba3782SJens Axboe 226403ba3782SJens Axboe /* 2265595043e5SJens Axboe * Start writeback of `nr_pages' pages on this bdi. If `nr_pages' is zero, 2266595043e5SJens Axboe * write back the whole world. 2267595043e5SJens Axboe */ 2268595043e5SJens Axboe static void __wakeup_flusher_threads_bdi(struct backing_dev_info *bdi, 2269e8e8a0c6SJens Axboe enum wb_reason reason) 2270595043e5SJens Axboe { 2271595043e5SJens Axboe struct bdi_writeback *wb; 2272595043e5SJens Axboe 2273595043e5SJens Axboe if (!bdi_has_dirty_io(bdi)) 2274595043e5SJens Axboe return; 2275595043e5SJens Axboe 2276595043e5SJens Axboe list_for_each_entry_rcu(wb, &bdi->wb_list, bdi_node) 2277e8e8a0c6SJens Axboe wb_start_writeback(wb, reason); 2278595043e5SJens Axboe } 2279595043e5SJens Axboe 2280595043e5SJens Axboe void wakeup_flusher_threads_bdi(struct backing_dev_info *bdi, 2281595043e5SJens Axboe enum wb_reason reason) 2282595043e5SJens Axboe { 2283595043e5SJens Axboe rcu_read_lock(); 2284e8e8a0c6SJens Axboe __wakeup_flusher_threads_bdi(bdi, reason); 2285595043e5SJens Axboe rcu_read_unlock(); 2286595043e5SJens Axboe } 2287595043e5SJens Axboe 2288595043e5SJens Axboe /* 22899ba4b2dfSJens Axboe * Wakeup the flusher threads to start writeback of all currently dirty pages 229003ba3782SJens Axboe */ 22919ba4b2dfSJens Axboe void wakeup_flusher_threads(enum wb_reason reason) 229203ba3782SJens Axboe { 2293b8c2f347SChristoph Hellwig struct backing_dev_info *bdi; 2294b8c2f347SChristoph Hellwig 229551350ea0SKonstantin Khlebnikov /* 229651350ea0SKonstantin Khlebnikov * If we are expecting writeback progress we must submit plugged IO. 229751350ea0SKonstantin Khlebnikov */ 229851350ea0SKonstantin Khlebnikov if (blk_needs_flush_plug(current)) 229951350ea0SKonstantin Khlebnikov blk_schedule_flush_plug(current); 230051350ea0SKonstantin Khlebnikov 2301b8c2f347SChristoph Hellwig rcu_read_lock(); 2302595043e5SJens Axboe list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) 2303e8e8a0c6SJens Axboe __wakeup_flusher_threads_bdi(bdi, reason); 2304b8c2f347SChristoph Hellwig rcu_read_unlock(); 230503ba3782SJens Axboe } 230603ba3782SJens Axboe 2307a2f48706STheodore Ts'o /* 2308a2f48706STheodore Ts'o * Wake up bdi's periodically to make sure dirtytime inodes gets 2309a2f48706STheodore Ts'o * written back periodically. We deliberately do *not* check the 2310a2f48706STheodore Ts'o * b_dirtytime list in wb_has_dirty_io(), since this would cause the 2311a2f48706STheodore Ts'o * kernel to be constantly waking up once there are any dirtytime 2312a2f48706STheodore Ts'o * inodes on the system. So instead we define a separate delayed work 2313a2f48706STheodore Ts'o * function which gets called much more rarely. (By default, only 2314a2f48706STheodore Ts'o * once every 12 hours.) 2315a2f48706STheodore Ts'o * 2316a2f48706STheodore Ts'o * If there is any other write activity going on in the file system, 2317a2f48706STheodore Ts'o * this function won't be necessary. But if the only thing that has 2318a2f48706STheodore Ts'o * happened on the file system is a dirtytime inode caused by an atime 2319a2f48706STheodore Ts'o * update, we need this infrastructure below to make sure that inode 2320a2f48706STheodore Ts'o * eventually gets pushed out to disk. 2321a2f48706STheodore Ts'o */ 2322a2f48706STheodore Ts'o static void wakeup_dirtytime_writeback(struct work_struct *w); 2323a2f48706STheodore Ts'o static DECLARE_DELAYED_WORK(dirtytime_work, wakeup_dirtytime_writeback); 2324a2f48706STheodore Ts'o 