11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * fs/fs-writeback.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 2002, Linus Torvalds. 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * Contains all the functions related to writing back and waiting 71da177e4SLinus Torvalds * upon dirty inodes against superblocks, and writing back dirty 81da177e4SLinus Torvalds * pages against inodes. ie: data writeback. Writeout of the 91da177e4SLinus Torvalds * inode itself is not handled here. 101da177e4SLinus Torvalds * 11e1f8e874SFrancois Cami * 10Apr2002 Andrew Morton 121da177e4SLinus Torvalds * Split out of fs/inode.c 131da177e4SLinus Torvalds * Additions for address_space-based writeback 141da177e4SLinus Torvalds */ 151da177e4SLinus Torvalds 161da177e4SLinus Torvalds #include <linux/kernel.h> 17630d9c47SPaul Gortmaker #include <linux/export.h> 181da177e4SLinus Torvalds #include <linux/spinlock.h> 195a0e3ad6STejun Heo #include <linux/slab.h> 201da177e4SLinus Torvalds #include <linux/sched.h> 211da177e4SLinus Torvalds #include <linux/fs.h> 221da177e4SLinus Torvalds #include <linux/mm.h> 23bc31b86aSWu Fengguang #include <linux/pagemap.h> 2403ba3782SJens Axboe #include <linux/kthread.h> 251da177e4SLinus Torvalds #include <linux/writeback.h> 261da177e4SLinus Torvalds #include <linux/blkdev.h> 271da177e4SLinus Torvalds #include <linux/backing-dev.h> 28455b2864SDave Chinner #include <linux/tracepoint.h> 29719ea2fbSAl Viro #include <linux/device.h> 3021c6321fSTejun Heo #include <linux/memcontrol.h> 3107f3f05cSDavid Howells #include "internal.h" 321da177e4SLinus Torvalds 33d0bceac7SJens Axboe /* 34bc31b86aSWu Fengguang * 4MB minimal write chunk size 35bc31b86aSWu Fengguang */ 3609cbfeafSKirill A. Shutemov #define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_SHIFT - 10)) 37bc31b86aSWu Fengguang 38cc395d7fSTejun Heo struct wb_completion { 39cc395d7fSTejun Heo atomic_t cnt; 40cc395d7fSTejun Heo }; 41cc395d7fSTejun Heo 42bc31b86aSWu Fengguang /* 43c4a77a6cSJens Axboe * Passed into wb_writeback(), essentially a subset of writeback_control 44c4a77a6cSJens Axboe */ 4583ba7b07SChristoph Hellwig struct wb_writeback_work { 46c4a77a6cSJens Axboe long nr_pages; 47c4a77a6cSJens Axboe struct super_block *sb; 480dc83bd3SJan Kara unsigned long *older_than_this; 49c4a77a6cSJens Axboe enum writeback_sync_modes sync_mode; 506e6938b6SWu Fengguang unsigned int tagged_writepages:1; 5152957fe1SH Hartley Sweeten unsigned int for_kupdate:1; 5252957fe1SH Hartley Sweeten unsigned int range_cyclic:1; 5352957fe1SH Hartley Sweeten unsigned int for_background:1; 547747bd4bSDave Chinner unsigned int for_sync:1; /* sync(2) WB_SYNC_ALL writeback */ 55ac7b19a3STejun Heo unsigned int auto_free:1; /* free on completion */ 560e175a18SCurt Wohlgemuth enum wb_reason reason; /* why was writeback initiated? */ 57c4a77a6cSJens Axboe 588010c3b6SJens Axboe struct list_head list; /* pending work list */ 59cc395d7fSTejun Heo struct wb_completion *done; /* set if the caller waits */ 6003ba3782SJens Axboe }; 6103ba3782SJens Axboe 62a2f48706STheodore Ts'o /* 63cc395d7fSTejun Heo * If one wants to wait for one or more wb_writeback_works, each work's 64cc395d7fSTejun Heo * ->done should be set to a wb_completion defined using the following 65cc395d7fSTejun Heo * macro. Once all work items are issued with wb_queue_work(), the caller 66cc395d7fSTejun Heo * can wait for the completion of all using wb_wait_for_completion(). Work 67cc395d7fSTejun Heo * items which are waited upon aren't freed automatically on completion. 68cc395d7fSTejun Heo */ 69cc395d7fSTejun Heo #define DEFINE_WB_COMPLETION_ONSTACK(cmpl) \ 70cc395d7fSTejun Heo struct wb_completion cmpl = { \ 71cc395d7fSTejun Heo .cnt = ATOMIC_INIT(1), \ 72cc395d7fSTejun Heo } 73cc395d7fSTejun Heo 74cc395d7fSTejun Heo 75cc395d7fSTejun Heo /* 76a2f48706STheodore Ts'o * If an inode is constantly having its pages dirtied, but then the 77a2f48706STheodore Ts'o * updates stop dirtytime_expire_interval seconds in the past, it's 78a2f48706STheodore Ts'o * possible for the worst case time between when an inode has its 79a2f48706STheodore Ts'o * timestamps updated and when they finally get written out to be two 80a2f48706STheodore Ts'o * dirtytime_expire_intervals. We set the default to 12 hours (in 81a2f48706STheodore Ts'o * seconds), which means most of the time inodes will have their 82a2f48706STheodore Ts'o * timestamps written to disk after 12 hours, but in the worst case a 83a2f48706STheodore Ts'o * few inodes might not their timestamps updated for 24 hours. 84a2f48706STheodore Ts'o */ 85a2f48706STheodore Ts'o unsigned int dirtytime_expire_interval = 12 * 60 * 60; 86a2f48706STheodore Ts'o 877ccf19a8SNick Piggin static inline struct inode *wb_inode(struct list_head *head) 887ccf19a8SNick Piggin { 89c7f54084SDave Chinner return list_entry(head, struct inode, i_io_list); 907ccf19a8SNick Piggin } 917ccf19a8SNick Piggin 9215eb77a0SWu Fengguang /* 9315eb77a0SWu Fengguang * Include the creation of the trace points after defining the 9415eb77a0SWu Fengguang * wb_writeback_work structure and inline functions so that the definition 9515eb77a0SWu Fengguang * remains local to this file. 9615eb77a0SWu Fengguang */ 9715eb77a0SWu Fengguang #define CREATE_TRACE_POINTS 9815eb77a0SWu Fengguang #include <trace/events/writeback.h> 9915eb77a0SWu Fengguang 100774016b2SSteven Whitehouse EXPORT_TRACEPOINT_SYMBOL_GPL(wbc_writepage); 101774016b2SSteven Whitehouse 102d6c10f1fSTejun Heo static bool wb_io_lists_populated(struct bdi_writeback *wb) 103d6c10f1fSTejun Heo { 104d6c10f1fSTejun Heo if (wb_has_dirty_io(wb)) { 105d6c10f1fSTejun Heo return false; 106d6c10f1fSTejun Heo } else { 107d6c10f1fSTejun Heo set_bit(WB_has_dirty_io, &wb->state); 10895a46c65STejun Heo WARN_ON_ONCE(!wb->avg_write_bandwidth); 109766a9d6eSTejun Heo atomic_long_add(wb->avg_write_bandwidth, 110766a9d6eSTejun Heo &wb->bdi->tot_write_bandwidth); 111d6c10f1fSTejun Heo return true; 112d6c10f1fSTejun Heo } 113d6c10f1fSTejun Heo } 114d6c10f1fSTejun Heo 115d6c10f1fSTejun Heo static void wb_io_lists_depopulated(struct bdi_writeback *wb) 116d6c10f1fSTejun Heo { 117d6c10f1fSTejun Heo if (wb_has_dirty_io(wb) && list_empty(&wb->b_dirty) && 118766a9d6eSTejun Heo list_empty(&wb->b_io) && list_empty(&wb->b_more_io)) { 119d6c10f1fSTejun Heo clear_bit(WB_has_dirty_io, &wb->state); 12095a46c65STejun Heo WARN_ON_ONCE(atomic_long_sub_return(wb->avg_write_bandwidth, 12195a46c65STejun Heo &wb->bdi->tot_write_bandwidth) < 0); 122766a9d6eSTejun Heo } 123d6c10f1fSTejun Heo } 124d6c10f1fSTejun Heo 125d6c10f1fSTejun Heo /** 126c7f54084SDave Chinner * inode_io_list_move_locked - move an inode onto a bdi_writeback IO list 127d6c10f1fSTejun Heo * @inode: inode to be moved 128d6c10f1fSTejun Heo * @wb: target bdi_writeback 129bbbc3c1cSWang Long * @head: one of @wb->b_{dirty|io|more_io|dirty_time} 130d6c10f1fSTejun Heo * 131c7f54084SDave Chinner * Move @inode->i_io_list to @list of @wb and set %WB_has_dirty_io. 132d6c10f1fSTejun Heo * Returns %true if @inode is the first occupant of the !dirty_time IO 133d6c10f1fSTejun Heo * lists; otherwise, %false. 134d6c10f1fSTejun Heo */ 135c7f54084SDave Chinner static bool inode_io_list_move_locked(struct inode *inode, 136d6c10f1fSTejun Heo struct bdi_writeback *wb, 137d6c10f1fSTejun Heo struct list_head *head) 138d6c10f1fSTejun Heo { 139d6c10f1fSTejun Heo assert_spin_locked(&wb->list_lock); 140d6c10f1fSTejun Heo 141c7f54084SDave Chinner list_move(&inode->i_io_list, head); 142d6c10f1fSTejun Heo 143d6c10f1fSTejun Heo /* dirty_time doesn't count as dirty_io until expiration */ 144d6c10f1fSTejun Heo if (head != &wb->b_dirty_time) 145d6c10f1fSTejun Heo return wb_io_lists_populated(wb); 146d6c10f1fSTejun Heo 147d6c10f1fSTejun Heo wb_io_lists_depopulated(wb); 148d6c10f1fSTejun Heo return false; 149d6c10f1fSTejun Heo } 150d6c10f1fSTejun Heo 151d6c10f1fSTejun Heo /** 152c7f54084SDave Chinner * inode_io_list_del_locked - remove an inode from its bdi_writeback IO list 153d6c10f1fSTejun Heo * @inode: inode to be removed 154d6c10f1fSTejun Heo * @wb: bdi_writeback @inode is being removed from 155d6c10f1fSTejun Heo * 156d6c10f1fSTejun Heo * Remove @inode which may be on one of @wb->b_{dirty|io|more_io} lists and 157d6c10f1fSTejun Heo * clear %WB_has_dirty_io if all are empty afterwards. 158d6c10f1fSTejun Heo */ 159c7f54084SDave Chinner static void inode_io_list_del_locked(struct inode *inode, 160d6c10f1fSTejun Heo struct bdi_writeback *wb) 161d6c10f1fSTejun Heo { 162d6c10f1fSTejun Heo assert_spin_locked(&wb->list_lock); 163d6c10f1fSTejun Heo 164c7f54084SDave Chinner list_del_init(&inode->i_io_list); 165d6c10f1fSTejun Heo wb_io_lists_depopulated(wb); 166d6c10f1fSTejun Heo } 167d6c10f1fSTejun Heo 168f0054bb1STejun Heo static void wb_wakeup(struct bdi_writeback *wb) 1695acda9d1SJan Kara { 170f0054bb1STejun Heo spin_lock_bh(&wb->work_lock); 171f0054bb1STejun Heo if (test_bit(WB_registered, &wb->state)) 172f0054bb1STejun Heo mod_delayed_work(bdi_wq, &wb->dwork, 0); 173f0054bb1STejun Heo spin_unlock_bh(&wb->work_lock); 1745acda9d1SJan Kara } 1755acda9d1SJan Kara 1764a3a485bSTahsin Erdogan static void finish_writeback_work(struct bdi_writeback *wb, 1774a3a485bSTahsin Erdogan struct wb_writeback_work *work) 1784a3a485bSTahsin Erdogan { 1794a3a485bSTahsin Erdogan struct wb_completion *done = work->done; 1804a3a485bSTahsin Erdogan 1814a3a485bSTahsin Erdogan if (work->auto_free) 1824a3a485bSTahsin Erdogan kfree(work); 1834a3a485bSTahsin Erdogan if (done && atomic_dec_and_test(&done->cnt)) 1844a3a485bSTahsin Erdogan wake_up_all(&wb->bdi->wb_waitq); 1854a3a485bSTahsin Erdogan } 1864a3a485bSTahsin Erdogan 187f0054bb1STejun Heo static void wb_queue_work(struct bdi_writeback *wb, 1886585027aSJan Kara struct wb_writeback_work *work) 1896585027aSJan Kara { 1905634cc2aSTejun Heo trace_writeback_queue(wb, work); 1916585027aSJan Kara 192cc395d7fSTejun Heo if (work->done) 193cc395d7fSTejun Heo atomic_inc(&work->done->cnt); 1944a3a485bSTahsin Erdogan 1954a3a485bSTahsin Erdogan spin_lock_bh(&wb->work_lock); 1964a3a485bSTahsin Erdogan 1974a3a485bSTahsin Erdogan if (test_bit(WB_registered, &wb->state)) { 198f0054bb1STejun Heo list_add_tail(&work->list, &wb->work_list); 199f0054bb1STejun Heo mod_delayed_work(bdi_wq, &wb->dwork, 0); 2004a3a485bSTahsin Erdogan } else 2014a3a485bSTahsin Erdogan finish_writeback_work(wb, work); 2024a3a485bSTahsin Erdogan 203f0054bb1STejun Heo spin_unlock_bh(&wb->work_lock); 20403ba3782SJens Axboe } 2051da177e4SLinus Torvalds 206cc395d7fSTejun Heo /** 207cc395d7fSTejun Heo * wb_wait_for_completion - wait for completion of bdi_writeback_works 208cc395d7fSTejun Heo * @bdi: bdi work items were issued to 209cc395d7fSTejun Heo * @done: target wb_completion 210cc395d7fSTejun Heo * 211cc395d7fSTejun Heo * Wait for one or more work items issued to @bdi with their ->done field 212cc395d7fSTejun Heo * set to @done, which should have been defined with 213cc395d7fSTejun Heo * DEFINE_WB_COMPLETION_ONSTACK(). This function returns after all such 214cc395d7fSTejun Heo * work items are completed. Work items which are waited upon aren't freed 215cc395d7fSTejun Heo * automatically on completion. 216cc395d7fSTejun Heo */ 217cc395d7fSTejun Heo static void wb_wait_for_completion(struct backing_dev_info *bdi, 218cc395d7fSTejun Heo struct wb_completion *done) 219cc395d7fSTejun Heo { 220cc395d7fSTejun Heo atomic_dec(&done->cnt); /* put down the initial count */ 221cc395d7fSTejun Heo wait_event(bdi->wb_waitq, !atomic_read(&done->cnt)); 222cc395d7fSTejun Heo } 223cc395d7fSTejun Heo 224703c2708STejun Heo #ifdef CONFIG_CGROUP_WRITEBACK 225703c2708STejun Heo 2262a814908STejun Heo /* parameters for foreign inode detection, see wb_detach_inode() */ 2272a814908STejun Heo #define WB_FRN_TIME_SHIFT 13 /* 1s = 2^13, upto 8 secs w/ 16bit */ 2282a814908STejun Heo #define WB_FRN_TIME_AVG_SHIFT 3 /* avg = avg * 7/8 + new * 1/8 */ 2292a814908STejun Heo #define WB_FRN_TIME_CUT_DIV 2 /* ignore rounds < avg / 2 */ 2302a814908STejun Heo #define WB_FRN_TIME_PERIOD (2 * (1 << WB_FRN_TIME_SHIFT)) /* 2s */ 2312a814908STejun Heo 2322a814908STejun Heo #define WB_FRN_HIST_SLOTS 16 /* inode->i_wb_frn_history is 16bit */ 2332a814908STejun Heo #define WB_FRN_HIST_UNIT (WB_FRN_TIME_PERIOD / WB_FRN_HIST_SLOTS) 2342a814908STejun Heo /* each slot's duration is 2s / 16 */ 2352a814908STejun Heo #define WB_FRN_HIST_THR_SLOTS (WB_FRN_HIST_SLOTS / 2) 2362a814908STejun Heo /* if foreign slots >= 8, switch */ 2372a814908STejun Heo #define WB_FRN_HIST_MAX_SLOTS (WB_FRN_HIST_THR_SLOTS / 2 + 1) 2382a814908STejun Heo /* one round can affect upto 5 slots */ 2392a814908STejun Heo 240a1a0e23eSTejun Heo static atomic_t isw_nr_in_flight = ATOMIC_INIT(0); 241a1a0e23eSTejun Heo static struct workqueue_struct *isw_wq; 242a1a0e23eSTejun Heo 24321c6321fSTejun Heo void __inode_attach_wb(struct inode *inode, struct page *page) 24421c6321fSTejun Heo { 24521c6321fSTejun Heo struct backing_dev_info *bdi = inode_to_bdi(inode); 24621c6321fSTejun Heo struct bdi_writeback *wb = NULL; 24721c6321fSTejun Heo 24821c6321fSTejun Heo if (inode_cgwb_enabled(inode)) { 24921c6321fSTejun Heo struct cgroup_subsys_state *memcg_css; 25021c6321fSTejun Heo 25121c6321fSTejun Heo if (page) { 25221c6321fSTejun Heo memcg_css = mem_cgroup_css_from_page(page); 25321c6321fSTejun Heo wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); 25421c6321fSTejun Heo } else { 25521c6321fSTejun Heo /* must pin memcg_css, see wb_get_create() */ 25621c6321fSTejun Heo memcg_css = task_get_css(current, memory_cgrp_id); 25721c6321fSTejun Heo wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); 25821c6321fSTejun Heo css_put(memcg_css); 25921c6321fSTejun Heo } 26021c6321fSTejun Heo } 26121c6321fSTejun Heo 26221c6321fSTejun Heo if (!wb) 26321c6321fSTejun Heo wb = &bdi->wb; 26421c6321fSTejun Heo 26521c6321fSTejun Heo /* 26621c6321fSTejun Heo * There may be multiple instances of this function racing to 26721c6321fSTejun Heo * update the same inode. Use cmpxchg() to tell the winner. 26821c6321fSTejun Heo */ 26921c6321fSTejun Heo if (unlikely(cmpxchg(&inode->i_wb, NULL, wb))) 27021c6321fSTejun Heo wb_put(wb); 27121c6321fSTejun Heo } 27221c6321fSTejun Heo 273703c2708STejun Heo /** 27487e1d789STejun Heo * locked_inode_to_wb_and_lock_list - determine a locked inode's wb and lock it 27587e1d789STejun Heo * @inode: inode of interest with i_lock held 27687e1d789STejun Heo * 27787e1d789STejun Heo * Returns @inode's wb with its list_lock held. @inode->i_lock must be 27887e1d789STejun Heo * held on entry and is released on return. The returned wb is guaranteed 27987e1d789STejun Heo * to stay @inode's associated wb until its list_lock is released. 28087e1d789STejun Heo */ 28187e1d789STejun Heo static struct bdi_writeback * 28287e1d789STejun Heo locked_inode_to_wb_and_lock_list(struct inode *inode) 28387e1d789STejun Heo __releases(&inode->i_lock) 28487e1d789STejun Heo __acquires(&wb->list_lock) 28587e1d789STejun Heo { 28687e1d789STejun Heo while (true) { 28787e1d789STejun Heo struct bdi_writeback *wb = inode_to_wb(inode); 28887e1d789STejun Heo 28987e1d789STejun Heo /* 29087e1d789STejun Heo * inode_to_wb() association is protected by both 29187e1d789STejun Heo * @inode->i_lock and @wb->list_lock but list_lock nests 29287e1d789STejun Heo * outside i_lock. Drop i_lock and verify that the 29387e1d789STejun Heo * association hasn't changed after acquiring list_lock. 29487e1d789STejun Heo */ 29587e1d789STejun Heo wb_get(wb); 29687e1d789STejun Heo spin_unlock(&inode->i_lock); 29787e1d789STejun Heo spin_lock(&wb->list_lock); 29887e1d789STejun Heo 299aaa2cacfSTejun Heo /* i_wb may have changed inbetween, can't use inode_to_wb() */ 300614a4e37STejun Heo if (likely(wb == inode->i_wb)) { 301614a4e37STejun Heo wb_put(wb); /* @inode already has ref */ 302614a4e37STejun Heo return wb; 303614a4e37STejun Heo } 30487e1d789STejun Heo 30587e1d789STejun Heo spin_unlock(&wb->list_lock); 306614a4e37STejun Heo wb_put(wb); 30787e1d789STejun Heo cpu_relax(); 30887e1d789STejun Heo spin_lock(&inode->i_lock); 30987e1d789STejun Heo } 31087e1d789STejun Heo } 31187e1d789STejun Heo 31287e1d789STejun Heo /** 31387e1d789STejun Heo * inode_to_wb_and_lock_list - determine an inode's wb and lock it 31487e1d789STejun Heo * @inode: inode of interest 31587e1d789STejun Heo * 31687e1d789STejun Heo * Same as locked_inode_to_wb_and_lock_list() but @inode->i_lock isn't held 31787e1d789STejun Heo * on entry. 