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> 17f5ff8422SJens Axboe #include <linux/module.h> 181da177e4SLinus Torvalds #include <linux/spinlock.h> 191da177e4SLinus Torvalds #include <linux/sched.h> 201da177e4SLinus Torvalds #include <linux/fs.h> 211da177e4SLinus Torvalds #include <linux/mm.h> 2203ba3782SJens Axboe #include <linux/kthread.h> 2303ba3782SJens Axboe #include <linux/freezer.h> 241da177e4SLinus Torvalds #include <linux/writeback.h> 251da177e4SLinus Torvalds #include <linux/blkdev.h> 261da177e4SLinus Torvalds #include <linux/backing-dev.h> 271da177e4SLinus Torvalds #include <linux/buffer_head.h> 2807f3f05cSDavid Howells #include "internal.h" 291da177e4SLinus Torvalds 3066f3b8e2SJens Axboe #define inode_to_bdi(inode) ((inode)->i_mapping->backing_dev_info) 31f11b00f3SAdrian Bunk 3203ba3782SJens Axboe /* 33d0bceac7SJens Axboe * We don't actually have pdflush, but this one is exported though /proc... 34d0bceac7SJens Axboe */ 35d0bceac7SJens Axboe int nr_pdflush_threads; 36d0bceac7SJens Axboe 37d0bceac7SJens Axboe /* 38c4a77a6cSJens Axboe * Passed into wb_writeback(), essentially a subset of writeback_control 39c4a77a6cSJens Axboe */ 40c4a77a6cSJens Axboe struct wb_writeback_args { 41c4a77a6cSJens Axboe long nr_pages; 42c4a77a6cSJens Axboe struct super_block *sb; 43c4a77a6cSJens Axboe enum writeback_sync_modes sync_mode; 44d3ddec76SWu Fengguang int for_kupdate:1; 45d3ddec76SWu Fengguang int range_cyclic:1; 46d3ddec76SWu Fengguang int for_background:1; 47c4a77a6cSJens Axboe }; 48c4a77a6cSJens Axboe 49c4a77a6cSJens Axboe /* 5003ba3782SJens Axboe * Work items for the bdi_writeback threads 51f11b00f3SAdrian Bunk */ 5203ba3782SJens Axboe struct bdi_work { 538010c3b6SJens Axboe struct list_head list; /* pending work list */ 548010c3b6SJens Axboe struct rcu_head rcu_head; /* for RCU free/clear of work */ 5503ba3782SJens Axboe 568010c3b6SJens Axboe unsigned long seen; /* threads that have seen this work */ 578010c3b6SJens Axboe atomic_t pending; /* number of threads still to do work */ 5803ba3782SJens Axboe 598010c3b6SJens Axboe struct wb_writeback_args args; /* writeback arguments */ 6003ba3782SJens Axboe 618010c3b6SJens Axboe unsigned long state; /* flag bits, see WS_* */ 6203ba3782SJens Axboe }; 6303ba3782SJens Axboe 6403ba3782SJens Axboe enum { 6503ba3782SJens Axboe WS_USED_B = 0, 6603ba3782SJens Axboe WS_ONSTACK_B, 6703ba3782SJens Axboe }; 6803ba3782SJens Axboe 6903ba3782SJens Axboe #define WS_USED (1 << WS_USED_B) 7003ba3782SJens Axboe #define WS_ONSTACK (1 << WS_ONSTACK_B) 7103ba3782SJens Axboe 7203ba3782SJens Axboe static inline bool bdi_work_on_stack(struct bdi_work *work) 73f11b00f3SAdrian Bunk { 7403ba3782SJens Axboe return test_bit(WS_ONSTACK_B, &work->state); 7503ba3782SJens Axboe } 7603ba3782SJens Axboe 7703ba3782SJens Axboe static inline void bdi_work_init(struct bdi_work *work, 78b6e51316SJens Axboe struct wb_writeback_args *args) 7903ba3782SJens Axboe { 8003ba3782SJens Axboe INIT_RCU_HEAD(&work->rcu_head); 81b6e51316SJens Axboe work->args = *args; 8203ba3782SJens Axboe work->state = WS_USED; 8303ba3782SJens Axboe } 8403ba3782SJens Axboe 85f11b00f3SAdrian Bunk /** 86f11b00f3SAdrian Bunk * writeback_in_progress - determine whether there is writeback in progress 87f11b00f3SAdrian Bunk * @bdi: the device's backing_dev_info structure. 88f11b00f3SAdrian Bunk * 8903ba3782SJens Axboe * Determine whether there is writeback waiting to be handled against a 9003ba3782SJens Axboe * backing device. 