2325a2f48706STheodore Ts'o static void wakeup_dirtytime_writeback(struct work_struct *w) 2326a2f48706STheodore Ts'o { 2327a2f48706STheodore Ts'o struct backing_dev_info *bdi; 2328a2f48706STheodore Ts'o 2329a2f48706STheodore Ts'o rcu_read_lock(); 2330a2f48706STheodore Ts'o list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { 2331001fe6f6STejun Heo struct bdi_writeback *wb; 2332001fe6f6STejun Heo 2333b817525aSTejun Heo list_for_each_entry_rcu(wb, &bdi->wb_list, bdi_node) 23346fdf860fSTejun Heo if (!list_empty(&wb->b_dirty_time)) 23356fdf860fSTejun Heo wb_wakeup(wb); 2336a2f48706STheodore Ts'o } 2337a2f48706STheodore Ts'o rcu_read_unlock(); 2338a2f48706STheodore Ts'o schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ); 2339a2f48706STheodore Ts'o } 2340a2f48706STheodore Ts'o 2341a2f48706STheodore Ts'o static int __init start_dirtytime_writeback(void) 2342a2f48706STheodore Ts'o { 2343a2f48706STheodore Ts'o schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ); 2344a2f48706STheodore Ts'o return 0; 2345a2f48706STheodore Ts'o } 2346a2f48706STheodore Ts'o __initcall(start_dirtytime_writeback); 2347a2f48706STheodore Ts'o 23481efff914STheodore Ts'o int dirtytime_interval_handler(struct ctl_table *table, int write, 23499ca48e20STobias Klauser void *buffer, size_t *lenp, loff_t *ppos) 23501efff914STheodore Ts'o { 23511efff914STheodore Ts'o int ret; 23521efff914STheodore Ts'o 23531efff914STheodore Ts'o ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); 23541efff914STheodore Ts'o if (ret == 0 && write) 23551efff914STheodore Ts'o mod_delayed_work(system_wq, &dirtytime_work, 0); 23561efff914STheodore Ts'o return ret; 23571efff914STheodore Ts'o } 23581efff914STheodore Ts'o 235903ba3782SJens Axboe /** 236035d14f27SEric Biggers * __mark_inode_dirty - internal function to mark an inode dirty 23610117d427SMauro Carvalho Chehab * 236203ba3782SJens Axboe * @inode: inode to mark 236335d14f27SEric Biggers * @flags: what kind of dirty, e.g. I_DIRTY_SYNC. This can be a combination of 236435d14f27SEric Biggers * multiple I_DIRTY_* flags, except that I_DIRTY_TIME can't be combined 236535d14f27SEric Biggers * with I_DIRTY_PAGES. 23660117d427SMauro Carvalho Chehab * 236735d14f27SEric Biggers * Mark an inode as dirty. We notify the filesystem, then update the inode's 236835d14f27SEric Biggers * dirty flags. Then, if needed we add the inode to the appropriate dirty list. 236903ba3782SJens Axboe * 237035d14f27SEric Biggers * Most callers should use mark_inode_dirty() or mark_inode_dirty_sync() 237135d14f27SEric Biggers * instead of calling this directly. 237203ba3782SJens Axboe * 237335d14f27SEric Biggers * CAREFUL! We only add the inode to the dirty list if it is hashed or if it 237435d14f27SEric Biggers * refers to a blockdev. Unhashed inodes will never be added to the dirty list 237535d14f27SEric Biggers * even if they are later hashed, as they will have been marked dirty already. 237603ba3782SJens Axboe * 237735d14f27SEric Biggers * In short, ensure you hash any inodes _before_ you start marking them dirty. 237803ba3782SJens Axboe * 237903ba3782SJens Axboe * Note that for blockdevs, inode->dirtied_when represents the dirtying time of 238003ba3782SJens Axboe * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of 238103ba3782SJens Axboe * the kernel-internal blockdev inode represents the dirtying time of the 238203ba3782SJens Axboe * blockdev's pages. This is why for I_DIRTY_PAGES we always use 238303ba3782SJens Axboe * page->mapping->host, so the page-dirtying time is recorded in the internal 238403ba3782SJens Axboe * blockdev inode. 