31887e1d789STejun Heo */ 31987e1d789STejun Heo static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode) 32087e1d789STejun Heo __acquires(&wb->list_lock) 32187e1d789STejun Heo { 32287e1d789STejun Heo spin_lock(&inode->i_lock); 32387e1d789STejun Heo return locked_inode_to_wb_and_lock_list(inode); 32487e1d789STejun Heo } 32587e1d789STejun Heo 326682aa8e1STejun Heo struct inode_switch_wbs_context { 327682aa8e1STejun Heo struct inode *inode; 328682aa8e1STejun Heo struct bdi_writeback *new_wb; 329682aa8e1STejun Heo 330682aa8e1STejun Heo struct rcu_head rcu_head; 331682aa8e1STejun Heo struct work_struct work; 332682aa8e1STejun Heo }; 333682aa8e1STejun Heo 334682aa8e1STejun Heo static void inode_switch_wbs_work_fn(struct work_struct *work) 335682aa8e1STejun Heo { 336682aa8e1STejun Heo struct inode_switch_wbs_context *isw = 337682aa8e1STejun Heo container_of(work, struct inode_switch_wbs_context, work); 338682aa8e1STejun Heo struct inode *inode = isw->inode; 339d10c8095STejun Heo struct address_space *mapping = inode->i_mapping; 340d10c8095STejun Heo struct bdi_writeback *old_wb = inode->i_wb; 341682aa8e1STejun Heo struct bdi_writeback *new_wb = isw->new_wb; 34204edf02cSMatthew Wilcox XA_STATE(xas, &mapping->i_pages, 0); 34304edf02cSMatthew Wilcox struct page *page; 344d10c8095STejun Heo bool switched = false; 345682aa8e1STejun Heo 346682aa8e1STejun Heo /* 347682aa8e1STejun Heo * By the time control reaches here, RCU grace period has passed 348682aa8e1STejun Heo * since I_WB_SWITCH assertion and all wb stat update transactions 349682aa8e1STejun Heo * between unlocked_inode_to_wb_begin/end() are guaranteed to be 350b93b0163SMatthew Wilcox * synchronizing against the i_pages lock. 351d10c8095STejun Heo * 352b93b0163SMatthew Wilcox * Grabbing old_wb->list_lock, inode->i_lock and the i_pages lock 353d10c8095STejun Heo * gives us exclusion against all wb related operations on @inode 354d10c8095STejun Heo * including IO list manipulations and stat updates. 355682aa8e1STejun Heo */ 356d10c8095STejun Heo if (old_wb < new_wb) { 357d10c8095STejun Heo spin_lock(&old_wb->list_lock); 358d10c8095STejun Heo spin_lock_nested(&new_wb->list_lock, SINGLE_DEPTH_NESTING); 359d10c8095STejun Heo } else { 360d10c8095STejun Heo spin_lock(&new_wb->list_lock); 361d10c8095STejun Heo spin_lock_nested(&old_wb->list_lock, SINGLE_DEPTH_NESTING); 362d10c8095STejun Heo } 363682aa8e1STejun Heo spin_lock(&inode->i_lock); 364b93b0163SMatthew Wilcox xa_lock_irq(&mapping->i_pages); 365682aa8e1STejun Heo 366d10c8095STejun Heo /* 367d10c8095STejun Heo * Once I_FREEING is visible under i_lock, the eviction path owns 368c7f54084SDave Chinner * the inode and we shouldn't modify ->i_io_list. 369d10c8095STejun Heo */ 370d10c8095STejun Heo if (unlikely(inode->i_state & I_FREEING)) 371d10c8095STejun Heo goto skip_switch; 372d10c8095STejun Heo 373d10c8095STejun Heo /* 374d10c8095STejun Heo * Count and transfer stats. Note that PAGECACHE_TAG_DIRTY points 375d10c8095STejun Heo * to possibly dirty pages while PAGECACHE_TAG_WRITEBACK points to 376b93b0163SMatthew Wilcox * pages actually under writeback. 377d10c8095STejun Heo */ 37804edf02cSMatthew Wilcox xas_for_each_marked(&xas, page, ULONG_MAX, PAGECACHE_TAG_DIRTY) { 37904edf02cSMatthew Wilcox if (PageDirty(page)) { 3803e8f399dSNikolay Borisov dec_wb_stat(old_wb, WB_RECLAIMABLE); 3813e8f399dSNikolay Borisov inc_wb_stat(new_wb, WB_RECLAIMABLE); 382d10c8095STejun Heo } 383d10c8095STejun Heo } 384d10c8095STejun Heo 38504edf02cSMatthew Wilcox xas_set(&xas, 0); 38604edf02cSMatthew Wilcox xas_for_each_marked(&xas, page, ULONG_MAX, PAGECACHE_TAG_WRITEBACK) { 387d10c8095STejun Heo WARN_ON_ONCE(!PageWriteback(page)); 3883e8f399dSNikolay Borisov dec_wb_stat(old_wb, WB_WRITEBACK); 3893e8f399dSNikolay Borisov inc_wb_stat(new_wb, WB_WRITEBACK); 390d10c8095STejun Heo } 391d10c8095STejun Heo 392d10c8095STejun Heo wb_get(new_wb); 393d10c8095STejun Heo 394d10c8095STejun Heo /* 395d10c8095STejun Heo * Transfer to @new_wb's IO list if necessary. The specific list 396d10c8095STejun Heo * @inode was on is ignored and the inode is put on ->b_dirty which 397d10c8095STejun Heo * is always correct including from ->b_dirty_time. The transfer 398d10c8095STejun Heo * preserves @inode->dirtied_when ordering. 399d10c8095STejun Heo */ 400c7f54084SDave Chinner if (!list_empty(&inode->i_io_list)) { 401d10c8095STejun Heo struct inode *pos; 402d10c8095STejun Heo 403c7f54084SDave Chinner inode_io_list_del_locked(inode, old_wb); 404d10c8095STejun Heo inode->i_wb = new_wb; 405c7f54084SDave Chinner list_for_each_entry(pos, &new_wb->b_dirty, i_io_list) 406d10c8095STejun Heo if (time_after_eq(inode->dirtied_when, 407d10c8095STejun Heo pos->dirtied_when)) 408d10c8095STejun Heo break; 409c7f54084SDave Chinner inode_io_list_move_locked(inode, new_wb, pos->i_io_list.prev); 410d10c8095STejun Heo } else { 411d10c8095STejun Heo inode->i_wb = new_wb; 412d10c8095STejun Heo } 413d10c8095STejun Heo 414d10c8095STejun Heo /* ->i_wb_frn updates may race wbc_detach_inode() but doesn't matter */ 415682aa8e1STejun Heo inode->i_wb_frn_winner = 0; 416682aa8e1STejun Heo inode->i_wb_frn_avg_time = 0; 417682aa8e1STejun Heo inode->i_wb_frn_history = 0; 418d10c8095STejun Heo switched = true; 419d10c8095STejun Heo skip_switch: 420682aa8e1STejun Heo /* 421682aa8e1STejun Heo * Paired with load_acquire in unlocked_inode_to_wb_begin() and 422682aa8e1STejun Heo * ensures that the new wb is visible if they see !I_WB_SWITCH. 423682aa8e1STejun Heo */ 424682aa8e1STejun Heo smp_store_release(&inode->i_state, inode->i_state & ~I_WB_SWITCH); 425682aa8e1STejun Heo 426b93b0163SMatthew Wilcox xa_unlock_irq(&mapping->i_pages); 427682aa8e1STejun Heo spin_unlock(&inode->i_lock); 428d10c8095STejun Heo spin_unlock(&new_wb->list_lock); 429d10c8095STejun Heo spin_unlock(&old_wb->list_lock); 430d10c8095STejun Heo 431d10c8095STejun Heo if (switched) { 432d10c8095STejun Heo wb_wakeup(new_wb); 433d10c8095STejun Heo wb_put(old_wb); 434d10c8095STejun Heo } 435d10c8095STejun Heo wb_put(new_wb); 436682aa8e1STejun Heo 437682aa8e1STejun Heo iput(inode); 438682aa8e1STejun Heo kfree(isw); 439a1a0e23eSTejun Heo 440a1a0e23eSTejun Heo atomic_dec(&isw_nr_in_flight); 441682aa8e1STejun Heo } 442682aa8e1STejun Heo 443682aa8e1STejun Heo static void inode_switch_wbs_rcu_fn(struct rcu_head *rcu_head) 444682aa8e1STejun Heo { 445682aa8e1STejun Heo struct inode_switch_wbs_context *isw = container_of(rcu_head, 446682aa8e1STejun Heo struct inode_switch_wbs_context, rcu_head); 447682aa8e1STejun Heo 448682aa8e1STejun Heo /* needs to grab bh-unsafe locks, bounce to work item */ 449682aa8e1STejun Heo INIT_WORK(&isw->work, inode_switch_wbs_work_fn); 450a1a0e23eSTejun Heo queue_work(isw_wq, &isw->work); 451682aa8e1STejun Heo } 452682aa8e1STejun Heo 453682aa8e1STejun Heo /** 454682aa8e1STejun Heo * inode_switch_wbs - change the wb association of an inode 455682aa8e1STejun Heo * @inode: target inode 456682aa8e1STejun Heo * @new_wb_id: ID of the new wb 457682aa8e1STejun Heo * 458682aa8e1STejun Heo * Switch @inode's wb association to the wb identified by @new_wb_id. The 459682aa8e1STejun Heo * switching is performed asynchronously and may fail silently. 460682aa8e1STejun Heo */ 461682aa8e1STejun Heo static void inode_switch_wbs(struct inode *inode, int new_wb_id) 462682aa8e1STejun Heo { 463682aa8e1STejun Heo struct backing_dev_info *bdi = inode_to_bdi(inode); 464682aa8e1STejun Heo struct cgroup_subsys_state *memcg_css; 465682aa8e1STejun Heo struct inode_switch_wbs_context *isw; 466682aa8e1STejun Heo 467682aa8e1STejun Heo /* noop if seems to be already in progress */ 468682aa8e1STejun Heo if (inode->i_state & I_WB_SWITCH) 469682aa8e1STejun Heo return; 470682aa8e1STejun Heo 471682aa8e1STejun Heo isw = kzalloc(sizeof(*isw), GFP_ATOMIC); 472682aa8e1STejun Heo if (!isw) 473682aa8e1STejun Heo return; 474682aa8e1STejun Heo 475682aa8e1STejun Heo /* find and pin the new wb */ 476682aa8e1STejun Heo rcu_read_lock(); 477682aa8e1STejun Heo memcg_css = css_from_id(new_wb_id, &memory_cgrp_subsys); 478682aa8e1STejun Heo if (memcg_css) 479682aa8e1STejun Heo isw->new_wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); 480682aa8e1STejun Heo rcu_read_unlock(); 481682aa8e1STejun Heo if (!isw->new_wb) 482682aa8e1STejun Heo goto out_free; 483682aa8e1STejun Heo 484682aa8e1STejun Heo /* while holding I_WB_SWITCH, no one else can update the association */ 485682aa8e1STejun Heo spin_lock(&inode->i_lock); 4861751e8a6SLinus Torvalds if (!(inode->i_sb->s_flags & SB_ACTIVE) || 487a1a0e23eSTejun Heo inode->i_state & (I_WB_SWITCH | I_FREEING) || 488a1a0e23eSTejun Heo inode_to_wb(inode) == isw->new_wb) { 489a1a0e23eSTejun Heo spin_unlock(&inode->i_lock); 490a1a0e23eSTejun Heo goto out_free; 491a1a0e23eSTejun Heo } 492682aa8e1STejun Heo inode->i_state |= I_WB_SWITCH; 49374524955STahsin Erdogan __iget(inode); 494682aa8e1STejun Heo spin_unlock(&inode->i_lock); 495682aa8e1STejun Heo 496682aa8e1STejun Heo isw->inode = inode; 497682aa8e1STejun Heo 498a1a0e23eSTejun Heo atomic_inc(&isw_nr_in_flight); 499a1a0e23eSTejun Heo 500682aa8e1STejun Heo /* 501682aa8e1STejun Heo * In addition to synchronizing among switchers, I_WB_SWITCH tells 502b93b0163SMatthew Wilcox * the RCU protected stat update paths to grab the i_page 503b93b0163SMatthew Wilcox * lock so that stat transfer can synchronize against them. 504682aa8e1STejun Heo * Let's continue after I_WB_SWITCH is guaranteed to be visible. 505682aa8e1STejun Heo */ 506682aa8e1STejun Heo call_rcu(&isw->rcu_head, inode_switch_wbs_rcu_fn); 507682aa8e1STejun Heo return; 508682aa8e1STejun Heo 509682aa8e1STejun Heo out_free: 510682aa8e1STejun Heo if (isw->new_wb) 511682aa8e1STejun Heo wb_put(isw->new_wb); 512682aa8e1STejun Heo kfree(isw); 513682aa8e1STejun Heo } 514682aa8e1STejun Heo 51587e1d789STejun Heo /** 516b16b1debSTejun Heo * wbc_attach_and_unlock_inode - associate wbc with target inode and unlock it 517b16b1debSTejun Heo * @wbc: writeback_control of interest 518b16b1debSTejun Heo * @inode: target inode 519b16b1debSTejun Heo * 520b16b1debSTejun Heo * @inode is locked and about to be written back under the control of @wbc. 521b16b1debSTejun Heo * Record @inode's writeback context into @wbc and unlock the i_lock. On 522b16b1debSTejun Heo * writeback completion, wbc_detach_inode() should be called. This is used 523b16b1debSTejun Heo * to track the cgroup writeback context. 524b16b1debSTejun Heo */ 525b16b1debSTejun Heo void wbc_attach_and_unlock_inode(struct writeback_control *wbc, 526b16b1debSTejun Heo struct inode *inode) 527b16b1debSTejun Heo { 528dd73e4b7STejun Heo if (!inode_cgwb_enabled(inode)) { 529dd73e4b7STejun Heo spin_unlock(&inode->i_lock); 530dd73e4b7STejun Heo return; 531dd73e4b7STejun Heo } 532dd73e4b7STejun Heo 533b16b1debSTejun Heo wbc->wb = inode_to_wb(inode); 5342a814908STejun Heo wbc->inode = inode; 5352a814908STejun Heo 5362a814908STejun Heo wbc->wb_id = wbc->wb->memcg_css->id; 5372a814908STejun Heo wbc->wb_lcand_id = inode->i_wb_frn_winner; 5382a814908STejun Heo wbc->wb_tcand_id = 0; 5392a814908STejun Heo wbc->wb_bytes = 0; 5402a814908STejun Heo wbc->wb_lcand_bytes = 0; 5412a814908STejun Heo wbc->wb_tcand_bytes = 0; 5422a814908STejun Heo 543b16b1debSTejun Heo wb_get(wbc->wb); 544b16b1debSTejun Heo spin_unlock(&inode->i_lock); 545e8a7abf5STejun Heo 546e8a7abf5STejun Heo /* 547e8a7abf5STejun Heo * A dying wb indicates that the memcg-blkcg mapping has changed 548e8a7abf5STejun Heo * and a new wb is already serving the memcg. Switch immediately. 549e8a7abf5STejun Heo */ 550e8a7abf5STejun Heo if (unlikely(wb_dying(wbc->wb))) 551e8a7abf5STejun Heo inode_switch_wbs(inode, wbc->wb_id); 552b16b1debSTejun Heo } 553b16b1debSTejun Heo 554b16b1debSTejun Heo /** 5552a814908STejun Heo * wbc_detach_inode - disassociate wbc from inode and perform foreign detection 5562a814908STejun Heo * @wbc: writeback_control of the just finished writeback 557b16b1debSTejun Heo * 558b16b1debSTejun Heo * To be called after a writeback attempt of an inode finishes and undoes 559b16b1debSTejun Heo * wbc_attach_and_unlock_inode(). Can be called under any context. 5602a814908STejun Heo * 5612a814908STejun Heo * As concurrent write sharing of an inode is expected to be very rare and 5622a814908STejun Heo * memcg only tracks page ownership on first-use basis severely confining 5632a814908STejun Heo * the usefulness of such sharing, cgroup writeback tracks ownership 5642a814908STejun Heo * per-inode. While the support for concurrent write sharing of an inode 5652a814908STejun Heo * is deemed unnecessary, an inode being written to by different cgroups at 5662a814908STejun Heo * different points in time is a lot more common, and, more importantly, 5672a814908STejun Heo * charging only by first-use can too readily lead to grossly incorrect 5682a814908STejun Heo * behaviors (single foreign page can lead to gigabytes of writeback to be 5692a814908STejun Heo * incorrectly attributed). 5702a814908STejun Heo * 5712a814908STejun Heo * To resolve this issue, cgroup writeback detects the majority dirtier of 5722a814908STejun Heo * an inode and transfers the ownership to it. To avoid unnnecessary 5732a814908STejun Heo * oscillation, the detection mechanism keeps track of history and gives 5742a814908STejun Heo * out the switch verdict only if the foreign usage pattern is stable over 5752a814908STejun Heo * a certain amount of time and/or writeback attempts. 5762a814908STejun Heo * 5772a814908STejun Heo * On each writeback attempt, @wbc tries to detect the majority writer 5782a814908STejun Heo * using Boyer-Moore majority vote algorithm. In addition to the byte 5792a814908STejun Heo * count from the majority voting, it also counts the bytes written for the 5802a814908STejun Heo * current wb and the last round's winner wb (max of last round's current 5812a814908STejun Heo * wb, the winner from two rounds ago, and the last round's majority 5822a814908STejun Heo * candidate). Keeping track of the historical winner helps the algorithm 5832a814908STejun Heo * to semi-reliably detect the most active writer even when it's not the 5842a814908STejun Heo * absolute majority. 5852a814908STejun Heo * 5862a814908STejun Heo * Once the winner of the round is determined, whether the winner is 5872a814908STejun Heo * foreign or not and how much IO time the round consumed is recorded in 5882a814908STejun Heo * inode->i_wb_frn_history. If the amount of recorded foreign IO time is 5892a814908STejun Heo * over a certain threshold, the switch verdict is given. 590b16b1debSTejun Heo */ 591b16b1debSTejun Heo void wbc_detach_inode(struct writeback_control *wbc) 592b16b1debSTejun Heo { 5932a814908STejun Heo struct bdi_writeback *wb = wbc->wb; 5942a814908STejun Heo struct inode *inode = wbc->inode; 595dd73e4b7STejun Heo unsigned long avg_time, max_bytes, max_time; 596dd73e4b7STejun Heo u16 history; 5972a814908STejun Heo int max_id; 5982a814908STejun Heo 599dd73e4b7STejun Heo if (!wb) 600dd73e4b7STejun Heo return; 601dd73e4b7STejun Heo 602dd73e4b7STejun Heo history = inode->i_wb_frn_history; 603dd73e4b7STejun Heo avg_time = inode->i_wb_frn_avg_time; 604dd73e4b7STejun Heo 6052a814908STejun Heo /* pick the winner of this round */ 6062a814908STejun Heo if (wbc->wb_bytes >= wbc->wb_lcand_bytes && 6072a814908STejun Heo wbc->wb_bytes >= wbc->wb_tcand_bytes) { 6082a814908STejun Heo max_id = wbc->wb_id; 6092a814908STejun Heo max_bytes = wbc->wb_bytes; 6102a814908STejun Heo } else if (wbc->wb_lcand_bytes >= wbc->wb_tcand_bytes) { 6112a814908STejun Heo max_id = wbc->wb_lcand_id; 6122a814908STejun Heo max_bytes = wbc->wb_lcand_bytes; 6132a814908STejun Heo } else { 6142a814908STejun Heo max_id = wbc->wb_tcand_id; 6152a814908STejun Heo max_bytes = wbc->wb_tcand_bytes; 6162a814908STejun Heo } 6172a814908STejun Heo 6182a814908STejun Heo /* 6192a814908STejun Heo * Calculate the amount of IO time the winner consumed and fold it 6202a814908STejun Heo * into the running average kept per inode. If the consumed IO 6212a814908STejun Heo * time is lower than avag / WB_FRN_TIME_CUT_DIV, ignore it for 6222a814908STejun Heo * deciding whether to switch or not. This is to prevent one-off 6232a814908STejun Heo * small dirtiers from skewing the verdict. 