91f11b00f3SAdrian Bunk */ 92f11b00f3SAdrian Bunk int writeback_in_progress(struct backing_dev_info *bdi) 93f11b00f3SAdrian Bunk { 9403ba3782SJens Axboe return !list_empty(&bdi->work_list); 95f11b00f3SAdrian Bunk } 96f11b00f3SAdrian Bunk 9703ba3782SJens Axboe static void bdi_work_clear(struct bdi_work *work) 98f11b00f3SAdrian Bunk { 9903ba3782SJens Axboe clear_bit(WS_USED_B, &work->state); 10003ba3782SJens Axboe smp_mb__after_clear_bit(); 1011ef7d9aaSNick Piggin /* 1021ef7d9aaSNick Piggin * work can have disappeared at this point. bit waitq functions 1031ef7d9aaSNick Piggin * should be able to tolerate this, provided bdi_sched_wait does 1041ef7d9aaSNick Piggin * not dereference it's pointer argument. 1051ef7d9aaSNick Piggin */ 10603ba3782SJens Axboe wake_up_bit(&work->state, WS_USED_B); 107f11b00f3SAdrian Bunk } 108f11b00f3SAdrian Bunk 10903ba3782SJens Axboe static void bdi_work_free(struct rcu_head *head) 1104195f73dSNick Piggin { 11103ba3782SJens Axboe struct bdi_work *work = container_of(head, struct bdi_work, rcu_head); 1124195f73dSNick Piggin 11303ba3782SJens Axboe if (!bdi_work_on_stack(work)) 11403ba3782SJens Axboe kfree(work); 11503ba3782SJens Axboe else 11603ba3782SJens Axboe bdi_work_clear(work); 1174195f73dSNick Piggin } 1184195f73dSNick Piggin 11903ba3782SJens Axboe static void wb_work_complete(struct bdi_work *work) 1201da177e4SLinus Torvalds { 121c4a77a6cSJens Axboe const enum writeback_sync_modes sync_mode = work->args.sync_mode; 12277b9d059SNick Piggin int onstack = bdi_work_on_stack(work); 1231da177e4SLinus Torvalds 1241da177e4SLinus Torvalds /* 12503ba3782SJens Axboe * For allocated work, we can clear the done/seen bit right here. 12603ba3782SJens Axboe * For on-stack work, we need to postpone both the clear and free 12703ba3782SJens Axboe * to after the RCU grace period, since the stack could be invalidated 12803ba3782SJens Axboe * as soon as bdi_work_clear() has done the wakeup. 1291da177e4SLinus Torvalds */ 13077b9d059SNick Piggin if (!onstack) 13103ba3782SJens Axboe bdi_work_clear(work); 13277b9d059SNick Piggin if (sync_mode == WB_SYNC_NONE || onstack) 13303ba3782SJens Axboe call_rcu(&work->rcu_head, bdi_work_free); 1341da177e4SLinus Torvalds } 1351da177e4SLinus Torvalds 13603ba3782SJens Axboe static void wb_clear_pending(struct bdi_writeback *wb, struct bdi_work *work) 13703ba3782SJens Axboe { 1381da177e4SLinus Torvalds /* 13903ba3782SJens Axboe * The caller has retrieved the work arguments from this work, 14003ba3782SJens Axboe * drop our reference. If this is the last ref, delete and free it 14103ba3782SJens Axboe */ 14203ba3782SJens Axboe if (atomic_dec_and_test(&work->pending)) { 14303ba3782SJens Axboe struct backing_dev_info *bdi = wb->bdi; 14403ba3782SJens Axboe 14503ba3782SJens Axboe spin_lock(&bdi->wb_lock); 14603ba3782SJens Axboe list_del_rcu(&work->list); 14703ba3782SJens Axboe spin_unlock(&bdi->wb_lock); 14803ba3782SJens Axboe 14903ba3782SJens Axboe wb_work_complete(work); 15003ba3782SJens Axboe } 15103ba3782SJens Axboe } 15203ba3782SJens Axboe 15303ba3782SJens Axboe static void bdi_queue_work(struct backing_dev_info *bdi, struct bdi_work *work) 15403ba3782SJens Axboe { 15503ba3782SJens Axboe work->seen = bdi->wb_mask; 15603ba3782SJens Axboe BUG_ON(!work->seen); 15703ba3782SJens Axboe atomic_set(&work->pending, bdi->wb_cnt); 15803ba3782SJens Axboe BUG_ON(!bdi->wb_cnt); 15903ba3782SJens Axboe 16003ba3782SJens Axboe /* 161deed62edSNick Piggin * list_add_tail_rcu() contains the necessary barriers to 162deed62edSNick Piggin * make sure the above stores are seen before the item is 163deed62edSNick Piggin * noticed on the list 1641da177e4SLinus Torvalds */ 16503ba3782SJens Axboe spin_lock(&bdi->wb_lock); 16603ba3782SJens Axboe list_add_tail_rcu(&work->list, &bdi->work_list); 16703ba3782SJens Axboe spin_unlock(&bdi->wb_lock); 