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 */ 36bc31b86aSWu Fengguang #define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_CACHE_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 129d6c10f1fSTejun Heo * @head: one of @wb->b_{dirty|io|more_io} 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 176f0054bb1STejun Heo static void wb_queue_work(struct bdi_writeback *wb, 1776585027aSJan Kara struct wb_writeback_work *work) 1786585027aSJan Kara { 1795634cc2aSTejun Heo trace_writeback_queue(wb, work); 1806585027aSJan Kara 181f0054bb1STejun Heo spin_lock_bh(&wb->work_lock); 1828a1270cdSTejun Heo if (!test_bit(WB_registered, &wb->state)) 1835acda9d1SJan Kara goto out_unlock; 184cc395d7fSTejun Heo if (work->done) 185cc395d7fSTejun Heo atomic_inc(&work->done->cnt); 186f0054bb1STejun Heo list_add_tail(&work->list, &wb->work_list); 187f0054bb1STejun Heo mod_delayed_work(bdi_wq, &wb->dwork, 0); 1885acda9d1SJan Kara out_unlock: 189f0054bb1STejun Heo spin_unlock_bh(&wb->work_lock); 19003ba3782SJens Axboe } 1911da177e4SLinus Torvalds 192cc395d7fSTejun Heo /** 193cc395d7fSTejun Heo * wb_wait_for_completion - wait for completion of bdi_writeback_works 194cc395d7fSTejun Heo * @bdi: bdi work items were issued to 195cc395d7fSTejun Heo * @done: target wb_completion 196cc395d7fSTejun Heo * 197cc395d7fSTejun Heo * Wait for one or more work items issued to @bdi with their ->done field 198cc395d7fSTejun Heo * set to @done, which should have been defined with 199cc395d7fSTejun Heo * DEFINE_WB_COMPLETION_ONSTACK(). This function returns after all such 200cc395d7fSTejun Heo * work items are completed. Work items which are waited upon aren't freed 201cc395d7fSTejun Heo * automatically on completion. 202cc395d7fSTejun Heo */ 203cc395d7fSTejun Heo static void wb_wait_for_completion(struct backing_dev_info *bdi, 204cc395d7fSTejun Heo struct wb_completion *done) 205cc395d7fSTejun Heo { 206cc395d7fSTejun Heo atomic_dec(&done->cnt); /* put down the initial count */ 207cc395d7fSTejun Heo wait_event(bdi->wb_waitq, !atomic_read(&done->cnt)); 208cc395d7fSTejun Heo } 209cc395d7fSTejun Heo 210703c2708STejun Heo #ifdef CONFIG_CGROUP_WRITEBACK 211703c2708STejun Heo 2122a814908STejun Heo /* parameters for foreign inode detection, see wb_detach_inode() */ 2132a814908STejun Heo #define WB_FRN_TIME_SHIFT 13 /* 1s = 2^13, upto 8 secs w/ 16bit */ 2142a814908STejun Heo #define WB_FRN_TIME_AVG_SHIFT 3 /* avg = avg * 7/8 + new * 1/8 */ 2152a814908STejun Heo #define WB_FRN_TIME_CUT_DIV 2 /* ignore rounds < avg / 2 */ 2162a814908STejun Heo #define WB_FRN_TIME_PERIOD (2 * (1 << WB_FRN_TIME_SHIFT)) /* 2s */ 2172a814908STejun Heo 2182a814908STejun Heo #define WB_FRN_HIST_SLOTS 16 /* inode->i_wb_frn_history is 16bit */ 2192a814908STejun Heo #define WB_FRN_HIST_UNIT (WB_FRN_TIME_PERIOD / WB_FRN_HIST_SLOTS) 2202a814908STejun Heo /* each slot's duration is 2s / 16 */ 2212a814908STejun Heo #define WB_FRN_HIST_THR_SLOTS (WB_FRN_HIST_SLOTS / 2) 2222a814908STejun Heo /* if foreign slots >= 8, switch */ 2232a814908STejun Heo #define WB_FRN_HIST_MAX_SLOTS (WB_FRN_HIST_THR_SLOTS / 2 + 1) 2242a814908STejun Heo /* one round can affect upto 5 slots */ 2252a814908STejun Heo 22621c6321fSTejun Heo void __inode_attach_wb(struct inode *inode, struct page *page) 22721c6321fSTejun Heo { 22821c6321fSTejun Heo struct backing_dev_info *bdi = inode_to_bdi(inode); 22921c6321fSTejun Heo struct bdi_writeback *wb = NULL; 23021c6321fSTejun Heo 23121c6321fSTejun Heo if (inode_cgwb_enabled(inode)) { 23221c6321fSTejun Heo struct cgroup_subsys_state *memcg_css; 23321c6321fSTejun Heo 23421c6321fSTejun Heo if (page) { 23521c6321fSTejun Heo memcg_css = mem_cgroup_css_from_page(page); 23621c6321fSTejun Heo wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); 23721c6321fSTejun Heo } else { 23821c6321fSTejun Heo /* must pin memcg_css, see wb_get_create() */ 23921c6321fSTejun Heo memcg_css = task_get_css(current, memory_cgrp_id); 24021c6321fSTejun Heo wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); 24121c6321fSTejun Heo css_put(memcg_css); 24221c6321fSTejun Heo } 24321c6321fSTejun Heo } 24421c6321fSTejun Heo 24521c6321fSTejun Heo if (!wb) 24621c6321fSTejun Heo wb = &bdi->wb; 24721c6321fSTejun Heo 24821c6321fSTejun Heo /* 24921c6321fSTejun Heo * There may be multiple instances of this function racing to 25021c6321fSTejun Heo * update the same inode. Use cmpxchg() to tell the winner. 25121c6321fSTejun Heo */ 25221c6321fSTejun Heo if (unlikely(cmpxchg(&inode->i_wb, NULL, wb))) 25321c6321fSTejun Heo wb_put(wb); 25421c6321fSTejun Heo } 25521c6321fSTejun Heo 256703c2708STejun Heo /** 25787e1d789STejun Heo * locked_inode_to_wb_and_lock_list - determine a locked inode's wb and lock it 25887e1d789STejun Heo * @inode: inode of interest with i_lock held 25987e1d789STejun Heo * 26087e1d789STejun Heo * Returns @inode's wb with its list_lock held. @inode->i_lock must be 26187e1d789STejun Heo * held on entry and is released on return. The returned wb is guaranteed 26287e1d789STejun Heo * to stay @inode's associated wb until its list_lock is released. 26387e1d789STejun Heo */ 26487e1d789STejun Heo static struct bdi_writeback * 26587e1d789STejun Heo locked_inode_to_wb_and_lock_list(struct inode *inode) 26687e1d789STejun Heo __releases(&inode->i_lock) 26787e1d789STejun Heo __acquires(&wb->list_lock) 26887e1d789STejun Heo { 26987e1d789STejun Heo while (true) { 27087e1d789STejun Heo struct bdi_writeback *wb = inode_to_wb(inode); 27187e1d789STejun Heo 27287e1d789STejun Heo /* 27387e1d789STejun Heo * inode_to_wb() association is protected by both 27487e1d789STejun Heo * @inode->i_lock and @wb->list_lock but list_lock nests 27587e1d789STejun Heo * outside i_lock. Drop i_lock and verify that the 27687e1d789STejun Heo * association hasn't changed after acquiring list_lock. 27787e1d789STejun Heo */ 27887e1d789STejun Heo wb_get(wb); 27987e1d789STejun Heo spin_unlock(&inode->i_lock); 28087e1d789STejun Heo spin_lock(&wb->list_lock); 28187e1d789STejun Heo wb_put(wb); /* not gonna deref it anymore */ 28287e1d789STejun Heo 283aaa2cacfSTejun Heo /* i_wb may have changed inbetween, can't use inode_to_wb() */ 284aaa2cacfSTejun Heo if (likely(wb == inode->i_wb)) 28587e1d789STejun Heo return wb; /* @inode already has ref */ 28687e1d789STejun Heo 28787e1d789STejun Heo spin_unlock(&wb->list_lock); 28887e1d789STejun Heo cpu_relax(); 28987e1d789STejun Heo spin_lock(&inode->i_lock); 29087e1d789STejun Heo } 29187e1d789STejun Heo } 29287e1d789STejun Heo 29387e1d789STejun Heo /** 29487e1d789STejun Heo * inode_to_wb_and_lock_list - determine an inode's wb and lock it 29587e1d789STejun Heo * @inode: inode of interest 29687e1d789STejun Heo * 29787e1d789STejun Heo * Same as locked_inode_to_wb_and_lock_list() but @inode->i_lock isn't held 29887e1d789STejun Heo * on entry. 29987e1d789STejun Heo */ 30087e1d789STejun Heo static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode) 30187e1d789STejun Heo __acquires(&wb->list_lock) 30287e1d789STejun Heo { 30387e1d789STejun Heo spin_lock(&inode->i_lock); 30487e1d789STejun Heo return locked_inode_to_wb_and_lock_list(inode); 30587e1d789STejun Heo } 30687e1d789STejun Heo 307682aa8e1STejun Heo struct inode_switch_wbs_context { 308682aa8e1STejun Heo struct inode *inode; 309682aa8e1STejun Heo struct bdi_writeback *new_wb; 310682aa8e1STejun Heo 311682aa8e1STejun Heo struct rcu_head rcu_head; 312682aa8e1STejun Heo struct work_struct work; 313682aa8e1STejun Heo }; 314682aa8e1STejun Heo 315682aa8e1STejun Heo static void inode_switch_wbs_work_fn(struct work_struct *work) 316682aa8e1STejun Heo { 317682aa8e1STejun Heo struct inode_switch_wbs_context *isw = 318682aa8e1STejun Heo container_of(work, struct inode_switch_wbs_context, work); 319682aa8e1STejun Heo struct inode *inode = isw->inode; 320d10c8095STejun Heo struct address_space *mapping = inode->i_mapping; 321d10c8095STejun Heo struct bdi_writeback *old_wb = inode->i_wb; 322682aa8e1STejun Heo struct bdi_writeback *new_wb = isw->new_wb; 323d10c8095STejun Heo struct radix_tree_iter iter; 324d10c8095STejun Heo bool switched = false; 325d10c8095STejun Heo void **slot; 326682aa8e1STejun Heo 327682aa8e1STejun Heo /* 328682aa8e1STejun Heo * By the time control reaches here, RCU grace period has passed 329682aa8e1STejun Heo * since I_WB_SWITCH assertion and all wb stat update transactions 330682aa8e1STejun Heo * between unlocked_inode_to_wb_begin/end() are guaranteed to be 331682aa8e1STejun Heo * synchronizing against mapping->tree_lock. 332d10c8095STejun Heo * 333d10c8095STejun Heo * Grabbing old_wb->list_lock, inode->i_lock and mapping->tree_lock 334d10c8095STejun Heo * gives us exclusion against all wb related operations on @inode 335d10c8095STejun Heo * including IO list manipulations and stat updates. 336682aa8e1STejun Heo */ 337d10c8095STejun Heo if (old_wb < new_wb) { 338d10c8095STejun Heo spin_lock(&old_wb->list_lock); 339d10c8095STejun Heo spin_lock_nested(&new_wb->list_lock, SINGLE_DEPTH_NESTING); 340d10c8095STejun Heo } else { 341d10c8095STejun Heo spin_lock(&new_wb->list_lock); 342d10c8095STejun Heo spin_lock_nested(&old_wb->list_lock, SINGLE_DEPTH_NESTING); 343d10c8095STejun Heo } 344682aa8e1STejun Heo spin_lock(&inode->i_lock); 345d10c8095STejun Heo spin_lock_irq(&mapping->tree_lock); 346682aa8e1STejun Heo 347d10c8095STejun Heo /* 348d10c8095STejun Heo * Once I_FREEING is visible under i_lock, the eviction path owns 349c7f54084SDave Chinner * the inode and we shouldn't modify ->i_io_list. 350d10c8095STejun Heo */ 351d10c8095STejun Heo if (unlikely(inode->i_state & I_FREEING)) 352d10c8095STejun Heo goto skip_switch; 353d10c8095STejun Heo 354d10c8095STejun Heo /* 355d10c8095STejun Heo * Count and transfer stats. Note that PAGECACHE_TAG_DIRTY points 356d10c8095STejun Heo * to possibly dirty pages while PAGECACHE_TAG_WRITEBACK points to 357d10c8095STejun Heo * pages actually under underwriteback. 358d10c8095STejun Heo */ 359d10c8095STejun Heo radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter, 0, 360d10c8095STejun Heo PAGECACHE_TAG_DIRTY) { 361d10c8095STejun Heo struct page *page = radix_tree_deref_slot_protected(slot, 362d10c8095STejun Heo &mapping->tree_lock); 363d10c8095STejun Heo if (likely(page) && PageDirty(page)) { 364d10c8095STejun Heo __dec_wb_stat(old_wb, WB_RECLAIMABLE); 365d10c8095STejun Heo __inc_wb_stat(new_wb, WB_RECLAIMABLE); 366d10c8095STejun Heo } 367d10c8095STejun Heo } 368d10c8095STejun Heo 369d10c8095STejun Heo radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter, 0, 370d10c8095STejun Heo PAGECACHE_TAG_WRITEBACK) { 371d10c8095STejun Heo struct page *page = radix_tree_deref_slot_protected(slot, 372d10c8095STejun Heo &mapping->tree_lock); 373d10c8095STejun Heo if (likely(page)) { 374d10c8095STejun Heo WARN_ON_ONCE(!PageWriteback(page)); 375d10c8095STejun Heo __dec_wb_stat(old_wb, WB_WRITEBACK); 376d10c8095STejun Heo __inc_wb_stat(new_wb, WB_WRITEBACK); 377d10c8095STejun Heo } 378d10c8095STejun Heo } 379d10c8095STejun Heo 380d10c8095STejun Heo wb_get(new_wb); 381d10c8095STejun Heo 382d10c8095STejun Heo /* 383d10c8095STejun Heo * Transfer to @new_wb's IO list if necessary. The specific list 384d10c8095STejun Heo * @inode was on is ignored and the inode is put on ->b_dirty which 385d10c8095STejun Heo * is always correct including from ->b_dirty_time. The transfer 386d10c8095STejun Heo * preserves @inode->dirtied_when ordering. 387d10c8095STejun Heo */ 388c7f54084SDave Chinner if (!list_empty(&inode->i_io_list)) { 389d10c8095STejun Heo struct inode *pos; 390d10c8095STejun Heo 391c7f54084SDave Chinner inode_io_list_del_locked(inode, old_wb); 392d10c8095STejun Heo inode->i_wb = new_wb; 393c7f54084SDave Chinner list_for_each_entry(pos, &new_wb->b_dirty, i_io_list) 394d10c8095STejun Heo if (time_after_eq(inode->dirtied_when, 395d10c8095STejun Heo pos->dirtied_when)) 396d10c8095STejun Heo break; 397c7f54084SDave Chinner inode_io_list_move_locked(inode, new_wb, pos->i_io_list.prev); 398d10c8095STejun Heo } else { 399d10c8095STejun Heo inode->i_wb = new_wb; 400d10c8095STejun Heo } 401d10c8095STejun Heo 402d10c8095STejun Heo /* ->i_wb_frn updates may race wbc_detach_inode() but doesn't matter */ 403682aa8e1STejun Heo inode->i_wb_frn_winner = 0; 404682aa8e1STejun Heo inode->i_wb_frn_avg_time = 0; 405682aa8e1STejun Heo inode->i_wb_frn_history = 0; 406d10c8095STejun Heo switched = true; 407d10c8095STejun Heo skip_switch: 408682aa8e1STejun Heo /* 409682aa8e1STejun Heo * Paired with load_acquire in unlocked_inode_to_wb_begin() and 410682aa8e1STejun Heo * ensures that the new wb is visible if they see !I_WB_SWITCH. 411682aa8e1STejun Heo */ 412682aa8e1STejun Heo smp_store_release(&inode->i_state, inode->i_state & ~I_WB_SWITCH); 413682aa8e1STejun Heo 414d10c8095STejun Heo spin_unlock_irq(&mapping->tree_lock); 415682aa8e1STejun Heo spin_unlock(&inode->i_lock); 416d10c8095STejun Heo spin_unlock(&new_wb->list_lock); 417d10c8095STejun Heo spin_unlock(&old_wb->list_lock); 418d10c8095STejun Heo 419d10c8095STejun Heo if (switched) { 420d10c8095STejun Heo wb_wakeup(new_wb); 421d10c8095STejun Heo wb_put(old_wb); 422d10c8095STejun Heo } 423d10c8095STejun Heo wb_put(new_wb); 424682aa8e1STejun Heo 425682aa8e1STejun Heo iput(inode); 426682aa8e1STejun Heo kfree(isw); 427682aa8e1STejun Heo } 428682aa8e1STejun Heo 429682aa8e1STejun Heo static void inode_switch_wbs_rcu_fn(struct rcu_head *rcu_head) 430682aa8e1STejun Heo { 431682aa8e1STejun Heo struct inode_switch_wbs_context *isw = container_of(rcu_head, 432682aa8e1STejun Heo struct inode_switch_wbs_context, rcu_head); 433682aa8e1STejun Heo 434682aa8e1STejun Heo /* needs to grab bh-unsafe locks, bounce to work item */ 435682aa8e1STejun Heo INIT_WORK(&isw->work, inode_switch_wbs_work_fn); 436682aa8e1STejun Heo schedule_work(&isw->work); 437682aa8e1STejun Heo } 438682aa8e1STejun Heo 439682aa8e1STejun Heo /** 440682aa8e1STejun Heo * inode_switch_wbs - change the wb association of an inode 441682aa8e1STejun Heo * @inode: target inode 442682aa8e1STejun Heo * @new_wb_id: ID of the new wb 443682aa8e1STejun Heo * 444682aa8e1STejun Heo * Switch @inode's wb association to the wb identified by @new_wb_id. The 445682aa8e1STejun Heo * switching is performed asynchronously and may fail silently. 