6242a814908STejun Heo */ 6252a814908STejun Heo max_time = DIV_ROUND_UP((max_bytes >> PAGE_SHIFT) << WB_FRN_TIME_SHIFT, 6262a814908STejun Heo wb->avg_write_bandwidth); 6272a814908STejun Heo if (avg_time) 6282a814908STejun Heo avg_time += (max_time >> WB_FRN_TIME_AVG_SHIFT) - 6292a814908STejun Heo (avg_time >> WB_FRN_TIME_AVG_SHIFT); 6302a814908STejun Heo else 6312a814908STejun Heo avg_time = max_time; /* immediate catch up on first run */ 6322a814908STejun Heo 6332a814908STejun Heo if (max_time >= avg_time / WB_FRN_TIME_CUT_DIV) { 6342a814908STejun Heo int slots; 6352a814908STejun Heo 6362a814908STejun Heo /* 6372a814908STejun Heo * The switch verdict is reached if foreign wb's consume 6382a814908STejun Heo * more than a certain proportion of IO time in a 6392a814908STejun Heo * WB_FRN_TIME_PERIOD. This is loosely tracked by 16 slot 6402a814908STejun Heo * history mask where each bit represents one sixteenth of 6412a814908STejun Heo * the period. Determine the number of slots to shift into 6422a814908STejun Heo * history from @max_time. 6432a814908STejun Heo */ 6442a814908STejun Heo slots = min(DIV_ROUND_UP(max_time, WB_FRN_HIST_UNIT), 6452a814908STejun Heo (unsigned long)WB_FRN_HIST_MAX_SLOTS); 6462a814908STejun Heo history <<= slots; 6472a814908STejun Heo if (wbc->wb_id != max_id) 6482a814908STejun Heo history |= (1U << slots) - 1; 6492a814908STejun Heo 6502a814908STejun Heo /* 6512a814908STejun Heo * Switch if the current wb isn't the consistent winner. 6522a814908STejun Heo * If there are multiple closely competing dirtiers, the 6532a814908STejun Heo * inode may switch across them repeatedly over time, which 6542a814908STejun Heo * is okay. The main goal is avoiding keeping an inode on 6552a814908STejun Heo * the wrong wb for an extended period of time. 6562a814908STejun Heo */ 657682aa8e1STejun Heo if (hweight32(history) > WB_FRN_HIST_THR_SLOTS) 658682aa8e1STejun Heo inode_switch_wbs(inode, max_id); 6592a814908STejun Heo } 6602a814908STejun Heo 6612a814908STejun Heo /* 6622a814908STejun Heo * Multiple instances of this function may race to update the 6632a814908STejun Heo * following fields but we don't mind occassional inaccuracies. 6642a814908STejun Heo */ 6652a814908STejun Heo inode->i_wb_frn_winner = max_id; 6662a814908STejun Heo inode->i_wb_frn_avg_time = min(avg_time, (unsigned long)U16_MAX); 6672a814908STejun Heo inode->i_wb_frn_history = history; 6682a814908STejun Heo 669b16b1debSTejun Heo wb_put(wbc->wb); 670b16b1debSTejun Heo wbc->wb = NULL; 671b16b1debSTejun Heo } 672b16b1debSTejun Heo 673b16b1debSTejun Heo /** 6742a814908STejun Heo * wbc_account_io - account IO issued during writeback 6752a814908STejun Heo * @wbc: writeback_control of the writeback in progress 6762a814908STejun Heo * @page: page being written out 6772a814908STejun Heo * @bytes: number of bytes being written out 6782a814908STejun Heo * 6792a814908STejun Heo * @bytes from @page are about to written out during the writeback 6802a814908STejun Heo * controlled by @wbc. Keep the book for foreign inode detection. See 6812a814908STejun Heo * wbc_detach_inode(). 6822a814908STejun Heo */ 6832a814908STejun Heo void wbc_account_io(struct writeback_control *wbc, struct page *page, 6842a814908STejun Heo size_t bytes) 6852a814908STejun Heo { 6862a814908STejun Heo int id; 6872a814908STejun Heo 6882a814908STejun Heo /* 6892a814908STejun Heo * pageout() path doesn't attach @wbc to the inode being written 6902a814908STejun Heo * out. This is intentional as we don't want the function to block 6912a814908STejun Heo * behind a slow cgroup. Ultimately, we want pageout() to kick off 6922a814908STejun Heo * regular writeback instead of writing things out itself. 6932a814908STejun Heo */ 6942a814908STejun Heo if (!wbc->wb) 6952a814908STejun Heo return; 6962a814908STejun Heo 6972a814908STejun Heo id = mem_cgroup_css_from_page(page)->id; 6982a814908STejun Heo 6992a814908STejun Heo if (id == wbc->wb_id) { 7002a814908STejun Heo wbc->wb_bytes += bytes; 7012a814908STejun Heo return; 7022a814908STejun Heo } 7032a814908STejun Heo 7042a814908STejun Heo if (id == wbc->wb_lcand_id) 7052a814908STejun Heo wbc->wb_lcand_bytes += bytes; 7062a814908STejun Heo 7072a814908STejun Heo /* Boyer-Moore majority vote algorithm */ 7082a814908STejun Heo if (!wbc->wb_tcand_bytes) 7092a814908STejun Heo wbc->wb_tcand_id = id; 7102a814908STejun Heo if (id == wbc->wb_tcand_id) 7112a814908STejun Heo wbc->wb_tcand_bytes += bytes; 7122a814908STejun Heo else 7132a814908STejun Heo wbc->wb_tcand_bytes -= min(bytes, wbc->wb_tcand_bytes); 7142a814908STejun Heo } 7155aa2a96bSTejun Heo EXPORT_SYMBOL_GPL(wbc_account_io); 7162a814908STejun Heo 7172a814908STejun Heo /** 718703c2708STejun Heo * inode_congested - test whether an inode is congested 71960292bccSTejun Heo * @inode: inode to test for congestion (may be NULL) 720703c2708STejun Heo * @cong_bits: mask of WB_[a]sync_congested bits to test 721703c2708STejun Heo * 722703c2708STejun Heo * Tests whether @inode is congested. @cong_bits is the mask of congestion 723703c2708STejun Heo * bits to test and the return value is the mask of set bits. 724703c2708STejun Heo * 725703c2708STejun Heo * If cgroup writeback is enabled for @inode, the congestion state is 726703c2708STejun Heo * determined by whether the cgwb (cgroup bdi_writeback) for the blkcg 727703c2708STejun Heo * associated with @inode is congested; otherwise, the root wb's congestion 728703c2708STejun Heo * state is used. 72960292bccSTejun Heo * 73060292bccSTejun Heo * @inode is allowed to be NULL as this function is often called on 73160292bccSTejun Heo * mapping->host which is NULL for the swapper space. 732703c2708STejun Heo */ 733703c2708STejun Heo int inode_congested(struct inode *inode, int cong_bits) 734703c2708STejun Heo { 7355cb8b824STejun Heo /* 7365cb8b824STejun Heo * Once set, ->i_wb never becomes NULL while the inode is alive. 7375cb8b824STejun Heo * Start transaction iff ->i_wb is visible. 7385cb8b824STejun Heo */ 739aaa2cacfSTejun Heo if (inode && inode_to_wb_is_valid(inode)) { 7405cb8b824STejun Heo struct bdi_writeback *wb; 7412e898e4cSGreg Thelen struct wb_lock_cookie lock_cookie = {}; 7422e898e4cSGreg Thelen bool congested; 7435cb8b824STejun Heo 7442e898e4cSGreg Thelen wb = unlocked_inode_to_wb_begin(inode, &lock_cookie); 7455cb8b824STejun Heo congested = wb_congested(wb, cong_bits); 7462e898e4cSGreg Thelen unlocked_inode_to_wb_end(inode, &lock_cookie); 7475cb8b824STejun Heo return congested; 748703c2708STejun Heo } 749703c2708STejun Heo 750703c2708STejun Heo return wb_congested(&inode_to_bdi(inode)->wb, cong_bits); 751703c2708STejun Heo } 752703c2708STejun Heo EXPORT_SYMBOL_GPL(inode_congested); 753703c2708STejun Heo 754f2b65121STejun Heo /** 755f2b65121STejun Heo * wb_split_bdi_pages - split nr_pages to write according to bandwidth 756f2b65121STejun Heo * @wb: target bdi_writeback to split @nr_pages to 757f2b65121STejun Heo * @nr_pages: number of pages to write for the whole bdi 758f2b65121STejun Heo * 759f2b65121STejun Heo * Split @wb's portion of @nr_pages according to @wb's write bandwidth in 760f2b65121STejun Heo * relation to the total write bandwidth of all wb's w/ dirty inodes on 761f2b65121STejun Heo * @wb->bdi. 762f2b65121STejun Heo */ 763f2b65121STejun Heo static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages) 764f2b65121STejun Heo { 765f2b65121STejun Heo unsigned long this_bw = wb->avg_write_bandwidth; 766f2b65121STejun Heo unsigned long tot_bw = atomic_long_read(&wb->bdi->tot_write_bandwidth); 767f2b65121STejun Heo 768f2b65121STejun Heo if (nr_pages == LONG_MAX) 769f2b65121STejun Heo return LONG_MAX; 770f2b65121STejun Heo 771f2b65121STejun Heo /* 772f2b65121STejun Heo * This may be called on clean wb's and proportional distribution 773f2b65121STejun Heo * may not make sense, just use the original @nr_pages in those 774f2b65121STejun Heo * cases. In general, we wanna err on the side of writing more. 775f2b65121STejun Heo */ 776f2b65121STejun Heo if (!tot_bw || this_bw >= tot_bw) 777f2b65121STejun Heo return nr_pages; 778f2b65121STejun Heo else 779f2b65121STejun Heo return DIV_ROUND_UP_ULL((u64)nr_pages * this_bw, tot_bw); 780f2b65121STejun Heo } 781f2b65121STejun Heo 782db125360STejun Heo /** 783db125360STejun Heo * bdi_split_work_to_wbs - split a wb_writeback_work to all wb's of a bdi 784db125360STejun Heo * @bdi: target backing_dev_info 785db125360STejun Heo * @base_work: wb_writeback_work to issue 786db125360STejun Heo * @skip_if_busy: skip wb's which already have writeback in progress 787db125360STejun Heo * 788db125360STejun Heo * Split and issue @base_work to all wb's (bdi_writeback's) of @bdi which 789db125360STejun Heo * have dirty inodes. If @base_work->nr_page isn't %LONG_MAX, it's 790db125360STejun Heo * distributed to the busy wbs according to each wb's proportion in the 791db125360STejun Heo * total active write bandwidth of @bdi. 792db125360STejun Heo */ 793db125360STejun Heo static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, 794db125360STejun Heo struct wb_writeback_work *base_work, 795db125360STejun Heo bool skip_if_busy) 796db125360STejun Heo { 797b817525aSTejun Heo struct bdi_writeback *last_wb = NULL; 798b33e18f6STejun Heo struct bdi_writeback *wb = list_entry(&bdi->wb_list, 799b817525aSTejun Heo struct bdi_writeback, bdi_node); 800db125360STejun Heo 801db125360STejun Heo might_sleep(); 802db125360STejun Heo restart: 803db125360STejun Heo rcu_read_lock(); 804b817525aSTejun Heo list_for_each_entry_continue_rcu(wb, &bdi->wb_list, bdi_node) { 8058a1270cdSTejun Heo DEFINE_WB_COMPLETION_ONSTACK(fallback_work_done); 8068a1270cdSTejun Heo struct wb_writeback_work fallback_work; 8078a1270cdSTejun Heo struct wb_writeback_work *work; 8088a1270cdSTejun Heo long nr_pages; 8098a1270cdSTejun Heo 810b817525aSTejun Heo if (last_wb) { 811b817525aSTejun Heo wb_put(last_wb); 812b817525aSTejun Heo last_wb = NULL; 813b817525aSTejun Heo } 814b817525aSTejun Heo 815006a0973STejun Heo /* SYNC_ALL writes out I_DIRTY_TIME too */ 816006a0973STejun Heo if (!wb_has_dirty_io(wb) && 817006a0973STejun Heo (base_work->sync_mode == WB_SYNC_NONE || 818006a0973STejun Heo list_empty(&wb->b_dirty_time))) 819006a0973STejun Heo continue; 820006a0973STejun Heo if (skip_if_busy && writeback_in_progress(wb)) 821db125360STejun Heo continue; 822db125360STejun Heo 8238a1270cdSTejun Heo nr_pages = wb_split_bdi_pages(wb, base_work->nr_pages); 8248a1270cdSTejun Heo 8258a1270cdSTejun Heo work = kmalloc(sizeof(*work), GFP_ATOMIC); 8268a1270cdSTejun Heo if (work) { 8278a1270cdSTejun Heo *work = *base_work; 8288a1270cdSTejun Heo work->nr_pages = nr_pages; 8298a1270cdSTejun Heo work->auto_free = 1; 8308a1270cdSTejun Heo wb_queue_work(wb, work); 8318a1270cdSTejun Heo continue; 832db125360STejun Heo } 8338a1270cdSTejun Heo 8348a1270cdSTejun Heo /* alloc failed, execute synchronously using on-stack fallback */ 8358a1270cdSTejun Heo work = &fallback_work; 8368a1270cdSTejun Heo *work = *base_work; 8378a1270cdSTejun Heo work->nr_pages = nr_pages; 8388a1270cdSTejun Heo work->auto_free = 0; 8398a1270cdSTejun Heo work->done = &fallback_work_done; 8408a1270cdSTejun Heo 8418a1270cdSTejun Heo wb_queue_work(wb, work); 8428a1270cdSTejun Heo 843b817525aSTejun Heo /* 844b817525aSTejun Heo * Pin @wb so that it stays on @bdi->wb_list. This allows 845b817525aSTejun Heo * continuing iteration from @wb after dropping and 846b817525aSTejun Heo * regrabbing rcu read lock. 847b817525aSTejun Heo */ 848b817525aSTejun Heo wb_get(wb); 849b817525aSTejun Heo last_wb = wb; 850b817525aSTejun Heo 851db125360STejun Heo rcu_read_unlock(); 8528a1270cdSTejun Heo wb_wait_for_completion(bdi, &fallback_work_done); 853db125360STejun Heo goto restart; 854db125360STejun Heo } 855db125360STejun Heo rcu_read_unlock(); 856b817525aSTejun Heo 857b817525aSTejun Heo if (last_wb) 858b817525aSTejun Heo wb_put(last_wb); 859db125360STejun Heo } 860db125360STejun Heo 861a1a0e23eSTejun Heo /** 862a1a0e23eSTejun Heo * cgroup_writeback_umount - flush inode wb switches for umount 863a1a0e23eSTejun Heo * 864a1a0e23eSTejun Heo * This function is called when a super_block is about to be destroyed and 865a1a0e23eSTejun Heo * flushes in-flight inode wb switches. An inode wb switch goes through 866a1a0e23eSTejun Heo * RCU and then workqueue, so the two need to be flushed in order to ensure 867a1a0e23eSTejun Heo * that all previously scheduled switches are finished. As wb switches are 868a1a0e23eSTejun Heo * rare occurrences and synchronize_rcu() can take a while, perform 869a1a0e23eSTejun Heo * flushing iff wb switches are in flight. 870a1a0e23eSTejun Heo */ 871a1a0e23eSTejun Heo void cgroup_writeback_umount(void) 872a1a0e23eSTejun Heo { 873a1a0e23eSTejun Heo if (atomic_read(&isw_nr_in_flight)) { 874a1a0e23eSTejun Heo synchronize_rcu(); 875a1a0e23eSTejun Heo flush_workqueue(isw_wq); 876a1a0e23eSTejun Heo } 877a1a0e23eSTejun Heo } 878a1a0e23eSTejun Heo 879a1a0e23eSTejun Heo static int __init cgroup_writeback_init(void) 880a1a0e23eSTejun Heo { 881a1a0e23eSTejun Heo isw_wq = alloc_workqueue("inode_switch_wbs", 0, 0); 882a1a0e23eSTejun Heo if (!isw_wq) 883a1a0e23eSTejun Heo return -ENOMEM; 884a1a0e23eSTejun Heo return 0; 885a1a0e23eSTejun Heo } 886a1a0e23eSTejun Heo fs_initcall(cgroup_writeback_init); 887a1a0e23eSTejun Heo 888f2b65121STejun Heo #else /* CONFIG_CGROUP_WRITEBACK */ 889f2b65121STejun Heo 89087e1d789STejun Heo static struct bdi_writeback * 89187e1d789STejun Heo locked_inode_to_wb_and_lock_list(struct inode *inode) 89287e1d789STejun Heo __releases(&inode->i_lock) 89387e1d789STejun Heo __acquires(&wb->list_lock) 89487e1d789STejun Heo { 89587e1d789STejun Heo struct bdi_writeback *wb = inode_to_wb(inode); 89687e1d789STejun Heo 89787e1d789STejun Heo spin_unlock(&inode->i_lock); 89887e1d789STejun Heo spin_lock(&wb->list_lock); 89987e1d789STejun Heo return wb; 90087e1d789STejun Heo } 90187e1d789STejun Heo 90287e1d789STejun Heo static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode) 90387e1d789STejun Heo __acquires(&wb->list_lock) 90487e1d789STejun Heo { 90587e1d789STejun Heo struct bdi_writeback *wb = inode_to_wb(inode); 90687e1d789STejun Heo 90787e1d789STejun Heo spin_lock(&wb->list_lock); 90887e1d789STejun Heo return wb; 90987e1d789STejun Heo } 91087e1d789STejun Heo 911f2b65121STejun Heo static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages) 912f2b65121STejun Heo { 913f2b65121STejun Heo return nr_pages; 914f2b65121STejun Heo } 915f2b65121STejun Heo 916db125360STejun Heo static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, 917db125360STejun Heo struct wb_writeback_work *base_work, 918db125360STejun Heo bool skip_if_busy) 919db125360STejun Heo { 920db125360STejun Heo might_sleep(); 921db125360STejun Heo 922006a0973STejun Heo if (!skip_if_busy || !writeback_in_progress(&bdi->wb)) { 923db125360STejun Heo base_work->auto_free = 0; 924db125360STejun Heo wb_queue_work(&bdi->wb, base_work); 925db125360STejun Heo } 926db125360STejun Heo } 927db125360STejun Heo 928703c2708STejun Heo #endif /* CONFIG_CGROUP_WRITEBACK */ 929703c2708STejun Heo 930e8e8a0c6SJens Axboe /* 931e8e8a0c6SJens Axboe * Add in the number of potentially dirty inodes, because each inode 932e8e8a0c6SJens Axboe * write can dirty pagecache in the underlying blockdev. 