1681da177e4SLinus Torvalds 1691da177e4SLinus Torvalds /* 17003ba3782SJens Axboe * If the default thread isn't there, make sure we add it. When 17103ba3782SJens Axboe * it gets created and wakes up, we'll run this work. 1721da177e4SLinus Torvalds */ 17303ba3782SJens Axboe if (unlikely(list_empty_careful(&bdi->wb_list))) 17403ba3782SJens Axboe wake_up_process(default_backing_dev_info.wb.task); 17503ba3782SJens Axboe else { 17603ba3782SJens Axboe struct bdi_writeback *wb = &bdi->wb; 1771da177e4SLinus Torvalds 1781ef7d9aaSNick Piggin if (wb->task) 17903ba3782SJens Axboe wake_up_process(wb->task); 1801da177e4SLinus Torvalds } 18103ba3782SJens Axboe } 1821da177e4SLinus Torvalds 1831da177e4SLinus Torvalds /* 18403ba3782SJens Axboe * Used for on-stack allocated work items. The caller needs to wait until 18503ba3782SJens Axboe * the wb threads have acked the work before it's safe to continue. 1861da177e4SLinus Torvalds */ 18703ba3782SJens Axboe static void bdi_wait_on_work_clear(struct bdi_work *work) 1881da177e4SLinus Torvalds { 18903ba3782SJens Axboe wait_on_bit(&work->state, WS_USED_B, bdi_sched_wait, 19003ba3782SJens Axboe TASK_UNINTERRUPTIBLE); 19103ba3782SJens Axboe } 19203ba3782SJens Axboe 193f11fcae8SJens Axboe static void bdi_alloc_queue_work(struct backing_dev_info *bdi, 194b6e51316SJens Axboe struct wb_writeback_args *args) 19503ba3782SJens Axboe { 19603ba3782SJens Axboe struct bdi_work *work; 19703ba3782SJens Axboe 198bcddc3f0SJens Axboe /* 199bcddc3f0SJens Axboe * This is WB_SYNC_NONE writeback, so if allocation fails just 200bcddc3f0SJens Axboe * wakeup the thread for old dirty data writeback 201bcddc3f0SJens Axboe */ 20203ba3782SJens Axboe work = kmalloc(sizeof(*work), GFP_ATOMIC); 203bcddc3f0SJens Axboe if (work) { 204b6e51316SJens Axboe bdi_work_init(work, args); 205f11fcae8SJens Axboe bdi_queue_work(bdi, work); 206bcddc3f0SJens Axboe } else { 207bcddc3f0SJens Axboe struct bdi_writeback *wb = &bdi->wb; 208bcddc3f0SJens Axboe 209bcddc3f0SJens Axboe if (wb->task) 210bcddc3f0SJens Axboe wake_up_process(wb->task); 211bcddc3f0SJens Axboe } 21203ba3782SJens Axboe } 21303ba3782SJens Axboe 214b6e51316SJens Axboe /** 215b6e51316SJens Axboe * bdi_sync_writeback - start and wait for writeback 216b6e51316SJens Axboe * @bdi: the backing device to write from 217b6e51316SJens Axboe * @sb: write inodes from this super_block 218b6e51316SJens Axboe * 219b6e51316SJens Axboe * Description: 220b6e51316SJens Axboe * This does WB_SYNC_ALL data integrity writeback and waits for the 221b6e51316SJens Axboe * IO to complete. Callers must hold the sb s_umount semaphore for 222b6e51316SJens Axboe * reading, to avoid having the super disappear before we are done. 22303ba3782SJens Axboe */ 224b6e51316SJens Axboe static void bdi_sync_writeback(struct backing_dev_info *bdi, 225b6e51316SJens Axboe struct super_block *sb) 226b6e51316SJens Axboe { 227b6e51316SJens Axboe struct wb_writeback_args args = { 228b6e51316SJens Axboe .sb = sb, 229b6e51316SJens Axboe .sync_mode = WB_SYNC_ALL, 230b6e51316SJens Axboe .nr_pages = LONG_MAX, 231b6e51316SJens Axboe .range_cyclic = 0, 232b6e51316SJens Axboe }; 233f0fad8a5SChristoph Hellwig struct bdi_work work; 234f0fad8a5SChristoph Hellwig 235b6e51316SJens Axboe bdi_work_init(&work, &args); 236f0fad8a5SChristoph Hellwig work.state |= WS_ONSTACK; 237f0fad8a5SChristoph Hellwig 238b6e51316SJens Axboe bdi_queue_work(bdi, &work); 239f0fad8a5SChristoph Hellwig bdi_wait_on_work_clear(&work); 24003ba3782SJens Axboe } 241b6e51316SJens Axboe 242b6e51316SJens Axboe /** 243b6e51316SJens Axboe * bdi_start_writeback - start writeback 244b6e51316SJens Axboe * @bdi: the backing device to write from 245b6e51316SJens Axboe * @nr_pages: the number of pages to write 246b6e51316SJens Axboe * 247b6e51316SJens Axboe * Description: 248b6e51316SJens Axboe * This does WB_SYNC_NONE opportunistic writeback. The IO is only 249b6e51316SJens Axboe * started when this function returns, we make no guarentees on 250b6e51316SJens Axboe * completion. Caller need not hold sb s_umount semaphore. 