446682aa8e1STejun Heo */ 447682aa8e1STejun Heo static void inode_switch_wbs(struct inode *inode, int new_wb_id) 448682aa8e1STejun Heo { 449682aa8e1STejun Heo struct backing_dev_info *bdi = inode_to_bdi(inode); 450682aa8e1STejun Heo struct cgroup_subsys_state *memcg_css; 451682aa8e1STejun Heo struct inode_switch_wbs_context *isw; 452682aa8e1STejun Heo 453682aa8e1STejun Heo /* noop if seems to be already in progress */ 454682aa8e1STejun Heo if (inode->i_state & I_WB_SWITCH) 455682aa8e1STejun Heo return; 456682aa8e1STejun Heo 457682aa8e1STejun Heo isw = kzalloc(sizeof(*isw), GFP_ATOMIC); 458682aa8e1STejun Heo if (!isw) 459682aa8e1STejun Heo return; 460682aa8e1STejun Heo 461682aa8e1STejun Heo /* find and pin the new wb */ 462682aa8e1STejun Heo rcu_read_lock(); 463682aa8e1STejun Heo memcg_css = css_from_id(new_wb_id, &memory_cgrp_subsys); 464682aa8e1STejun Heo if (memcg_css) 465682aa8e1STejun Heo isw->new_wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); 466682aa8e1STejun Heo rcu_read_unlock(); 467682aa8e1STejun Heo if (!isw->new_wb) 468682aa8e1STejun Heo goto out_free; 469682aa8e1STejun Heo 470682aa8e1STejun Heo /* while holding I_WB_SWITCH, no one else can update the association */ 471682aa8e1STejun Heo spin_lock(&inode->i_lock); 472682aa8e1STejun Heo if (inode->i_state & (I_WB_SWITCH | I_FREEING) || 473682aa8e1STejun Heo inode_to_wb(inode) == isw->new_wb) { 474682aa8e1STejun Heo spin_unlock(&inode->i_lock); 475682aa8e1STejun Heo goto out_free; 476682aa8e1STejun Heo } 477682aa8e1STejun Heo inode->i_state |= I_WB_SWITCH; 478682aa8e1STejun Heo spin_unlock(&inode->i_lock); 479682aa8e1STejun Heo 480682aa8e1STejun Heo ihold(inode); 481682aa8e1STejun Heo isw->inode = inode; 482682aa8e1STejun Heo 483682aa8e1STejun Heo /* 484682aa8e1STejun Heo * In addition to synchronizing among switchers, I_WB_SWITCH tells 485682aa8e1STejun Heo * the RCU protected stat update paths to grab the mapping's 486682aa8e1STejun Heo * tree_lock so that stat transfer can synchronize against them. 487682aa8e1STejun Heo * Let's continue after I_WB_SWITCH is guaranteed to be visible. 488682aa8e1STejun Heo */ 489682aa8e1STejun Heo call_rcu(&isw->rcu_head, inode_switch_wbs_rcu_fn); 490682aa8e1STejun Heo return; 491682aa8e1STejun Heo 492682aa8e1STejun Heo out_free: 493682aa8e1STejun Heo if (isw->new_wb) 494682aa8e1STejun Heo wb_put(isw->new_wb); 495682aa8e1STejun Heo kfree(isw); 496682aa8e1STejun Heo } 497682aa8e1STejun Heo 49887e1d789STejun Heo /** 499b16b1debSTejun Heo * wbc_attach_and_unlock_inode - associate wbc with target inode and unlock it 500b16b1debSTejun Heo * @wbc: writeback_control of interest 501b16b1debSTejun Heo * @inode: target inode 502b16b1debSTejun Heo * 503b16b1debSTejun Heo * @inode is locked and about to be written back under the control of @wbc. 504b16b1debSTejun Heo * Record @inode's writeback context into @wbc and unlock the i_lock. On 505b16b1debSTejun Heo * writeback completion, wbc_detach_inode() should be called. This is used 506b16b1debSTejun Heo * to track the cgroup writeback context. 507b16b1debSTejun Heo */ 508b16b1debSTejun Heo void wbc_attach_and_unlock_inode(struct writeback_control *wbc, 509b16b1debSTejun Heo struct inode *inode) 510b16b1debSTejun Heo { 511dd73e4b7STejun Heo if (!inode_cgwb_enabled(inode)) { 512dd73e4b7STejun Heo spin_unlock(&inode->i_lock); 513dd73e4b7STejun Heo return; 514dd73e4b7STejun Heo } 515dd73e4b7STejun Heo 516b16b1debSTejun Heo wbc->wb = inode_to_wb(inode); 5172a814908STejun Heo wbc->inode = inode; 5182a814908STejun Heo 5192a814908STejun Heo wbc->wb_id = wbc->wb->memcg_css->id; 5202a814908STejun Heo wbc->wb_lcand_id = inode->i_wb_frn_winner; 5212a814908STejun Heo wbc->wb_tcand_id = 0; 5222a814908STejun Heo wbc->wb_bytes = 0; 5232a814908STejun Heo wbc->wb_lcand_bytes = 0; 5242a814908STejun Heo wbc->wb_tcand_bytes = 0; 5252a814908STejun Heo 526b16b1debSTejun Heo wb_get(wbc->wb); 527b16b1debSTejun Heo spin_unlock(&inode->i_lock); 528e8a7abf5STejun Heo 529e8a7abf5STejun Heo /* 530e8a7abf5STejun Heo * A dying wb indicates that the memcg-blkcg mapping has changed 531e8a7abf5STejun Heo * and a new wb is already serving the memcg. Switch immediately. 532e8a7abf5STejun Heo */ 533e8a7abf5STejun Heo if (unlikely(wb_dying(wbc->wb))) 534e8a7abf5STejun Heo inode_switch_wbs(inode, wbc->wb_id); 535b16b1debSTejun Heo } 536b16b1debSTejun Heo 537b16b1debSTejun Heo /** 5382a814908STejun Heo * wbc_detach_inode - disassociate wbc from inode and perform foreign detection 5392a814908STejun Heo * @wbc: writeback_control of the just finished writeback 540b16b1debSTejun Heo * 541b16b1debSTejun Heo * To be called after a writeback attempt of an inode finishes and undoes 542b16b1debSTejun Heo * wbc_attach_and_unlock_inode(). Can be called under any context. 5432a814908STejun Heo * 5442a814908STejun Heo * As concurrent write sharing of an inode is expected to be very rare and 5452a814908STejun Heo * memcg only tracks page ownership on first-use basis severely confining 5462a814908STejun Heo * the usefulness of such sharing, cgroup writeback tracks ownership 5472a814908STejun Heo * per-inode. While the support for concurrent write sharing of an inode 5482a814908STejun Heo * is deemed unnecessary, an inode being written to by different cgroups at 5492a814908STejun Heo * different points in time is a lot more common, and, more importantly, 5502a814908STejun Heo * charging only by first-use can too readily lead to grossly incorrect 5512a814908STejun Heo * behaviors (single foreign page can lead to gigabytes of writeback to be 5522a814908STejun Heo * incorrectly attributed). 5532a814908STejun Heo * 5542a814908STejun Heo * To resolve this issue, cgroup writeback detects the majority dirtier of 5552a814908STejun Heo * an inode and transfers the ownership to it. To avoid unnnecessary 5562a814908STejun Heo * oscillation, the detection mechanism keeps track of history and gives 5572a814908STejun Heo * out the switch verdict only if the foreign usage pattern is stable over 5582a814908STejun Heo * a certain amount of time and/or writeback attempts. 5592a814908STejun Heo * 5602a814908STejun Heo * On each writeback attempt, @wbc tries to detect the majority writer 5612a814908STejun Heo * using Boyer-Moore majority vote algorithm. In addition to the byte 5622a814908STejun Heo * count from the majority voting, it also counts the bytes written for the 5632a814908STejun Heo * current wb and the last round's winner wb (max of last round's current 5642a814908STejun Heo * wb, the winner from two rounds ago, and the last round's majority 5652a814908STejun Heo * candidate). Keeping track of the historical winner helps the algorithm 5662a814908STejun Heo * to semi-reliably detect the most active writer even when it's not the 5672a814908STejun Heo * absolute majority. 5682a814908STejun Heo * 5692a814908STejun Heo * Once the winner of the round is determined, whether the winner is 5702a814908STejun Heo * foreign or not and how much IO time the round consumed is recorded in 5712a814908STejun Heo * inode->i_wb_frn_history. If the amount of recorded foreign IO time is 5722a814908STejun Heo * over a certain threshold, the switch verdict is given. 573b16b1debSTejun Heo */ 574b16b1debSTejun Heo void wbc_detach_inode(struct writeback_control *wbc) 575b16b1debSTejun Heo { 5762a814908STejun Heo struct bdi_writeback *wb = wbc->wb; 5772a814908STejun Heo struct inode *inode = wbc->inode; 578dd73e4b7STejun Heo unsigned long avg_time, max_bytes, max_time; 579dd73e4b7STejun Heo u16 history; 5802a814908STejun Heo int max_id; 5812a814908STejun Heo 582dd73e4b7STejun Heo if (!wb) 583dd73e4b7STejun Heo return; 584dd73e4b7STejun Heo 585dd73e4b7STejun Heo history = inode->i_wb_frn_history; 586dd73e4b7STejun Heo avg_time = inode->i_wb_frn_avg_time; 587dd73e4b7STejun Heo 5882a814908STejun Heo /* pick the winner of this round */ 5892a814908STejun Heo if (wbc->wb_bytes >= wbc->wb_lcand_bytes && 5902a814908STejun Heo wbc->wb_bytes >= wbc->wb_tcand_bytes) { 5912a814908STejun Heo max_id = wbc->wb_id; 5922a814908STejun Heo max_bytes = wbc->wb_bytes; 5932a814908STejun Heo } else if (wbc->wb_lcand_bytes >= wbc->wb_tcand_bytes) { 5942a814908STejun Heo max_id = wbc->wb_lcand_id; 5952a814908STejun Heo max_bytes = wbc->wb_lcand_bytes; 5962a814908STejun Heo } else { 5972a814908STejun Heo max_id = wbc->wb_tcand_id; 5982a814908STejun Heo max_bytes = wbc->wb_tcand_bytes; 5992a814908STejun Heo } 6002a814908STejun Heo 6012a814908STejun Heo /* 6022a814908STejun Heo * Calculate the amount of IO time the winner consumed and fold it 6032a814908STejun Heo * into the running average kept per inode. If the consumed IO 6042a814908STejun Heo * time is lower than avag / WB_FRN_TIME_CUT_DIV, ignore it for 6052a814908STejun Heo * deciding whether to switch or not. This is to prevent one-off 6062a814908STejun Heo * small dirtiers from skewing the verdict. 6072a814908STejun Heo */ 6082a814908STejun Heo max_time = DIV_ROUND_UP((max_bytes >> PAGE_SHIFT) << WB_FRN_TIME_SHIFT, 6092a814908STejun Heo wb->avg_write_bandwidth); 6102a814908STejun Heo if (avg_time) 6112a814908STejun Heo avg_time += (max_time >> WB_FRN_TIME_AVG_SHIFT) - 6122a814908STejun Heo (avg_time >> WB_FRN_TIME_AVG_SHIFT); 6132a814908STejun Heo else 6142a814908STejun Heo avg_time = max_time; /* immediate catch up on first run */ 6152a814908STejun Heo 6162a814908STejun Heo if (max_time >= avg_time / WB_FRN_TIME_CUT_DIV) { 6172a814908STejun Heo int slots; 6182a814908STejun Heo 6192a814908STejun Heo /* 6202a814908STejun Heo * The switch verdict is reached if foreign wb's consume 6212a814908STejun Heo * more than a certain proportion of IO time in a 6222a814908STejun Heo * WB_FRN_TIME_PERIOD. This is loosely tracked by 16 slot 6232a814908STejun Heo * history mask where each bit represents one sixteenth of 6242a814908STejun Heo * the period. Determine the number of slots to shift into 6252a814908STejun Heo * history from @max_time. 6262a814908STejun Heo */ 6272a814908STejun Heo slots = min(DIV_ROUND_UP(max_time, WB_FRN_HIST_UNIT), 6282a814908STejun Heo (unsigned long)WB_FRN_HIST_MAX_SLOTS); 6292a814908STejun Heo history <<= slots; 6302a814908STejun Heo if (wbc->wb_id != max_id) 6312a814908STejun Heo history |= (1U << slots) - 1; 6322a814908STejun Heo 6332a814908STejun Heo /* 6342a814908STejun Heo * Switch if the current wb isn't the consistent winner. 6352a814908STejun Heo * If there are multiple closely competing dirtiers, the 6362a814908STejun Heo * inode may switch across them repeatedly over time, which 6372a814908STejun Heo * is okay. The main goal is avoiding keeping an inode on 6382a814908STejun Heo * the wrong wb for an extended period of time. 6392a814908STejun Heo */ 640682aa8e1STejun Heo if (hweight32(history) > WB_FRN_HIST_THR_SLOTS) 641682aa8e1STejun Heo inode_switch_wbs(inode, max_id); 6422a814908STejun Heo } 6432a814908STejun Heo 6442a814908STejun Heo /* 6452a814908STejun Heo * Multiple instances of this function may race to update the 6462a814908STejun Heo * following fields but we don't mind occassional inaccuracies. 6472a814908STejun Heo */ 6482a814908STejun Heo inode->i_wb_frn_winner = max_id; 6492a814908STejun Heo inode->i_wb_frn_avg_time = min(avg_time, (unsigned long)U16_MAX); 6502a814908STejun Heo inode->i_wb_frn_history = history; 6512a814908STejun Heo 652b16b1debSTejun Heo wb_put(wbc->wb); 653b16b1debSTejun Heo wbc->wb = NULL; 654b16b1debSTejun Heo } 655b16b1debSTejun Heo 656b16b1debSTejun Heo /** 6572a814908STejun Heo * wbc_account_io - account IO issued during writeback 6582a814908STejun Heo * @wbc: writeback_control of the writeback in progress 6592a814908STejun Heo * @page: page being written out 6602a814908STejun Heo * @bytes: number of bytes being written out 6612a814908STejun Heo * 6622a814908STejun Heo * @bytes from @page are about to written out during the writeback 6632a814908STejun Heo * controlled by @wbc. Keep the book for foreign inode detection. See 6642a814908STejun Heo * wbc_detach_inode(). 6652a814908STejun Heo */ 6662a814908STejun Heo void wbc_account_io(struct writeback_control *wbc, struct page *page, 6672a814908STejun Heo size_t bytes) 6682a814908STejun Heo { 6692a814908STejun Heo int id; 6702a814908STejun Heo 6712a814908STejun Heo /* 6722a814908STejun Heo * pageout() path doesn't attach @wbc to the inode being written 6732a814908STejun Heo * out. This is intentional as we don't want the function to block 6742a814908STejun Heo * behind a slow cgroup. Ultimately, we want pageout() to kick off 6752a814908STejun Heo * regular writeback instead of writing things out itself. 6762a814908STejun Heo */ 6772a814908STejun Heo if (!wbc->wb) 6782a814908STejun Heo return; 6792a814908STejun Heo 6802a814908STejun Heo rcu_read_lock(); 6812a814908STejun Heo id = mem_cgroup_css_from_page(page)->id; 6822a814908STejun Heo rcu_read_unlock(); 6832a814908STejun Heo 6842a814908STejun Heo if (id == wbc->wb_id) { 6852a814908STejun Heo wbc->wb_bytes += bytes; 6862a814908STejun Heo return; 6872a814908STejun Heo } 6882a814908STejun Heo 6892a814908STejun Heo if (id == wbc->wb_lcand_id) 6902a814908STejun Heo wbc->wb_lcand_bytes += bytes; 6912a814908STejun Heo 6922a814908STejun Heo /* Boyer-Moore majority vote algorithm */ 6932a814908STejun Heo if (!wbc->wb_tcand_bytes) 6942a814908STejun Heo wbc->wb_tcand_id = id; 6952a814908STejun Heo if (id == wbc->wb_tcand_id) 6962a814908STejun Heo wbc->wb_tcand_bytes += bytes; 6972a814908STejun Heo else 6982a814908STejun Heo wbc->wb_tcand_bytes -= min(bytes, wbc->wb_tcand_bytes); 6992a814908STejun Heo } 7005aa2a96bSTejun Heo EXPORT_SYMBOL_GPL(wbc_account_io); 7012a814908STejun Heo 7022a814908STejun Heo /** 703703c2708STejun Heo * inode_congested - test whether an inode is congested 70460292bccSTejun Heo * @inode: inode to test for congestion (may be NULL) 705703c2708STejun Heo * @cong_bits: mask of WB_[a]sync_congested bits to test 706703c2708STejun Heo * 707703c2708STejun Heo * Tests whether @inode is congested. @cong_bits is the mask of congestion 708703c2708STejun Heo * bits to test and the return value is the mask of set bits. 709703c2708STejun Heo * 710703c2708STejun Heo * If cgroup writeback is enabled for @inode, the congestion state is 711703c2708STejun Heo * determined by whether the cgwb (cgroup bdi_writeback) for the blkcg 712703c2708STejun Heo * associated with @inode is congested; otherwise, the root wb's congestion 713703c2708STejun Heo * state is used. 71460292bccSTejun Heo * 71560292bccSTejun Heo * @inode is allowed to be NULL as this function is often called on 71660292bccSTejun Heo * mapping->host which is NULL for the swapper space. 