238503ba3782SJens Axboe */ 238603ba3782SJens Axboe void __mark_inode_dirty(struct inode *inode, int flags) 238703ba3782SJens Axboe { 238803ba3782SJens Axboe struct super_block *sb = inode->i_sb; 238935d14f27SEric Biggers int dirtytime = 0; 23900ae45f63STheodore Ts'o 23910ae45f63STheodore Ts'o trace_writeback_mark_inode_dirty(inode, flags); 239203ba3782SJens Axboe 2393e2728c56SEric Biggers if (flags & I_DIRTY_INODE) { 239435d14f27SEric Biggers /* 239535d14f27SEric Biggers * Notify the filesystem about the inode being dirtied, so that 239635d14f27SEric Biggers * (if needed) it can update on-disk fields and journal the 239735d14f27SEric Biggers * inode. This is only needed when the inode itself is being 239835d14f27SEric Biggers * dirtied now. I.e. it's only needed for I_DIRTY_INODE, not 239935d14f27SEric Biggers * for just I_DIRTY_PAGES or I_DIRTY_TIME. 240035d14f27SEric Biggers */ 24019fb0a7daSTejun Heo trace_writeback_dirty_inode_start(inode, flags); 240203ba3782SJens Axboe if (sb->s_op->dirty_inode) 2403a38ed483SEric Biggers sb->s_op->dirty_inode(inode, flags & I_DIRTY_INODE); 24049fb0a7daSTejun Heo trace_writeback_dirty_inode(inode, flags); 2405e2728c56SEric Biggers 240635d14f27SEric Biggers /* I_DIRTY_INODE supersedes I_DIRTY_TIME. */ 24070ae45f63STheodore Ts'o flags &= ~I_DIRTY_TIME; 240835d14f27SEric Biggers } else { 240935d14f27SEric Biggers /* 241035d14f27SEric Biggers * Else it's either I_DIRTY_PAGES, I_DIRTY_TIME, or nothing. 241135d14f27SEric Biggers * (We don't support setting both I_DIRTY_PAGES and I_DIRTY_TIME 241235d14f27SEric Biggers * in one call to __mark_inode_dirty().) 241335d14f27SEric Biggers */ 24140ae45f63STheodore Ts'o dirtytime = flags & I_DIRTY_TIME; 241535d14f27SEric Biggers WARN_ON_ONCE(dirtytime && flags != I_DIRTY_TIME); 241635d14f27SEric Biggers } 241703ba3782SJens Axboe 241803ba3782SJens Axboe /* 24199c6ac78eSTejun Heo * Paired with smp_mb() in __writeback_single_inode() for the 24209c6ac78eSTejun Heo * following lockless i_state test. See there for details. 242103ba3782SJens Axboe */ 242203ba3782SJens Axboe smp_mb(); 242303ba3782SJens Axboe 24240ae45f63STheodore Ts'o if (((inode->i_state & flags) == flags) || 24250ae45f63STheodore Ts'o (dirtytime && (inode->i_state & I_DIRTY_INODE))) 242603ba3782SJens Axboe return; 242703ba3782SJens Axboe 2428250df6edSDave Chinner spin_lock(&inode->i_lock); 24290ae45f63STheodore Ts'o if (dirtytime && (inode->i_state & I_DIRTY_INODE)) 24300ae45f63STheodore Ts'o goto out_unlock_inode; 243103ba3782SJens Axboe if ((inode->i_state & flags) != flags) { 243203ba3782SJens Axboe const int was_dirty = inode->i_state & I_DIRTY; 243303ba3782SJens Axboe 243452ebea74STejun Heo inode_attach_wb(inode, NULL); 243552ebea74STejun Heo 243635d14f27SEric Biggers /* I_DIRTY_INODE supersedes I_DIRTY_TIME. */ 24370ae45f63STheodore Ts'o if (flags & I_DIRTY_INODE) 24380ae45f63STheodore Ts'o inode->i_state &= ~I_DIRTY_TIME; 243903ba3782SJens Axboe inode->i_state |= flags; 244003ba3782SJens Axboe 244103ba3782SJens Axboe /* 24425afced3bSJan Kara * If the inode is queued for writeback by flush worker, just 24435afced3bSJan Kara * update its dirty state. Once the flush worker is done with 24445afced3bSJan Kara * the inode it will place it on the appropriate superblock 24455afced3bSJan Kara * list, based upon its state. 