933e8e8a0c6SJens Axboe */ 934e8e8a0c6SJens Axboe static unsigned long get_nr_dirty_pages(void) 935e8e8a0c6SJens Axboe { 936e8e8a0c6SJens Axboe return global_node_page_state(NR_FILE_DIRTY) + 937e8e8a0c6SJens Axboe global_node_page_state(NR_UNSTABLE_NFS) + 938e8e8a0c6SJens Axboe get_nr_dirty_inodes(); 939e8e8a0c6SJens Axboe } 940e8e8a0c6SJens Axboe 941e8e8a0c6SJens Axboe static void wb_start_writeback(struct bdi_writeback *wb, enum wb_reason reason) 942b6e51316SJens Axboe { 943c00ddad3STejun Heo if (!wb_has_dirty_io(wb)) 944c00ddad3STejun Heo return; 945c00ddad3STejun Heo 946c00ddad3STejun Heo /* 947aac8d41cSJens Axboe * All callers of this function want to start writeback of all 948aac8d41cSJens Axboe * dirty pages. Places like vmscan can call this at a very 949aac8d41cSJens Axboe * high frequency, causing pointless allocations of tons of 950aac8d41cSJens Axboe * work items and keeping the flusher threads busy retrieving 951aac8d41cSJens Axboe * that work. Ensure that we only allow one of them pending and 95285009b4fSJens Axboe * inflight at the time. 953aac8d41cSJens Axboe */ 95485009b4fSJens Axboe if (test_bit(WB_start_all, &wb->state) || 95585009b4fSJens Axboe test_and_set_bit(WB_start_all, &wb->state)) 956aac8d41cSJens Axboe return; 957aac8d41cSJens Axboe 95885009b4fSJens Axboe wb->start_all_reason = reason; 959c00ddad3STejun Heo wb_wakeup(wb); 960d3ddec76SWu Fengguang } 961d3ddec76SWu Fengguang 962c5444198SChristoph Hellwig /** 9639ecf4866STejun Heo * wb_start_background_writeback - start background writeback 9649ecf4866STejun Heo * @wb: bdi_writback to write from 965c5444198SChristoph Hellwig * 966c5444198SChristoph Hellwig * Description: 9676585027aSJan Kara * This makes sure WB_SYNC_NONE background writeback happens. When 9689ecf4866STejun Heo * this function returns, it is only guaranteed that for given wb 9696585027aSJan Kara * some IO is happening if we are over background dirty threshold. 9706585027aSJan Kara * Caller need not hold sb s_umount semaphore. 971c5444198SChristoph Hellwig */ 9729ecf4866STejun Heo void wb_start_background_writeback(struct bdi_writeback *wb) 973c5444198SChristoph Hellwig { 9746585027aSJan Kara /* 9756585027aSJan Kara * We just wake up the flusher thread. It will perform background 9766585027aSJan Kara * writeback as soon as there is no other work to do. 9776585027aSJan Kara */ 9785634cc2aSTejun Heo trace_writeback_wake_background(wb); 9799ecf4866STejun Heo wb_wakeup(wb); 9801da177e4SLinus Torvalds } 9811da177e4SLinus Torvalds 9821da177e4SLinus Torvalds /* 983a66979abSDave Chinner * Remove the inode from the writeback list it is on. 984a66979abSDave Chinner */ 985c7f54084SDave Chinner void inode_io_list_del(struct inode *inode) 986a66979abSDave Chinner { 98787e1d789STejun Heo struct bdi_writeback *wb; 988a66979abSDave Chinner 98987e1d789STejun Heo wb = inode_to_wb_and_lock_list(inode); 990c7f54084SDave Chinner inode_io_list_del_locked(inode, wb); 99152ebea74STejun Heo spin_unlock(&wb->list_lock); 992f758eeabSChristoph Hellwig } 993a66979abSDave Chinner 994a66979abSDave Chinner /* 9956c60d2b5SDave Chinner * mark an inode as under writeback on the sb 9966c60d2b5SDave Chinner */ 9976c60d2b5SDave Chinner void sb_mark_inode_writeback(struct inode *inode) 9986c60d2b5SDave Chinner { 9996c60d2b5SDave Chinner struct super_block *sb = inode->i_sb; 10006c60d2b5SDave Chinner unsigned long flags; 10016c60d2b5SDave Chinner 10026c60d2b5SDave Chinner if (list_empty(&inode->i_wb_list)) { 10036c60d2b5SDave Chinner spin_lock_irqsave(&sb->s_inode_wblist_lock, flags); 10049a46b04fSBrian Foster if (list_empty(&inode->i_wb_list)) { 10056c60d2b5SDave Chinner list_add_tail(&inode->i_wb_list, &sb->s_inodes_wb); 10069a46b04fSBrian Foster trace_sb_mark_inode_writeback(inode); 10079a46b04fSBrian Foster } 10086c60d2b5SDave Chinner spin_unlock_irqrestore(&sb->s_inode_wblist_lock, flags); 10096c60d2b5SDave Chinner } 10106c60d2b5SDave Chinner } 10116c60d2b5SDave Chinner 10126c60d2b5SDave Chinner /* 10136c60d2b5SDave Chinner * clear an inode as under writeback on the sb 10146c60d2b5SDave Chinner */ 10156c60d2b5SDave Chinner void sb_clear_inode_writeback(struct inode *inode) 10166c60d2b5SDave Chinner { 10176c60d2b5SDave Chinner struct super_block *sb = inode->i_sb; 10186c60d2b5SDave Chinner unsigned long flags; 10196c60d2b5SDave Chinner 10206c60d2b5SDave Chinner if (!list_empty(&inode->i_wb_list)) { 10216c60d2b5SDave Chinner spin_lock_irqsave(&sb->s_inode_wblist_lock, flags); 10229a46b04fSBrian Foster if (!list_empty(&inode->i_wb_list)) { 10236c60d2b5SDave Chinner list_del_init(&inode->i_wb_list); 10249a46b04fSBrian Foster trace_sb_clear_inode_writeback(inode); 10259a46b04fSBrian Foster } 10266c60d2b5SDave Chinner spin_unlock_irqrestore(&sb->s_inode_wblist_lock, flags); 10276c60d2b5SDave Chinner } 10286c60d2b5SDave Chinner } 10296c60d2b5SDave Chinner 10306c60d2b5SDave Chinner /* 10316610a0bcSAndrew Morton * Redirty an inode: set its when-it-was dirtied timestamp and move it to the 10326610a0bcSAndrew Morton * furthest end of its superblock's dirty-inode list. 10336610a0bcSAndrew Morton * 10346610a0bcSAndrew Morton * Before stamping the inode's ->dirtied_when, we check to see whether it is 103566f3b8e2SJens Axboe * already the most-recently-dirtied inode on the b_dirty list. If that is 10366610a0bcSAndrew Morton * the case then the inode must have been redirtied while it was being written 10376610a0bcSAndrew Morton * out and we don't reset its dirtied_when. 10386610a0bcSAndrew Morton */ 1039f758eeabSChristoph Hellwig static void redirty_tail(struct inode *inode, struct bdi_writeback *wb) 10406610a0bcSAndrew Morton { 104103ba3782SJens Axboe if (!list_empty(&wb->b_dirty)) { 104266f3b8e2SJens Axboe struct inode *tail; 10436610a0bcSAndrew Morton 10447ccf19a8SNick Piggin tail = wb_inode(wb->b_dirty.next); 104566f3b8e2SJens Axboe if (time_before(inode->dirtied_when, tail->dirtied_when)) 10466610a0bcSAndrew Morton inode->dirtied_when = jiffies; 10476610a0bcSAndrew Morton } 1048c7f54084SDave Chinner inode_io_list_move_locked(inode, wb, &wb->b_dirty); 10496610a0bcSAndrew Morton } 10506610a0bcSAndrew Morton 10516610a0bcSAndrew Morton /* 105266f3b8e2SJens Axboe * requeue inode for re-scanning after bdi->b_io list is exhausted. 1053c986d1e2SAndrew Morton */ 1054f758eeabSChristoph Hellwig static void requeue_io(struct inode *inode, struct bdi_writeback *wb) 1055c986d1e2SAndrew Morton { 1056c7f54084SDave Chinner inode_io_list_move_locked(inode, wb, &wb->b_more_io); 1057c986d1e2SAndrew Morton } 1058c986d1e2SAndrew Morton 10591c0eeaf5SJoern Engel static void inode_sync_complete(struct inode *inode) 10601c0eeaf5SJoern Engel { 1061365b94aeSJan Kara inode->i_state &= ~I_SYNC; 10624eff96ddSJan Kara /* If inode is clean an unused, put it into LRU now... */ 10634eff96ddSJan Kara inode_add_lru(inode); 1064365b94aeSJan Kara /* Waiters must see I_SYNC cleared before being woken up */ 10651c0eeaf5SJoern Engel smp_mb(); 10661c0eeaf5SJoern Engel wake_up_bit(&inode->i_state, __I_SYNC); 10671c0eeaf5SJoern Engel } 10681c0eeaf5SJoern Engel 1069d2caa3c5SJeff Layton static bool inode_dirtied_after(struct inode *inode, unsigned long t) 1070d2caa3c5SJeff Layton { 1071d2caa3c5SJeff Layton bool ret = time_after(inode->dirtied_when, t); 1072d2caa3c5SJeff Layton #ifndef CONFIG_64BIT 1073d2caa3c5SJeff Layton /* 1074d2caa3c5SJeff Layton * For inodes being constantly redirtied, dirtied_when can get stuck. 1075d2caa3c5SJeff Layton * It _appears_ to be in the future, but is actually in distant past. 1076d2caa3c5SJeff Layton * This test is necessary to prevent such wrapped-around relative times 10775b0830cbSJens Axboe * from permanently stopping the whole bdi writeback. 1078d2caa3c5SJeff Layton */ 1079d2caa3c5SJeff Layton ret = ret && time_before_eq(inode->dirtied_when, jiffies); 1080d2caa3c5SJeff Layton #endif 1081d2caa3c5SJeff Layton return ret; 1082d2caa3c5SJeff Layton } 1083d2caa3c5SJeff Layton 10840ae45f63STheodore Ts'o #define EXPIRE_DIRTY_ATIME 0x0001 10850ae45f63STheodore Ts'o 1086c986d1e2SAndrew Morton /* 10870e2f2b23SWang Sheng-Hui * Move expired (dirtied before work->older_than_this) dirty inodes from 1088697e6fedSJan Kara * @delaying_queue to @dispatch_queue. 10892c136579SFengguang Wu */ 1090e84d0a4fSWu Fengguang static int move_expired_inodes(struct list_head *delaying_queue, 10912c136579SFengguang Wu struct list_head *dispatch_queue, 10920ae45f63STheodore Ts'o int flags, 1093ad4e38ddSCurt Wohlgemuth struct wb_writeback_work *work) 10942c136579SFengguang Wu { 10950ae45f63STheodore Ts'o unsigned long *older_than_this = NULL; 10960ae45f63STheodore Ts'o unsigned long expire_time; 10975c03449dSShaohua Li LIST_HEAD(tmp); 10985c03449dSShaohua Li struct list_head *pos, *node; 1099cf137307SJens Axboe struct super_block *sb = NULL; 11005c03449dSShaohua Li struct inode *inode; 1101cf137307SJens Axboe int do_sb_sort = 0; 1102e84d0a4fSWu Fengguang int moved = 0; 11035c03449dSShaohua Li 11040ae45f63STheodore Ts'o if ((flags & EXPIRE_DIRTY_ATIME) == 0) 11050ae45f63STheodore Ts'o older_than_this = work->older_than_this; 1106a2f48706STheodore Ts'o else if (!work->for_sync) { 1107a2f48706STheodore Ts'o expire_time = jiffies - (dirtytime_expire_interval * HZ); 11080ae45f63STheodore Ts'o older_than_this = &expire_time; 11090ae45f63STheodore Ts'o } 11102c136579SFengguang Wu while (!list_empty(delaying_queue)) { 11117ccf19a8SNick Piggin inode = wb_inode(delaying_queue->prev); 11120ae45f63STheodore Ts'o if (older_than_this && 11130ae45f63STheodore Ts'o inode_dirtied_after(inode, *older_than_this)) 11142c136579SFengguang Wu break; 1115c7f54084SDave Chinner list_move(&inode->i_io_list, &tmp); 1116a8855990SJan Kara moved++; 11170ae45f63STheodore Ts'o if (flags & EXPIRE_DIRTY_ATIME) 11180ae45f63STheodore Ts'o set_bit(__I_DIRTY_TIME_EXPIRED, &inode->i_state); 1119a8855990SJan Kara if (sb_is_blkdev_sb(inode->i_sb)) 1120a8855990SJan Kara continue; 1121cf137307SJens Axboe if (sb && sb != inode->i_sb) 1122cf137307SJens Axboe do_sb_sort = 1; 1123cf137307SJens Axboe sb = inode->i_sb; 11245c03449dSShaohua Li } 11255c03449dSShaohua Li 1126cf137307SJens Axboe /* just one sb in list, splice to dispatch_queue and we're done */ 1127cf137307SJens Axboe if (!do_sb_sort) { 1128cf137307SJens Axboe list_splice(&tmp, dispatch_queue); 1129e84d0a4fSWu Fengguang goto out; 1130cf137307SJens Axboe } 1131cf137307SJens Axboe 11325c03449dSShaohua Li /* Move inodes from one superblock together */ 11335c03449dSShaohua Li while (!list_empty(&tmp)) { 11347ccf19a8SNick Piggin sb = wb_inode(tmp.prev)->i_sb; 11355c03449dSShaohua Li list_for_each_prev_safe(pos, node, &tmp) { 11367ccf19a8SNick Piggin inode = wb_inode(pos); 11375c03449dSShaohua Li if (inode->i_sb == sb) 1138c7f54084SDave Chinner list_move(&inode->i_io_list, dispatch_queue); 11392c136579SFengguang Wu } 11402c136579SFengguang Wu } 1141e84d0a4fSWu Fengguang out: 1142e84d0a4fSWu Fengguang return moved; 11435c03449dSShaohua Li } 11442c136579SFengguang Wu 11452c136579SFengguang Wu /* 11462c136579SFengguang Wu * Queue all expired dirty inodes for io, eldest first. 11474ea879b9SWu Fengguang * Before 11484ea879b9SWu Fengguang * newly dirtied b_dirty b_io b_more_io 11494ea879b9SWu Fengguang * =============> gf edc BA 11504ea879b9SWu Fengguang * After 11514ea879b9SWu Fengguang * newly dirtied b_dirty b_io b_more_io 11524ea879b9SWu Fengguang * =============> g fBAedc 11534ea879b9SWu Fengguang * | 11544ea879b9SWu Fengguang * +--> dequeue for IO 11552c136579SFengguang Wu */ 1156ad4e38ddSCurt Wohlgemuth static void queue_io(struct bdi_writeback *wb, struct wb_writeback_work *work) 11572c136579SFengguang Wu { 1158e84d0a4fSWu Fengguang int moved; 11590ae45f63STheodore Ts'o 1160f758eeabSChristoph Hellwig assert_spin_locked(&wb->list_lock); 11614ea879b9SWu Fengguang list_splice_init(&wb->b_more_io, &wb->b_io); 11620ae45f63STheodore Ts'o moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, 0, work); 11630ae45f63STheodore Ts'o moved += move_expired_inodes(&wb->b_dirty_time, &wb->b_io, 11640ae45f63STheodore Ts'o EXPIRE_DIRTY_ATIME, work); 1165d6c10f1fSTejun Heo if (moved) 1166d6c10f1fSTejun Heo wb_io_lists_populated(wb); 1167ad4e38ddSCurt Wohlgemuth trace_writeback_queue_io(wb, work, moved); 116866f3b8e2SJens Axboe } 116966f3b8e2SJens Axboe 1170a9185b41SChristoph Hellwig static int write_inode(struct inode *inode, struct writeback_control *wbc) 117166f3b8e2SJens Axboe { 11729fb0a7daSTejun Heo int ret; 11739fb0a7daSTejun Heo 11749fb0a7daSTejun Heo if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) { 11759fb0a7daSTejun Heo trace_writeback_write_inode_start(inode, wbc); 11769fb0a7daSTejun Heo ret = inode->i_sb->s_op->write_inode(inode, wbc); 11779fb0a7daSTejun Heo trace_writeback_write_inode(inode, wbc); 11789fb0a7daSTejun Heo return ret; 11799fb0a7daSTejun Heo } 118003ba3782SJens Axboe return 0; 118166f3b8e2SJens Axboe } 118208d8e974SFengguang Wu 11832c136579SFengguang Wu /* 1184169ebd90SJan Kara * Wait for writeback on an inode to complete. Called with i_lock held. 1185169ebd90SJan Kara * Caller must make sure inode cannot go away when we drop i_lock. 118601c03194SChristoph Hellwig */ 1187169ebd90SJan Kara static void __inode_wait_for_writeback(struct inode *inode) 1188169ebd90SJan Kara __releases(inode->i_lock) 1189169ebd90SJan Kara __acquires(inode->i_lock) 119001c03194SChristoph Hellwig { 119101c03194SChristoph Hellwig DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); 119201c03194SChristoph Hellwig wait_queue_head_t *wqh; 119301c03194SChristoph Hellwig 119401c03194SChristoph Hellwig wqh = bit_waitqueue(&inode->i_state, __I_SYNC); 119558a9d3d8SRichard Kennedy while (inode->i_state & I_SYNC) { 1196250df6edSDave Chinner spin_unlock(&inode->i_lock); 119774316201SNeilBrown __wait_on_bit(wqh, &wq, bit_wait, 119874316201SNeilBrown TASK_UNINTERRUPTIBLE); 1199250df6edSDave Chinner spin_lock(&inode->i_lock); 120058a9d3d8SRichard Kennedy } 120101c03194SChristoph Hellwig } 120201c03194SChristoph Hellwig 120301c03194SChristoph Hellwig /* 1204169ebd90SJan Kara * Wait for writeback on an inode to complete. Caller must have inode pinned. 1205169ebd90SJan Kara */ 1206169ebd90SJan Kara void inode_wait_for_writeback(struct inode *inode) 1207169ebd90SJan Kara { 1208169ebd90SJan Kara spin_lock(&inode->i_lock); 1209169ebd90SJan Kara __inode_wait_for_writeback(inode); 1210169ebd90SJan Kara spin_unlock(&inode->i_lock); 1211169ebd90SJan Kara } 1212169ebd90SJan Kara 1213169ebd90SJan Kara /* 1214169ebd90SJan Kara * Sleep until I_SYNC is cleared. This function must be called with i_lock 1215169ebd90SJan Kara * held and drops it. It is aimed for callers not holding any inode reference 1216169ebd90SJan Kara * so once i_lock is dropped, inode can go away. 1217169ebd90SJan Kara */ 1218169ebd90SJan Kara static void inode_sleep_on_writeback(struct inode *inode) 1219169ebd90SJan Kara __releases(inode->i_lock) 1220169ebd90SJan Kara { 1221169ebd90SJan Kara DEFINE_WAIT(wait); 1222169ebd90SJan Kara wait_queue_head_t *wqh = bit_waitqueue(&inode->i_state, __I_SYNC); 1223169ebd90SJan Kara int sleep; 1224169ebd90SJan Kara 1225169ebd90SJan Kara prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); 1226169ebd90SJan Kara sleep = inode->i_state & I_SYNC; 1227169ebd90SJan Kara spin_unlock(&inode->i_lock); 1228169ebd90SJan Kara if (sleep) 1229169ebd90SJan Kara schedule(); 1230169ebd90SJan Kara finish_wait(wqh, &wait); 1231169ebd90SJan Kara } 1232169ebd90SJan Kara 1233169ebd90SJan Kara /* 1234ccb26b5aSJan Kara * Find proper writeback list for the inode depending on its current state and 1235ccb26b5aSJan Kara * possibly also change of its state while we were doing writeback. Here we 1236ccb26b5aSJan Kara * handle things such as livelock prevention or fairness of writeback among 1237ccb26b5aSJan Kara * inodes. This function can be called only by flusher thread - noone else 1238ccb26b5aSJan Kara * processes all inodes in writeback lists and requeueing inodes behind flusher 1239ccb26b5aSJan Kara * thread's back can have unexpected consequences. 