717703c2708STejun Heo */ 718703c2708STejun Heo int inode_congested(struct inode *inode, int cong_bits) 719703c2708STejun Heo { 7205cb8b824STejun Heo /* 7215cb8b824STejun Heo * Once set, ->i_wb never becomes NULL while the inode is alive. 7225cb8b824STejun Heo * Start transaction iff ->i_wb is visible. 7235cb8b824STejun Heo */ 724aaa2cacfSTejun Heo if (inode && inode_to_wb_is_valid(inode)) { 7255cb8b824STejun Heo struct bdi_writeback *wb; 7265cb8b824STejun Heo bool locked, congested; 7275cb8b824STejun Heo 7285cb8b824STejun Heo wb = unlocked_inode_to_wb_begin(inode, &locked); 7295cb8b824STejun Heo congested = wb_congested(wb, cong_bits); 7305cb8b824STejun Heo unlocked_inode_to_wb_end(inode, locked); 7315cb8b824STejun Heo return congested; 732703c2708STejun Heo } 733703c2708STejun Heo 734703c2708STejun Heo return wb_congested(&inode_to_bdi(inode)->wb, cong_bits); 735703c2708STejun Heo } 736703c2708STejun Heo EXPORT_SYMBOL_GPL(inode_congested); 737703c2708STejun Heo 738f2b65121STejun Heo /** 739f2b65121STejun Heo * wb_split_bdi_pages - split nr_pages to write according to bandwidth 740f2b65121STejun Heo * @wb: target bdi_writeback to split @nr_pages to 741f2b65121STejun Heo * @nr_pages: number of pages to write for the whole bdi 742f2b65121STejun Heo * 743f2b65121STejun Heo * Split @wb's portion of @nr_pages according to @wb's write bandwidth in 744f2b65121STejun Heo * relation to the total write bandwidth of all wb's w/ dirty inodes on 745f2b65121STejun Heo * @wb->bdi. 746f2b65121STejun Heo */ 747f2b65121STejun Heo static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages) 748f2b65121STejun Heo { 749f2b65121STejun Heo unsigned long this_bw = wb->avg_write_bandwidth; 750f2b65121STejun Heo unsigned long tot_bw = atomic_long_read(&wb->bdi->tot_write_bandwidth); 751f2b65121STejun Heo 752f2b65121STejun Heo if (nr_pages == LONG_MAX) 753f2b65121STejun Heo return LONG_MAX; 754f2b65121STejun Heo 755f2b65121STejun Heo /* 756f2b65121STejun Heo * This may be called on clean wb's and proportional distribution 757f2b65121STejun Heo * may not make sense, just use the original @nr_pages in those 758f2b65121STejun Heo * cases. In general, we wanna err on the side of writing more. 759f2b65121STejun Heo */ 760f2b65121STejun Heo if (!tot_bw || this_bw >= tot_bw) 761f2b65121STejun Heo return nr_pages; 762f2b65121STejun Heo else 763f2b65121STejun Heo return DIV_ROUND_UP_ULL((u64)nr_pages * this_bw, tot_bw); 764f2b65121STejun Heo } 765f2b65121STejun Heo 766db125360STejun Heo /** 767db125360STejun Heo * bdi_split_work_to_wbs - split a wb_writeback_work to all wb's of a bdi 768db125360STejun Heo * @bdi: target backing_dev_info 769db125360STejun Heo * @base_work: wb_writeback_work to issue 770db125360STejun Heo * @skip_if_busy: skip wb's which already have writeback in progress 771db125360STejun Heo * 772db125360STejun Heo * Split and issue @base_work to all wb's (bdi_writeback's) of @bdi which 773db125360STejun Heo * have dirty inodes. If @base_work->nr_page isn't %LONG_MAX, it's 774db125360STejun Heo * distributed to the busy wbs according to each wb's proportion in the 775db125360STejun Heo * total active write bandwidth of @bdi. 776db125360STejun Heo */ 777db125360STejun Heo static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, 778db125360STejun Heo struct wb_writeback_work *base_work, 779db125360STejun Heo bool skip_if_busy) 780db125360STejun Heo { 7811ed8d48cSTejun Heo int next_memcg_id = 0; 782db125360STejun Heo struct bdi_writeback *wb; 783db125360STejun Heo struct wb_iter iter; 784db125360STejun Heo 785db125360STejun Heo might_sleep(); 786db125360STejun Heo restart: 787db125360STejun Heo rcu_read_lock(); 7881ed8d48cSTejun Heo bdi_for_each_wb(wb, bdi, &iter, next_memcg_id) { 7898a1270cdSTejun Heo DEFINE_WB_COMPLETION_ONSTACK(fallback_work_done); 7908a1270cdSTejun Heo struct wb_writeback_work fallback_work; 7918a1270cdSTejun Heo struct wb_writeback_work *work; 7928a1270cdSTejun Heo long nr_pages; 7938a1270cdSTejun Heo 794006a0973STejun Heo /* SYNC_ALL writes out I_DIRTY_TIME too */ 795006a0973STejun Heo if (!wb_has_dirty_io(wb) && 796006a0973STejun Heo (base_work->sync_mode == WB_SYNC_NONE || 797006a0973STejun Heo list_empty(&wb->b_dirty_time))) 798006a0973STejun Heo continue; 799006a0973STejun Heo if (skip_if_busy && writeback_in_progress(wb)) 800db125360STejun Heo continue; 801db125360STejun Heo 8028a1270cdSTejun Heo nr_pages = wb_split_bdi_pages(wb, base_work->nr_pages); 8038a1270cdSTejun Heo 8048a1270cdSTejun Heo work = kmalloc(sizeof(*work), GFP_ATOMIC); 8058a1270cdSTejun Heo if (work) { 8068a1270cdSTejun Heo *work = *base_work; 8078a1270cdSTejun Heo work->nr_pages = nr_pages; 8088a1270cdSTejun Heo work->auto_free = 1; 8098a1270cdSTejun Heo wb_queue_work(wb, work); 8108a1270cdSTejun Heo continue; 811db125360STejun Heo } 8128a1270cdSTejun Heo 8138a1270cdSTejun Heo /* alloc failed, execute synchronously using on-stack fallback */ 8148a1270cdSTejun Heo work = &fallback_work; 8158a1270cdSTejun Heo *work = *base_work; 8168a1270cdSTejun Heo work->nr_pages = nr_pages; 8178a1270cdSTejun Heo work->auto_free = 0; 8188a1270cdSTejun Heo work->done = &fallback_work_done; 8198a1270cdSTejun Heo 8208a1270cdSTejun Heo wb_queue_work(wb, work); 8218a1270cdSTejun Heo 8221ed8d48cSTejun Heo next_memcg_id = wb->memcg_css->id + 1; 823db125360STejun Heo rcu_read_unlock(); 8248a1270cdSTejun Heo wb_wait_for_completion(bdi, &fallback_work_done); 825db125360STejun Heo goto restart; 826db125360STejun Heo } 827db125360STejun Heo rcu_read_unlock(); 828db125360STejun Heo } 829db125360STejun Heo 830f2b65121STejun Heo #else /* CONFIG_CGROUP_WRITEBACK */ 831f2b65121STejun Heo 83287e1d789STejun Heo static struct bdi_writeback * 83387e1d789STejun Heo locked_inode_to_wb_and_lock_list(struct inode *inode) 83487e1d789STejun Heo __releases(&inode->i_lock) 83587e1d789STejun Heo __acquires(&wb->list_lock) 83687e1d789STejun Heo { 83787e1d789STejun Heo struct bdi_writeback *wb = inode_to_wb(inode); 83887e1d789STejun Heo 83987e1d789STejun Heo spin_unlock(&inode->i_lock); 84087e1d789STejun Heo spin_lock(&wb->list_lock); 84187e1d789STejun Heo return wb; 84287e1d789STejun Heo } 84387e1d789STejun Heo 84487e1d789STejun Heo static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode) 84587e1d789STejun Heo __acquires(&wb->list_lock) 84687e1d789STejun Heo { 84787e1d789STejun Heo struct bdi_writeback *wb = inode_to_wb(inode); 84887e1d789STejun Heo 84987e1d789STejun Heo spin_lock(&wb->list_lock); 85087e1d789STejun Heo return wb; 85187e1d789STejun Heo } 85287e1d789STejun Heo 853f2b65121STejun Heo static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages) 854f2b65121STejun Heo { 855f2b65121STejun Heo return nr_pages; 856f2b65121STejun Heo } 857f2b65121STejun Heo 858db125360STejun Heo static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, 859db125360STejun Heo struct wb_writeback_work *base_work, 860db125360STejun Heo bool skip_if_busy) 861db125360STejun Heo { 862db125360STejun Heo might_sleep(); 863db125360STejun Heo 864006a0973STejun Heo if (!skip_if_busy || !writeback_in_progress(&bdi->wb)) { 865db125360STejun Heo base_work->auto_free = 0; 866db125360STejun Heo wb_queue_work(&bdi->wb, base_work); 867db125360STejun Heo } 868db125360STejun Heo } 869db125360STejun Heo 870703c2708STejun Heo #endif /* CONFIG_CGROUP_WRITEBACK */ 871703c2708STejun Heo 872c00ddad3STejun Heo void wb_start_writeback(struct bdi_writeback *wb, long nr_pages, 873c00ddad3STejun Heo bool range_cyclic, enum wb_reason reason) 874b6e51316SJens Axboe { 875c00ddad3STejun Heo struct wb_writeback_work *work; 876c00ddad3STejun Heo 877c00ddad3STejun Heo if (!wb_has_dirty_io(wb)) 878c00ddad3STejun Heo return; 879c00ddad3STejun Heo 880c00ddad3STejun Heo /* 881c00ddad3STejun Heo * This is WB_SYNC_NONE writeback, so if allocation fails just 882c00ddad3STejun Heo * wakeup the thread for old dirty data writeback 883c00ddad3STejun Heo */ 884c00ddad3STejun Heo work = kzalloc(sizeof(*work), GFP_ATOMIC); 885c00ddad3STejun Heo if (!work) { 8865634cc2aSTejun Heo trace_writeback_nowork(wb); 887c00ddad3STejun Heo wb_wakeup(wb); 888c00ddad3STejun Heo return; 889c00ddad3STejun Heo } 890c00ddad3STejun Heo 891c00ddad3STejun Heo work->sync_mode = WB_SYNC_NONE; 892c00ddad3STejun Heo work->nr_pages = nr_pages; 893c00ddad3STejun Heo work->range_cyclic = range_cyclic; 894c00ddad3STejun Heo work->reason = reason; 895ac7b19a3STejun Heo work->auto_free = 1; 896c00ddad3STejun Heo 897c00ddad3STejun Heo wb_queue_work(wb, work); 898d3ddec76SWu Fengguang } 899d3ddec76SWu Fengguang 900c5444198SChristoph Hellwig /** 9019ecf4866STejun Heo * wb_start_background_writeback - start background writeback 9029ecf4866STejun Heo * @wb: bdi_writback to write from 903c5444198SChristoph Hellwig * 904c5444198SChristoph Hellwig * Description: 9056585027aSJan Kara * This makes sure WB_SYNC_NONE background writeback happens. When 9069ecf4866STejun Heo * this function returns, it is only guaranteed that for given wb 9076585027aSJan Kara * some IO is happening if we are over background dirty threshold. 9086585027aSJan Kara * Caller need not hold sb s_umount semaphore. 909c5444198SChristoph Hellwig */ 9109ecf4866STejun Heo void wb_start_background_writeback(struct bdi_writeback *wb) 911c5444198SChristoph Hellwig { 9126585027aSJan Kara /* 9136585027aSJan Kara * We just wake up the flusher thread. It will perform background 9146585027aSJan Kara * writeback as soon as there is no other work to do. 9156585027aSJan Kara */ 9165634cc2aSTejun Heo trace_writeback_wake_background(wb); 9179ecf4866STejun Heo wb_wakeup(wb); 9181da177e4SLinus Torvalds } 9191da177e4SLinus Torvalds 9201da177e4SLinus Torvalds /* 921a66979abSDave Chinner * Remove the inode from the writeback list it is on. 922a66979abSDave Chinner */ 923c7f54084SDave Chinner void inode_io_list_del(struct inode *inode) 924a66979abSDave Chinner { 92587e1d789STejun Heo struct bdi_writeback *wb; 926a66979abSDave Chinner 92787e1d789STejun Heo wb = inode_to_wb_and_lock_list(inode); 928c7f54084SDave Chinner inode_io_list_del_locked(inode, wb); 92952ebea74STejun Heo spin_unlock(&wb->list_lock); 930f758eeabSChristoph Hellwig } 931a66979abSDave Chinner 932a66979abSDave Chinner /* 9336610a0bcSAndrew Morton * Redirty an inode: set its when-it-was dirtied timestamp and move it to the 9346610a0bcSAndrew Morton * furthest end of its superblock's dirty-inode list. 9356610a0bcSAndrew Morton * 9366610a0bcSAndrew Morton * Before stamping the inode's ->dirtied_when, we check to see whether it is 93766f3b8e2SJens Axboe * already the most-recently-dirtied inode on the b_dirty list. If that is 9386610a0bcSAndrew Morton * the case then the inode must have been redirtied while it was being written 9396610a0bcSAndrew Morton * out and we don't reset its dirtied_when. 9406610a0bcSAndrew Morton */ 941f758eeabSChristoph Hellwig static void redirty_tail(struct inode *inode, struct bdi_writeback *wb) 9426610a0bcSAndrew Morton { 94303ba3782SJens Axboe if (!list_empty(&wb->b_dirty)) { 94466f3b8e2SJens Axboe struct inode *tail; 9456610a0bcSAndrew Morton 9467ccf19a8SNick Piggin tail = wb_inode(wb->b_dirty.next); 94766f3b8e2SJens Axboe if (time_before(inode->dirtied_when, tail->dirtied_when)) 9486610a0bcSAndrew Morton inode->dirtied_when = jiffies; 9496610a0bcSAndrew Morton } 950c7f54084SDave Chinner inode_io_list_move_locked(inode, wb, &wb->b_dirty); 9516610a0bcSAndrew Morton } 9526610a0bcSAndrew Morton 9536610a0bcSAndrew Morton /* 95466f3b8e2SJens Axboe * requeue inode for re-scanning after bdi->b_io list is exhausted. 955c986d1e2SAndrew Morton */ 956f758eeabSChristoph Hellwig static void requeue_io(struct inode *inode, struct bdi_writeback *wb) 957c986d1e2SAndrew Morton { 958c7f54084SDave Chinner inode_io_list_move_locked(inode, wb, &wb->b_more_io); 959c986d1e2SAndrew Morton } 960c986d1e2SAndrew Morton 9611c0eeaf5SJoern Engel static void inode_sync_complete(struct inode *inode) 9621c0eeaf5SJoern Engel { 963365b94aeSJan Kara inode->i_state &= ~I_SYNC; 9644eff96ddSJan Kara /* If inode is clean an unused, put it into LRU now... */ 9654eff96ddSJan Kara inode_add_lru(inode); 966365b94aeSJan Kara /* Waiters must see I_SYNC cleared before being woken up */ 9671c0eeaf5SJoern Engel smp_mb(); 9681c0eeaf5SJoern Engel wake_up_bit(&inode->i_state, __I_SYNC); 9691c0eeaf5SJoern Engel } 9701c0eeaf5SJoern Engel 971d2caa3c5SJeff Layton static bool inode_dirtied_after(struct inode *inode, unsigned long t) 972d2caa3c5SJeff Layton { 973d2caa3c5SJeff Layton bool ret = time_after(inode->dirtied_when, t); 974d2caa3c5SJeff Layton #ifndef CONFIG_64BIT 975d2caa3c5SJeff Layton /* 976d2caa3c5SJeff Layton * For inodes being constantly redirtied, dirtied_when can get stuck. 977d2caa3c5SJeff Layton * It _appears_ to be in the future, but is actually in distant past. 978d2caa3c5SJeff Layton * This test is necessary to prevent such wrapped-around relative times 9795b0830cbSJens Axboe * from permanently stopping the whole bdi writeback. 980d2caa3c5SJeff Layton */ 981d2caa3c5SJeff Layton ret = ret && time_before_eq(inode->dirtied_when, jiffies); 982d2caa3c5SJeff Layton #endif 983d2caa3c5SJeff Layton return ret; 984d2caa3c5SJeff Layton } 985d2caa3c5SJeff Layton 9860ae45f63STheodore Ts'o #define EXPIRE_DIRTY_ATIME 0x0001 9870ae45f63STheodore Ts'o 988c986d1e2SAndrew Morton /* 9890e2f2b23SWang Sheng-Hui * Move expired (dirtied before work->older_than_this) dirty inodes from 990697e6fedSJan Kara * @delaying_queue to @dispatch_queue. 