244603ba3782SJens Axboe */ 24475afced3bSJan Kara if (inode->i_state & I_SYNC_QUEUED) 2448250df6edSDave Chinner goto out_unlock_inode; 244903ba3782SJens Axboe 245003ba3782SJens Axboe /* 245103ba3782SJens Axboe * Only add valid (hashed) inodes to the superblock's 245203ba3782SJens Axboe * dirty list. Add blockdev inodes as well. 245303ba3782SJens Axboe */ 245403ba3782SJens Axboe if (!S_ISBLK(inode->i_mode)) { 24551d3382cbSAl Viro if (inode_unhashed(inode)) 2456250df6edSDave Chinner goto out_unlock_inode; 245703ba3782SJens Axboe } 2458a4ffdde6SAl Viro if (inode->i_state & I_FREEING) 2459250df6edSDave Chinner goto out_unlock_inode; 246003ba3782SJens Axboe 246103ba3782SJens Axboe /* 246203ba3782SJens Axboe * If the inode was already on b_dirty/b_io/b_more_io, don't 246303ba3782SJens Axboe * reposition it (that would break b_dirty time-ordering). 246403ba3782SJens Axboe */ 246503ba3782SJens Axboe if (!was_dirty) { 246687e1d789STejun Heo struct bdi_writeback *wb; 2467d6c10f1fSTejun Heo struct list_head *dirty_list; 2468a66979abSDave Chinner bool wakeup_bdi = false; 2469500b067cSJens Axboe 247087e1d789STejun Heo wb = locked_inode_to_wb_and_lock_list(inode); 2471253c34e9SArtem Bityutskiy 247203ba3782SJens Axboe inode->dirtied_when = jiffies; 2473a2f48706STheodore Ts'o if (dirtytime) 2474a2f48706STheodore Ts'o inode->dirtied_time_when = jiffies; 2475d6c10f1fSTejun Heo 24760e11f644SChristoph Hellwig if (inode->i_state & I_DIRTY) 24770747259dSTejun Heo dirty_list = &wb->b_dirty; 2478a2f48706STheodore Ts'o else 24790747259dSTejun Heo dirty_list = &wb->b_dirty_time; 2480d6c10f1fSTejun Heo 2481c7f54084SDave Chinner wakeup_bdi = inode_io_list_move_locked(inode, wb, 2482d6c10f1fSTejun Heo dirty_list); 2483d6c10f1fSTejun Heo 24840747259dSTejun Heo spin_unlock(&wb->list_lock); 24850ae45f63STheodore Ts'o trace_writeback_dirty_inode_enqueue(inode); 2486253c34e9SArtem Bityutskiy 2487d6c10f1fSTejun Heo /* 2488d6c10f1fSTejun Heo * If this is the first dirty inode for this bdi, 2489d6c10f1fSTejun Heo * we have to wake-up the corresponding bdi thread 2490d6c10f1fSTejun Heo * to make sure background write-back happens 2491d6c10f1fSTejun Heo * later. 2492d6c10f1fSTejun Heo */ 2493f56753acSChristoph Hellwig if (wakeup_bdi && 2494f56753acSChristoph Hellwig (wb->bdi->capabilities & BDI_CAP_WRITEBACK)) 24950747259dSTejun Heo wb_wakeup_delayed(wb); 2496a66979abSDave Chinner return; 2497a66979abSDave Chinner } 2498a66979abSDave Chinner } 2499a66979abSDave Chinner out_unlock_inode: 2500a66979abSDave Chinner spin_unlock(&inode->i_lock); 250103ba3782SJens Axboe } 250203ba3782SJens Axboe EXPORT_SYMBOL(__mark_inode_dirty); 250303ba3782SJens Axboe 2504e97fedb9SDave Chinner /* 2505e97fedb9SDave Chinner * The @s_sync_lock is used to serialise concurrent sync operations 2506e97fedb9SDave Chinner * to avoid lock contention problems with concurrent wait_sb_inodes() calls. 2507e97fedb9SDave Chinner * Concurrent callers will block on the s_sync_lock rather than doing contending 2508e97fedb9SDave Chinner * walks. The queueing maintains sync(2) required behaviour as all the IO that 2509e97fedb9SDave Chinner * has been issued up to the time this function is enter is guaranteed to be 2510e97fedb9SDave Chinner * completed by the time we have gained the lock and waited for all IO that is 2511e97fedb9SDave Chinner * in progress regardless of the order callers are granted the lock. 2512e97fedb9SDave Chinner */ 2513b6e51316SJens Axboe static void wait_sb_inodes(struct super_block *sb) 251466f3b8e2SJens Axboe { 25156c60d2b5SDave Chinner LIST_HEAD(sync_list); 251638f21977SNick Piggin 251703ba3782SJens Axboe /* 251803ba3782SJens Axboe * We need to be protected against the filesystem going from 251903ba3782SJens Axboe * r/o to r/w or vice versa. 