1240ccb26b5aSJan Kara */ 1241ccb26b5aSJan Kara static void requeue_inode(struct inode *inode, struct bdi_writeback *wb, 1242ccb26b5aSJan Kara struct writeback_control *wbc) 1243ccb26b5aSJan Kara { 1244ccb26b5aSJan Kara if (inode->i_state & I_FREEING) 1245ccb26b5aSJan Kara return; 1246ccb26b5aSJan Kara 1247ccb26b5aSJan Kara /* 1248ccb26b5aSJan Kara * Sync livelock prevention. Each inode is tagged and synced in one 1249ccb26b5aSJan Kara * shot. If still dirty, it will be redirty_tail()'ed below. Update 1250ccb26b5aSJan Kara * the dirty time to prevent enqueue and sync it again. 1251ccb26b5aSJan Kara */ 1252ccb26b5aSJan Kara if ((inode->i_state & I_DIRTY) && 1253ccb26b5aSJan Kara (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)) 1254ccb26b5aSJan Kara inode->dirtied_when = jiffies; 1255ccb26b5aSJan Kara 12564f8ad655SJan Kara if (wbc->pages_skipped) { 12574f8ad655SJan Kara /* 12584f8ad655SJan Kara * writeback is not making progress due to locked 12594f8ad655SJan Kara * buffers. Skip this inode for now. 12604f8ad655SJan Kara */ 12614f8ad655SJan Kara redirty_tail(inode, wb); 12624f8ad655SJan Kara return; 12634f8ad655SJan Kara } 12644f8ad655SJan Kara 1265ccb26b5aSJan Kara if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) { 1266ccb26b5aSJan Kara /* 1267ccb26b5aSJan Kara * We didn't write back all the pages. nfs_writepages() 1268ccb26b5aSJan Kara * sometimes bales out without doing anything. 1269ccb26b5aSJan Kara */ 1270ccb26b5aSJan Kara if (wbc->nr_to_write <= 0) { 1271ccb26b5aSJan Kara /* Slice used up. Queue for next turn. */ 1272ccb26b5aSJan Kara requeue_io(inode, wb); 1273ccb26b5aSJan Kara } else { 1274ccb26b5aSJan Kara /* 1275ccb26b5aSJan Kara * Writeback blocked by something other than 1276ccb26b5aSJan Kara * congestion. Delay the inode for some time to 1277ccb26b5aSJan Kara * avoid spinning on the CPU (100% iowait) 1278ccb26b5aSJan Kara * retrying writeback of the dirty page/inode 1279ccb26b5aSJan Kara * that cannot be performed immediately. 1280ccb26b5aSJan Kara */ 1281ccb26b5aSJan Kara redirty_tail(inode, wb); 1282ccb26b5aSJan Kara } 1283ccb26b5aSJan Kara } else if (inode->i_state & I_DIRTY) { 1284ccb26b5aSJan Kara /* 1285ccb26b5aSJan Kara * Filesystems can dirty the inode during writeback operations, 1286ccb26b5aSJan Kara * such as delayed allocation during submission or metadata 1287ccb26b5aSJan Kara * updates after data IO completion. 1288ccb26b5aSJan Kara */ 1289ccb26b5aSJan Kara redirty_tail(inode, wb); 12900ae45f63STheodore Ts'o } else if (inode->i_state & I_DIRTY_TIME) { 1291a2f48706STheodore Ts'o inode->dirtied_when = jiffies; 1292c7f54084SDave Chinner inode_io_list_move_locked(inode, wb, &wb->b_dirty_time); 1293ccb26b5aSJan Kara } else { 1294ccb26b5aSJan Kara /* The inode is clean. Remove from writeback lists. */ 1295c7f54084SDave Chinner inode_io_list_del_locked(inode, wb); 1296ccb26b5aSJan Kara } 1297ccb26b5aSJan Kara } 1298ccb26b5aSJan Kara 1299ccb26b5aSJan Kara /* 13004f8ad655SJan Kara * Write out an inode and its dirty pages. Do not update the writeback list 13014f8ad655SJan Kara * linkage. That is left to the caller. The caller is also responsible for 13024f8ad655SJan Kara * setting I_SYNC flag and calling inode_sync_complete() to clear it. 13031da177e4SLinus Torvalds */ 13041da177e4SLinus Torvalds static int 1305cd8ed2a4SYan Hong __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) 13061da177e4SLinus Torvalds { 13071da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 1308251d6a47SWu Fengguang long nr_to_write = wbc->nr_to_write; 130901c03194SChristoph Hellwig unsigned dirty; 13101da177e4SLinus Torvalds int ret; 13111da177e4SLinus Torvalds 13124f8ad655SJan Kara WARN_ON(!(inode->i_state & I_SYNC)); 13131da177e4SLinus Torvalds 13149fb0a7daSTejun Heo trace_writeback_single_inode_start(inode, wbc, nr_to_write); 13159fb0a7daSTejun Heo 13161da177e4SLinus Torvalds ret = do_writepages(mapping, wbc); 13171da177e4SLinus Torvalds 131826821ed4SChristoph Hellwig /* 131926821ed4SChristoph Hellwig * Make sure to wait on the data before writing out the metadata. 132026821ed4SChristoph Hellwig * This is important for filesystems that modify metadata on data 13217747bd4bSDave Chinner * I/O completion. We don't do it for sync(2) writeback because it has a 13227747bd4bSDave Chinner * separate, external IO completion path and ->sync_fs for guaranteeing 13237747bd4bSDave Chinner * inode metadata is written back correctly. 132426821ed4SChristoph Hellwig */ 13257747bd4bSDave Chinner if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync) { 132626821ed4SChristoph Hellwig int err = filemap_fdatawait(mapping); 13271da177e4SLinus Torvalds if (ret == 0) 13281da177e4SLinus Torvalds ret = err; 13291da177e4SLinus Torvalds } 13301da177e4SLinus Torvalds 13315547e8aaSDmitry Monakhov /* 13325547e8aaSDmitry Monakhov * Some filesystems may redirty the inode during the writeback 13335547e8aaSDmitry Monakhov * due to delalloc, clear dirty metadata flags right before 13345547e8aaSDmitry Monakhov * write_inode() 13355547e8aaSDmitry Monakhov */ 1336250df6edSDave Chinner spin_lock(&inode->i_lock); 13379c6ac78eSTejun Heo 13385547e8aaSDmitry Monakhov dirty = inode->i_state & I_DIRTY; 1339a2f48706STheodore Ts'o if (inode->i_state & I_DIRTY_TIME) { 13400e11f644SChristoph Hellwig if ((dirty & I_DIRTY_INODE) || 1341dc5ff2b1SJan Kara wbc->sync_mode == WB_SYNC_ALL || 1342a2f48706STheodore Ts'o unlikely(inode->i_state & I_DIRTY_TIME_EXPIRED) || 1343a2f48706STheodore Ts'o unlikely(time_after(jiffies, 1344a2f48706STheodore Ts'o (inode->dirtied_time_when + 1345a2f48706STheodore Ts'o dirtytime_expire_interval * HZ)))) { 13460ae45f63STheodore Ts'o dirty |= I_DIRTY_TIME | I_DIRTY_TIME_EXPIRED; 13470ae45f63STheodore Ts'o trace_writeback_lazytime(inode); 13480ae45f63STheodore Ts'o } 1349a2f48706STheodore Ts'o } else 1350a2f48706STheodore Ts'o inode->i_state &= ~I_DIRTY_TIME_EXPIRED; 13510ae45f63STheodore Ts'o inode->i_state &= ~dirty; 13529c6ac78eSTejun Heo 13539c6ac78eSTejun Heo /* 13549c6ac78eSTejun Heo * Paired with smp_mb() in __mark_inode_dirty(). This allows 13559c6ac78eSTejun Heo * __mark_inode_dirty() to test i_state without grabbing i_lock - 13569c6ac78eSTejun Heo * either they see the I_DIRTY bits cleared or we see the dirtied 13579c6ac78eSTejun Heo * inode. 13589c6ac78eSTejun Heo * 13599c6ac78eSTejun Heo * I_DIRTY_PAGES is always cleared together above even if @mapping 13609c6ac78eSTejun Heo * still has dirty pages. The flag is reinstated after smp_mb() if 13619c6ac78eSTejun Heo * necessary. This guarantees that either __mark_inode_dirty() 13629c6ac78eSTejun Heo * sees clear I_DIRTY_PAGES or we see PAGECACHE_TAG_DIRTY. 13639c6ac78eSTejun Heo */ 13649c6ac78eSTejun Heo smp_mb(); 13659c6ac78eSTejun Heo 13669c6ac78eSTejun Heo if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) 13679c6ac78eSTejun Heo inode->i_state |= I_DIRTY_PAGES; 13689c6ac78eSTejun Heo 1369250df6edSDave Chinner spin_unlock(&inode->i_lock); 13709c6ac78eSTejun Heo 13710ae45f63STheodore Ts'o if (dirty & I_DIRTY_TIME) 13720ae45f63STheodore Ts'o mark_inode_dirty_sync(inode); 137326821ed4SChristoph Hellwig /* Don't write the inode if only I_DIRTY_PAGES was set */ 13740ae45f63STheodore Ts'o if (dirty & ~I_DIRTY_PAGES) { 1375a9185b41SChristoph Hellwig int err = write_inode(inode, wbc); 13761da177e4SLinus Torvalds if (ret == 0) 13771da177e4SLinus Torvalds ret = err; 13781da177e4SLinus Torvalds } 13794f8ad655SJan Kara trace_writeback_single_inode(inode, wbc, nr_to_write); 13804f8ad655SJan Kara return ret; 13814f8ad655SJan Kara } 13824f8ad655SJan Kara 13834f8ad655SJan Kara /* 13844f8ad655SJan Kara * Write out an inode's dirty pages. Either the caller has an active reference 13854f8ad655SJan Kara * on the inode or the inode has I_WILL_FREE set. 13864f8ad655SJan Kara * 13874f8ad655SJan Kara * This function is designed to be called for writing back one inode which 13884f8ad655SJan Kara * we go e.g. from filesystem. Flusher thread uses __writeback_single_inode() 13894f8ad655SJan Kara * and does more profound writeback list handling in writeback_sb_inodes(). 13904f8ad655SJan Kara */ 1391aaf25593STejun Heo static int writeback_single_inode(struct inode *inode, 13924f8ad655SJan Kara struct writeback_control *wbc) 13934f8ad655SJan Kara { 1394aaf25593STejun Heo struct bdi_writeback *wb; 13954f8ad655SJan Kara int ret = 0; 13964f8ad655SJan Kara 13974f8ad655SJan Kara spin_lock(&inode->i_lock); 13984f8ad655SJan Kara if (!atomic_read(&inode->i_count)) 13994f8ad655SJan Kara WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); 14004f8ad655SJan Kara else 14014f8ad655SJan Kara WARN_ON(inode->i_state & I_WILL_FREE); 14024f8ad655SJan Kara 14034f8ad655SJan Kara if (inode->i_state & I_SYNC) { 14044f8ad655SJan Kara if (wbc->sync_mode != WB_SYNC_ALL) 14054f8ad655SJan Kara goto out; 14064f8ad655SJan Kara /* 1407169ebd90SJan Kara * It's a data-integrity sync. We must wait. Since callers hold 1408169ebd90SJan Kara * inode reference or inode has I_WILL_FREE set, it cannot go 1409169ebd90SJan Kara * away under us. 14104f8ad655SJan Kara */ 1411169ebd90SJan Kara __inode_wait_for_writeback(inode); 14124f8ad655SJan Kara } 14134f8ad655SJan Kara WARN_ON(inode->i_state & I_SYNC); 14144f8ad655SJan Kara /* 1415f9b0e058SJan Kara * Skip inode if it is clean and we have no outstanding writeback in 1416f9b0e058SJan Kara * WB_SYNC_ALL mode. We don't want to mess with writeback lists in this 1417f9b0e058SJan Kara * function since flusher thread may be doing for example sync in 1418f9b0e058SJan Kara * parallel and if we move the inode, it could get skipped. So here we 1419f9b0e058SJan Kara * make sure inode is on some writeback list and leave it there unless 1420f9b0e058SJan Kara * we have completely cleaned the inode. 14214f8ad655SJan Kara */ 14220ae45f63STheodore Ts'o if (!(inode->i_state & I_DIRTY_ALL) && 1423f9b0e058SJan Kara (wbc->sync_mode != WB_SYNC_ALL || 1424f9b0e058SJan Kara !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))) 14254f8ad655SJan Kara goto out; 14264f8ad655SJan Kara inode->i_state |= I_SYNC; 1427b16b1debSTejun Heo wbc_attach_and_unlock_inode(wbc, inode); 14284f8ad655SJan Kara 1429cd8ed2a4SYan Hong ret = __writeback_single_inode(inode, wbc); 14301da177e4SLinus Torvalds 1431b16b1debSTejun Heo wbc_detach_inode(wbc); 1432aaf25593STejun Heo 1433aaf25593STejun Heo wb = inode_to_wb_and_lock_list(inode); 1434250df6edSDave Chinner spin_lock(&inode->i_lock); 14354f8ad655SJan Kara /* 14364f8ad655SJan Kara * If inode is clean, remove it from writeback lists. Otherwise don't 14374f8ad655SJan Kara * touch it. See comment above for explanation. 14384f8ad655SJan Kara */ 14390ae45f63STheodore Ts'o if (!(inode->i_state & I_DIRTY_ALL)) 1440c7f54084SDave Chinner inode_io_list_del_locked(inode, wb); 14414f8ad655SJan Kara spin_unlock(&wb->list_lock); 14421c0eeaf5SJoern Engel inode_sync_complete(inode); 14434f8ad655SJan Kara out: 14444f8ad655SJan Kara spin_unlock(&inode->i_lock); 14451da177e4SLinus Torvalds return ret; 14461da177e4SLinus Torvalds } 14471da177e4SLinus Torvalds 1448a88a341aSTejun Heo static long writeback_chunk_size(struct bdi_writeback *wb, 14491a12d8bdSWu Fengguang struct wb_writeback_work *work) 1450d46db3d5SWu Fengguang { 1451d46db3d5SWu Fengguang long pages; 1452d46db3d5SWu Fengguang 1453d46db3d5SWu Fengguang /* 1454d46db3d5SWu Fengguang * WB_SYNC_ALL mode does livelock avoidance by syncing dirty 1455d46db3d5SWu Fengguang * inodes/pages in one big loop. Setting wbc.nr_to_write=LONG_MAX 1456d46db3d5SWu Fengguang * here avoids calling into writeback_inodes_wb() more than once. 1457d46db3d5SWu Fengguang * 1458d46db3d5SWu Fengguang * The intended call sequence for WB_SYNC_ALL writeback is: 1459d46db3d5SWu Fengguang * 1460d46db3d5SWu Fengguang * wb_writeback() 1461d46db3d5SWu Fengguang * writeback_sb_inodes() <== called only once 1462d46db3d5SWu Fengguang * write_cache_pages() <== called once for each inode 1463d46db3d5SWu Fengguang * (quickly) tag currently dirty pages 1464d46db3d5SWu Fengguang * (maybe slowly) sync all tagged pages 1465d46db3d5SWu Fengguang */ 1466d46db3d5SWu Fengguang if (work->sync_mode == WB_SYNC_ALL || work->tagged_writepages) 1467d46db3d5SWu Fengguang pages = LONG_MAX; 14681a12d8bdSWu Fengguang else { 1469a88a341aSTejun Heo pages = min(wb->avg_write_bandwidth / 2, 1470dcc25ae7STejun Heo global_wb_domain.dirty_limit / DIRTY_SCOPE); 14711a12d8bdSWu Fengguang pages = min(pages, work->nr_pages); 14721a12d8bdSWu Fengguang pages = round_down(pages + MIN_WRITEBACK_PAGES, 14731a12d8bdSWu Fengguang MIN_WRITEBACK_PAGES); 14741a12d8bdSWu Fengguang } 1475d46db3d5SWu Fengguang 1476d46db3d5SWu Fengguang return pages; 1477d46db3d5SWu Fengguang } 1478d46db3d5SWu Fengguang 147903ba3782SJens Axboe /* 1480f11c9c5cSEdward Shishkin * Write a portion of b_io inodes which belong to @sb. 1481edadfb10SChristoph Hellwig * 1482d46db3d5SWu Fengguang * Return the number of pages and/or inodes written. 14830ba13fd1SLinus Torvalds * 14840ba13fd1SLinus Torvalds * NOTE! This is called with wb->list_lock held, and will 14850ba13fd1SLinus Torvalds * unlock and relock that for each inode it ends up doing 14860ba13fd1SLinus Torvalds * IO for. 1487f11c9c5cSEdward Shishkin */ 1488d46db3d5SWu Fengguang static long writeback_sb_inodes(struct super_block *sb, 1489d46db3d5SWu Fengguang struct bdi_writeback *wb, 1490d46db3d5SWu Fengguang struct wb_writeback_work *work) 149103ba3782SJens Axboe { 1492d46db3d5SWu Fengguang struct writeback_control wbc = { 1493d46db3d5SWu Fengguang .sync_mode = work->sync_mode, 1494d46db3d5SWu Fengguang .tagged_writepages = work->tagged_writepages, 1495d46db3d5SWu Fengguang .for_kupdate = work->for_kupdate, 1496d46db3d5SWu Fengguang .for_background = work->for_background, 14977747bd4bSDave Chinner .for_sync = work->for_sync, 1498d46db3d5SWu Fengguang .range_cyclic = work->range_cyclic, 1499d46db3d5SWu Fengguang .range_start = 0, 1500d46db3d5SWu Fengguang .range_end = LLONG_MAX, 1501d46db3d5SWu Fengguang }; 1502d46db3d5SWu Fengguang unsigned long start_time = jiffies; 1503d46db3d5SWu Fengguang long write_chunk; 1504d46db3d5SWu Fengguang long wrote = 0; /* count both pages and inodes */ 1505d46db3d5SWu Fengguang 150603ba3782SJens Axboe while (!list_empty(&wb->b_io)) { 15077ccf19a8SNick Piggin struct inode *inode = wb_inode(wb->b_io.prev); 1508aaf25593STejun Heo struct bdi_writeback *tmp_wb; 1509edadfb10SChristoph Hellwig 1510edadfb10SChristoph Hellwig if (inode->i_sb != sb) { 1511d46db3d5SWu Fengguang if (work->sb) { 1512edadfb10SChristoph Hellwig /* 1513edadfb10SChristoph Hellwig * We only want to write back data for this 1514edadfb10SChristoph Hellwig * superblock, move all inodes not belonging 1515edadfb10SChristoph Hellwig * to it back onto the dirty list. 1516edadfb10SChristoph Hellwig */ 1517f758eeabSChristoph Hellwig redirty_tail(inode, wb); 151866f3b8e2SJens Axboe continue; 151966f3b8e2SJens Axboe } 1520edadfb10SChristoph Hellwig 1521edadfb10SChristoph Hellwig /* 1522edadfb10SChristoph Hellwig * The inode belongs to a different superblock. 1523edadfb10SChristoph Hellwig * Bounce back to the caller to unpin this and 1524edadfb10SChristoph Hellwig * pin the next superblock. 1525edadfb10SChristoph Hellwig */ 1526d46db3d5SWu Fengguang break; 1527edadfb10SChristoph Hellwig } 1528edadfb10SChristoph Hellwig 15299843b76aSChristoph Hellwig /* 1530331cbdeeSWanpeng Li * Don't bother with new inodes or inodes being freed, first 1531331cbdeeSWanpeng Li * kind does not need periodic writeout yet, and for the latter 15329843b76aSChristoph Hellwig * kind writeout is handled by the freer. 