9912c136579SFengguang Wu */ 992e84d0a4fSWu Fengguang static int move_expired_inodes(struct list_head *delaying_queue, 9932c136579SFengguang Wu struct list_head *dispatch_queue, 9940ae45f63STheodore Ts'o int flags, 995ad4e38ddSCurt Wohlgemuth struct wb_writeback_work *work) 9962c136579SFengguang Wu { 9970ae45f63STheodore Ts'o unsigned long *older_than_this = NULL; 9980ae45f63STheodore Ts'o unsigned long expire_time; 9995c03449dSShaohua Li LIST_HEAD(tmp); 10005c03449dSShaohua Li struct list_head *pos, *node; 1001cf137307SJens Axboe struct super_block *sb = NULL; 10025c03449dSShaohua Li struct inode *inode; 1003cf137307SJens Axboe int do_sb_sort = 0; 1004e84d0a4fSWu Fengguang int moved = 0; 10055c03449dSShaohua Li 10060ae45f63STheodore Ts'o if ((flags & EXPIRE_DIRTY_ATIME) == 0) 10070ae45f63STheodore Ts'o older_than_this = work->older_than_this; 1008a2f48706STheodore Ts'o else if (!work->for_sync) { 1009a2f48706STheodore Ts'o expire_time = jiffies - (dirtytime_expire_interval * HZ); 10100ae45f63STheodore Ts'o older_than_this = &expire_time; 10110ae45f63STheodore Ts'o } 10122c136579SFengguang Wu while (!list_empty(delaying_queue)) { 10137ccf19a8SNick Piggin inode = wb_inode(delaying_queue->prev); 10140ae45f63STheodore Ts'o if (older_than_this && 10150ae45f63STheodore Ts'o inode_dirtied_after(inode, *older_than_this)) 10162c136579SFengguang Wu break; 1017c7f54084SDave Chinner list_move(&inode->i_io_list, &tmp); 1018a8855990SJan Kara moved++; 10190ae45f63STheodore Ts'o if (flags & EXPIRE_DIRTY_ATIME) 10200ae45f63STheodore Ts'o set_bit(__I_DIRTY_TIME_EXPIRED, &inode->i_state); 1021a8855990SJan Kara if (sb_is_blkdev_sb(inode->i_sb)) 1022a8855990SJan Kara continue; 1023cf137307SJens Axboe if (sb && sb != inode->i_sb) 1024cf137307SJens Axboe do_sb_sort = 1; 1025cf137307SJens Axboe sb = inode->i_sb; 10265c03449dSShaohua Li } 10275c03449dSShaohua Li 1028cf137307SJens Axboe /* just one sb in list, splice to dispatch_queue and we're done */ 1029cf137307SJens Axboe if (!do_sb_sort) { 1030cf137307SJens Axboe list_splice(&tmp, dispatch_queue); 1031e84d0a4fSWu Fengguang goto out; 1032cf137307SJens Axboe } 1033cf137307SJens Axboe 10345c03449dSShaohua Li /* Move inodes from one superblock together */ 10355c03449dSShaohua Li while (!list_empty(&tmp)) { 10367ccf19a8SNick Piggin sb = wb_inode(tmp.prev)->i_sb; 10375c03449dSShaohua Li list_for_each_prev_safe(pos, node, &tmp) { 10387ccf19a8SNick Piggin inode = wb_inode(pos); 10395c03449dSShaohua Li if (inode->i_sb == sb) 1040c7f54084SDave Chinner list_move(&inode->i_io_list, dispatch_queue); 10412c136579SFengguang Wu } 10422c136579SFengguang Wu } 1043e84d0a4fSWu Fengguang out: 1044e84d0a4fSWu Fengguang return moved; 10455c03449dSShaohua Li } 10462c136579SFengguang Wu 10472c136579SFengguang Wu /* 10482c136579SFengguang Wu * Queue all expired dirty inodes for io, eldest first. 10494ea879b9SWu Fengguang * Before 10504ea879b9SWu Fengguang * newly dirtied b_dirty b_io b_more_io 10514ea879b9SWu Fengguang * =============> gf edc BA 10524ea879b9SWu Fengguang * After 10534ea879b9SWu Fengguang * newly dirtied b_dirty b_io b_more_io 10544ea879b9SWu Fengguang * =============> g fBAedc 10554ea879b9SWu Fengguang * | 10564ea879b9SWu Fengguang * +--> dequeue for IO 10572c136579SFengguang Wu */ 1058ad4e38ddSCurt Wohlgemuth static void queue_io(struct bdi_writeback *wb, struct wb_writeback_work *work) 10592c136579SFengguang Wu { 1060e84d0a4fSWu Fengguang int moved; 10610ae45f63STheodore Ts'o 1062f758eeabSChristoph Hellwig assert_spin_locked(&wb->list_lock); 10634ea879b9SWu Fengguang list_splice_init(&wb->b_more_io, &wb->b_io); 10640ae45f63STheodore Ts'o moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, 0, work); 10650ae45f63STheodore Ts'o moved += move_expired_inodes(&wb->b_dirty_time, &wb->b_io, 10660ae45f63STheodore Ts'o EXPIRE_DIRTY_ATIME, work); 1067d6c10f1fSTejun Heo if (moved) 1068d6c10f1fSTejun Heo wb_io_lists_populated(wb); 1069ad4e38ddSCurt Wohlgemuth trace_writeback_queue_io(wb, work, moved); 107066f3b8e2SJens Axboe } 107166f3b8e2SJens Axboe 1072a9185b41SChristoph Hellwig static int write_inode(struct inode *inode, struct writeback_control *wbc) 107366f3b8e2SJens Axboe { 10749fb0a7daSTejun Heo int ret; 10759fb0a7daSTejun Heo 10769fb0a7daSTejun Heo if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) { 10779fb0a7daSTejun Heo trace_writeback_write_inode_start(inode, wbc); 10789fb0a7daSTejun Heo ret = inode->i_sb->s_op->write_inode(inode, wbc); 10799fb0a7daSTejun Heo trace_writeback_write_inode(inode, wbc); 10809fb0a7daSTejun Heo return ret; 10819fb0a7daSTejun Heo } 108203ba3782SJens Axboe return 0; 108366f3b8e2SJens Axboe } 108408d8e974SFengguang Wu 10852c136579SFengguang Wu /* 1086169ebd90SJan Kara * Wait for writeback on an inode to complete. Called with i_lock held. 1087169ebd90SJan Kara * Caller must make sure inode cannot go away when we drop i_lock. 108801c03194SChristoph Hellwig */ 1089169ebd90SJan Kara static void __inode_wait_for_writeback(struct inode *inode) 1090169ebd90SJan Kara __releases(inode->i_lock) 1091169ebd90SJan Kara __acquires(inode->i_lock) 109201c03194SChristoph Hellwig { 109301c03194SChristoph Hellwig DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); 109401c03194SChristoph Hellwig wait_queue_head_t *wqh; 109501c03194SChristoph Hellwig 109601c03194SChristoph Hellwig wqh = bit_waitqueue(&inode->i_state, __I_SYNC); 109758a9d3d8SRichard Kennedy while (inode->i_state & I_SYNC) { 1098250df6edSDave Chinner spin_unlock(&inode->i_lock); 109974316201SNeilBrown __wait_on_bit(wqh, &wq, bit_wait, 110074316201SNeilBrown TASK_UNINTERRUPTIBLE); 1101250df6edSDave Chinner spin_lock(&inode->i_lock); 110258a9d3d8SRichard Kennedy } 110301c03194SChristoph Hellwig } 110401c03194SChristoph Hellwig 110501c03194SChristoph Hellwig /* 1106169ebd90SJan Kara * Wait for writeback on an inode to complete. Caller must have inode pinned. 1107169ebd90SJan Kara */ 1108169ebd90SJan Kara void inode_wait_for_writeback(struct inode *inode) 1109169ebd90SJan Kara { 1110169ebd90SJan Kara spin_lock(&inode->i_lock); 1111169ebd90SJan Kara __inode_wait_for_writeback(inode); 1112169ebd90SJan Kara spin_unlock(&inode->i_lock); 1113169ebd90SJan Kara } 1114169ebd90SJan Kara 1115169ebd90SJan Kara /* 1116169ebd90SJan Kara * Sleep until I_SYNC is cleared. This function must be called with i_lock 1117169ebd90SJan Kara * held and drops it. It is aimed for callers not holding any inode reference 1118169ebd90SJan Kara * so once i_lock is dropped, inode can go away. 1119169ebd90SJan Kara */ 1120169ebd90SJan Kara static void inode_sleep_on_writeback(struct inode *inode) 1121169ebd90SJan Kara __releases(inode->i_lock) 1122169ebd90SJan Kara { 1123169ebd90SJan Kara DEFINE_WAIT(wait); 1124169ebd90SJan Kara wait_queue_head_t *wqh = bit_waitqueue(&inode->i_state, __I_SYNC); 1125169ebd90SJan Kara int sleep; 1126169ebd90SJan Kara 1127169ebd90SJan Kara prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); 1128169ebd90SJan Kara sleep = inode->i_state & I_SYNC; 1129169ebd90SJan Kara spin_unlock(&inode->i_lock); 1130169ebd90SJan Kara if (sleep) 1131169ebd90SJan Kara schedule(); 1132169ebd90SJan Kara finish_wait(wqh, &wait); 1133169ebd90SJan Kara } 1134169ebd90SJan Kara 1135169ebd90SJan Kara /* 1136ccb26b5aSJan Kara * Find proper writeback list for the inode depending on its current state and 1137ccb26b5aSJan Kara * possibly also change of its state while we were doing writeback. Here we 1138ccb26b5aSJan Kara * handle things such as livelock prevention or fairness of writeback among 1139ccb26b5aSJan Kara * inodes. This function can be called only by flusher thread - noone else 1140ccb26b5aSJan Kara * processes all inodes in writeback lists and requeueing inodes behind flusher 1141ccb26b5aSJan Kara * thread's back can have unexpected consequences. 1142ccb26b5aSJan Kara */ 1143ccb26b5aSJan Kara static void requeue_inode(struct inode *inode, struct bdi_writeback *wb, 1144ccb26b5aSJan Kara struct writeback_control *wbc) 1145ccb26b5aSJan Kara { 1146ccb26b5aSJan Kara if (inode->i_state & I_FREEING) 1147ccb26b5aSJan Kara return; 1148ccb26b5aSJan Kara 1149ccb26b5aSJan Kara /* 1150ccb26b5aSJan Kara * Sync livelock prevention. Each inode is tagged and synced in one 1151ccb26b5aSJan Kara * shot. If still dirty, it will be redirty_tail()'ed below. Update 1152ccb26b5aSJan Kara * the dirty time to prevent enqueue and sync it again. 1153ccb26b5aSJan Kara */ 1154ccb26b5aSJan Kara if ((inode->i_state & I_DIRTY) && 1155ccb26b5aSJan Kara (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)) 1156ccb26b5aSJan Kara inode->dirtied_when = jiffies; 1157ccb26b5aSJan Kara 11584f8ad655SJan Kara if (wbc->pages_skipped) { 11594f8ad655SJan Kara /* 11604f8ad655SJan Kara * writeback is not making progress due to locked 11614f8ad655SJan Kara * buffers. Skip this inode for now. 11624f8ad655SJan Kara */ 11634f8ad655SJan Kara redirty_tail(inode, wb); 11644f8ad655SJan Kara return; 11654f8ad655SJan Kara } 11664f8ad655SJan Kara 1167ccb26b5aSJan Kara if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) { 1168ccb26b5aSJan Kara /* 1169ccb26b5aSJan Kara * We didn't write back all the pages. nfs_writepages() 1170ccb26b5aSJan Kara * sometimes bales out without doing anything. 1171ccb26b5aSJan Kara */ 1172ccb26b5aSJan Kara if (wbc->nr_to_write <= 0) { 1173ccb26b5aSJan Kara /* Slice used up. Queue for next turn. */ 1174ccb26b5aSJan Kara requeue_io(inode, wb); 1175ccb26b5aSJan Kara } else { 1176ccb26b5aSJan Kara /* 1177ccb26b5aSJan Kara * Writeback blocked by something other than 1178ccb26b5aSJan Kara * congestion. Delay the inode for some time to 1179ccb26b5aSJan Kara * avoid spinning on the CPU (100% iowait) 1180ccb26b5aSJan Kara * retrying writeback of the dirty page/inode 1181ccb26b5aSJan Kara * that cannot be performed immediately. 1182ccb26b5aSJan Kara */ 1183ccb26b5aSJan Kara redirty_tail(inode, wb); 1184ccb26b5aSJan Kara } 1185ccb26b5aSJan Kara } else if (inode->i_state & I_DIRTY) { 1186ccb26b5aSJan Kara /* 1187ccb26b5aSJan Kara * Filesystems can dirty the inode during writeback operations, 1188ccb26b5aSJan Kara * such as delayed allocation during submission or metadata 1189ccb26b5aSJan Kara * updates after data IO completion. 1190ccb26b5aSJan Kara */ 1191ccb26b5aSJan Kara redirty_tail(inode, wb); 11920ae45f63STheodore Ts'o } else if (inode->i_state & I_DIRTY_TIME) { 1193a2f48706STheodore Ts'o inode->dirtied_when = jiffies; 1194c7f54084SDave Chinner inode_io_list_move_locked(inode, wb, &wb->b_dirty_time); 1195ccb26b5aSJan Kara } else { 1196ccb26b5aSJan Kara /* The inode is clean. Remove from writeback lists. */ 1197c7f54084SDave Chinner inode_io_list_del_locked(inode, wb); 1198ccb26b5aSJan Kara } 1199ccb26b5aSJan Kara } 1200ccb26b5aSJan Kara 1201ccb26b5aSJan Kara /* 12024f8ad655SJan Kara * Write out an inode and its dirty pages. Do not update the writeback list 12034f8ad655SJan Kara * linkage. That is left to the caller. The caller is also responsible for 12044f8ad655SJan Kara * setting I_SYNC flag and calling inode_sync_complete() to clear it. 12051da177e4SLinus Torvalds */ 12061da177e4SLinus Torvalds static int 1207cd8ed2a4SYan Hong __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) 12081da177e4SLinus Torvalds { 12091da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 1210251d6a47SWu Fengguang long nr_to_write = wbc->nr_to_write; 121101c03194SChristoph Hellwig unsigned dirty; 12121da177e4SLinus Torvalds int ret; 12131da177e4SLinus Torvalds 12144f8ad655SJan Kara WARN_ON(!(inode->i_state & I_SYNC)); 12151da177e4SLinus Torvalds 12169fb0a7daSTejun Heo trace_writeback_single_inode_start(inode, wbc, nr_to_write); 12179fb0a7daSTejun Heo 12181da177e4SLinus Torvalds ret = do_writepages(mapping, wbc); 12191da177e4SLinus Torvalds 122026821ed4SChristoph Hellwig /* 122126821ed4SChristoph Hellwig * Make sure to wait on the data before writing out the metadata. 122226821ed4SChristoph Hellwig * This is important for filesystems that modify metadata on data 12237747bd4bSDave Chinner * I/O completion. We don't do it for sync(2) writeback because it has a 12247747bd4bSDave Chinner * separate, external IO completion path and ->sync_fs for guaranteeing 12257747bd4bSDave Chinner * inode metadata is written back correctly. 122626821ed4SChristoph Hellwig */ 12277747bd4bSDave Chinner if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync) { 122826821ed4SChristoph Hellwig int err = filemap_fdatawait(mapping); 12291da177e4SLinus Torvalds if (ret == 0) 12301da177e4SLinus Torvalds ret = err; 12311da177e4SLinus Torvalds } 12321da177e4SLinus Torvalds 12335547e8aaSDmitry Monakhov /* 12345547e8aaSDmitry Monakhov * Some filesystems may redirty the inode during the writeback 12355547e8aaSDmitry Monakhov * due to delalloc, clear dirty metadata flags right before 12365547e8aaSDmitry Monakhov * write_inode() 12375547e8aaSDmitry Monakhov */ 1238250df6edSDave Chinner spin_lock(&inode->i_lock); 12399c6ac78eSTejun Heo 12405547e8aaSDmitry Monakhov dirty = inode->i_state & I_DIRTY; 1241a2f48706STheodore Ts'o if (inode->i_state & I_DIRTY_TIME) { 1242a2f48706STheodore Ts'o if ((dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) || 1243a2f48706STheodore Ts'o unlikely(inode->i_state & I_DIRTY_TIME_EXPIRED) || 1244a2f48706STheodore Ts'o unlikely(time_after(jiffies, 1245a2f48706STheodore Ts'o (inode->dirtied_time_when + 1246a2f48706STheodore Ts'o dirtytime_expire_interval * HZ)))) { 12470ae45f63STheodore Ts'o dirty |= I_DIRTY_TIME | I_DIRTY_TIME_EXPIRED; 12480ae45f63STheodore Ts'o trace_writeback_lazytime(inode); 12490ae45f63STheodore Ts'o } 1250a2f48706STheodore Ts'o } else 1251a2f48706STheodore Ts'o inode->i_state &= ~I_DIRTY_TIME_EXPIRED; 12520ae45f63STheodore Ts'o inode->i_state &= ~dirty; 12539c6ac78eSTejun Heo 12549c6ac78eSTejun Heo /* 12559c6ac78eSTejun Heo * Paired with smp_mb() in __mark_inode_dirty(). This allows 12569c6ac78eSTejun Heo * __mark_inode_dirty() to test i_state without grabbing i_lock - 12579c6ac78eSTejun Heo * either they see the I_DIRTY bits cleared or we see the dirtied 12589c6ac78eSTejun Heo * inode. 