251b6e51316SJens Axboe * 252b6e51316SJens Axboe */ 253b6e51316SJens Axboe void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages) 254b6e51316SJens Axboe { 255b6e51316SJens Axboe struct wb_writeback_args args = { 256b6e51316SJens Axboe .sync_mode = WB_SYNC_NONE, 257b6e51316SJens Axboe .nr_pages = nr_pages, 258b6e51316SJens Axboe .range_cyclic = 1, 259b6e51316SJens Axboe }; 260b6e51316SJens Axboe 261d3ddec76SWu Fengguang /* 262d3ddec76SWu Fengguang * We treat @nr_pages=0 as the special case to do background writeback, 263d3ddec76SWu Fengguang * ie. to sync pages until the background dirty threshold is reached. 264d3ddec76SWu Fengguang */ 265d3ddec76SWu Fengguang if (!nr_pages) { 266d3ddec76SWu Fengguang args.nr_pages = LONG_MAX; 267d3ddec76SWu Fengguang args.for_background = 1; 268d3ddec76SWu Fengguang } 269d3ddec76SWu Fengguang 270b6e51316SJens Axboe bdi_alloc_queue_work(bdi, &args); 2711da177e4SLinus Torvalds } 2721da177e4SLinus Torvalds 2731da177e4SLinus Torvalds /* 2746610a0bcSAndrew Morton * Redirty an inode: set its when-it-was dirtied timestamp and move it to the 2756610a0bcSAndrew Morton * furthest end of its superblock's dirty-inode list. 2766610a0bcSAndrew Morton * 2776610a0bcSAndrew Morton * Before stamping the inode's ->dirtied_when, we check to see whether it is 27866f3b8e2SJens Axboe * already the most-recently-dirtied inode on the b_dirty list. If that is 2796610a0bcSAndrew Morton * the case then the inode must have been redirtied while it was being written 2806610a0bcSAndrew Morton * out and we don't reset its dirtied_when. 2816610a0bcSAndrew Morton */ 2826610a0bcSAndrew Morton static void redirty_tail(struct inode *inode) 2836610a0bcSAndrew Morton { 28403ba3782SJens Axboe struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; 2856610a0bcSAndrew Morton 28603ba3782SJens Axboe if (!list_empty(&wb->b_dirty)) { 28766f3b8e2SJens Axboe struct inode *tail; 2886610a0bcSAndrew Morton 28903ba3782SJens Axboe tail = list_entry(wb->b_dirty.next, struct inode, i_list); 29066f3b8e2SJens Axboe if (time_before(inode->dirtied_when, tail->dirtied_when)) 2916610a0bcSAndrew Morton inode->dirtied_when = jiffies; 2926610a0bcSAndrew Morton } 29303ba3782SJens Axboe list_move(&inode->i_list, &wb->b_dirty); 2946610a0bcSAndrew Morton } 2956610a0bcSAndrew Morton 2966610a0bcSAndrew Morton /* 29766f3b8e2SJens Axboe * requeue inode for re-scanning after bdi->b_io list is exhausted. 298c986d1e2SAndrew Morton */ 2990e0f4fc2SKen Chen static void requeue_io(struct inode *inode) 300c986d1e2SAndrew Morton { 30103ba3782SJens Axboe struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; 30203ba3782SJens Axboe 30303ba3782SJens Axboe list_move(&inode->i_list, &wb->b_more_io); 304c986d1e2SAndrew Morton } 305c986d1e2SAndrew Morton 3061c0eeaf5SJoern Engel static void inode_sync_complete(struct inode *inode) 3071c0eeaf5SJoern Engel { 3081c0eeaf5SJoern Engel /* 3091c0eeaf5SJoern Engel * Prevent speculative execution through spin_unlock(&inode_lock); 3101c0eeaf5SJoern Engel */ 3111c0eeaf5SJoern Engel smp_mb(); 3121c0eeaf5SJoern Engel wake_up_bit(&inode->i_state, __I_SYNC); 3131c0eeaf5SJoern Engel } 3141c0eeaf5SJoern Engel 315d2caa3c5SJeff Layton static bool inode_dirtied_after(struct inode *inode, unsigned long t) 316d2caa3c5SJeff Layton { 317d2caa3c5SJeff Layton bool ret = time_after(inode->dirtied_when, t); 318d2caa3c5SJeff Layton #ifndef CONFIG_64BIT 319d2caa3c5SJeff Layton /* 320d2caa3c5SJeff Layton * For inodes being constantly redirtied, dirtied_when can get stuck. 