15339843b76aSChristoph Hellwig */ 1534250df6edSDave Chinner spin_lock(&inode->i_lock); 15359843b76aSChristoph Hellwig if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { 1536250df6edSDave Chinner spin_unlock(&inode->i_lock); 1537fcc5c222SWu Fengguang redirty_tail(inode, wb); 15387ef0d737SNick Piggin continue; 15397ef0d737SNick Piggin } 1540cc1676d9SJan Kara if ((inode->i_state & I_SYNC) && wbc.sync_mode != WB_SYNC_ALL) { 1541cc1676d9SJan Kara /* 1542cc1676d9SJan Kara * If this inode is locked for writeback and we are not 1543cc1676d9SJan Kara * doing writeback-for-data-integrity, move it to 1544cc1676d9SJan Kara * b_more_io so that writeback can proceed with the 1545cc1676d9SJan Kara * other inodes on s_io. 1546cc1676d9SJan Kara * 1547cc1676d9SJan Kara * We'll have another go at writing back this inode 1548cc1676d9SJan Kara * when we completed a full scan of b_io. 1549cc1676d9SJan Kara */ 1550cc1676d9SJan Kara spin_unlock(&inode->i_lock); 1551cc1676d9SJan Kara requeue_io(inode, wb); 1552cc1676d9SJan Kara trace_writeback_sb_inodes_requeue(inode); 1553cc1676d9SJan Kara continue; 1554cc1676d9SJan Kara } 1555f0d07b7fSJan Kara spin_unlock(&wb->list_lock); 1556f0d07b7fSJan Kara 15574f8ad655SJan Kara /* 15584f8ad655SJan Kara * We already requeued the inode if it had I_SYNC set and we 15594f8ad655SJan Kara * are doing WB_SYNC_NONE writeback. So this catches only the 15604f8ad655SJan Kara * WB_SYNC_ALL case. 15614f8ad655SJan Kara */ 1562169ebd90SJan Kara if (inode->i_state & I_SYNC) { 1563169ebd90SJan Kara /* Wait for I_SYNC. This function drops i_lock... */ 1564169ebd90SJan Kara inode_sleep_on_writeback(inode); 1565169ebd90SJan Kara /* Inode may be gone, start again */ 1566ead188f9SJan Kara spin_lock(&wb->list_lock); 1567169ebd90SJan Kara continue; 1568169ebd90SJan Kara } 15694f8ad655SJan Kara inode->i_state |= I_SYNC; 1570b16b1debSTejun Heo wbc_attach_and_unlock_inode(&wbc, inode); 1571169ebd90SJan Kara 1572a88a341aSTejun Heo write_chunk = writeback_chunk_size(wb, work); 1573d46db3d5SWu Fengguang wbc.nr_to_write = write_chunk; 1574d46db3d5SWu Fengguang wbc.pages_skipped = 0; 1575250df6edSDave Chinner 1576169ebd90SJan Kara /* 1577169ebd90SJan Kara * We use I_SYNC to pin the inode in memory. While it is set 1578169ebd90SJan Kara * evict_inode() will wait so the inode cannot be freed. 1579169ebd90SJan Kara */ 1580cd8ed2a4SYan Hong __writeback_single_inode(inode, &wbc); 1581d46db3d5SWu Fengguang 1582b16b1debSTejun Heo wbc_detach_inode(&wbc); 1583d46db3d5SWu Fengguang work->nr_pages -= write_chunk - wbc.nr_to_write; 1584d46db3d5SWu Fengguang wrote += write_chunk - wbc.nr_to_write; 1585590dca3aSChris Mason 1586590dca3aSChris Mason if (need_resched()) { 1587590dca3aSChris Mason /* 1588590dca3aSChris Mason * We're trying to balance between building up a nice 1589590dca3aSChris Mason * long list of IOs to improve our merge rate, and 1590590dca3aSChris Mason * getting those IOs out quickly for anyone throttling 1591590dca3aSChris Mason * in balance_dirty_pages(). cond_resched() doesn't 1592590dca3aSChris Mason * unplug, so get our IOs out the door before we 1593590dca3aSChris Mason * give up the CPU. 1594590dca3aSChris Mason */ 1595590dca3aSChris Mason blk_flush_plug(current); 1596590dca3aSChris Mason cond_resched(); 1597590dca3aSChris Mason } 1598590dca3aSChris Mason 1599aaf25593STejun Heo /* 1600aaf25593STejun Heo * Requeue @inode if still dirty. Be careful as @inode may 1601aaf25593STejun Heo * have been switched to another wb in the meantime. 1602aaf25593STejun Heo */ 1603aaf25593STejun Heo tmp_wb = inode_to_wb_and_lock_list(inode); 16044f8ad655SJan Kara spin_lock(&inode->i_lock); 16050ae45f63STheodore Ts'o if (!(inode->i_state & I_DIRTY_ALL)) 1606d46db3d5SWu Fengguang wrote++; 1607aaf25593STejun Heo requeue_inode(inode, tmp_wb, &wbc); 16084f8ad655SJan Kara inode_sync_complete(inode); 16090f1b1fd8SDave Chinner spin_unlock(&inode->i_lock); 1610590dca3aSChris Mason 1611aaf25593STejun Heo if (unlikely(tmp_wb != wb)) { 1612aaf25593STejun Heo spin_unlock(&tmp_wb->list_lock); 1613aaf25593STejun Heo spin_lock(&wb->list_lock); 1614aaf25593STejun Heo } 1615aaf25593STejun Heo 1616d46db3d5SWu Fengguang /* 1617d46db3d5SWu Fengguang * bail out to wb_writeback() often enough to check 1618d46db3d5SWu Fengguang * background threshold and other termination conditions. 1619d46db3d5SWu Fengguang */ 1620d46db3d5SWu Fengguang if (wrote) { 1621d46db3d5SWu Fengguang if (time_is_before_jiffies(start_time + HZ / 10UL)) 1622d46db3d5SWu Fengguang break; 1623d46db3d5SWu Fengguang if (work->nr_pages <= 0) 1624d46db3d5SWu Fengguang break; 16251da177e4SLinus Torvalds } 16268bc3be27SFengguang Wu } 1627d46db3d5SWu Fengguang return wrote; 1628f11c9c5cSEdward Shishkin } 162938f21977SNick Piggin 1630d46db3d5SWu Fengguang static long __writeback_inodes_wb(struct bdi_writeback *wb, 1631d46db3d5SWu Fengguang struct wb_writeback_work *work) 1632f11c9c5cSEdward Shishkin { 1633d46db3d5SWu Fengguang unsigned long start_time = jiffies; 1634d46db3d5SWu Fengguang long wrote = 0; 1635f11c9c5cSEdward Shishkin 1636f11c9c5cSEdward Shishkin while (!list_empty(&wb->b_io)) { 16377ccf19a8SNick Piggin struct inode *inode = wb_inode(wb->b_io.prev); 1638f11c9c5cSEdward Shishkin struct super_block *sb = inode->i_sb; 1639f11c9c5cSEdward Shishkin 1640eb6ef3dfSKonstantin Khlebnikov if (!trylock_super(sb)) { 16410e995816SWu Fengguang /* 1642eb6ef3dfSKonstantin Khlebnikov * trylock_super() may fail consistently due to 16430e995816SWu Fengguang * s_umount being grabbed by someone else. Don't use 16440e995816SWu Fengguang * requeue_io() to avoid busy retrying the inode/sb. 16450e995816SWu Fengguang */ 16460e995816SWu Fengguang redirty_tail(inode, wb); 1647d19de7edSChristoph Hellwig continue; 1648334132aeSChristoph Hellwig } 1649d46db3d5SWu Fengguang wrote += writeback_sb_inodes(sb, wb, work); 1650eb6ef3dfSKonstantin Khlebnikov up_read(&sb->s_umount); 1651f11c9c5cSEdward Shishkin 1652d46db3d5SWu Fengguang /* refer to the same tests at the end of writeback_sb_inodes */ 1653d46db3d5SWu Fengguang if (wrote) { 1654d46db3d5SWu Fengguang if (time_is_before_jiffies(start_time + HZ / 10UL)) 1655d46db3d5SWu Fengguang break; 1656d46db3d5SWu Fengguang if (work->nr_pages <= 0) 1657f11c9c5cSEdward Shishkin break; 1658f11c9c5cSEdward Shishkin } 1659d46db3d5SWu Fengguang } 166066f3b8e2SJens Axboe /* Leave any unwritten inodes on b_io */ 1661d46db3d5SWu Fengguang return wrote; 166266f3b8e2SJens Axboe } 166366f3b8e2SJens Axboe 16647d9f073bSWanpeng Li static long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, 16650e175a18SCurt Wohlgemuth enum wb_reason reason) 1666edadfb10SChristoph Hellwig { 1667d46db3d5SWu Fengguang struct wb_writeback_work work = { 1668d46db3d5SWu Fengguang .nr_pages = nr_pages, 1669d46db3d5SWu Fengguang .sync_mode = WB_SYNC_NONE, 1670d46db3d5SWu Fengguang .range_cyclic = 1, 16710e175a18SCurt Wohlgemuth .reason = reason, 1672d46db3d5SWu Fengguang }; 1673505a666eSLinus Torvalds struct blk_plug plug; 1674edadfb10SChristoph Hellwig 1675505a666eSLinus Torvalds blk_start_plug(&plug); 1676f758eeabSChristoph Hellwig spin_lock(&wb->list_lock); 1677424b351fSWu Fengguang if (list_empty(&wb->b_io)) 1678ad4e38ddSCurt Wohlgemuth queue_io(wb, &work); 1679d46db3d5SWu Fengguang __writeback_inodes_wb(wb, &work); 1680f758eeabSChristoph Hellwig spin_unlock(&wb->list_lock); 1681505a666eSLinus Torvalds blk_finish_plug(&plug); 1682edadfb10SChristoph Hellwig 1683d46db3d5SWu Fengguang return nr_pages - work.nr_pages; 168466f3b8e2SJens Axboe } 168566f3b8e2SJens Axboe 168603ba3782SJens Axboe /* 168703ba3782SJens Axboe * Explicit flushing or periodic writeback of "old" data. 168803ba3782SJens Axboe * 168903ba3782SJens Axboe * Define "old": the first time one of an inode's pages is dirtied, we mark the 169003ba3782SJens Axboe * dirtying-time in the inode's address_space. So this periodic writeback code 169103ba3782SJens Axboe * just walks the superblock inode list, writing back any inodes which are 169203ba3782SJens Axboe * older than a specific point in time. 169303ba3782SJens Axboe * 169403ba3782SJens Axboe * Try to run once per dirty_writeback_interval. But if a writeback event 169503ba3782SJens Axboe * takes longer than a dirty_writeback_interval interval, then leave a 169603ba3782SJens Axboe * one-second gap. 169703ba3782SJens Axboe * 169803ba3782SJens Axboe * older_than_this takes precedence over nr_to_write. So we'll only write back 169903ba3782SJens Axboe * all dirty pages if they are all attached to "old" mappings. 170003ba3782SJens Axboe */ 1701c4a77a6cSJens Axboe static long wb_writeback(struct bdi_writeback *wb, 170283ba7b07SChristoph Hellwig struct wb_writeback_work *work) 170303ba3782SJens Axboe { 1704e98be2d5SWu Fengguang unsigned long wb_start = jiffies; 1705d46db3d5SWu Fengguang long nr_pages = work->nr_pages; 17060dc83bd3SJan Kara unsigned long oldest_jif; 1707a5989bdcSJan Kara struct inode *inode; 1708d46db3d5SWu Fengguang long progress; 1709505a666eSLinus Torvalds struct blk_plug plug; 171003ba3782SJens Axboe 17110dc83bd3SJan Kara oldest_jif = jiffies; 17120dc83bd3SJan Kara work->older_than_this = &oldest_jif; 171303ba3782SJens Axboe 1714505a666eSLinus Torvalds blk_start_plug(&plug); 1715e8dfc305SWu Fengguang spin_lock(&wb->list_lock); 171603ba3782SJens Axboe for (;;) { 171703ba3782SJens Axboe /* 1718d3ddec76SWu Fengguang * Stop writeback when nr_pages has been consumed 171903ba3782SJens Axboe */ 172083ba7b07SChristoph Hellwig if (work->nr_pages <= 0) 172103ba3782SJens Axboe break; 172203ba3782SJens Axboe 172303ba3782SJens Axboe /* 1724aa373cf5SJan Kara * Background writeout and kupdate-style writeback may 1725aa373cf5SJan Kara * run forever. Stop them if there is other work to do 1726aa373cf5SJan Kara * so that e.g. sync can proceed. They'll be restarted 1727aa373cf5SJan Kara * after the other works are all done. 1728aa373cf5SJan Kara */ 1729aa373cf5SJan Kara if ((work->for_background || work->for_kupdate) && 1730f0054bb1STejun Heo !list_empty(&wb->work_list)) 1731aa373cf5SJan Kara break; 1732aa373cf5SJan Kara 1733aa373cf5SJan Kara /* 1734d3ddec76SWu Fengguang * For background writeout, stop when we are below the 1735d3ddec76SWu Fengguang * background dirty threshold 173603ba3782SJens Axboe */ 1737aa661bbeSTejun Heo if (work->for_background && !wb_over_bg_thresh(wb)) 173803ba3782SJens Axboe break; 173903ba3782SJens Axboe 17401bc36b64SJan Kara /* 17411bc36b64SJan Kara * Kupdate and background works are special and we want to 17421bc36b64SJan Kara * include all inodes that need writing. Livelock avoidance is 17431bc36b64SJan Kara * handled by these works yielding to any other work so we are 17441bc36b64SJan Kara * safe. 17451bc36b64SJan Kara */ 1746ba9aa839SWu Fengguang if (work->for_kupdate) { 17470dc83bd3SJan Kara oldest_jif = jiffies - 1748ba9aa839SWu Fengguang msecs_to_jiffies(dirty_expire_interval * 10); 17491bc36b64SJan Kara } else if (work->for_background) 17500dc83bd3SJan Kara oldest_jif = jiffies; 1751028c2dd1SDave Chinner 17525634cc2aSTejun Heo trace_writeback_start(wb, work); 1753e8dfc305SWu Fengguang if (list_empty(&wb->b_io)) 1754ad4e38ddSCurt Wohlgemuth queue_io(wb, work); 175583ba7b07SChristoph Hellwig if (work->sb) 1756d46db3d5SWu Fengguang progress = writeback_sb_inodes(work->sb, wb, work); 1757edadfb10SChristoph Hellwig else 1758d46db3d5SWu Fengguang progress = __writeback_inodes_wb(wb, work); 17595634cc2aSTejun Heo trace_writeback_written(wb, work); 1760028c2dd1SDave Chinner 1761e98be2d5SWu Fengguang wb_update_bandwidth(wb, wb_start); 176203ba3782SJens Axboe 176303ba3782SJens Axboe /* 176471fd05a8SJens Axboe * Did we write something? Try for more 1765e6fb6da2SWu Fengguang * 1766e6fb6da2SWu Fengguang * Dirty inodes are moved to b_io for writeback in batches. 1767e6fb6da2SWu Fengguang * The completion of the current batch does not necessarily 1768e6fb6da2SWu Fengguang * mean the overall work is done. So we keep looping as long 1769e6fb6da2SWu Fengguang * as made some progress on cleaning pages or inodes. 177071fd05a8SJens Axboe */ 1771d46db3d5SWu Fengguang if (progress) 177203ba3782SJens Axboe continue; 1773a5989bdcSJan Kara /* 1774e6fb6da2SWu Fengguang * No more inodes for IO, bail 1775a5989bdcSJan Kara */ 1776b7a2441fSWu Fengguang if (list_empty(&wb->b_more_io)) 177703ba3782SJens Axboe break; 177803ba3782SJens Axboe /* 17798010c3b6SJens Axboe * Nothing written. Wait for some inode to 17808010c3b6SJens Axboe * become available for writeback. Otherwise 17818010c3b6SJens Axboe * we'll just busyloop. 178203ba3782SJens Axboe */ 17835634cc2aSTejun Heo trace_writeback_wait(wb, work); 178403ba3782SJens Axboe inode = wb_inode(wb->b_more_io.prev); 1785250df6edSDave Chinner spin_lock(&inode->i_lock); 1786f0d07b7fSJan Kara spin_unlock(&wb->list_lock); 1787169ebd90SJan Kara /* This function drops i_lock... */ 1788169ebd90SJan Kara inode_sleep_on_writeback(inode); 1789f0d07b7fSJan Kara spin_lock(&wb->list_lock); 179003ba3782SJens Axboe } 1791e8dfc305SWu Fengguang spin_unlock(&wb->list_lock); 1792505a666eSLinus Torvalds blk_finish_plug(&plug); 179303ba3782SJens Axboe 1794d46db3d5SWu Fengguang return nr_pages - work->nr_pages; 179503ba3782SJens Axboe } 179603ba3782SJens Axboe 179703ba3782SJens Axboe /* 179883ba7b07SChristoph Hellwig * Return the next wb_writeback_work struct that hasn't been processed yet. 179903ba3782SJens Axboe */ 1800f0054bb1STejun Heo static struct wb_writeback_work *get_next_work_item(struct bdi_writeback *wb) 180103ba3782SJens Axboe { 180283ba7b07SChristoph Hellwig struct wb_writeback_work *work = NULL; 180303ba3782SJens Axboe 1804f0054bb1STejun Heo spin_lock_bh(&wb->work_lock); 1805f0054bb1STejun Heo if (!list_empty(&wb->work_list)) { 1806f0054bb1STejun Heo work = list_entry(wb->work_list.next, 180783ba7b07SChristoph Hellwig struct wb_writeback_work, list); 180883ba7b07SChristoph Hellwig list_del_init(&work->list); 180903ba3782SJens Axboe } 1810f0054bb1STejun Heo spin_unlock_bh(&wb->work_lock); 181183ba7b07SChristoph Hellwig return work; 181203ba3782SJens Axboe } 181303ba3782SJens Axboe 18146585027aSJan Kara static long wb_check_background_flush(struct bdi_writeback *wb) 18156585027aSJan Kara { 1816aa661bbeSTejun Heo if (wb_over_bg_thresh(wb)) { 18176585027aSJan Kara 18186585027aSJan Kara struct wb_writeback_work work = { 18196585027aSJan Kara .nr_pages = LONG_MAX, 18206585027aSJan Kara .sync_mode = WB_SYNC_NONE, 18216585027aSJan Kara .for_background = 1, 18226585027aSJan Kara .range_cyclic = 1, 18230e175a18SCurt Wohlgemuth .reason = WB_REASON_BACKGROUND, 18246585027aSJan Kara }; 18256585027aSJan Kara 18266585027aSJan Kara return wb_writeback(wb, &work); 18276585027aSJan Kara } 18286585027aSJan Kara 18296585027aSJan Kara return 0; 18306585027aSJan Kara } 18316585027aSJan Kara 183203ba3782SJens Axboe static long wb_check_old_data_flush(struct bdi_writeback *wb) 183303ba3782SJens Axboe { 183403ba3782SJens Axboe unsigned long expired; 183503ba3782SJens Axboe long nr_pages; 183603ba3782SJens Axboe 183769b62d01SJens Axboe /* 183869b62d01SJens Axboe * When set to zero, disable periodic writeback 183969b62d01SJens Axboe */ 184069b62d01SJens Axboe if (!dirty_writeback_interval) 184169b62d01SJens Axboe return 0; 184269b62d01SJens Axboe 184303ba3782SJens Axboe expired = wb->last_old_flush + 184403ba3782SJens Axboe msecs_to_jiffies(dirty_writeback_interval * 10); 184503ba3782SJens Axboe if (time_before(jiffies, expired)) 184603ba3782SJens Axboe return 0; 184703ba3782SJens Axboe 184803ba3782SJens Axboe wb->last_old_flush = jiffies; 1849cdf01dd5SLinus Torvalds nr_pages = get_nr_dirty_pages(); 185003ba3782SJens Axboe 1851c4a77a6cSJens Axboe if (nr_pages) { 185283ba7b07SChristoph Hellwig struct wb_writeback_work work = { 1853c4a77a6cSJens Axboe .nr_pages = nr_pages, 1854c4a77a6cSJens Axboe .sync_mode = WB_SYNC_NONE, 1855c4a77a6cSJens Axboe .for_kupdate = 1, 1856c4a77a6cSJens Axboe .range_cyclic = 1, 18570e175a18SCurt Wohlgemuth .reason = WB_REASON_PERIODIC, 1858c4a77a6cSJens Axboe }; 1859c4a77a6cSJens Axboe 186083ba7b07SChristoph Hellwig return wb_writeback(wb, &work); 1861c4a77a6cSJens Axboe } 186203ba3782SJens Axboe 186303ba3782SJens Axboe return 0; 186403ba3782SJens Axboe } 186503ba3782SJens Axboe 186685009b4fSJens Axboe static long wb_check_start_all(struct bdi_writeback *wb) 186785009b4fSJens Axboe { 186885009b4fSJens Axboe long nr_pages; 186985009b4fSJens Axboe 187085009b4fSJens Axboe if (!test_bit(WB_start_all, &wb->state)) 187185009b4fSJens Axboe return 0; 187285009b4fSJens Axboe 187385009b4fSJens Axboe nr_pages = get_nr_dirty_pages(); 187485009b4fSJens Axboe if (nr_pages) { 187585009b4fSJens Axboe struct wb_writeback_work work = { 187685009b4fSJens Axboe .nr_pages = wb_split_bdi_pages(wb, nr_pages), 187785009b4fSJens Axboe .sync_mode = WB_SYNC_NONE, 187885009b4fSJens Axboe .range_cyclic = 1, 187985009b4fSJens Axboe .reason = wb->start_all_reason, 188085009b4fSJens Axboe }; 188185009b4fSJens Axboe 188285009b4fSJens Axboe nr_pages = wb_writeback(wb, &work); 188385009b4fSJens Axboe } 188485009b4fSJens Axboe 188585009b4fSJens Axboe clear_bit(WB_start_all, &wb->state); 188685009b4fSJens Axboe return nr_pages; 188785009b4fSJens Axboe } 188885009b4fSJens Axboe 188985009b4fSJens Axboe 189003ba3782SJens Axboe /* 189103ba3782SJens Axboe * Retrieve work items and do the writeback they describe 189203ba3782SJens Axboe */ 189325d130baSWanpeng Li static long wb_do_writeback(struct bdi_writeback *wb) 189403ba3782SJens Axboe { 189583ba7b07SChristoph Hellwig struct wb_writeback_work *work; 1896c4a77a6cSJens Axboe long wrote = 0; 189703ba3782SJens Axboe 18984452226eSTejun Heo set_bit(WB_writeback_running, &wb->state); 1899f0054bb1STejun Heo while ((work = get_next_work_item(wb)) != NULL) { 19005634cc2aSTejun Heo trace_writeback_exec(wb, work); 190183ba7b07SChristoph Hellwig wrote += wb_writeback(wb, work); 19024a3a485bSTahsin Erdogan finish_writeback_work(wb, work); 190303ba3782SJens Axboe } 190403ba3782SJens Axboe 190503ba3782SJens Axboe /* 190685009b4fSJens Axboe * Check for a flush-everything request 190785009b4fSJens Axboe */ 190885009b4fSJens Axboe wrote += wb_check_start_all(wb); 190985009b4fSJens Axboe 191085009b4fSJens Axboe /* 191103ba3782SJens Axboe * Check for periodic writeback, kupdated() style 191203ba3782SJens Axboe */ 191303ba3782SJens Axboe wrote += wb_check_old_data_flush(wb); 19146585027aSJan Kara wrote += wb_check_background_flush(wb); 19154452226eSTejun Heo clear_bit(WB_writeback_running, &wb->state); 191603ba3782SJens Axboe 191703ba3782SJens Axboe return wrote; 191803ba3782SJens Axboe } 191903ba3782SJens Axboe 192003ba3782SJens Axboe /* 192103ba3782SJens Axboe * Handle writeback of dirty data for the device backed by this bdi. Also 1922839a8e86STejun Heo * reschedules periodically and does kupdated style flushing. 