252003ba3782SJens Axboe */ 2521b6e51316SJens Axboe WARN_ON(!rwsem_is_locked(&sb->s_umount)); 252203ba3782SJens Axboe 2523e97fedb9SDave Chinner mutex_lock(&sb->s_sync_lock); 252466f3b8e2SJens Axboe 252538f21977SNick Piggin /* 25266c60d2b5SDave Chinner * Splice the writeback list onto a temporary list to avoid waiting on 25276c60d2b5SDave Chinner * inodes that have started writeback after this point. 25286c60d2b5SDave Chinner * 25296c60d2b5SDave Chinner * Use rcu_read_lock() to keep the inodes around until we have a 25306c60d2b5SDave Chinner * reference. s_inode_wblist_lock protects sb->s_inodes_wb as well as 25316c60d2b5SDave Chinner * the local list because inodes can be dropped from either by writeback 25326c60d2b5SDave Chinner * completion. 253338f21977SNick Piggin */ 25346c60d2b5SDave Chinner rcu_read_lock(); 25356c60d2b5SDave Chinner spin_lock_irq(&sb->s_inode_wblist_lock); 25366c60d2b5SDave Chinner list_splice_init(&sb->s_inodes_wb, &sync_list); 25376c60d2b5SDave Chinner 25386c60d2b5SDave Chinner /* 25396c60d2b5SDave Chinner * Data integrity sync. Must wait for all pages under writeback, because 25406c60d2b5SDave Chinner * there may have been pages dirtied before our sync call, but which had 25416c60d2b5SDave Chinner * writeout started before we write it out. In which case, the inode 25426c60d2b5SDave Chinner * may not be on the dirty list, but we still have to wait for that 25436c60d2b5SDave Chinner * writeout. 25446c60d2b5SDave Chinner */ 25456c60d2b5SDave Chinner while (!list_empty(&sync_list)) { 25466c60d2b5SDave Chinner struct inode *inode = list_first_entry(&sync_list, struct inode, 25476c60d2b5SDave Chinner i_wb_list); 2548250df6edSDave Chinner struct address_space *mapping = inode->i_mapping; 254938f21977SNick Piggin 25506c60d2b5SDave Chinner /* 25516c60d2b5SDave Chinner * Move each inode back to the wb list before we drop the lock 25526c60d2b5SDave Chinner * to preserve consistency between i_wb_list and the mapping 25536c60d2b5SDave Chinner * writeback tag. Writeback completion is responsible to remove 25546c60d2b5SDave Chinner * the inode from either list once the writeback tag is cleared. 25556c60d2b5SDave Chinner */ 25566c60d2b5SDave Chinner list_move_tail(&inode->i_wb_list, &sb->s_inodes_wb); 25576c60d2b5SDave Chinner 25586c60d2b5SDave Chinner /* 25596c60d2b5SDave Chinner * The mapping can appear untagged while still on-list since we 25606c60d2b5SDave Chinner * do not have the mapping lock. Skip it here, wb completion 25616c60d2b5SDave Chinner * will remove it. 25626c60d2b5SDave Chinner */ 25636c60d2b5SDave Chinner if (!mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK)) 25646c60d2b5SDave Chinner continue; 25656c60d2b5SDave Chinner 25666c60d2b5SDave Chinner spin_unlock_irq(&sb->s_inode_wblist_lock); 25676c60d2b5SDave Chinner 2568250df6edSDave Chinner spin_lock(&inode->i_lock); 25696c60d2b5SDave Chinner if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) { 2570250df6edSDave Chinner spin_unlock(&inode->i_lock); 25716c60d2b5SDave Chinner 25726c60d2b5SDave Chinner spin_lock_irq(&sb->s_inode_wblist_lock); 257338f21977SNick Piggin continue; 2574250df6edSDave Chinner } 257538f21977SNick Piggin __iget(inode); 2576250df6edSDave Chinner spin_unlock(&inode->i_lock); 25776c60d2b5SDave Chinner rcu_read_unlock(); 257838f21977SNick Piggin 2579aa750fd7SJunichi Nomura /* 2580aa750fd7SJunichi Nomura * We keep the error status of individual mapping so that 2581aa750fd7SJunichi Nomura * applications can catch the writeback error using fsync(2). 