321d2caa3c5SJeff Layton * It _appears_ to be in the future, but is actually in distant past. 322d2caa3c5SJeff Layton * This test is necessary to prevent such wrapped-around relative times 323d2caa3c5SJeff Layton * from permanently stopping the whole pdflush writeback. 324d2caa3c5SJeff Layton */ 325d2caa3c5SJeff Layton ret = ret && time_before_eq(inode->dirtied_when, jiffies); 326d2caa3c5SJeff Layton #endif 327d2caa3c5SJeff Layton return ret; 328d2caa3c5SJeff Layton } 329d2caa3c5SJeff Layton 330c986d1e2SAndrew Morton /* 3312c136579SFengguang Wu * Move expired dirty inodes from @delaying_queue to @dispatch_queue. 3322c136579SFengguang Wu */ 3332c136579SFengguang Wu static void move_expired_inodes(struct list_head *delaying_queue, 3342c136579SFengguang Wu struct list_head *dispatch_queue, 3352c136579SFengguang Wu unsigned long *older_than_this) 3362c136579SFengguang Wu { 3372c136579SFengguang Wu while (!list_empty(delaying_queue)) { 3382c136579SFengguang Wu struct inode *inode = list_entry(delaying_queue->prev, 3392c136579SFengguang Wu struct inode, i_list); 3402c136579SFengguang Wu if (older_than_this && 341d2caa3c5SJeff Layton inode_dirtied_after(inode, *older_than_this)) 3422c136579SFengguang Wu break; 3432c136579SFengguang Wu list_move(&inode->i_list, dispatch_queue); 3442c136579SFengguang Wu } 3452c136579SFengguang Wu } 3462c136579SFengguang Wu 3472c136579SFengguang Wu /* 3482c136579SFengguang Wu * Queue all expired dirty inodes for io, eldest first. 3492c136579SFengguang Wu */ 35003ba3782SJens Axboe static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this) 3512c136579SFengguang Wu { 35203ba3782SJens Axboe list_splice_init(&wb->b_more_io, wb->b_io.prev); 35303ba3782SJens Axboe move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this); 35466f3b8e2SJens Axboe } 35566f3b8e2SJens Axboe 35603ba3782SJens Axboe static int write_inode(struct inode *inode, int sync) 35766f3b8e2SJens Axboe { 35803ba3782SJens Axboe if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) 35903ba3782SJens Axboe return inode->i_sb->s_op->write_inode(inode, sync); 36003ba3782SJens Axboe return 0; 36166f3b8e2SJens Axboe } 36208d8e974SFengguang Wu 3632c136579SFengguang Wu /* 36401c03194SChristoph Hellwig * Wait for writeback on an inode to complete. 36501c03194SChristoph Hellwig */ 36601c03194SChristoph Hellwig static void inode_wait_for_writeback(struct inode *inode) 36701c03194SChristoph Hellwig { 36801c03194SChristoph Hellwig DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); 36901c03194SChristoph Hellwig wait_queue_head_t *wqh; 37001c03194SChristoph Hellwig 37101c03194SChristoph Hellwig wqh = bit_waitqueue(&inode->i_state, __I_SYNC); 37201c03194SChristoph Hellwig do { 37301c03194SChristoph Hellwig spin_unlock(&inode_lock); 37401c03194SChristoph Hellwig __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); 37501c03194SChristoph Hellwig spin_lock(&inode_lock); 37601c03194SChristoph Hellwig } while (inode->i_state & I_SYNC); 37701c03194SChristoph Hellwig } 37801c03194SChristoph Hellwig 37901c03194SChristoph Hellwig /* 38001c03194SChristoph Hellwig * Write out an inode's dirty pages. Called under inode_lock. Either the 38101c03194SChristoph Hellwig * caller has ref on the inode (either via __iget or via syscall against an fd) 38201c03194SChristoph Hellwig * or the inode has I_WILL_FREE set (via generic_forget_inode) 38301c03194SChristoph Hellwig * 3841da177e4SLinus Torvalds * If `wait' is set, wait on the writeout. 