12599c6ac78eSTejun Heo * 12609c6ac78eSTejun Heo * I_DIRTY_PAGES is always cleared together above even if @mapping 12619c6ac78eSTejun Heo * still has dirty pages. The flag is reinstated after smp_mb() if 12629c6ac78eSTejun Heo * necessary. This guarantees that either __mark_inode_dirty() 12639c6ac78eSTejun Heo * sees clear I_DIRTY_PAGES or we see PAGECACHE_TAG_DIRTY. 12649c6ac78eSTejun Heo */ 12659c6ac78eSTejun Heo smp_mb(); 12669c6ac78eSTejun Heo 12679c6ac78eSTejun Heo if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) 12689c6ac78eSTejun Heo inode->i_state |= I_DIRTY_PAGES; 12699c6ac78eSTejun Heo 1270250df6edSDave Chinner spin_unlock(&inode->i_lock); 12719c6ac78eSTejun Heo 12720ae45f63STheodore Ts'o if (dirty & I_DIRTY_TIME) 12730ae45f63STheodore Ts'o mark_inode_dirty_sync(inode); 127426821ed4SChristoph Hellwig /* Don't write the inode if only I_DIRTY_PAGES was set */ 12750ae45f63STheodore Ts'o if (dirty & ~I_DIRTY_PAGES) { 1276a9185b41SChristoph Hellwig int err = write_inode(inode, wbc); 12771da177e4SLinus Torvalds if (ret == 0) 12781da177e4SLinus Torvalds ret = err; 12791da177e4SLinus Torvalds } 12804f8ad655SJan Kara trace_writeback_single_inode(inode, wbc, nr_to_write); 12814f8ad655SJan Kara return ret; 12824f8ad655SJan Kara } 12834f8ad655SJan Kara 12844f8ad655SJan Kara /* 12854f8ad655SJan Kara * Write out an inode's dirty pages. Either the caller has an active reference 12864f8ad655SJan Kara * on the inode or the inode has I_WILL_FREE set. 12874f8ad655SJan Kara * 12884f8ad655SJan Kara * This function is designed to be called for writing back one inode which 12894f8ad655SJan Kara * we go e.g. from filesystem. Flusher thread uses __writeback_single_inode() 12904f8ad655SJan Kara * and does more profound writeback list handling in writeback_sb_inodes(). 12914f8ad655SJan Kara */ 12924f8ad655SJan Kara static int 12934f8ad655SJan Kara writeback_single_inode(struct inode *inode, struct bdi_writeback *wb, 12944f8ad655SJan Kara struct writeback_control *wbc) 12954f8ad655SJan Kara { 12964f8ad655SJan Kara int ret = 0; 12974f8ad655SJan Kara 12984f8ad655SJan Kara spin_lock(&inode->i_lock); 12994f8ad655SJan Kara if (!atomic_read(&inode->i_count)) 13004f8ad655SJan Kara WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); 13014f8ad655SJan Kara else 13024f8ad655SJan Kara WARN_ON(inode->i_state & I_WILL_FREE); 13034f8ad655SJan Kara 13044f8ad655SJan Kara if (inode->i_state & I_SYNC) { 13054f8ad655SJan Kara if (wbc->sync_mode != WB_SYNC_ALL) 13064f8ad655SJan Kara goto out; 13074f8ad655SJan Kara /* 1308169ebd90SJan Kara * It's a data-integrity sync. We must wait. Since callers hold 1309169ebd90SJan Kara * inode reference or inode has I_WILL_FREE set, it cannot go 1310169ebd90SJan Kara * away under us. 13114f8ad655SJan Kara */ 1312169ebd90SJan Kara __inode_wait_for_writeback(inode); 13134f8ad655SJan Kara } 13144f8ad655SJan Kara WARN_ON(inode->i_state & I_SYNC); 13154f8ad655SJan Kara /* 1316f9b0e058SJan Kara * Skip inode if it is clean and we have no outstanding writeback in 1317f9b0e058SJan Kara * WB_SYNC_ALL mode. We don't want to mess with writeback lists in this 1318f9b0e058SJan Kara * function since flusher thread may be doing for example sync in 1319f9b0e058SJan Kara * parallel and if we move the inode, it could get skipped. So here we 1320f9b0e058SJan Kara * make sure inode is on some writeback list and leave it there unless 1321f9b0e058SJan Kara * we have completely cleaned the inode. 13224f8ad655SJan Kara */ 13230ae45f63STheodore Ts'o if (!(inode->i_state & I_DIRTY_ALL) && 1324f9b0e058SJan Kara (wbc->sync_mode != WB_SYNC_ALL || 1325f9b0e058SJan Kara !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))) 13264f8ad655SJan Kara goto out; 13274f8ad655SJan Kara inode->i_state |= I_SYNC; 1328b16b1debSTejun Heo wbc_attach_and_unlock_inode(wbc, inode); 13294f8ad655SJan Kara 1330cd8ed2a4SYan Hong ret = __writeback_single_inode(inode, wbc); 13311da177e4SLinus Torvalds 1332b16b1debSTejun Heo wbc_detach_inode(wbc); 1333f758eeabSChristoph Hellwig spin_lock(&wb->list_lock); 1334250df6edSDave Chinner spin_lock(&inode->i_lock); 13354f8ad655SJan Kara /* 13364f8ad655SJan Kara * If inode is clean, remove it from writeback lists. Otherwise don't 13374f8ad655SJan Kara * touch it. See comment above for explanation. 13384f8ad655SJan Kara */ 13390ae45f63STheodore Ts'o if (!(inode->i_state & I_DIRTY_ALL)) 1340c7f54084SDave Chinner inode_io_list_del_locked(inode, wb); 13414f8ad655SJan Kara spin_unlock(&wb->list_lock); 13421c0eeaf5SJoern Engel inode_sync_complete(inode); 13434f8ad655SJan Kara out: 13444f8ad655SJan Kara spin_unlock(&inode->i_lock); 13451da177e4SLinus Torvalds return ret; 13461da177e4SLinus Torvalds } 13471da177e4SLinus Torvalds 1348a88a341aSTejun Heo static long writeback_chunk_size(struct bdi_writeback *wb, 13491a12d8bdSWu Fengguang struct wb_writeback_work *work) 1350d46db3d5SWu Fengguang { 1351d46db3d5SWu Fengguang long pages; 1352d46db3d5SWu Fengguang 1353d46db3d5SWu Fengguang /* 1354d46db3d5SWu Fengguang * WB_SYNC_ALL mode does livelock avoidance by syncing dirty 1355d46db3d5SWu Fengguang * inodes/pages in one big loop. Setting wbc.nr_to_write=LONG_MAX 1356d46db3d5SWu Fengguang * here avoids calling into writeback_inodes_wb() more than once. 1357d46db3d5SWu Fengguang * 1358d46db3d5SWu Fengguang * The intended call sequence for WB_SYNC_ALL writeback is: 1359d46db3d5SWu Fengguang * 1360d46db3d5SWu Fengguang * wb_writeback() 1361d46db3d5SWu Fengguang * writeback_sb_inodes() <== called only once 1362d46db3d5SWu Fengguang * write_cache_pages() <== called once for each inode 1363d46db3d5SWu Fengguang * (quickly) tag currently dirty pages 1364d46db3d5SWu Fengguang * (maybe slowly) sync all tagged pages 1365d46db3d5SWu Fengguang */ 1366d46db3d5SWu Fengguang if (work->sync_mode == WB_SYNC_ALL || work->tagged_writepages) 1367d46db3d5SWu Fengguang pages = LONG_MAX; 13681a12d8bdSWu Fengguang else { 1369a88a341aSTejun Heo pages = min(wb->avg_write_bandwidth / 2, 1370dcc25ae7STejun Heo global_wb_domain.dirty_limit / DIRTY_SCOPE); 13711a12d8bdSWu Fengguang pages = min(pages, work->nr_pages); 13721a12d8bdSWu Fengguang pages = round_down(pages + MIN_WRITEBACK_PAGES, 13731a12d8bdSWu Fengguang MIN_WRITEBACK_PAGES); 13741a12d8bdSWu Fengguang } 1375d46db3d5SWu Fengguang 1376d46db3d5SWu Fengguang return pages; 1377d46db3d5SWu Fengguang } 1378d46db3d5SWu Fengguang 137903ba3782SJens Axboe /* 1380f11c9c5cSEdward Shishkin * Write a portion of b_io inodes which belong to @sb. 1381edadfb10SChristoph Hellwig * 1382d46db3d5SWu Fengguang * Return the number of pages and/or inodes written. 13830ba13fd1SLinus Torvalds * 13840ba13fd1SLinus Torvalds * NOTE! This is called with wb->list_lock held, and will 13850ba13fd1SLinus Torvalds * unlock and relock that for each inode it ends up doing 13860ba13fd1SLinus Torvalds * IO for. 1387f11c9c5cSEdward Shishkin */ 1388d46db3d5SWu Fengguang static long writeback_sb_inodes(struct super_block *sb, 1389d46db3d5SWu Fengguang struct bdi_writeback *wb, 1390d46db3d5SWu Fengguang struct wb_writeback_work *work) 139103ba3782SJens Axboe { 1392d46db3d5SWu Fengguang struct writeback_control wbc = { 1393d46db3d5SWu Fengguang .sync_mode = work->sync_mode, 1394d46db3d5SWu Fengguang .tagged_writepages = work->tagged_writepages, 1395d46db3d5SWu Fengguang .for_kupdate = work->for_kupdate, 1396d46db3d5SWu Fengguang .for_background = work->for_background, 13977747bd4bSDave Chinner .for_sync = work->for_sync, 1398d46db3d5SWu Fengguang .range_cyclic = work->range_cyclic, 1399d46db3d5SWu Fengguang .range_start = 0, 1400d46db3d5SWu Fengguang .range_end = LLONG_MAX, 1401d46db3d5SWu Fengguang }; 1402d46db3d5SWu Fengguang unsigned long start_time = jiffies; 1403d46db3d5SWu Fengguang long write_chunk; 1404d46db3d5SWu Fengguang long wrote = 0; /* count both pages and inodes */ 1405d46db3d5SWu Fengguang 140603ba3782SJens Axboe while (!list_empty(&wb->b_io)) { 14077ccf19a8SNick Piggin struct inode *inode = wb_inode(wb->b_io.prev); 1408edadfb10SChristoph Hellwig 1409edadfb10SChristoph Hellwig if (inode->i_sb != sb) { 1410d46db3d5SWu Fengguang if (work->sb) { 1411edadfb10SChristoph Hellwig /* 1412edadfb10SChristoph Hellwig * We only want to write back data for this 1413edadfb10SChristoph Hellwig * superblock, move all inodes not belonging 1414edadfb10SChristoph Hellwig * to it back onto the dirty list. 1415edadfb10SChristoph Hellwig */ 1416f758eeabSChristoph Hellwig redirty_tail(inode, wb); 141766f3b8e2SJens Axboe continue; 141866f3b8e2SJens Axboe } 1419edadfb10SChristoph Hellwig 1420edadfb10SChristoph Hellwig /* 1421edadfb10SChristoph Hellwig * The inode belongs to a different superblock. 1422edadfb10SChristoph Hellwig * Bounce back to the caller to unpin this and 1423edadfb10SChristoph Hellwig * pin the next superblock. 1424edadfb10SChristoph Hellwig */ 1425d46db3d5SWu Fengguang break; 1426edadfb10SChristoph Hellwig } 1427edadfb10SChristoph Hellwig 14289843b76aSChristoph Hellwig /* 1429331cbdeeSWanpeng Li * Don't bother with new inodes or inodes being freed, first 1430331cbdeeSWanpeng Li * kind does not need periodic writeout yet, and for the latter 14319843b76aSChristoph Hellwig * kind writeout is handled by the freer. 14329843b76aSChristoph Hellwig */ 1433250df6edSDave Chinner spin_lock(&inode->i_lock); 14349843b76aSChristoph Hellwig if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { 1435250df6edSDave Chinner spin_unlock(&inode->i_lock); 1436fcc5c222SWu Fengguang redirty_tail(inode, wb); 14377ef0d737SNick Piggin continue; 14387ef0d737SNick Piggin } 1439cc1676d9SJan Kara if ((inode->i_state & I_SYNC) && wbc.sync_mode != WB_SYNC_ALL) { 1440cc1676d9SJan Kara /* 1441cc1676d9SJan Kara * If this inode is locked for writeback and we are not 1442cc1676d9SJan Kara * doing writeback-for-data-integrity, move it to 1443cc1676d9SJan Kara * b_more_io so that writeback can proceed with the 1444cc1676d9SJan Kara * other inodes on s_io. 1445cc1676d9SJan Kara * 1446cc1676d9SJan Kara * We'll have another go at writing back this inode 1447cc1676d9SJan Kara * when we completed a full scan of b_io. 1448cc1676d9SJan Kara */ 1449cc1676d9SJan Kara spin_unlock(&inode->i_lock); 1450cc1676d9SJan Kara requeue_io(inode, wb); 1451cc1676d9SJan Kara trace_writeback_sb_inodes_requeue(inode); 1452cc1676d9SJan Kara continue; 1453cc1676d9SJan Kara } 1454f0d07b7fSJan Kara spin_unlock(&wb->list_lock); 1455f0d07b7fSJan Kara 14564f8ad655SJan Kara /* 14574f8ad655SJan Kara * We already requeued the inode if it had I_SYNC set and we 14584f8ad655SJan Kara * are doing WB_SYNC_NONE writeback. So this catches only the 14594f8ad655SJan Kara * WB_SYNC_ALL case. 14604f8ad655SJan Kara */ 1461169ebd90SJan Kara if (inode->i_state & I_SYNC) { 1462169ebd90SJan Kara /* Wait for I_SYNC. This function drops i_lock... */ 1463169ebd90SJan Kara inode_sleep_on_writeback(inode); 1464169ebd90SJan Kara /* Inode may be gone, start again */ 1465ead188f9SJan Kara spin_lock(&wb->list_lock); 1466169ebd90SJan Kara continue; 1467169ebd90SJan Kara } 14684f8ad655SJan Kara inode->i_state |= I_SYNC; 1469b16b1debSTejun Heo wbc_attach_and_unlock_inode(&wbc, inode); 1470169ebd90SJan Kara 1471a88a341aSTejun Heo write_chunk = writeback_chunk_size(wb, work); 1472d46db3d5SWu Fengguang wbc.nr_to_write = write_chunk; 1473d46db3d5SWu Fengguang wbc.pages_skipped = 0; 1474250df6edSDave Chinner 1475169ebd90SJan Kara /* 1476169ebd90SJan Kara * We use I_SYNC to pin the inode in memory. While it is set 1477169ebd90SJan Kara * evict_inode() will wait so the inode cannot be freed. 1478169ebd90SJan Kara */ 1479cd8ed2a4SYan Hong __writeback_single_inode(inode, &wbc); 1480d46db3d5SWu Fengguang 1481b16b1debSTejun Heo wbc_detach_inode(&wbc); 1482d46db3d5SWu Fengguang work->nr_pages -= write_chunk - wbc.nr_to_write; 1483d46db3d5SWu Fengguang wrote += write_chunk - wbc.nr_to_write; 1484590dca3aSChris Mason 1485590dca3aSChris Mason if (need_resched()) { 1486590dca3aSChris Mason /* 1487590dca3aSChris Mason * We're trying to balance between building up a nice 1488590dca3aSChris Mason * long list of IOs to improve our merge rate, and 1489590dca3aSChris Mason * getting those IOs out quickly for anyone throttling 1490590dca3aSChris Mason * in balance_dirty_pages(). cond_resched() doesn't 1491590dca3aSChris Mason * unplug, so get our IOs out the door before we 1492590dca3aSChris Mason * give up the CPU. 1493590dca3aSChris Mason */ 1494590dca3aSChris Mason blk_flush_plug(current); 1495590dca3aSChris Mason cond_resched(); 1496590dca3aSChris Mason } 1497590dca3aSChris Mason 1498590dca3aSChris Mason 14994f8ad655SJan Kara spin_lock(&wb->list_lock); 15004f8ad655SJan Kara spin_lock(&inode->i_lock); 15010ae45f63STheodore Ts'o if (!(inode->i_state & I_DIRTY_ALL)) 1502d46db3d5SWu Fengguang wrote++; 15034f8ad655SJan Kara requeue_inode(inode, wb, &wbc); 15044f8ad655SJan Kara inode_sync_complete(inode); 15050f1b1fd8SDave Chinner spin_unlock(&inode->i_lock); 1506590dca3aSChris Mason 1507d46db3d5SWu Fengguang /* 1508d46db3d5SWu Fengguang * bail out to wb_writeback() often enough to check 1509d46db3d5SWu Fengguang * background threshold and other termination conditions. 