2582aa750fd7SJunichi Nomura * See filemap_fdatawait_keep_errors() for details. 2583aa750fd7SJunichi Nomura */ 2584aa750fd7SJunichi Nomura filemap_fdatawait_keep_errors(mapping); 258538f21977SNick Piggin 258638f21977SNick Piggin cond_resched(); 258738f21977SNick Piggin 25886c60d2b5SDave Chinner iput(inode); 25896c60d2b5SDave Chinner 25906c60d2b5SDave Chinner rcu_read_lock(); 25916c60d2b5SDave Chinner spin_lock_irq(&sb->s_inode_wblist_lock); 259238f21977SNick Piggin } 25936c60d2b5SDave Chinner spin_unlock_irq(&sb->s_inode_wblist_lock); 25946c60d2b5SDave Chinner rcu_read_unlock(); 2595e97fedb9SDave Chinner mutex_unlock(&sb->s_sync_lock); 259666f3b8e2SJens Axboe } 25971da177e4SLinus Torvalds 2598f30a7d0cSTejun Heo static void __writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr, 2599f30a7d0cSTejun Heo enum wb_reason reason, bool skip_if_busy) 26001da177e4SLinus Torvalds { 26015b9cce4cSTejun Heo struct backing_dev_info *bdi = sb->s_bdi; 26025b9cce4cSTejun Heo DEFINE_WB_COMPLETION(done, bdi); 260383ba7b07SChristoph Hellwig struct wb_writeback_work work = { 26043c4d7165SChristoph Hellwig .sb = sb, 26053c4d7165SChristoph Hellwig .sync_mode = WB_SYNC_NONE, 26066e6938b6SWu Fengguang .tagged_writepages = 1, 260783ba7b07SChristoph Hellwig .done = &done, 26083259f8beSChris Mason .nr_pages = nr, 26090e175a18SCurt Wohlgemuth .reason = reason, 26103c4d7165SChristoph Hellwig }; 26110e3c9a22SJens Axboe 2612e7972912STejun Heo if (!bdi_has_dirty_io(bdi) || bdi == &noop_backing_dev_info) 26136eedc701SJan Kara return; 2614cf37e972SChristoph Hellwig WARN_ON(!rwsem_is_locked(&sb->s_umount)); 2615f30a7d0cSTejun Heo 2616db125360STejun Heo bdi_split_work_to_wbs(sb->s_bdi, &work, skip_if_busy); 26175b9cce4cSTejun Heo wb_wait_for_completion(&done); 26181da177e4SLinus Torvalds } 2619f30a7d0cSTejun Heo 2620f30a7d0cSTejun Heo /** 2621f30a7d0cSTejun Heo * writeback_inodes_sb_nr - writeback dirty inodes from given super_block 2622f30a7d0cSTejun Heo * @sb: the superblock 2623f30a7d0cSTejun Heo * @nr: the number of pages to write 2624f30a7d0cSTejun Heo * @reason: reason why some writeback work initiated 2625f30a7d0cSTejun Heo * 2626f30a7d0cSTejun Heo * Start writeback on some inodes on this super_block. No guarantees are made 2627f30a7d0cSTejun Heo * on how many (if any) will be written, and this function does not wait 2628f30a7d0cSTejun Heo * for IO completion of submitted IO. 2629f30a7d0cSTejun Heo */ 2630f30a7d0cSTejun Heo void writeback_inodes_sb_nr(struct super_block *sb, 2631f30a7d0cSTejun Heo unsigned long nr, 2632f30a7d0cSTejun Heo enum wb_reason reason) 2633f30a7d0cSTejun Heo { 2634f30a7d0cSTejun Heo __writeback_inodes_sb_nr(sb, nr, reason, false); 2635f30a7d0cSTejun Heo } 26363259f8beSChris Mason EXPORT_SYMBOL(writeback_inodes_sb_nr); 26373259f8beSChris Mason 26383259f8beSChris Mason /** 26393259f8beSChris Mason * writeback_inodes_sb - writeback dirty inodes from given super_block 26403259f8beSChris Mason * @sb: the superblock 2641786228abSMarcos Paulo de Souza * @reason: reason why some writeback work was initiated 26423259f8beSChris Mason * 26433259f8beSChris Mason * Start writeback on some inodes on this super_block. No guarantees are made 