192303ba3782SJens Axboe */ 1924f0054bb1STejun Heo void wb_workfn(struct work_struct *work) 192503ba3782SJens Axboe { 1926839a8e86STejun Heo struct bdi_writeback *wb = container_of(to_delayed_work(work), 1927839a8e86STejun Heo struct bdi_writeback, dwork); 192803ba3782SJens Axboe long pages_written; 192903ba3782SJens Axboe 1930f0054bb1STejun Heo set_worker_desc("flush-%s", dev_name(wb->bdi->dev)); 1931766f9164SPeter Zijlstra current->flags |= PF_SWAPWRITE; 193203ba3782SJens Axboe 1933839a8e86STejun Heo if (likely(!current_is_workqueue_rescuer() || 19344452226eSTejun Heo !test_bit(WB_registered, &wb->state))) { 193503ba3782SJens Axboe /* 1936f0054bb1STejun Heo * The normal path. Keep writing back @wb until its 1937839a8e86STejun Heo * work_list is empty. Note that this path is also taken 1938f0054bb1STejun Heo * if @wb is shutting down even when we're running off the 1939839a8e86STejun Heo * rescuer as work_list needs to be drained. 194003ba3782SJens Axboe */ 1941839a8e86STejun Heo do { 194225d130baSWanpeng Li pages_written = wb_do_writeback(wb); 1943455b2864SDave Chinner trace_writeback_pages_written(pages_written); 1944f0054bb1STejun Heo } while (!list_empty(&wb->work_list)); 1945839a8e86STejun Heo } else { 1946253c34e9SArtem Bityutskiy /* 1947839a8e86STejun Heo * bdi_wq can't get enough workers and we're running off 1948839a8e86STejun Heo * the emergency worker. Don't hog it. Hopefully, 1024 is 1949839a8e86STejun Heo * enough for efficient IO. 1950253c34e9SArtem Bityutskiy */ 1951f0054bb1STejun Heo pages_written = writeback_inodes_wb(wb, 1024, 1952839a8e86STejun Heo WB_REASON_FORKER_THREAD); 1953839a8e86STejun Heo trace_writeback_pages_written(pages_written); 195403ba3782SJens Axboe } 195503ba3782SJens Axboe 1956f0054bb1STejun Heo if (!list_empty(&wb->work_list)) 1957b8b78495SJan Kara wb_wakeup(wb); 19586ca738d6SDerek Basehore else if (wb_has_dirty_io(wb) && dirty_writeback_interval) 1959f0054bb1STejun Heo wb_wakeup_delayed(wb); 1960455b2864SDave Chinner 1961839a8e86STejun Heo current->flags &= ~PF_SWAPWRITE; 196203ba3782SJens Axboe } 196303ba3782SJens Axboe 196403ba3782SJens Axboe /* 1965595043e5SJens Axboe * Start writeback of `nr_pages' pages on this bdi. If `nr_pages' is zero, 1966595043e5SJens Axboe * write back the whole world. 1967595043e5SJens Axboe */ 1968595043e5SJens Axboe static void __wakeup_flusher_threads_bdi(struct backing_dev_info *bdi, 1969e8e8a0c6SJens Axboe enum wb_reason reason) 1970595043e5SJens Axboe { 1971595043e5SJens Axboe struct bdi_writeback *wb; 1972595043e5SJens Axboe 1973595043e5SJens Axboe if (!bdi_has_dirty_io(bdi)) 1974595043e5SJens Axboe return; 1975595043e5SJens Axboe 1976595043e5SJens Axboe list_for_each_entry_rcu(wb, &bdi->wb_list, bdi_node) 1977e8e8a0c6SJens Axboe wb_start_writeback(wb, reason); 1978595043e5SJens Axboe } 1979595043e5SJens Axboe 1980595043e5SJens Axboe void wakeup_flusher_threads_bdi(struct backing_dev_info *bdi, 1981595043e5SJens Axboe enum wb_reason reason) 1982595043e5SJens Axboe { 1983595043e5SJens Axboe rcu_read_lock(); 1984e8e8a0c6SJens Axboe __wakeup_flusher_threads_bdi(bdi, reason); 1985595043e5SJens Axboe rcu_read_unlock(); 1986595043e5SJens Axboe } 1987595043e5SJens Axboe 1988595043e5SJens Axboe /* 19899ba4b2dfSJens Axboe * Wakeup the flusher threads to start writeback of all currently dirty pages 199003ba3782SJens Axboe */ 19919ba4b2dfSJens Axboe void wakeup_flusher_threads(enum wb_reason reason) 199203ba3782SJens Axboe { 1993b8c2f347SChristoph Hellwig struct backing_dev_info *bdi; 1994b8c2f347SChristoph Hellwig 199551350ea0SKonstantin Khlebnikov /* 199651350ea0SKonstantin Khlebnikov * If we are expecting writeback progress we must submit plugged IO. 199751350ea0SKonstantin Khlebnikov */ 199851350ea0SKonstantin Khlebnikov if (blk_needs_flush_plug(current)) 199951350ea0SKonstantin Khlebnikov blk_schedule_flush_plug(current); 200051350ea0SKonstantin Khlebnikov 2001b8c2f347SChristoph Hellwig rcu_read_lock(); 2002595043e5SJens Axboe list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) 2003e8e8a0c6SJens Axboe __wakeup_flusher_threads_bdi(bdi, reason); 2004b8c2f347SChristoph Hellwig rcu_read_unlock(); 200503ba3782SJens Axboe } 200603ba3782SJens Axboe 2007a2f48706STheodore Ts'o /* 2008a2f48706STheodore Ts'o * Wake up bdi's periodically to make sure dirtytime inodes gets 2009a2f48706STheodore Ts'o * written back periodically. We deliberately do *not* check the 2010a2f48706STheodore Ts'o * b_dirtytime list in wb_has_dirty_io(), since this would cause the 2011a2f48706STheodore Ts'o * kernel to be constantly waking up once there are any dirtytime 2012a2f48706STheodore Ts'o * inodes on the system. So instead we define a separate delayed work 2013a2f48706STheodore Ts'o * function which gets called much more rarely. (By default, only 2014a2f48706STheodore Ts'o * once every 12 hours.) 2015a2f48706STheodore Ts'o * 2016a2f48706STheodore Ts'o * If there is any other write activity going on in the file system, 2017a2f48706STheodore Ts'o * this function won't be necessary. But if the only thing that has 2018a2f48706STheodore Ts'o * happened on the file system is a dirtytime inode caused by an atime 2019a2f48706STheodore Ts'o * update, we need this infrastructure below to make sure that inode 2020a2f48706STheodore Ts'o * eventually gets pushed out to disk. 2021a2f48706STheodore Ts'o */ 2022a2f48706STheodore Ts'o static void wakeup_dirtytime_writeback(struct work_struct *w); 2023a2f48706STheodore Ts'o static DECLARE_DELAYED_WORK(dirtytime_work, wakeup_dirtytime_writeback); 2024a2f48706STheodore Ts'o 2025a2f48706STheodore Ts'o static void wakeup_dirtytime_writeback(struct work_struct *w) 2026a2f48706STheodore Ts'o { 2027a2f48706STheodore Ts'o struct backing_dev_info *bdi; 2028a2f48706STheodore Ts'o 2029a2f48706STheodore Ts'o rcu_read_lock(); 2030a2f48706STheodore Ts'o list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { 2031001fe6f6STejun Heo struct bdi_writeback *wb; 2032001fe6f6STejun Heo 2033b817525aSTejun Heo list_for_each_entry_rcu(wb, &bdi->wb_list, bdi_node) 20346fdf860fSTejun Heo if (!list_empty(&wb->b_dirty_time)) 20356fdf860fSTejun Heo wb_wakeup(wb); 2036a2f48706STheodore Ts'o } 2037a2f48706STheodore Ts'o rcu_read_unlock(); 2038a2f48706STheodore Ts'o schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ); 2039a2f48706STheodore Ts'o } 2040a2f48706STheodore Ts'o 2041a2f48706STheodore Ts'o static int __init start_dirtytime_writeback(void) 2042a2f48706STheodore Ts'o { 2043a2f48706STheodore Ts'o schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ); 2044a2f48706STheodore Ts'o return 0; 2045a2f48706STheodore Ts'o } 2046a2f48706STheodore Ts'o __initcall(start_dirtytime_writeback); 2047a2f48706STheodore Ts'o 20481efff914STheodore Ts'o int dirtytime_interval_handler(struct ctl_table *table, int write, 20491efff914STheodore Ts'o void __user *buffer, size_t *lenp, loff_t *ppos) 20501efff914STheodore Ts'o { 20511efff914STheodore Ts'o int ret; 20521efff914STheodore Ts'o 20531efff914STheodore Ts'o ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); 20541efff914STheodore Ts'o if (ret == 0 && write) 20551efff914STheodore Ts'o mod_delayed_work(system_wq, &dirtytime_work, 0); 20561efff914STheodore Ts'o return ret; 20571efff914STheodore Ts'o } 20581efff914STheodore Ts'o 205903ba3782SJens Axboe static noinline void block_dump___mark_inode_dirty(struct inode *inode) 206003ba3782SJens Axboe { 206103ba3782SJens Axboe if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { 206203ba3782SJens Axboe struct dentry *dentry; 206303ba3782SJens Axboe const char *name = "?"; 206403ba3782SJens Axboe 206503ba3782SJens Axboe dentry = d_find_alias(inode); 206603ba3782SJens Axboe if (dentry) { 206703ba3782SJens Axboe spin_lock(&dentry->d_lock); 206803ba3782SJens Axboe name = (const char *) dentry->d_name.name; 206903ba3782SJens Axboe } 207003ba3782SJens Axboe printk(KERN_DEBUG 207103ba3782SJens Axboe "%s(%d): dirtied inode %lu (%s) on %s\n", 207203ba3782SJens Axboe current->comm, task_pid_nr(current), inode->i_ino, 207303ba3782SJens Axboe name, inode->i_sb->s_id); 207403ba3782SJens Axboe if (dentry) { 207503ba3782SJens Axboe spin_unlock(&dentry->d_lock); 207603ba3782SJens Axboe dput(dentry); 207703ba3782SJens Axboe } 207803ba3782SJens Axboe } 207903ba3782SJens Axboe } 208003ba3782SJens Axboe 208103ba3782SJens Axboe /** 208203ba3782SJens Axboe * __mark_inode_dirty - internal function 20830117d427SMauro Carvalho Chehab * 208403ba3782SJens Axboe * @inode: inode to mark 208503ba3782SJens Axboe * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) 20860117d427SMauro Carvalho Chehab * 208703ba3782SJens Axboe * Mark an inode as dirty. Callers should use mark_inode_dirty or 208803ba3782SJens Axboe * mark_inode_dirty_sync. 208903ba3782SJens Axboe * 209003ba3782SJens Axboe * Put the inode on the super block's dirty list. 209103ba3782SJens Axboe * 209203ba3782SJens Axboe * CAREFUL! We mark it dirty unconditionally, but move it onto the 209303ba3782SJens Axboe * dirty list only if it is hashed or if it refers to a blockdev. 209403ba3782SJens Axboe * If it was not hashed, it will never be added to the dirty list 209503ba3782SJens Axboe * even if it is later hashed, as it will have been marked dirty already. 209603ba3782SJens Axboe * 209703ba3782SJens Axboe * In short, make sure you hash any inodes _before_ you start marking 209803ba3782SJens Axboe * them dirty. 209903ba3782SJens Axboe * 210003ba3782SJens Axboe * Note that for blockdevs, inode->dirtied_when represents the dirtying time of 210103ba3782SJens Axboe * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of 210203ba3782SJens Axboe * the kernel-internal blockdev inode represents the dirtying time of the 210303ba3782SJens Axboe * blockdev's pages. This is why for I_DIRTY_PAGES we always use 210403ba3782SJens Axboe * page->mapping->host, so the page-dirtying time is recorded in the internal 210503ba3782SJens Axboe * blockdev inode. 210603ba3782SJens Axboe */ 210703ba3782SJens Axboe void __mark_inode_dirty(struct inode *inode, int flags) 210803ba3782SJens Axboe { 210903ba3782SJens Axboe struct super_block *sb = inode->i_sb; 21100ae45f63STheodore Ts'o int dirtytime; 21110ae45f63STheodore Ts'o 21120ae45f63STheodore Ts'o trace_writeback_mark_inode_dirty(inode, flags); 211303ba3782SJens Axboe 211403ba3782SJens Axboe /* 211503ba3782SJens Axboe * Don't do this for I_DIRTY_PAGES - that doesn't actually 211603ba3782SJens Axboe * dirty the inode itself 211703ba3782SJens Axboe */ 21180e11f644SChristoph Hellwig if (flags & (I_DIRTY_INODE | I_DIRTY_TIME)) { 21199fb0a7daSTejun Heo trace_writeback_dirty_inode_start(inode, flags); 21209fb0a7daSTejun Heo 212103ba3782SJens Axboe if (sb->s_op->dirty_inode) 2122aa385729SChristoph Hellwig sb->s_op->dirty_inode(inode, flags); 21239fb0a7daSTejun Heo 21249fb0a7daSTejun Heo trace_writeback_dirty_inode(inode, flags); 212503ba3782SJens Axboe } 21260ae45f63STheodore Ts'o if (flags & I_DIRTY_INODE) 21270ae45f63STheodore Ts'o flags &= ~I_DIRTY_TIME; 21280ae45f63STheodore Ts'o dirtytime = flags & I_DIRTY_TIME; 212903ba3782SJens Axboe 213003ba3782SJens Axboe /* 21319c6ac78eSTejun Heo * Paired with smp_mb() in __writeback_single_inode() for the 21329c6ac78eSTejun Heo * following lockless i_state test. See there for details. 213303ba3782SJens Axboe */ 213403ba3782SJens Axboe smp_mb(); 213503ba3782SJens Axboe 21360ae45f63STheodore Ts'o if (((inode->i_state & flags) == flags) || 21370ae45f63STheodore Ts'o (dirtytime && (inode->i_state & I_DIRTY_INODE))) 213803ba3782SJens Axboe return; 213903ba3782SJens Axboe 214003ba3782SJens Axboe if (unlikely(block_dump)) 214103ba3782SJens Axboe block_dump___mark_inode_dirty(inode); 214203ba3782SJens Axboe 2143250df6edSDave Chinner spin_lock(&inode->i_lock); 21440ae45f63STheodore Ts'o if (dirtytime && (inode->i_state & I_DIRTY_INODE)) 21450ae45f63STheodore Ts'o goto out_unlock_inode; 214603ba3782SJens Axboe if ((inode->i_state & flags) != flags) { 214703ba3782SJens Axboe const int was_dirty = inode->i_state & I_DIRTY; 214803ba3782SJens Axboe 214952ebea74STejun Heo inode_attach_wb(inode, NULL); 215052ebea74STejun Heo 21510ae45f63STheodore Ts'o if (flags & I_DIRTY_INODE) 21520ae45f63STheodore Ts'o inode->i_state &= ~I_DIRTY_TIME; 215303ba3782SJens Axboe inode->i_state |= flags; 215403ba3782SJens Axboe 215503ba3782SJens Axboe /* 215603ba3782SJens Axboe * If the inode is being synced, just update its dirty state. 215703ba3782SJens Axboe * The unlocker will place the inode on the appropriate 215803ba3782SJens Axboe * superblock list, based upon its state. 215903ba3782SJens Axboe */ 216003ba3782SJens Axboe if (inode->i_state & I_SYNC) 2161250df6edSDave Chinner goto out_unlock_inode; 216203ba3782SJens Axboe 216303ba3782SJens Axboe /* 216403ba3782SJens Axboe * Only add valid (hashed) inodes to the superblock's 216503ba3782SJens Axboe * dirty list. Add blockdev inodes as well. 216603ba3782SJens Axboe */ 216703ba3782SJens Axboe if (!S_ISBLK(inode->i_mode)) { 21681d3382cbSAl Viro if (inode_unhashed(inode)) 2169250df6edSDave Chinner goto out_unlock_inode; 217003ba3782SJens Axboe } 2171a4ffdde6SAl Viro if (inode->i_state & I_FREEING) 2172250df6edSDave Chinner goto out_unlock_inode; 217303ba3782SJens Axboe 217403ba3782SJens Axboe /* 217503ba3782SJens Axboe * If the inode was already on b_dirty/b_io/b_more_io, don't 217603ba3782SJens Axboe * reposition it (that would break b_dirty time-ordering). 