1510d46db3d5SWu Fengguang */ 1511d46db3d5SWu Fengguang if (wrote) { 1512d46db3d5SWu Fengguang if (time_is_before_jiffies(start_time + HZ / 10UL)) 1513d46db3d5SWu Fengguang break; 1514d46db3d5SWu Fengguang if (work->nr_pages <= 0) 1515d46db3d5SWu Fengguang break; 15161da177e4SLinus Torvalds } 15178bc3be27SFengguang Wu } 1518d46db3d5SWu Fengguang return wrote; 1519f11c9c5cSEdward Shishkin } 152038f21977SNick Piggin 1521d46db3d5SWu Fengguang static long __writeback_inodes_wb(struct bdi_writeback *wb, 1522d46db3d5SWu Fengguang struct wb_writeback_work *work) 1523f11c9c5cSEdward Shishkin { 1524d46db3d5SWu Fengguang unsigned long start_time = jiffies; 1525d46db3d5SWu Fengguang long wrote = 0; 1526f11c9c5cSEdward Shishkin 1527f11c9c5cSEdward Shishkin while (!list_empty(&wb->b_io)) { 15287ccf19a8SNick Piggin struct inode *inode = wb_inode(wb->b_io.prev); 1529f11c9c5cSEdward Shishkin struct super_block *sb = inode->i_sb; 1530f11c9c5cSEdward Shishkin 1531eb6ef3dfSKonstantin Khlebnikov if (!trylock_super(sb)) { 15320e995816SWu Fengguang /* 1533eb6ef3dfSKonstantin Khlebnikov * trylock_super() may fail consistently due to 15340e995816SWu Fengguang * s_umount being grabbed by someone else. Don't use 15350e995816SWu Fengguang * requeue_io() to avoid busy retrying the inode/sb. 15360e995816SWu Fengguang */ 15370e995816SWu Fengguang redirty_tail(inode, wb); 1538d19de7edSChristoph Hellwig continue; 1539334132aeSChristoph Hellwig } 1540d46db3d5SWu Fengguang wrote += writeback_sb_inodes(sb, wb, work); 1541eb6ef3dfSKonstantin Khlebnikov up_read(&sb->s_umount); 1542f11c9c5cSEdward Shishkin 1543d46db3d5SWu Fengguang /* refer to the same tests at the end of writeback_sb_inodes */ 1544d46db3d5SWu Fengguang if (wrote) { 1545d46db3d5SWu Fengguang if (time_is_before_jiffies(start_time + HZ / 10UL)) 1546d46db3d5SWu Fengguang break; 1547d46db3d5SWu Fengguang if (work->nr_pages <= 0) 1548f11c9c5cSEdward Shishkin break; 1549f11c9c5cSEdward Shishkin } 1550d46db3d5SWu Fengguang } 155166f3b8e2SJens Axboe /* Leave any unwritten inodes on b_io */ 1552d46db3d5SWu Fengguang return wrote; 155366f3b8e2SJens Axboe } 155466f3b8e2SJens Axboe 15557d9f073bSWanpeng Li static long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, 15560e175a18SCurt Wohlgemuth enum wb_reason reason) 1557edadfb10SChristoph Hellwig { 1558d46db3d5SWu Fengguang struct wb_writeback_work work = { 1559d46db3d5SWu Fengguang .nr_pages = nr_pages, 1560d46db3d5SWu Fengguang .sync_mode = WB_SYNC_NONE, 1561d46db3d5SWu Fengguang .range_cyclic = 1, 15620e175a18SCurt Wohlgemuth .reason = reason, 1563d46db3d5SWu Fengguang }; 1564505a666eSLinus Torvalds struct blk_plug plug; 1565edadfb10SChristoph Hellwig 1566505a666eSLinus Torvalds blk_start_plug(&plug); 1567f758eeabSChristoph Hellwig spin_lock(&wb->list_lock); 1568424b351fSWu Fengguang if (list_empty(&wb->b_io)) 1569ad4e38ddSCurt Wohlgemuth queue_io(wb, &work); 1570d46db3d5SWu Fengguang __writeback_inodes_wb(wb, &work); 1571f758eeabSChristoph Hellwig spin_unlock(&wb->list_lock); 1572505a666eSLinus Torvalds blk_finish_plug(&plug); 1573edadfb10SChristoph Hellwig 1574d46db3d5SWu Fengguang return nr_pages - work.nr_pages; 157566f3b8e2SJens Axboe } 157666f3b8e2SJens Axboe 157703ba3782SJens Axboe /* 157803ba3782SJens Axboe * Explicit flushing or periodic writeback of "old" data. 157903ba3782SJens Axboe * 158003ba3782SJens Axboe * Define "old": the first time one of an inode's pages is dirtied, we mark the 158103ba3782SJens Axboe * dirtying-time in the inode's address_space. So this periodic writeback code 158203ba3782SJens Axboe * just walks the superblock inode list, writing back any inodes which are 158303ba3782SJens Axboe * older than a specific point in time. 158403ba3782SJens Axboe * 158503ba3782SJens Axboe * Try to run once per dirty_writeback_interval. But if a writeback event 158603ba3782SJens Axboe * takes longer than a dirty_writeback_interval interval, then leave a 158703ba3782SJens Axboe * one-second gap. 158803ba3782SJens Axboe * 158903ba3782SJens Axboe * older_than_this takes precedence over nr_to_write. So we'll only write back 159003ba3782SJens Axboe * all dirty pages if they are all attached to "old" mappings. 159103ba3782SJens Axboe */ 1592c4a77a6cSJens Axboe static long wb_writeback(struct bdi_writeback *wb, 159383ba7b07SChristoph Hellwig struct wb_writeback_work *work) 159403ba3782SJens Axboe { 1595e98be2d5SWu Fengguang unsigned long wb_start = jiffies; 1596d46db3d5SWu Fengguang long nr_pages = work->nr_pages; 15970dc83bd3SJan Kara unsigned long oldest_jif; 1598a5989bdcSJan Kara struct inode *inode; 1599d46db3d5SWu Fengguang long progress; 1600505a666eSLinus Torvalds struct blk_plug plug; 160103ba3782SJens Axboe 16020dc83bd3SJan Kara oldest_jif = jiffies; 16030dc83bd3SJan Kara work->older_than_this = &oldest_jif; 160403ba3782SJens Axboe 1605505a666eSLinus Torvalds blk_start_plug(&plug); 1606e8dfc305SWu Fengguang spin_lock(&wb->list_lock); 160703ba3782SJens Axboe for (;;) { 160803ba3782SJens Axboe /* 1609d3ddec76SWu Fengguang * Stop writeback when nr_pages has been consumed 161003ba3782SJens Axboe */ 161183ba7b07SChristoph Hellwig if (work->nr_pages <= 0) 161203ba3782SJens Axboe break; 161303ba3782SJens Axboe 161403ba3782SJens Axboe /* 1615aa373cf5SJan Kara * Background writeout and kupdate-style writeback may 1616aa373cf5SJan Kara * run forever. Stop them if there is other work to do 1617aa373cf5SJan Kara * so that e.g. sync can proceed. They'll be restarted 1618aa373cf5SJan Kara * after the other works are all done. 1619aa373cf5SJan Kara */ 1620aa373cf5SJan Kara if ((work->for_background || work->for_kupdate) && 1621f0054bb1STejun Heo !list_empty(&wb->work_list)) 1622aa373cf5SJan Kara break; 1623aa373cf5SJan Kara 1624aa373cf5SJan Kara /* 1625d3ddec76SWu Fengguang * For background writeout, stop when we are below the 1626d3ddec76SWu Fengguang * background dirty threshold 162703ba3782SJens Axboe */ 1628aa661bbeSTejun Heo if (work->for_background && !wb_over_bg_thresh(wb)) 162903ba3782SJens Axboe break; 163003ba3782SJens Axboe 16311bc36b64SJan Kara /* 16321bc36b64SJan Kara * Kupdate and background works are special and we want to 16331bc36b64SJan Kara * include all inodes that need writing. Livelock avoidance is 16341bc36b64SJan Kara * handled by these works yielding to any other work so we are 16351bc36b64SJan Kara * safe. 16361bc36b64SJan Kara */ 1637ba9aa839SWu Fengguang if (work->for_kupdate) { 16380dc83bd3SJan Kara oldest_jif = jiffies - 1639ba9aa839SWu Fengguang msecs_to_jiffies(dirty_expire_interval * 10); 16401bc36b64SJan Kara } else if (work->for_background) 16410dc83bd3SJan Kara oldest_jif = jiffies; 1642028c2dd1SDave Chinner 16435634cc2aSTejun Heo trace_writeback_start(wb, work); 1644e8dfc305SWu Fengguang if (list_empty(&wb->b_io)) 1645ad4e38ddSCurt Wohlgemuth queue_io(wb, work); 164683ba7b07SChristoph Hellwig if (work->sb) 1647d46db3d5SWu Fengguang progress = writeback_sb_inodes(work->sb, wb, work); 1648edadfb10SChristoph Hellwig else 1649d46db3d5SWu Fengguang progress = __writeback_inodes_wb(wb, work); 16505634cc2aSTejun Heo trace_writeback_written(wb, work); 1651028c2dd1SDave Chinner 1652e98be2d5SWu Fengguang wb_update_bandwidth(wb, wb_start); 165303ba3782SJens Axboe 165403ba3782SJens Axboe /* 165571fd05a8SJens Axboe * Did we write something? Try for more 1656e6fb6da2SWu Fengguang * 1657e6fb6da2SWu Fengguang * Dirty inodes are moved to b_io for writeback in batches. 1658e6fb6da2SWu Fengguang * The completion of the current batch does not necessarily 1659e6fb6da2SWu Fengguang * mean the overall work is done. So we keep looping as long 1660e6fb6da2SWu Fengguang * as made some progress on cleaning pages or inodes. 166171fd05a8SJens Axboe */ 1662d46db3d5SWu Fengguang if (progress) 166303ba3782SJens Axboe continue; 1664a5989bdcSJan Kara /* 1665e6fb6da2SWu Fengguang * No more inodes for IO, bail 1666a5989bdcSJan Kara */ 1667b7a2441fSWu Fengguang if (list_empty(&wb->b_more_io)) 166803ba3782SJens Axboe break; 166903ba3782SJens Axboe /* 16708010c3b6SJens Axboe * Nothing written. Wait for some inode to 16718010c3b6SJens Axboe * become available for writeback. Otherwise 16728010c3b6SJens Axboe * we'll just busyloop. 167303ba3782SJens Axboe */ 167403ba3782SJens Axboe if (!list_empty(&wb->b_more_io)) { 16755634cc2aSTejun Heo trace_writeback_wait(wb, work); 167603ba3782SJens Axboe inode = wb_inode(wb->b_more_io.prev); 1677250df6edSDave Chinner spin_lock(&inode->i_lock); 1678f0d07b7fSJan Kara spin_unlock(&wb->list_lock); 1679169ebd90SJan Kara /* This function drops i_lock... */ 1680169ebd90SJan Kara inode_sleep_on_writeback(inode); 1681f0d07b7fSJan Kara spin_lock(&wb->list_lock); 168203ba3782SJens Axboe } 168303ba3782SJens Axboe } 1684e8dfc305SWu Fengguang spin_unlock(&wb->list_lock); 1685505a666eSLinus Torvalds blk_finish_plug(&plug); 168603ba3782SJens Axboe 1687d46db3d5SWu Fengguang return nr_pages - work->nr_pages; 168803ba3782SJens Axboe } 168903ba3782SJens Axboe 169003ba3782SJens Axboe /* 169183ba7b07SChristoph Hellwig * Return the next wb_writeback_work struct that hasn't been processed yet. 169203ba3782SJens Axboe */ 1693f0054bb1STejun Heo static struct wb_writeback_work *get_next_work_item(struct bdi_writeback *wb) 169403ba3782SJens Axboe { 169583ba7b07SChristoph Hellwig struct wb_writeback_work *work = NULL; 169603ba3782SJens Axboe 1697f0054bb1STejun Heo spin_lock_bh(&wb->work_lock); 1698f0054bb1STejun Heo if (!list_empty(&wb->work_list)) { 1699f0054bb1STejun Heo work = list_entry(wb->work_list.next, 170083ba7b07SChristoph Hellwig struct wb_writeback_work, list); 170183ba7b07SChristoph Hellwig list_del_init(&work->list); 170203ba3782SJens Axboe } 1703f0054bb1STejun Heo spin_unlock_bh(&wb->work_lock); 170483ba7b07SChristoph Hellwig return work; 170503ba3782SJens Axboe } 170603ba3782SJens Axboe 1707cdf01dd5SLinus Torvalds /* 1708cdf01dd5SLinus Torvalds * Add in the number of potentially dirty inodes, because each inode 1709cdf01dd5SLinus Torvalds * write can dirty pagecache in the underlying blockdev. 1710cdf01dd5SLinus Torvalds */ 1711cdf01dd5SLinus Torvalds static unsigned long get_nr_dirty_pages(void) 1712cdf01dd5SLinus Torvalds { 1713cdf01dd5SLinus Torvalds return global_page_state(NR_FILE_DIRTY) + 1714cdf01dd5SLinus Torvalds global_page_state(NR_UNSTABLE_NFS) + 1715cdf01dd5SLinus Torvalds get_nr_dirty_inodes(); 1716cdf01dd5SLinus Torvalds } 1717cdf01dd5SLinus Torvalds 17186585027aSJan Kara static long wb_check_background_flush(struct bdi_writeback *wb) 17196585027aSJan Kara { 1720aa661bbeSTejun Heo if (wb_over_bg_thresh(wb)) { 17216585027aSJan Kara 17226585027aSJan Kara struct wb_writeback_work work = { 17236585027aSJan Kara .nr_pages = LONG_MAX, 17246585027aSJan Kara .sync_mode = WB_SYNC_NONE, 17256585027aSJan Kara .for_background = 1, 17266585027aSJan Kara .range_cyclic = 1, 17270e175a18SCurt Wohlgemuth .reason = WB_REASON_BACKGROUND, 17286585027aSJan Kara }; 17296585027aSJan Kara 17306585027aSJan Kara return wb_writeback(wb, &work); 17316585027aSJan Kara } 17326585027aSJan Kara 17336585027aSJan Kara return 0; 17346585027aSJan Kara } 17356585027aSJan Kara 173603ba3782SJens Axboe static long wb_check_old_data_flush(struct bdi_writeback *wb) 173703ba3782SJens Axboe { 173803ba3782SJens Axboe unsigned long expired; 173903ba3782SJens Axboe long nr_pages; 174003ba3782SJens Axboe 174169b62d01SJens Axboe /* 174269b62d01SJens Axboe * When set to zero, disable periodic writeback 174369b62d01SJens Axboe */ 174469b62d01SJens Axboe if (!dirty_writeback_interval) 174569b62d01SJens Axboe return 0; 174669b62d01SJens Axboe 174703ba3782SJens Axboe expired = wb->last_old_flush + 174803ba3782SJens Axboe msecs_to_jiffies(dirty_writeback_interval * 10); 174903ba3782SJens Axboe if (time_before(jiffies, expired)) 175003ba3782SJens Axboe return 0; 175103ba3782SJens Axboe 175203ba3782SJens Axboe wb->last_old_flush = jiffies; 1753cdf01dd5SLinus Torvalds nr_pages = get_nr_dirty_pages(); 175403ba3782SJens Axboe 1755c4a77a6cSJens Axboe if (nr_pages) { 175683ba7b07SChristoph Hellwig struct wb_writeback_work work = { 1757c4a77a6cSJens Axboe .nr_pages = nr_pages, 1758c4a77a6cSJens Axboe .sync_mode = WB_SYNC_NONE, 1759c4a77a6cSJens Axboe .for_kupdate = 1, 1760c4a77a6cSJens Axboe .range_cyclic = 1, 17610e175a18SCurt Wohlgemuth .reason = WB_REASON_PERIODIC, 1762c4a77a6cSJens Axboe }; 1763c4a77a6cSJens Axboe 176483ba7b07SChristoph Hellwig return wb_writeback(wb, &work); 1765c4a77a6cSJens Axboe } 176603ba3782SJens Axboe 176703ba3782SJens Axboe return 0; 176803ba3782SJens Axboe } 176903ba3782SJens Axboe 177003ba3782SJens Axboe /* 177103ba3782SJens Axboe * Retrieve work items and do the writeback they describe 177203ba3782SJens Axboe */ 177325d130baSWanpeng Li static long wb_do_writeback(struct bdi_writeback *wb) 177403ba3782SJens Axboe { 177583ba7b07SChristoph Hellwig struct wb_writeback_work *work; 1776c4a77a6cSJens Axboe long wrote = 0; 177703ba3782SJens Axboe 17784452226eSTejun Heo set_bit(WB_writeback_running, &wb->state); 1779f0054bb1STejun Heo while ((work = get_next_work_item(wb)) != NULL) { 1780cc395d7fSTejun Heo struct wb_completion *done = work->done; 178183ba7b07SChristoph Hellwig 17825634cc2aSTejun Heo trace_writeback_exec(wb, work); 1783455b2864SDave Chinner 178483ba7b07SChristoph Hellwig wrote += wb_writeback(wb, work); 178503ba3782SJens Axboe 17868a1270cdSTejun Heo if (work->auto_free) 178783ba7b07SChristoph Hellwig kfree(work); 1788cc395d7fSTejun Heo if (done && atomic_dec_and_test(&done->cnt)) 1789cc395d7fSTejun Heo wake_up_all(&wb->bdi->wb_waitq); 179003ba3782SJens Axboe } 179103ba3782SJens Axboe 179203ba3782SJens Axboe /* 179303ba3782SJens Axboe * Check for periodic writeback, kupdated() style 179403ba3782SJens Axboe */ 179503ba3782SJens Axboe wrote += wb_check_old_data_flush(wb); 17966585027aSJan Kara wrote += wb_check_background_flush(wb); 17974452226eSTejun Heo clear_bit(WB_writeback_running, &wb->state); 179803ba3782SJens Axboe 179903ba3782SJens Axboe return wrote; 180003ba3782SJens Axboe } 180103ba3782SJens Axboe 180203ba3782SJens Axboe /* 180303ba3782SJens Axboe * Handle writeback of dirty data for the device backed by this bdi. Also 1804839a8e86STejun Heo * reschedules periodically and does kupdated style flushing. 