3851da177e4SLinus Torvalds * 3861da177e4SLinus Torvalds * The whole writeout design is quite complex and fragile. We want to avoid 3871da177e4SLinus Torvalds * starvation of particular inodes when others are being redirtied, prevent 3881da177e4SLinus Torvalds * livelocks, etc. 3891da177e4SLinus Torvalds * 3901da177e4SLinus Torvalds * Called under inode_lock. 3911da177e4SLinus Torvalds */ 3921da177e4SLinus Torvalds static int 39301c03194SChristoph Hellwig writeback_single_inode(struct inode *inode, struct writeback_control *wbc) 3941da177e4SLinus Torvalds { 3951da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 3961da177e4SLinus Torvalds int wait = wbc->sync_mode == WB_SYNC_ALL; 39701c03194SChristoph Hellwig unsigned dirty; 3981da177e4SLinus Torvalds int ret; 3991da177e4SLinus Torvalds 40001c03194SChristoph Hellwig if (!atomic_read(&inode->i_count)) 40101c03194SChristoph Hellwig WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); 40201c03194SChristoph Hellwig else 40301c03194SChristoph Hellwig WARN_ON(inode->i_state & I_WILL_FREE); 40401c03194SChristoph Hellwig 40501c03194SChristoph Hellwig if (inode->i_state & I_SYNC) { 40601c03194SChristoph Hellwig /* 40701c03194SChristoph Hellwig * If this inode is locked for writeback and we are not doing 40866f3b8e2SJens Axboe * writeback-for-data-integrity, move it to b_more_io so that 40901c03194SChristoph Hellwig * writeback can proceed with the other inodes on s_io. 41001c03194SChristoph Hellwig * 41101c03194SChristoph Hellwig * We'll have another go at writing back this inode when we 41266f3b8e2SJens Axboe * completed a full scan of b_io. 41301c03194SChristoph Hellwig */ 41401c03194SChristoph Hellwig if (!wait) { 41501c03194SChristoph Hellwig requeue_io(inode); 41601c03194SChristoph Hellwig return 0; 41701c03194SChristoph Hellwig } 41801c03194SChristoph Hellwig 41901c03194SChristoph Hellwig /* 42001c03194SChristoph Hellwig * It's a data-integrity sync. We must wait. 42101c03194SChristoph Hellwig */ 42201c03194SChristoph Hellwig inode_wait_for_writeback(inode); 42301c03194SChristoph Hellwig } 42401c03194SChristoph Hellwig 4251c0eeaf5SJoern Engel BUG_ON(inode->i_state & I_SYNC); 4261da177e4SLinus Torvalds 4271c0eeaf5SJoern Engel /* Set I_SYNC, reset I_DIRTY */ 4281da177e4SLinus Torvalds dirty = inode->i_state & I_DIRTY; 4291c0eeaf5SJoern Engel inode->i_state |= I_SYNC; 4301da177e4SLinus Torvalds inode->i_state &= ~I_DIRTY; 4311da177e4SLinus Torvalds 4321da177e4SLinus Torvalds spin_unlock(&inode_lock); 4331da177e4SLinus Torvalds 4341da177e4SLinus Torvalds ret = do_writepages(mapping, wbc); 4351da177e4SLinus Torvalds 4361da177e4SLinus Torvalds /* Don't write the inode if only I_DIRTY_PAGES was set */ 4371da177e4SLinus Torvalds if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { 4381da177e4SLinus Torvalds int err = write_inode(inode, wait); 4391da177e4SLinus Torvalds if (ret == 0) 4401da177e4SLinus Torvalds ret = err; 4411da177e4SLinus Torvalds } 4421da177e4SLinus Torvalds 4431da177e4SLinus Torvalds if (wait) { 4441da177e4SLinus Torvalds int err = filemap_fdatawait(mapping); 4451da177e4SLinus Torvalds if (ret == 0) 4461da177e4SLinus Torvalds ret = err; 4471da177e4SLinus Torvalds } 4481da177e4SLinus Torvalds 4491da177e4SLinus Torvalds spin_lock(&inode_lock); 4501c0eeaf5SJoern Engel inode->i_state &= ~I_SYNC; 45184a89245SWu Fengguang if (!(inode->i_state & (I_FREEING | I_CLEAR))) { 452ae1b7f7dSWu Fengguang if (inode->i_state & I_DIRTY) { 453ae1b7f7dSWu Fengguang /* 454ae1b7f7dSWu Fengguang * Someone redirtied the inode while were writing back 455ae1b7f7dSWu Fengguang * the pages. 