217703ba3782SJens Axboe */ 217803ba3782SJens Axboe if (!was_dirty) { 217987e1d789STejun Heo struct bdi_writeback *wb; 2180d6c10f1fSTejun Heo struct list_head *dirty_list; 2181a66979abSDave Chinner bool wakeup_bdi = false; 2182500b067cSJens Axboe 218387e1d789STejun Heo wb = locked_inode_to_wb_and_lock_list(inode); 2184253c34e9SArtem Bityutskiy 21850747259dSTejun Heo WARN(bdi_cap_writeback_dirty(wb->bdi) && 21860747259dSTejun Heo !test_bit(WB_registered, &wb->state), 21870747259dSTejun Heo "bdi-%s not registered\n", wb->bdi->name); 218803ba3782SJens Axboe 218903ba3782SJens Axboe inode->dirtied_when = jiffies; 2190a2f48706STheodore Ts'o if (dirtytime) 2191a2f48706STheodore Ts'o inode->dirtied_time_when = jiffies; 2192d6c10f1fSTejun Heo 21930e11f644SChristoph Hellwig if (inode->i_state & I_DIRTY) 21940747259dSTejun Heo dirty_list = &wb->b_dirty; 2195a2f48706STheodore Ts'o else 21960747259dSTejun Heo dirty_list = &wb->b_dirty_time; 2197d6c10f1fSTejun Heo 2198c7f54084SDave Chinner wakeup_bdi = inode_io_list_move_locked(inode, wb, 2199d6c10f1fSTejun Heo dirty_list); 2200d6c10f1fSTejun Heo 22010747259dSTejun Heo spin_unlock(&wb->list_lock); 22020ae45f63STheodore Ts'o trace_writeback_dirty_inode_enqueue(inode); 2203253c34e9SArtem Bityutskiy 2204d6c10f1fSTejun Heo /* 2205d6c10f1fSTejun Heo * If this is the first dirty inode for this bdi, 2206d6c10f1fSTejun Heo * we have to wake-up the corresponding bdi thread 2207d6c10f1fSTejun Heo * to make sure background write-back happens 2208d6c10f1fSTejun Heo * later. 2209d6c10f1fSTejun Heo */ 22100747259dSTejun Heo if (bdi_cap_writeback_dirty(wb->bdi) && wakeup_bdi) 22110747259dSTejun Heo wb_wakeup_delayed(wb); 2212a66979abSDave Chinner return; 2213a66979abSDave Chinner } 2214a66979abSDave Chinner } 2215a66979abSDave Chinner out_unlock_inode: 2216a66979abSDave Chinner spin_unlock(&inode->i_lock); 221703ba3782SJens Axboe } 221803ba3782SJens Axboe EXPORT_SYMBOL(__mark_inode_dirty); 221903ba3782SJens Axboe 2220e97fedb9SDave Chinner /* 2221e97fedb9SDave Chinner * The @s_sync_lock is used to serialise concurrent sync operations 2222e97fedb9SDave Chinner * to avoid lock contention problems with concurrent wait_sb_inodes() calls. 2223e97fedb9SDave Chinner * Concurrent callers will block on the s_sync_lock rather than doing contending 2224e97fedb9SDave Chinner * walks. The queueing maintains sync(2) required behaviour as all the IO that 2225e97fedb9SDave Chinner * has been issued up to the time this function is enter is guaranteed to be 2226e97fedb9SDave Chinner * completed by the time we have gained the lock and waited for all IO that is 2227e97fedb9SDave Chinner * in progress regardless of the order callers are granted the lock. 2228e97fedb9SDave Chinner */ 2229b6e51316SJens Axboe static void wait_sb_inodes(struct super_block *sb) 223066f3b8e2SJens Axboe { 22316c60d2b5SDave Chinner LIST_HEAD(sync_list); 223238f21977SNick Piggin 223303ba3782SJens Axboe /* 223403ba3782SJens Axboe * We need to be protected against the filesystem going from 223503ba3782SJens Axboe * r/o to r/w or vice versa. 223603ba3782SJens Axboe */ 2237b6e51316SJens Axboe WARN_ON(!rwsem_is_locked(&sb->s_umount)); 223803ba3782SJens Axboe 2239e97fedb9SDave Chinner mutex_lock(&sb->s_sync_lock); 224066f3b8e2SJens Axboe 224138f21977SNick Piggin /* 22426c60d2b5SDave Chinner * Splice the writeback list onto a temporary list to avoid waiting on 22436c60d2b5SDave Chinner * inodes that have started writeback after this point. 22446c60d2b5SDave Chinner * 22456c60d2b5SDave Chinner * Use rcu_read_lock() to keep the inodes around until we have a 22466c60d2b5SDave Chinner * reference. s_inode_wblist_lock protects sb->s_inodes_wb as well as 22476c60d2b5SDave Chinner * the local list because inodes can be dropped from either by writeback 22486c60d2b5SDave Chinner * completion. 224938f21977SNick Piggin */ 22506c60d2b5SDave Chinner rcu_read_lock(); 22516c60d2b5SDave Chinner spin_lock_irq(&sb->s_inode_wblist_lock); 22526c60d2b5SDave Chinner list_splice_init(&sb->s_inodes_wb, &sync_list); 22536c60d2b5SDave Chinner 22546c60d2b5SDave Chinner /* 22556c60d2b5SDave Chinner * Data integrity sync. Must wait for all pages under writeback, because 22566c60d2b5SDave Chinner * there may have been pages dirtied before our sync call, but which had 22576c60d2b5SDave Chinner * writeout started before we write it out. In which case, the inode 22586c60d2b5SDave Chinner * may not be on the dirty list, but we still have to wait for that 22596c60d2b5SDave Chinner * writeout. 22606c60d2b5SDave Chinner */ 22616c60d2b5SDave Chinner while (!list_empty(&sync_list)) { 22626c60d2b5SDave Chinner struct inode *inode = list_first_entry(&sync_list, struct inode, 22636c60d2b5SDave Chinner i_wb_list); 2264250df6edSDave Chinner struct address_space *mapping = inode->i_mapping; 226538f21977SNick Piggin 22666c60d2b5SDave Chinner /* 22676c60d2b5SDave Chinner * Move each inode back to the wb list before we drop the lock 22686c60d2b5SDave Chinner * to preserve consistency between i_wb_list and the mapping 22696c60d2b5SDave Chinner * writeback tag. Writeback completion is responsible to remove 22706c60d2b5SDave Chinner * the inode from either list once the writeback tag is cleared. 22716c60d2b5SDave Chinner */ 22726c60d2b5SDave Chinner list_move_tail(&inode->i_wb_list, &sb->s_inodes_wb); 22736c60d2b5SDave Chinner 22746c60d2b5SDave Chinner /* 22756c60d2b5SDave Chinner * The mapping can appear untagged while still on-list since we 22766c60d2b5SDave Chinner * do not have the mapping lock. Skip it here, wb completion 22776c60d2b5SDave Chinner * will remove it. 22786c60d2b5SDave Chinner */ 22796c60d2b5SDave Chinner if (!mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK)) 22806c60d2b5SDave Chinner continue; 22816c60d2b5SDave Chinner 22826c60d2b5SDave Chinner spin_unlock_irq(&sb->s_inode_wblist_lock); 22836c60d2b5SDave Chinner 2284250df6edSDave Chinner spin_lock(&inode->i_lock); 22856c60d2b5SDave Chinner if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) { 2286250df6edSDave Chinner spin_unlock(&inode->i_lock); 22876c60d2b5SDave Chinner 22886c60d2b5SDave Chinner spin_lock_irq(&sb->s_inode_wblist_lock); 228938f21977SNick Piggin continue; 2290250df6edSDave Chinner } 229138f21977SNick Piggin __iget(inode); 2292250df6edSDave Chinner spin_unlock(&inode->i_lock); 22936c60d2b5SDave Chinner rcu_read_unlock(); 229438f21977SNick Piggin 2295aa750fd7SJunichi Nomura /* 2296aa750fd7SJunichi Nomura * We keep the error status of individual mapping so that 2297aa750fd7SJunichi Nomura * applications can catch the writeback error using fsync(2). 2298aa750fd7SJunichi Nomura * See filemap_fdatawait_keep_errors() for details. 2299aa750fd7SJunichi Nomura */ 2300aa750fd7SJunichi Nomura filemap_fdatawait_keep_errors(mapping); 230138f21977SNick Piggin 230238f21977SNick Piggin cond_resched(); 230338f21977SNick Piggin 23046c60d2b5SDave Chinner iput(inode); 23056c60d2b5SDave Chinner 23066c60d2b5SDave Chinner rcu_read_lock(); 23076c60d2b5SDave Chinner spin_lock_irq(&sb->s_inode_wblist_lock); 230838f21977SNick Piggin } 23096c60d2b5SDave Chinner spin_unlock_irq(&sb->s_inode_wblist_lock); 23106c60d2b5SDave Chinner rcu_read_unlock(); 2311e97fedb9SDave Chinner mutex_unlock(&sb->s_sync_lock); 231266f3b8e2SJens Axboe } 23131da177e4SLinus Torvalds 2314f30a7d0cSTejun Heo static void __writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr, 2315f30a7d0cSTejun Heo enum wb_reason reason, bool skip_if_busy) 23161da177e4SLinus Torvalds { 2317cc395d7fSTejun Heo DEFINE_WB_COMPLETION_ONSTACK(done); 231883ba7b07SChristoph Hellwig struct wb_writeback_work work = { 23193c4d7165SChristoph Hellwig .sb = sb, 23203c4d7165SChristoph Hellwig .sync_mode = WB_SYNC_NONE, 23216e6938b6SWu Fengguang .tagged_writepages = 1, 232283ba7b07SChristoph Hellwig .done = &done, 23233259f8beSChris Mason .nr_pages = nr, 23240e175a18SCurt Wohlgemuth .reason = reason, 23253c4d7165SChristoph Hellwig }; 2326e7972912STejun Heo struct backing_dev_info *bdi = sb->s_bdi; 23270e3c9a22SJens Axboe 2328e7972912STejun Heo if (!bdi_has_dirty_io(bdi) || bdi == &noop_backing_dev_info) 23296eedc701SJan Kara return; 2330cf37e972SChristoph Hellwig WARN_ON(!rwsem_is_locked(&sb->s_umount)); 2331f30a7d0cSTejun Heo 2332db125360STejun Heo bdi_split_work_to_wbs(sb->s_bdi, &work, skip_if_busy); 2333cc395d7fSTejun Heo wb_wait_for_completion(bdi, &done); 23341da177e4SLinus Torvalds } 2335f30a7d0cSTejun Heo 2336f30a7d0cSTejun Heo /** 2337f30a7d0cSTejun Heo * writeback_inodes_sb_nr - writeback dirty inodes from given super_block 2338f30a7d0cSTejun Heo * @sb: the superblock 2339f30a7d0cSTejun Heo * @nr: the number of pages to write 2340f30a7d0cSTejun Heo * @reason: reason why some writeback work initiated 2341f30a7d0cSTejun Heo * 2342f30a7d0cSTejun Heo * Start writeback on some inodes on this super_block. No guarantees are made 2343f30a7d0cSTejun Heo * on how many (if any) will be written, and this function does not wait 2344f30a7d0cSTejun Heo * for IO completion of submitted IO. 2345f30a7d0cSTejun Heo */ 2346f30a7d0cSTejun Heo void writeback_inodes_sb_nr(struct super_block *sb, 2347f30a7d0cSTejun Heo unsigned long nr, 2348f30a7d0cSTejun Heo enum wb_reason reason) 2349f30a7d0cSTejun Heo { 2350f30a7d0cSTejun Heo __writeback_inodes_sb_nr(sb, nr, reason, false); 2351f30a7d0cSTejun Heo } 23523259f8beSChris Mason EXPORT_SYMBOL(writeback_inodes_sb_nr); 23533259f8beSChris Mason 23543259f8beSChris Mason /** 23553259f8beSChris Mason * writeback_inodes_sb - writeback dirty inodes from given super_block 23563259f8beSChris Mason * @sb: the superblock 2357786228abSMarcos Paulo de Souza * @reason: reason why some writeback work was initiated 23583259f8beSChris Mason * 23593259f8beSChris Mason * Start writeback on some inodes on this super_block. No guarantees are made 23603259f8beSChris Mason * on how many (if any) will be written, and this function does not wait 23613259f8beSChris Mason * for IO completion of submitted IO. 23623259f8beSChris Mason */ 23630e175a18SCurt Wohlgemuth void writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) 23643259f8beSChris Mason { 23650e175a18SCurt Wohlgemuth return writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); 23663259f8beSChris Mason } 2367d8a8559cSJens Axboe EXPORT_SYMBOL(writeback_inodes_sb); 2368d8a8559cSJens Axboe 2369d8a8559cSJens Axboe /** 237010ee27a0SMiao Xie * try_to_writeback_inodes_sb - try to start writeback if none underway 237110ee27a0SMiao Xie * @sb: the superblock 237210ee27a0SMiao Xie * @reason: reason why some writeback work was initiated 237310ee27a0SMiao Xie * 23748264c321SRakesh Pandit * Invoke __writeback_inodes_sb_nr if no writeback is currently underway. 237510ee27a0SMiao Xie */ 23768264c321SRakesh Pandit void try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) 237710ee27a0SMiao Xie { 23788264c321SRakesh Pandit if (!down_read_trylock(&sb->s_umount)) 23798264c321SRakesh Pandit return; 23808264c321SRakesh Pandit 23818264c321SRakesh Pandit __writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason, true); 23828264c321SRakesh Pandit up_read(&sb->s_umount); 238310ee27a0SMiao Xie } 238410ee27a0SMiao Xie EXPORT_SYMBOL(try_to_writeback_inodes_sb); 23853259f8beSChris Mason 23863259f8beSChris Mason /** 2387d8a8559cSJens Axboe * sync_inodes_sb - sync sb inode pages 2388d8a8559cSJens Axboe * @sb: the superblock 2389d8a8559cSJens Axboe * 2390d8a8559cSJens Axboe * This function writes and waits on any dirty inode belonging to this 23910dc83bd3SJan Kara * super_block. 2392d8a8559cSJens Axboe */ 23930dc83bd3SJan Kara void sync_inodes_sb(struct super_block *sb) 2394d8a8559cSJens Axboe { 2395cc395d7fSTejun Heo DEFINE_WB_COMPLETION_ONSTACK(done); 239683ba7b07SChristoph Hellwig struct wb_writeback_work work = { 23973c4d7165SChristoph Hellwig .sb = sb, 23983c4d7165SChristoph Hellwig .sync_mode = WB_SYNC_ALL, 23993c4d7165SChristoph Hellwig .nr_pages = LONG_MAX, 24003c4d7165SChristoph Hellwig .range_cyclic = 0, 240183ba7b07SChristoph Hellwig .done = &done, 24020e175a18SCurt Wohlgemuth .reason = WB_REASON_SYNC, 24037747bd4bSDave Chinner .for_sync = 1, 24043c4d7165SChristoph Hellwig }; 2405e7972912STejun Heo struct backing_dev_info *bdi = sb->s_bdi; 24063c4d7165SChristoph Hellwig 2407006a0973STejun Heo /* 2408006a0973STejun Heo * Can't skip on !bdi_has_dirty() because we should wait for !dirty 2409006a0973STejun Heo * inodes under writeback and I_DIRTY_TIME inodes ignored by 2410006a0973STejun Heo * bdi_has_dirty() need to be written out too. 2411006a0973STejun Heo */ 2412006a0973STejun Heo if (bdi == &noop_backing_dev_info) 24136eedc701SJan Kara return; 2414cf37e972SChristoph Hellwig WARN_ON(!rwsem_is_locked(&sb->s_umount)); 2415cf37e972SChristoph Hellwig 2416db125360STejun Heo bdi_split_work_to_wbs(bdi, &work, false); 2417cc395d7fSTejun Heo wb_wait_for_completion(bdi, &done); 241883ba7b07SChristoph Hellwig 2419b6e51316SJens Axboe wait_sb_inodes(sb); 2420d8a8559cSJens Axboe } 2421d8a8559cSJens Axboe EXPORT_SYMBOL(sync_inodes_sb); 24221da177e4SLinus Torvalds 24231da177e4SLinus Torvalds /** 24241da177e4SLinus Torvalds * write_inode_now - write an inode to disk 24251da177e4SLinus Torvalds * @inode: inode to write to disk 24261da177e4SLinus Torvalds * @sync: whether the write should be synchronous or not 24271da177e4SLinus Torvalds * 24287f04c26dSAndrea Arcangeli * This function commits an inode to disk immediately if it is dirty. This is 24297f04c26dSAndrea Arcangeli * primarily needed by knfsd. 24307f04c26dSAndrea Arcangeli * 24317f04c26dSAndrea Arcangeli * The caller must either have a ref on the inode or must have set I_WILL_FREE. 24321da177e4SLinus Torvalds */ 24331da177e4SLinus Torvalds int write_inode_now(struct inode *inode, int sync) 24341da177e4SLinus Torvalds { 24351da177e4SLinus Torvalds struct writeback_control wbc = { 24361da177e4SLinus Torvalds .nr_to_write = LONG_MAX, 243718914b18SMike Galbraith .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, 2438111ebb6eSOGAWA Hirofumi .range_start = 0, 2439111ebb6eSOGAWA Hirofumi .range_end = LLONG_MAX, 24401da177e4SLinus Torvalds }; 24411da177e4SLinus Torvalds 24421da177e4SLinus Torvalds if (!mapping_cap_writeback_dirty(inode->i_mapping)) 244349364ce2SAndrew Morton wbc.nr_to_write = 0; 24441da177e4SLinus Torvalds 24451da177e4SLinus Torvalds might_sleep(); 2446aaf25593STejun Heo return writeback_single_inode(inode, &wbc); 24471da177e4SLinus Torvalds } 24481da177e4SLinus Torvalds EXPORT_SYMBOL(write_inode_now); 24491da177e4SLinus Torvalds 24501da177e4SLinus Torvalds /** 24511da177e4SLinus Torvalds * sync_inode - write an inode and its pages to disk. 24521da177e4SLinus Torvalds * @inode: the inode to sync 24531da177e4SLinus Torvalds * @wbc: controls the writeback mode 24541da177e4SLinus Torvalds * 24551da177e4SLinus Torvalds * sync_inode() will write an inode and its pages to disk. It will also 24561da177e4SLinus Torvalds * correctly update the inode on its superblock's dirty inode lists and will 24571da177e4SLinus Torvalds * update inode->i_state. 24581da177e4SLinus Torvalds * 24591da177e4SLinus Torvalds * The caller must have a ref on the inode. 24601da177e4SLinus Torvalds */ 24611da177e4SLinus Torvalds int sync_inode(struct inode *inode, struct writeback_control *wbc) 24621da177e4SLinus Torvalds { 2463aaf25593STejun Heo return writeback_single_inode(inode, wbc); 24641da177e4SLinus Torvalds } 24651da177e4SLinus Torvalds EXPORT_SYMBOL(sync_inode); 2466c3765016SChristoph Hellwig 2467c3765016SChristoph Hellwig /** 2468c691b9d9SAndrew Morton * sync_inode_metadata - write an inode to disk 2469c3765016SChristoph Hellwig * @inode: the inode to sync 2470c3765016SChristoph Hellwig * @wait: wait for I/O to complete. 2471c3765016SChristoph Hellwig * 2472c691b9d9SAndrew Morton * Write an inode to disk and adjust its dirty state after completion. 2473c3765016SChristoph Hellwig * 2474c3765016SChristoph Hellwig * Note: only writes the actual inode, no associated data or other metadata. 2475c3765016SChristoph Hellwig */ 2476c3765016SChristoph Hellwig int sync_inode_metadata(struct inode *inode, int wait) 2477c3765016SChristoph Hellwig { 2478c3765016SChristoph Hellwig struct writeback_control wbc = { 2479c3765016SChristoph Hellwig .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_NONE, 2480c3765016SChristoph Hellwig .nr_to_write = 0, /* metadata-only */ 2481c3765016SChristoph Hellwig }; 2482c3765016SChristoph Hellwig 2483c3765016SChristoph Hellwig return sync_inode(inode, &wbc); 2484c3765016SChristoph Hellwig } 2485c3765016SChristoph Hellwig EXPORT_SYMBOL(sync_inode_metadata); 2486