26443259f8beSChris Mason * on how many (if any) will be written, and this function does not wait 26453259f8beSChris Mason * for IO completion of submitted IO. 26463259f8beSChris Mason */ 26470e175a18SCurt Wohlgemuth void writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) 26483259f8beSChris Mason { 26490e175a18SCurt Wohlgemuth return writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); 26503259f8beSChris Mason } 2651d8a8559cSJens Axboe EXPORT_SYMBOL(writeback_inodes_sb); 2652d8a8559cSJens Axboe 2653d8a8559cSJens Axboe /** 265410ee27a0SMiao Xie * try_to_writeback_inodes_sb - try to start writeback if none underway 265510ee27a0SMiao Xie * @sb: the superblock 265610ee27a0SMiao Xie * @reason: reason why some writeback work was initiated 265710ee27a0SMiao Xie * 26588264c321SRakesh Pandit * Invoke __writeback_inodes_sb_nr if no writeback is currently underway. 265910ee27a0SMiao Xie */ 26608264c321SRakesh Pandit void try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) 266110ee27a0SMiao Xie { 26628264c321SRakesh Pandit if (!down_read_trylock(&sb->s_umount)) 26638264c321SRakesh Pandit return; 26648264c321SRakesh Pandit 26658264c321SRakesh Pandit __writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason, true); 26668264c321SRakesh Pandit up_read(&sb->s_umount); 266710ee27a0SMiao Xie } 266810ee27a0SMiao Xie EXPORT_SYMBOL(try_to_writeback_inodes_sb); 26693259f8beSChris Mason 26703259f8beSChris Mason /** 2671d8a8559cSJens Axboe * sync_inodes_sb - sync sb inode pages 2672d8a8559cSJens Axboe * @sb: the superblock 2673d8a8559cSJens Axboe * 2674d8a8559cSJens Axboe * This function writes and waits on any dirty inode belonging to this 26750dc83bd3SJan Kara * super_block. 2676d8a8559cSJens Axboe */ 26770dc83bd3SJan Kara void sync_inodes_sb(struct super_block *sb) 2678d8a8559cSJens Axboe { 26795b9cce4cSTejun Heo struct backing_dev_info *bdi = sb->s_bdi; 26805b9cce4cSTejun Heo DEFINE_WB_COMPLETION(done, bdi); 268183ba7b07SChristoph Hellwig struct wb_writeback_work work = { 26823c4d7165SChristoph Hellwig .sb = sb, 26833c4d7165SChristoph Hellwig .sync_mode = WB_SYNC_ALL, 26843c4d7165SChristoph Hellwig .nr_pages = LONG_MAX, 26853c4d7165SChristoph Hellwig .range_cyclic = 0, 268683ba7b07SChristoph Hellwig .done = &done, 26870e175a18SCurt Wohlgemuth .reason = WB_REASON_SYNC, 26887747bd4bSDave Chinner .for_sync = 1, 26893c4d7165SChristoph Hellwig }; 26903c4d7165SChristoph Hellwig 2691006a0973STejun Heo /* 2692006a0973STejun Heo * Can't skip on !bdi_has_dirty() because we should wait for !dirty 2693006a0973STejun Heo * inodes under writeback and I_DIRTY_TIME inodes ignored by 2694006a0973STejun Heo * bdi_has_dirty() need to be written out too. 2695006a0973STejun Heo */ 2696006a0973STejun Heo if (bdi == &noop_backing_dev_info) 26976eedc701SJan Kara return; 2698cf37e972SChristoph Hellwig WARN_ON(!rwsem_is_locked(&sb->s_umount)); 2699cf37e972SChristoph Hellwig 27007fc5854fSTejun Heo /* protect against inode wb switch, see inode_switch_wbs_work_fn() */ 27017fc5854fSTejun Heo bdi_down_write_wb_switch_rwsem(bdi); 2702db125360STejun Heo bdi_split_work_to_wbs(bdi, &work, false); 27035b9cce4cSTejun Heo wb_wait_for_completion(&done); 27047fc5854fSTejun Heo bdi_up_write_wb_switch_rwsem(bdi); 270583ba7b07SChristoph Hellwig 2706b6e51316SJens Axboe wait_sb_inodes(sb); 2707d8a8559cSJens Axboe } 2708d8a8559cSJens Axboe EXPORT_SYMBOL(sync_inodes_sb); 27091da177e4SLinus Torvalds 27101da177e4SLinus Torvalds /** 27111da177e4SLinus Torvalds * write_inode_now - write an inode to disk 27121da177e4SLinus Torvalds * @inode: inode to write to disk 27131da177e4SLinus Torvalds * @sync: whether the write should be synchronous or not 27141da177e4SLinus Torvalds * 27157f04c26dSAndrea Arcangeli * This function commits an inode to disk immediately if it is dirty. This is 27167f04c26dSAndrea Arcangeli * primarily needed by knfsd. 