456ae1b7f7dSWu Fengguang */ 457ae1b7f7dSWu Fengguang redirty_tail(inode); 458ae1b7f7dSWu Fengguang } else if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { 4591da177e4SLinus Torvalds /* 4601da177e4SLinus Torvalds * We didn't write back all the pages. nfs_writepages() 4611da177e4SLinus Torvalds * sometimes bales out without doing anything. Redirty 46266f3b8e2SJens Axboe * the inode; Move it from b_io onto b_more_io/b_dirty. 4631b43ef91SAndrew Morton */ 4641b43ef91SAndrew Morton /* 4651b43ef91SAndrew Morton * akpm: if the caller was the kupdate function we put 46666f3b8e2SJens Axboe * this inode at the head of b_dirty so it gets first 4671b43ef91SAndrew Morton * consideration. Otherwise, move it to the tail, for 4681b43ef91SAndrew Morton * the reasons described there. I'm not really sure 4691b43ef91SAndrew Morton * how much sense this makes. Presumably I had a good 4701b43ef91SAndrew Morton * reasons for doing it this way, and I'd rather not 4711b43ef91SAndrew Morton * muck with it at present. 4721da177e4SLinus Torvalds */ 4731da177e4SLinus Torvalds if (wbc->for_kupdate) { 4741da177e4SLinus Torvalds /* 4752c136579SFengguang Wu * For the kupdate function we move the inode 47666f3b8e2SJens Axboe * to b_more_io so it will get more writeout as 4772c136579SFengguang Wu * soon as the queue becomes uncongested. 4781da177e4SLinus Torvalds */ 4791da177e4SLinus Torvalds inode->i_state |= I_DIRTY_PAGES; 4808bc3be27SFengguang Wu if (wbc->nr_to_write <= 0) { 4818bc3be27SFengguang Wu /* 4828bc3be27SFengguang Wu * slice used up: queue for next turn 4838bc3be27SFengguang Wu */ 4840e0f4fc2SKen Chen requeue_io(inode); 4851da177e4SLinus Torvalds } else { 4861da177e4SLinus Torvalds /* 4878bc3be27SFengguang Wu * somehow blocked: retry later 4888bc3be27SFengguang Wu */ 4898bc3be27SFengguang Wu redirty_tail(inode); 4908bc3be27SFengguang Wu } 4918bc3be27SFengguang Wu } else { 4928bc3be27SFengguang Wu /* 4931da177e4SLinus Torvalds * Otherwise fully redirty the inode so that 4941da177e4SLinus Torvalds * other inodes on this superblock will get some 4951da177e4SLinus Torvalds * writeout. Otherwise heavy writing to one 4961da177e4SLinus Torvalds * file would indefinitely suspend writeout of 4971da177e4SLinus Torvalds * all the other files. 4981da177e4SLinus Torvalds */ 4991da177e4SLinus Torvalds inode->i_state |= I_DIRTY_PAGES; 5001b43ef91SAndrew Morton redirty_tail(inode); 5011da177e4SLinus Torvalds } 5021da177e4SLinus Torvalds } else if (atomic_read(&inode->i_count)) { 5031da177e4SLinus Torvalds /* 5041da177e4SLinus Torvalds * The inode is clean, inuse 5051da177e4SLinus Torvalds */ 5061da177e4SLinus Torvalds list_move(&inode->i_list, &inode_in_use); 5071da177e4SLinus Torvalds } else { 5081da177e4SLinus Torvalds /* 5091da177e4SLinus Torvalds * The inode is clean, unused 5101da177e4SLinus Torvalds */ 5111da177e4SLinus Torvalds list_move(&inode->i_list, &inode_unused); 5121da177e4SLinus Torvalds } 5131da177e4SLinus Torvalds } 5141c0eeaf5SJoern Engel inode_sync_complete(inode); 5151da177e4SLinus Torvalds return ret; 5161da177e4SLinus Torvalds } 5171da177e4SLinus Torvalds 51803ba3782SJens Axboe /* 51903ba3782SJens Axboe * For WB_SYNC_NONE writeback, the caller does not have the sb pinned 52003ba3782SJens Axboe * before calling writeback. So make sure that we do pin it, so it doesn't 52103ba3782SJens Axboe * go away while we are writing inodes from it. 52203ba3782SJens Axboe * 52303ba3782SJens Axboe * Returns 0 if the super was successfully pinned (or pinning wasn't needed), 52403ba3782SJens Axboe * 1 if we failed. 