180503ba3782SJens Axboe */ 1806f0054bb1STejun Heo void wb_workfn(struct work_struct *work) 180703ba3782SJens Axboe { 1808839a8e86STejun Heo struct bdi_writeback *wb = container_of(to_delayed_work(work), 1809839a8e86STejun Heo struct bdi_writeback, dwork); 181003ba3782SJens Axboe long pages_written; 181103ba3782SJens Axboe 1812f0054bb1STejun Heo set_worker_desc("flush-%s", dev_name(wb->bdi->dev)); 1813766f9164SPeter Zijlstra current->flags |= PF_SWAPWRITE; 181403ba3782SJens Axboe 1815839a8e86STejun Heo if (likely(!current_is_workqueue_rescuer() || 18164452226eSTejun Heo !test_bit(WB_registered, &wb->state))) { 181703ba3782SJens Axboe /* 1818f0054bb1STejun Heo * The normal path. Keep writing back @wb until its 1819839a8e86STejun Heo * work_list is empty. Note that this path is also taken 1820f0054bb1STejun Heo * if @wb is shutting down even when we're running off the 1821839a8e86STejun Heo * rescuer as work_list needs to be drained. 182203ba3782SJens Axboe */ 1823839a8e86STejun Heo do { 182425d130baSWanpeng Li pages_written = wb_do_writeback(wb); 1825455b2864SDave Chinner trace_writeback_pages_written(pages_written); 1826f0054bb1STejun Heo } while (!list_empty(&wb->work_list)); 1827839a8e86STejun Heo } else { 1828253c34e9SArtem Bityutskiy /* 1829839a8e86STejun Heo * bdi_wq can't get enough workers and we're running off 1830839a8e86STejun Heo * the emergency worker. Don't hog it. Hopefully, 1024 is 1831839a8e86STejun Heo * enough for efficient IO. 1832253c34e9SArtem Bityutskiy */ 1833f0054bb1STejun Heo pages_written = writeback_inodes_wb(wb, 1024, 1834839a8e86STejun Heo WB_REASON_FORKER_THREAD); 1835839a8e86STejun Heo trace_writeback_pages_written(pages_written); 183603ba3782SJens Axboe } 183703ba3782SJens Axboe 1838f0054bb1STejun Heo if (!list_empty(&wb->work_list)) 18396ca738d6SDerek Basehore mod_delayed_work(bdi_wq, &wb->dwork, 0); 18406ca738d6SDerek Basehore else if (wb_has_dirty_io(wb) && dirty_writeback_interval) 1841f0054bb1STejun Heo wb_wakeup_delayed(wb); 1842455b2864SDave Chinner 1843839a8e86STejun Heo current->flags &= ~PF_SWAPWRITE; 184403ba3782SJens Axboe } 184503ba3782SJens Axboe 184603ba3782SJens Axboe /* 184703ba3782SJens Axboe * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back 184803ba3782SJens Axboe * the whole world. 184903ba3782SJens Axboe */ 18500e175a18SCurt Wohlgemuth void wakeup_flusher_threads(long nr_pages, enum wb_reason reason) 185103ba3782SJens Axboe { 1852b8c2f347SChristoph Hellwig struct backing_dev_info *bdi; 1853b8c2f347SChristoph Hellwig 185447df3ddeSJan Kara if (!nr_pages) 185547df3ddeSJan Kara nr_pages = get_nr_dirty_pages(); 1856b8c2f347SChristoph Hellwig 1857b8c2f347SChristoph Hellwig rcu_read_lock(); 1858f2b65121STejun Heo list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { 1859f2b65121STejun Heo struct bdi_writeback *wb; 1860f2b65121STejun Heo struct wb_iter iter; 1861f2b65121STejun Heo 1862f2b65121STejun Heo if (!bdi_has_dirty_io(bdi)) 1863f2b65121STejun Heo continue; 1864f2b65121STejun Heo 1865f2b65121STejun Heo bdi_for_each_wb(wb, bdi, &iter, 0) 1866f2b65121STejun Heo wb_start_writeback(wb, wb_split_bdi_pages(wb, nr_pages), 1867f2b65121STejun Heo false, reason); 1868f2b65121STejun Heo } 1869b8c2f347SChristoph Hellwig rcu_read_unlock(); 187003ba3782SJens Axboe } 187103ba3782SJens Axboe 1872a2f48706STheodore Ts'o /* 1873a2f48706STheodore Ts'o * Wake up bdi's periodically to make sure dirtytime inodes gets 1874a2f48706STheodore Ts'o * written back periodically. We deliberately do *not* check the 1875a2f48706STheodore Ts'o * b_dirtytime list in wb_has_dirty_io(), since this would cause the 1876a2f48706STheodore Ts'o * kernel to be constantly waking up once there are any dirtytime 1877a2f48706STheodore Ts'o * inodes on the system. So instead we define a separate delayed work 1878a2f48706STheodore Ts'o * function which gets called much more rarely. (By default, only 1879a2f48706STheodore Ts'o * once every 12 hours.) 1880a2f48706STheodore Ts'o * 1881a2f48706STheodore Ts'o * If there is any other write activity going on in the file system, 1882a2f48706STheodore Ts'o * this function won't be necessary. But if the only thing that has 1883a2f48706STheodore Ts'o * happened on the file system is a dirtytime inode caused by an atime 1884a2f48706STheodore Ts'o * update, we need this infrastructure below to make sure that inode 1885a2f48706STheodore Ts'o * eventually gets pushed out to disk. 1886a2f48706STheodore Ts'o */ 1887a2f48706STheodore Ts'o static void wakeup_dirtytime_writeback(struct work_struct *w); 1888a2f48706STheodore Ts'o static DECLARE_DELAYED_WORK(dirtytime_work, wakeup_dirtytime_writeback); 1889a2f48706STheodore Ts'o 1890a2f48706STheodore Ts'o static void wakeup_dirtytime_writeback(struct work_struct *w) 1891a2f48706STheodore Ts'o { 1892a2f48706STheodore Ts'o struct backing_dev_info *bdi; 1893a2f48706STheodore Ts'o 1894a2f48706STheodore Ts'o rcu_read_lock(); 1895a2f48706STheodore Ts'o list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { 1896001fe6f6STejun Heo struct bdi_writeback *wb; 1897001fe6f6STejun Heo struct wb_iter iter; 1898001fe6f6STejun Heo 1899001fe6f6STejun Heo bdi_for_each_wb(wb, bdi, &iter, 0) 19006fdf860fSTejun Heo if (!list_empty(&wb->b_dirty_time)) 19016fdf860fSTejun Heo wb_wakeup(wb); 1902a2f48706STheodore Ts'o } 1903a2f48706STheodore Ts'o rcu_read_unlock(); 1904a2f48706STheodore Ts'o schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ); 1905a2f48706STheodore Ts'o } 1906a2f48706STheodore Ts'o 1907a2f48706STheodore Ts'o static int __init start_dirtytime_writeback(void) 1908a2f48706STheodore Ts'o { 1909a2f48706STheodore Ts'o schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ); 1910a2f48706STheodore Ts'o return 0; 1911a2f48706STheodore Ts'o } 1912a2f48706STheodore Ts'o __initcall(start_dirtytime_writeback); 1913a2f48706STheodore Ts'o 19141efff914STheodore Ts'o int dirtytime_interval_handler(struct ctl_table *table, int write, 19151efff914STheodore Ts'o void __user *buffer, size_t *lenp, loff_t *ppos) 19161efff914STheodore Ts'o { 19171efff914STheodore Ts'o int ret; 19181efff914STheodore Ts'o 19191efff914STheodore Ts'o ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); 19201efff914STheodore Ts'o if (ret == 0 && write) 19211efff914STheodore Ts'o mod_delayed_work(system_wq, &dirtytime_work, 0); 19221efff914STheodore Ts'o return ret; 19231efff914STheodore Ts'o } 19241efff914STheodore Ts'o 192503ba3782SJens Axboe static noinline void block_dump___mark_inode_dirty(struct inode *inode) 192603ba3782SJens Axboe { 192703ba3782SJens Axboe if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { 192803ba3782SJens Axboe struct dentry *dentry; 192903ba3782SJens Axboe const char *name = "?"; 193003ba3782SJens Axboe 193103ba3782SJens Axboe dentry = d_find_alias(inode); 193203ba3782SJens Axboe if (dentry) { 193303ba3782SJens Axboe spin_lock(&dentry->d_lock); 193403ba3782SJens Axboe name = (const char *) dentry->d_name.name; 193503ba3782SJens Axboe } 193603ba3782SJens Axboe printk(KERN_DEBUG 193703ba3782SJens Axboe "%s(%d): dirtied inode %lu (%s) on %s\n", 193803ba3782SJens Axboe current->comm, task_pid_nr(current), inode->i_ino, 193903ba3782SJens Axboe name, inode->i_sb->s_id); 194003ba3782SJens Axboe if (dentry) { 194103ba3782SJens Axboe spin_unlock(&dentry->d_lock); 194203ba3782SJens Axboe dput(dentry); 194303ba3782SJens Axboe } 194403ba3782SJens Axboe } 194503ba3782SJens Axboe } 194603ba3782SJens Axboe 194703ba3782SJens Axboe /** 194803ba3782SJens Axboe * __mark_inode_dirty - internal function 194903ba3782SJens Axboe * @inode: inode to mark 195003ba3782SJens Axboe * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) 195103ba3782SJens Axboe * Mark an inode as dirty. Callers should use mark_inode_dirty or 195203ba3782SJens Axboe * mark_inode_dirty_sync. 195303ba3782SJens Axboe * 195403ba3782SJens Axboe * Put the inode on the super block's dirty list. 195503ba3782SJens Axboe * 195603ba3782SJens Axboe * CAREFUL! We mark it dirty unconditionally, but move it onto the 195703ba3782SJens Axboe * dirty list only if it is hashed or if it refers to a blockdev. 195803ba3782SJens Axboe * If it was not hashed, it will never be added to the dirty list 195903ba3782SJens Axboe * even if it is later hashed, as it will have been marked dirty already. 196003ba3782SJens Axboe * 196103ba3782SJens Axboe * In short, make sure you hash any inodes _before_ you start marking 196203ba3782SJens Axboe * them dirty. 196303ba3782SJens Axboe * 196403ba3782SJens Axboe * Note that for blockdevs, inode->dirtied_when represents the dirtying time of 196503ba3782SJens Axboe * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of 196603ba3782SJens Axboe * the kernel-internal blockdev inode represents the dirtying time of the 196703ba3782SJens Axboe * blockdev's pages. This is why for I_DIRTY_PAGES we always use 196803ba3782SJens Axboe * page->mapping->host, so the page-dirtying time is recorded in the internal 196903ba3782SJens Axboe * blockdev inode. 197003ba3782SJens Axboe */ 19710ae45f63STheodore Ts'o #define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC) 197203ba3782SJens Axboe void __mark_inode_dirty(struct inode *inode, int flags) 197303ba3782SJens Axboe { 197403ba3782SJens Axboe struct super_block *sb = inode->i_sb; 19750ae45f63STheodore Ts'o int dirtytime; 19760ae45f63STheodore Ts'o 19770ae45f63STheodore Ts'o trace_writeback_mark_inode_dirty(inode, flags); 197803ba3782SJens Axboe 197903ba3782SJens Axboe /* 198003ba3782SJens Axboe * Don't do this for I_DIRTY_PAGES - that doesn't actually 198103ba3782SJens Axboe * dirty the inode itself 198203ba3782SJens Axboe */ 19830ae45f63STheodore Ts'o if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC | I_DIRTY_TIME)) { 19849fb0a7daSTejun Heo trace_writeback_dirty_inode_start(inode, flags); 19859fb0a7daSTejun Heo 198603ba3782SJens Axboe if (sb->s_op->dirty_inode) 1987aa385729SChristoph Hellwig sb->s_op->dirty_inode(inode, flags); 19889fb0a7daSTejun Heo 19899fb0a7daSTejun Heo trace_writeback_dirty_inode(inode, flags); 199003ba3782SJens Axboe } 19910ae45f63STheodore Ts'o if (flags & I_DIRTY_INODE) 19920ae45f63STheodore Ts'o flags &= ~I_DIRTY_TIME; 19930ae45f63STheodore Ts'o dirtytime = flags & I_DIRTY_TIME; 199403ba3782SJens Axboe 199503ba3782SJens Axboe /* 19969c6ac78eSTejun Heo * Paired with smp_mb() in __writeback_single_inode() for the 19979c6ac78eSTejun Heo * following lockless i_state test. See there for details. 199803ba3782SJens Axboe */ 199903ba3782SJens Axboe smp_mb(); 200003ba3782SJens Axboe 20010ae45f63STheodore Ts'o if (((inode->i_state & flags) == flags) || 20020ae45f63STheodore Ts'o (dirtytime && (inode->i_state & I_DIRTY_INODE))) 200303ba3782SJens Axboe return; 200403ba3782SJens Axboe 200503ba3782SJens Axboe if (unlikely(block_dump)) 200603ba3782SJens Axboe block_dump___mark_inode_dirty(inode); 200703ba3782SJens Axboe 2008250df6edSDave Chinner spin_lock(&inode->i_lock); 20090ae45f63STheodore Ts'o if (dirtytime && (inode->i_state & I_DIRTY_INODE)) 20100ae45f63STheodore Ts'o goto out_unlock_inode; 201103ba3782SJens Axboe if ((inode->i_state & flags) != flags) { 201203ba3782SJens Axboe const int was_dirty = inode->i_state & I_DIRTY; 201303ba3782SJens Axboe 201452ebea74STejun Heo inode_attach_wb(inode, NULL); 201552ebea74STejun Heo 20160ae45f63STheodore Ts'o if (flags & I_DIRTY_INODE) 20170ae45f63STheodore Ts'o inode->i_state &= ~I_DIRTY_TIME; 201803ba3782SJens Axboe inode->i_state |= flags; 201903ba3782SJens Axboe 202003ba3782SJens Axboe /* 202103ba3782SJens Axboe * If the inode is being synced, just update its dirty state. 202203ba3782SJens Axboe * The unlocker will place the inode on the appropriate 202303ba3782SJens Axboe * superblock list, based upon its state. 202403ba3782SJens Axboe */ 202503ba3782SJens Axboe if (inode->i_state & I_SYNC) 2026250df6edSDave Chinner goto out_unlock_inode; 202703ba3782SJens Axboe 202803ba3782SJens Axboe /* 202903ba3782SJens Axboe * Only add valid (hashed) inodes to the superblock's 203003ba3782SJens Axboe * dirty list. Add blockdev inodes as well. 203103ba3782SJens Axboe */ 203203ba3782SJens Axboe if (!S_ISBLK(inode->i_mode)) { 20331d3382cbSAl Viro if (inode_unhashed(inode)) 2034250df6edSDave Chinner goto out_unlock_inode; 203503ba3782SJens Axboe } 2036a4ffdde6SAl Viro if (inode->i_state & I_FREEING) 2037250df6edSDave Chinner goto out_unlock_inode; 203803ba3782SJens Axboe 203903ba3782SJens Axboe /* 204003ba3782SJens Axboe * If the inode was already on b_dirty/b_io/b_more_io, don't 204103ba3782SJens Axboe * reposition it (that would break b_dirty time-ordering). 204203ba3782SJens Axboe */ 204303ba3782SJens Axboe if (!was_dirty) { 204487e1d789STejun Heo struct bdi_writeback *wb; 2045d6c10f1fSTejun Heo struct list_head *dirty_list; 2046a66979abSDave Chinner bool wakeup_bdi = false; 2047500b067cSJens Axboe 204887e1d789STejun Heo wb = locked_inode_to_wb_and_lock_list(inode); 2049253c34e9SArtem Bityutskiy 20500747259dSTejun Heo WARN(bdi_cap_writeback_dirty(wb->bdi) && 20510747259dSTejun Heo !test_bit(WB_registered, &wb->state), 20520747259dSTejun Heo "bdi-%s not registered\n", wb->bdi->name); 205303ba3782SJens Axboe 205403ba3782SJens Axboe inode->dirtied_when = jiffies; 2055a2f48706STheodore Ts'o if (dirtytime) 2056a2f48706STheodore Ts'o inode->dirtied_time_when = jiffies; 2057d6c10f1fSTejun Heo 2058a2f48706STheodore Ts'o if (inode->i_state & (I_DIRTY_INODE | I_DIRTY_PAGES)) 20590747259dSTejun Heo dirty_list = &wb->b_dirty; 2060a2f48706STheodore Ts'o else 20610747259dSTejun Heo dirty_list = &wb->b_dirty_time; 2062d6c10f1fSTejun Heo 2063c7f54084SDave Chinner wakeup_bdi = inode_io_list_move_locked(inode, wb, 2064d6c10f1fSTejun Heo dirty_list); 2065d6c10f1fSTejun Heo 20660747259dSTejun Heo spin_unlock(&wb->list_lock); 20670ae45f63STheodore Ts'o trace_writeback_dirty_inode_enqueue(inode); 2068253c34e9SArtem Bityutskiy 2069d6c10f1fSTejun Heo /* 2070d6c10f1fSTejun Heo * If this is the first dirty inode for this bdi, 2071d6c10f1fSTejun Heo * we have to wake-up the corresponding bdi thread 2072d6c10f1fSTejun Heo * to make sure background write-back happens 2073d6c10f1fSTejun Heo * later. 2074d6c10f1fSTejun Heo */ 20750747259dSTejun Heo if (bdi_cap_writeback_dirty(wb->bdi) && wakeup_bdi) 20760747259dSTejun Heo wb_wakeup_delayed(wb); 2077a66979abSDave Chinner return; 2078a66979abSDave Chinner } 2079a66979abSDave Chinner } 2080a66979abSDave Chinner out_unlock_inode: 2081a66979abSDave Chinner spin_unlock(&inode->i_lock); 2082a66979abSDave Chinner 208303ba3782SJens Axboe } 208403ba3782SJens Axboe EXPORT_SYMBOL(__mark_inode_dirty); 208503ba3782SJens Axboe 2086e97fedb9SDave Chinner /* 2087e97fedb9SDave Chinner * The @s_sync_lock is used to serialise concurrent sync operations 2088e97fedb9SDave Chinner * to avoid lock contention problems with concurrent wait_sb_inodes() calls. 