27177f04c26dSAndrea Arcangeli * 27187f04c26dSAndrea Arcangeli * The caller must either have a ref on the inode or must have set I_WILL_FREE. 27191da177e4SLinus Torvalds */ 27201da177e4SLinus Torvalds int write_inode_now(struct inode *inode, int sync) 27211da177e4SLinus Torvalds { 27221da177e4SLinus Torvalds struct writeback_control wbc = { 27231da177e4SLinus Torvalds .nr_to_write = LONG_MAX, 272418914b18SMike Galbraith .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, 2725111ebb6eSOGAWA Hirofumi .range_start = 0, 2726111ebb6eSOGAWA Hirofumi .range_end = LLONG_MAX, 27271da177e4SLinus Torvalds }; 27281da177e4SLinus Torvalds 2729f56753acSChristoph Hellwig if (!mapping_can_writeback(inode->i_mapping)) 273049364ce2SAndrew Morton wbc.nr_to_write = 0; 27311da177e4SLinus Torvalds 27321da177e4SLinus Torvalds might_sleep(); 2733aaf25593STejun Heo return writeback_single_inode(inode, &wbc); 27341da177e4SLinus Torvalds } 27351da177e4SLinus Torvalds EXPORT_SYMBOL(write_inode_now); 27361da177e4SLinus Torvalds 27371da177e4SLinus Torvalds /** 27381da177e4SLinus Torvalds * sync_inode - write an inode and its pages to disk. 27391da177e4SLinus Torvalds * @inode: the inode to sync 27401da177e4SLinus Torvalds * @wbc: controls the writeback mode 27411da177e4SLinus Torvalds * 27421da177e4SLinus Torvalds * sync_inode() will write an inode and its pages to disk. It will also 27431da177e4SLinus Torvalds * correctly update the inode on its superblock's dirty inode lists and will 27441da177e4SLinus Torvalds * update inode->i_state. 27451da177e4SLinus Torvalds * 27461da177e4SLinus Torvalds * The caller must have a ref on the inode. 27471da177e4SLinus Torvalds */ 27481da177e4SLinus Torvalds int sync_inode(struct inode *inode, struct writeback_control *wbc) 27491da177e4SLinus Torvalds { 2750aaf25593STejun Heo return writeback_single_inode(inode, wbc); 27511da177e4SLinus Torvalds } 27521da177e4SLinus Torvalds EXPORT_SYMBOL(sync_inode); 2753c3765016SChristoph Hellwig 2754c3765016SChristoph Hellwig /** 2755c691b9d9SAndrew Morton * sync_inode_metadata - write an inode to disk 2756c3765016SChristoph Hellwig * @inode: the inode to sync 2757c3765016SChristoph Hellwig * @wait: wait for I/O to complete. 2758c3765016SChristoph Hellwig * 2759c691b9d9SAndrew Morton * Write an inode to disk and adjust its dirty state after completion. 2760c3765016SChristoph Hellwig * 2761c3765016SChristoph Hellwig * Note: only writes the actual inode, no associated data or other metadata. 2762c3765016SChristoph Hellwig */ 2763c3765016SChristoph Hellwig int sync_inode_metadata(struct inode *inode, int wait) 2764c3765016SChristoph Hellwig { 2765c3765016SChristoph Hellwig struct writeback_control wbc = { 2766c3765016SChristoph Hellwig .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_NONE, 2767c3765016SChristoph Hellwig .nr_to_write = 0, /* metadata-only */ 2768c3765016SChristoph Hellwig }; 2769c3765016SChristoph Hellwig 2770c3765016SChristoph Hellwig return sync_inode(inode, &wbc); 2771c3765016SChristoph Hellwig } 2772c3765016SChristoph Hellwig EXPORT_SYMBOL(sync_inode_metadata); 2773