2089e97fedb9SDave Chinner * Concurrent callers will block on the s_sync_lock rather than doing contending 2090e97fedb9SDave Chinner * walks. The queueing maintains sync(2) required behaviour as all the IO that 2091e97fedb9SDave Chinner * has been issued up to the time this function is enter is guaranteed to be 2092e97fedb9SDave Chinner * completed by the time we have gained the lock and waited for all IO that is 2093e97fedb9SDave Chinner * in progress regardless of the order callers are granted the lock. 2094e97fedb9SDave Chinner */ 2095b6e51316SJens Axboe static void wait_sb_inodes(struct super_block *sb) 209666f3b8e2SJens Axboe { 209738f21977SNick Piggin struct inode *inode, *old_inode = NULL; 209838f21977SNick Piggin 209903ba3782SJens Axboe /* 210003ba3782SJens Axboe * We need to be protected against the filesystem going from 210103ba3782SJens Axboe * r/o to r/w or vice versa. 210203ba3782SJens Axboe */ 2103b6e51316SJens Axboe WARN_ON(!rwsem_is_locked(&sb->s_umount)); 210403ba3782SJens Axboe 2105e97fedb9SDave Chinner mutex_lock(&sb->s_sync_lock); 210674278da9SDave Chinner spin_lock(&sb->s_inode_list_lock); 210766f3b8e2SJens Axboe 210838f21977SNick Piggin /* 210938f21977SNick Piggin * Data integrity sync. Must wait for all pages under writeback, 211038f21977SNick Piggin * because there may have been pages dirtied before our sync 211138f21977SNick Piggin * call, but which had writeout started before we write it out. 211238f21977SNick Piggin * In which case, the inode may not be on the dirty list, but 211338f21977SNick Piggin * we still have to wait for that writeout. 211438f21977SNick Piggin */ 2115b6e51316SJens Axboe list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { 2116250df6edSDave Chinner struct address_space *mapping = inode->i_mapping; 211738f21977SNick Piggin 2118250df6edSDave Chinner spin_lock(&inode->i_lock); 2119250df6edSDave Chinner if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || 2120250df6edSDave Chinner (mapping->nrpages == 0)) { 2121250df6edSDave Chinner spin_unlock(&inode->i_lock); 212238f21977SNick Piggin continue; 2123250df6edSDave Chinner } 212438f21977SNick Piggin __iget(inode); 2125250df6edSDave Chinner spin_unlock(&inode->i_lock); 212674278da9SDave Chinner spin_unlock(&sb->s_inode_list_lock); 212755fa6091SDave Chinner 212838f21977SNick Piggin /* 212955fa6091SDave Chinner * We hold a reference to 'inode' so it couldn't have been 213055fa6091SDave Chinner * removed from s_inodes list while we dropped the 213174278da9SDave Chinner * s_inode_list_lock. We cannot iput the inode now as we can 213255fa6091SDave Chinner * be holding the last reference and we cannot iput it under 213374278da9SDave Chinner * s_inode_list_lock. So we keep the reference and iput it 213455fa6091SDave Chinner * later. 213538f21977SNick Piggin */ 213638f21977SNick Piggin iput(old_inode); 213738f21977SNick Piggin old_inode = inode; 213838f21977SNick Piggin 213938f21977SNick Piggin filemap_fdatawait(mapping); 214038f21977SNick Piggin 214138f21977SNick Piggin cond_resched(); 214238f21977SNick Piggin 214374278da9SDave Chinner spin_lock(&sb->s_inode_list_lock); 214438f21977SNick Piggin } 214574278da9SDave Chinner spin_unlock(&sb->s_inode_list_lock); 214638f21977SNick Piggin iput(old_inode); 2147e97fedb9SDave Chinner mutex_unlock(&sb->s_sync_lock); 214866f3b8e2SJens Axboe } 21491da177e4SLinus Torvalds 2150f30a7d0cSTejun Heo static void __writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr, 2151f30a7d0cSTejun Heo enum wb_reason reason, bool skip_if_busy) 21521da177e4SLinus Torvalds { 2153cc395d7fSTejun Heo DEFINE_WB_COMPLETION_ONSTACK(done); 215483ba7b07SChristoph Hellwig struct wb_writeback_work work = { 21553c4d7165SChristoph Hellwig .sb = sb, 21563c4d7165SChristoph Hellwig .sync_mode = WB_SYNC_NONE, 21576e6938b6SWu Fengguang .tagged_writepages = 1, 215883ba7b07SChristoph Hellwig .done = &done, 21593259f8beSChris Mason .nr_pages = nr, 21600e175a18SCurt Wohlgemuth .reason = reason, 21613c4d7165SChristoph Hellwig }; 2162e7972912STejun Heo struct backing_dev_info *bdi = sb->s_bdi; 21630e3c9a22SJens Axboe 2164e7972912STejun Heo if (!bdi_has_dirty_io(bdi) || bdi == &noop_backing_dev_info) 21656eedc701SJan Kara return; 2166cf37e972SChristoph Hellwig WARN_ON(!rwsem_is_locked(&sb->s_umount)); 2167f30a7d0cSTejun Heo 2168db125360STejun Heo bdi_split_work_to_wbs(sb->s_bdi, &work, skip_if_busy); 2169cc395d7fSTejun Heo wb_wait_for_completion(bdi, &done); 21701da177e4SLinus Torvalds } 2171f30a7d0cSTejun Heo 2172f30a7d0cSTejun Heo /** 2173f30a7d0cSTejun Heo * writeback_inodes_sb_nr - writeback dirty inodes from given super_block 2174f30a7d0cSTejun Heo * @sb: the superblock 2175f30a7d0cSTejun Heo * @nr: the number of pages to write 2176f30a7d0cSTejun Heo * @reason: reason why some writeback work initiated 2177f30a7d0cSTejun Heo * 2178f30a7d0cSTejun Heo * Start writeback on some inodes on this super_block. No guarantees are made 2179f30a7d0cSTejun Heo * on how many (if any) will be written, and this function does not wait 2180f30a7d0cSTejun Heo * for IO completion of submitted IO. 2181f30a7d0cSTejun Heo */ 2182f30a7d0cSTejun Heo void writeback_inodes_sb_nr(struct super_block *sb, 2183f30a7d0cSTejun Heo unsigned long nr, 2184f30a7d0cSTejun Heo enum wb_reason reason) 2185f30a7d0cSTejun Heo { 2186f30a7d0cSTejun Heo __writeback_inodes_sb_nr(sb, nr, reason, false); 2187f30a7d0cSTejun Heo } 21883259f8beSChris Mason EXPORT_SYMBOL(writeback_inodes_sb_nr); 21893259f8beSChris Mason 21903259f8beSChris Mason /** 21913259f8beSChris Mason * writeback_inodes_sb - writeback dirty inodes from given super_block 21923259f8beSChris Mason * @sb: the superblock 2193786228abSMarcos Paulo de Souza * @reason: reason why some writeback work was initiated 21943259f8beSChris Mason * 21953259f8beSChris Mason * Start writeback on some inodes on this super_block. No guarantees are made 21963259f8beSChris Mason * on how many (if any) will be written, and this function does not wait 21973259f8beSChris Mason * for IO completion of submitted IO. 21983259f8beSChris Mason */ 21990e175a18SCurt Wohlgemuth void writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) 22003259f8beSChris Mason { 22010e175a18SCurt Wohlgemuth return writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); 22023259f8beSChris Mason } 2203d8a8559cSJens Axboe EXPORT_SYMBOL(writeback_inodes_sb); 2204d8a8559cSJens Axboe 2205d8a8559cSJens Axboe /** 220610ee27a0SMiao Xie * try_to_writeback_inodes_sb_nr - try to start writeback if none underway 22073259f8beSChris Mason * @sb: the superblock 22083259f8beSChris Mason * @nr: the number of pages to write 220910ee27a0SMiao Xie * @reason: the reason of writeback 22103259f8beSChris Mason * 221110ee27a0SMiao Xie * Invoke writeback_inodes_sb_nr if no writeback is currently underway. 22123259f8beSChris Mason * Returns 1 if writeback was started, 0 if not. 22133259f8beSChris Mason */ 2214f30a7d0cSTejun Heo bool try_to_writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr, 22150e175a18SCurt Wohlgemuth enum wb_reason reason) 22163259f8beSChris Mason { 221710ee27a0SMiao Xie if (!down_read_trylock(&sb->s_umount)) 2218f30a7d0cSTejun Heo return false; 221910ee27a0SMiao Xie 2220f30a7d0cSTejun Heo __writeback_inodes_sb_nr(sb, nr, reason, true); 22213259f8beSChris Mason up_read(&sb->s_umount); 2222f30a7d0cSTejun Heo return true; 22233259f8beSChris Mason } 222410ee27a0SMiao Xie EXPORT_SYMBOL(try_to_writeback_inodes_sb_nr); 222510ee27a0SMiao Xie 222610ee27a0SMiao Xie /** 222710ee27a0SMiao Xie * try_to_writeback_inodes_sb - try to start writeback if none underway 222810ee27a0SMiao Xie * @sb: the superblock 222910ee27a0SMiao Xie * @reason: reason why some writeback work was initiated 223010ee27a0SMiao Xie * 223110ee27a0SMiao Xie * Implement by try_to_writeback_inodes_sb_nr() 223210ee27a0SMiao Xie * Returns 1 if writeback was started, 0 if not. 223310ee27a0SMiao Xie */ 2234f30a7d0cSTejun Heo bool try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) 223510ee27a0SMiao Xie { 223610ee27a0SMiao Xie return try_to_writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); 223710ee27a0SMiao Xie } 223810ee27a0SMiao Xie EXPORT_SYMBOL(try_to_writeback_inodes_sb); 22393259f8beSChris Mason 22403259f8beSChris Mason /** 2241d8a8559cSJens Axboe * sync_inodes_sb - sync sb inode pages 2242d8a8559cSJens Axboe * @sb: the superblock 2243d8a8559cSJens Axboe * 2244d8a8559cSJens Axboe * This function writes and waits on any dirty inode belonging to this 22450dc83bd3SJan Kara * super_block. 2246d8a8559cSJens Axboe */ 22470dc83bd3SJan Kara void sync_inodes_sb(struct super_block *sb) 2248d8a8559cSJens Axboe { 2249cc395d7fSTejun Heo DEFINE_WB_COMPLETION_ONSTACK(done); 225083ba7b07SChristoph Hellwig struct wb_writeback_work work = { 22513c4d7165SChristoph Hellwig .sb = sb, 22523c4d7165SChristoph Hellwig .sync_mode = WB_SYNC_ALL, 22533c4d7165SChristoph Hellwig .nr_pages = LONG_MAX, 22543c4d7165SChristoph Hellwig .range_cyclic = 0, 225583ba7b07SChristoph Hellwig .done = &done, 22560e175a18SCurt Wohlgemuth .reason = WB_REASON_SYNC, 22577747bd4bSDave Chinner .for_sync = 1, 22583c4d7165SChristoph Hellwig }; 2259e7972912STejun Heo struct backing_dev_info *bdi = sb->s_bdi; 22603c4d7165SChristoph Hellwig 2261006a0973STejun Heo /* 2262006a0973STejun Heo * Can't skip on !bdi_has_dirty() because we should wait for !dirty 2263006a0973STejun Heo * inodes under writeback and I_DIRTY_TIME inodes ignored by 2264006a0973STejun Heo * bdi_has_dirty() need to be written out too. 2265006a0973STejun Heo */ 2266006a0973STejun Heo if (bdi == &noop_backing_dev_info) 22676eedc701SJan Kara return; 2268cf37e972SChristoph Hellwig WARN_ON(!rwsem_is_locked(&sb->s_umount)); 2269cf37e972SChristoph Hellwig 2270db125360STejun Heo bdi_split_work_to_wbs(bdi, &work, false); 2271cc395d7fSTejun Heo wb_wait_for_completion(bdi, &done); 227283ba7b07SChristoph Hellwig 2273b6e51316SJens Axboe wait_sb_inodes(sb); 2274d8a8559cSJens Axboe } 2275d8a8559cSJens Axboe EXPORT_SYMBOL(sync_inodes_sb); 22761da177e4SLinus Torvalds 22771da177e4SLinus Torvalds /** 22781da177e4SLinus Torvalds * write_inode_now - write an inode to disk 22791da177e4SLinus Torvalds * @inode: inode to write to disk 22801da177e4SLinus Torvalds * @sync: whether the write should be synchronous or not 22811da177e4SLinus Torvalds * 22827f04c26dSAndrea Arcangeli * This function commits an inode to disk immediately if it is dirty. This is 22837f04c26dSAndrea Arcangeli * primarily needed by knfsd. 22847f04c26dSAndrea Arcangeli * 22857f04c26dSAndrea Arcangeli * The caller must either have a ref on the inode or must have set I_WILL_FREE. 22861da177e4SLinus Torvalds */ 22871da177e4SLinus Torvalds int write_inode_now(struct inode *inode, int sync) 22881da177e4SLinus Torvalds { 2289f758eeabSChristoph Hellwig struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; 22901da177e4SLinus Torvalds struct writeback_control wbc = { 22911da177e4SLinus Torvalds .nr_to_write = LONG_MAX, 229218914b18SMike Galbraith .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, 2293111ebb6eSOGAWA Hirofumi .range_start = 0, 2294111ebb6eSOGAWA Hirofumi .range_end = LLONG_MAX, 22951da177e4SLinus Torvalds }; 22961da177e4SLinus Torvalds 22971da177e4SLinus Torvalds if (!mapping_cap_writeback_dirty(inode->i_mapping)) 229849364ce2SAndrew Morton wbc.nr_to_write = 0; 22991da177e4SLinus Torvalds 23001da177e4SLinus Torvalds might_sleep(); 23014f8ad655SJan Kara return writeback_single_inode(inode, wb, &wbc); 23021da177e4SLinus Torvalds } 23031da177e4SLinus Torvalds EXPORT_SYMBOL(write_inode_now); 23041da177e4SLinus Torvalds 23051da177e4SLinus Torvalds /** 23061da177e4SLinus Torvalds * sync_inode - write an inode and its pages to disk. 23071da177e4SLinus Torvalds * @inode: the inode to sync 23081da177e4SLinus Torvalds * @wbc: controls the writeback mode 23091da177e4SLinus Torvalds * 23101da177e4SLinus Torvalds * sync_inode() will write an inode and its pages to disk. It will also 23111da177e4SLinus Torvalds * correctly update the inode on its superblock's dirty inode lists and will 23121da177e4SLinus Torvalds * update inode->i_state. 23131da177e4SLinus Torvalds * 23141da177e4SLinus Torvalds * The caller must have a ref on the inode. 23151da177e4SLinus Torvalds */ 23161da177e4SLinus Torvalds int sync_inode(struct inode *inode, struct writeback_control *wbc) 23171da177e4SLinus Torvalds { 23184f8ad655SJan Kara return writeback_single_inode(inode, &inode_to_bdi(inode)->wb, wbc); 23191da177e4SLinus Torvalds } 23201da177e4SLinus Torvalds EXPORT_SYMBOL(sync_inode); 2321c3765016SChristoph Hellwig 2322c3765016SChristoph Hellwig /** 2323c691b9d9SAndrew Morton * sync_inode_metadata - write an inode to disk 2324c3765016SChristoph Hellwig * @inode: the inode to sync 2325c3765016SChristoph Hellwig * @wait: wait for I/O to complete. 2326c3765016SChristoph Hellwig * 2327c691b9d9SAndrew Morton * Write an inode to disk and adjust its dirty state after completion. 2328c3765016SChristoph Hellwig * 2329c3765016SChristoph Hellwig * Note: only writes the actual inode, no associated data or other metadata. 2330c3765016SChristoph Hellwig */ 2331c3765016SChristoph Hellwig int sync_inode_metadata(struct inode *inode, int wait) 2332c3765016SChristoph Hellwig { 2333c3765016SChristoph Hellwig struct writeback_control wbc = { 2334c3765016SChristoph Hellwig .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_NONE, 2335c3765016SChristoph Hellwig .nr_to_write = 0, /* metadata-only */ 2336c3765016SChristoph Hellwig }; 2337c3765016SChristoph Hellwig 2338c3765016SChristoph Hellwig return sync_inode(inode, &wbc); 2339c3765016SChristoph Hellwig } 2340c3765016SChristoph Hellwig EXPORT_SYMBOL(sync_inode_metadata); 2341