52503ba3782SJens Axboe */ 52603ba3782SJens Axboe static int pin_sb_for_writeback(struct writeback_control *wbc, 52703ba3782SJens Axboe struct inode *inode) 5281da177e4SLinus Torvalds { 52903ba3782SJens Axboe struct super_block *sb = inode->i_sb; 53003ba3782SJens Axboe 53103ba3782SJens Axboe /* 53203ba3782SJens Axboe * Caller must already hold the ref for this 53303ba3782SJens Axboe */ 53403ba3782SJens Axboe if (wbc->sync_mode == WB_SYNC_ALL) { 53503ba3782SJens Axboe WARN_ON(!rwsem_is_locked(&sb->s_umount)); 53603ba3782SJens Axboe return 0; 53703ba3782SJens Axboe } 53803ba3782SJens Axboe 53903ba3782SJens Axboe spin_lock(&sb_lock); 54003ba3782SJens Axboe sb->s_count++; 54103ba3782SJens Axboe if (down_read_trylock(&sb->s_umount)) { 54203ba3782SJens Axboe if (sb->s_root) { 54303ba3782SJens Axboe spin_unlock(&sb_lock); 54403ba3782SJens Axboe return 0; 54503ba3782SJens Axboe } 54603ba3782SJens Axboe /* 54703ba3782SJens Axboe * umounted, drop rwsem again and fall through to failure 54803ba3782SJens Axboe */ 54903ba3782SJens Axboe up_read(&sb->s_umount); 55003ba3782SJens Axboe } 55103ba3782SJens Axboe 55203ba3782SJens Axboe sb->s_count--; 55303ba3782SJens Axboe spin_unlock(&sb_lock); 55403ba3782SJens Axboe return 1; 55503ba3782SJens Axboe } 55603ba3782SJens Axboe 55703ba3782SJens Axboe static void unpin_sb_for_writeback(struct writeback_control *wbc, 55803ba3782SJens Axboe struct inode *inode) 55903ba3782SJens Axboe { 56003ba3782SJens Axboe struct super_block *sb = inode->i_sb; 56103ba3782SJens Axboe 56203ba3782SJens Axboe if (wbc->sync_mode == WB_SYNC_ALL) 56303ba3782SJens Axboe return; 56403ba3782SJens Axboe 56503ba3782SJens Axboe up_read(&sb->s_umount); 56603ba3782SJens Axboe put_super(sb); 56703ba3782SJens Axboe } 56803ba3782SJens Axboe 56903ba3782SJens Axboe static void writeback_inodes_wb(struct bdi_writeback *wb, 57003ba3782SJens Axboe struct writeback_control *wbc) 57103ba3782SJens Axboe { 57203ba3782SJens Axboe struct super_block *sb = wbc->sb; 57366f3b8e2SJens Axboe const int is_blkdev_sb = sb_is_blkdev_sb(sb); 5741da177e4SLinus Torvalds const unsigned long start = jiffies; /* livelock avoidance */ 5751da177e4SLinus Torvalds 576ae8547b0SHans Reiser spin_lock(&inode_lock); 5771da177e4SLinus Torvalds 57803ba3782SJens Axboe if (!wbc->for_kupdate || list_empty(&wb->b_io)) 57903ba3782SJens Axboe queue_io(wb, wbc->older_than_this); 58066f3b8e2SJens Axboe 58103ba3782SJens Axboe while (!list_empty(&wb->b_io)) { 58203ba3782SJens Axboe struct inode *inode = list_entry(wb->b_io.prev, 5831da177e4SLinus Torvalds struct inode, i_list); 5841da177e4SLinus Torvalds long pages_skipped; 5851da177e4SLinus Torvalds 58666f3b8e2SJens Axboe /* 58766f3b8e2SJens Axboe * super block given and doesn't match, skip this inode 58866f3b8e2SJens Axboe */ 58966f3b8e2SJens Axboe if (sb && sb != inode->i_sb) { 59066f3b8e2SJens Axboe redirty_tail(inode); 59166f3b8e2SJens Axboe continue; 59266f3b8e2SJens Axboe } 59366f3b8e2SJens Axboe 59403ba3782SJens Axboe if (!bdi_cap_writeback_dirty(wb->bdi)) { 5959852a0e7SAndrew Morton redirty_tail(inode); 59666f3b8e2SJens Axboe if (is_blkdev_sb) { 5971da177e4SLinus Torvalds /* 5981da177e4SLinus Torvalds * Dirty memory-backed blockdev: the ramdisk 5991da177e4SLinus Torvalds * driver does this. Skip just this inode 6001da177e4SLinus Torvalds */ 6011da177e4SLinus Torvalds continue; 6021da177e4SLinus Torvalds } 6031da177e4SLinus Torvalds /* 6041da177e4SLinus Torvalds * Dirty memory-backed inode against a filesystem other 6051da177e4SLinus Torvalds * than the kernel-internal bdev filesystem. Skip the 6061da177e4SLinus Torvalds * entire superblock. 6071da177e4SLinus Torvalds */ 6081da177e4SLinus Torvalds break; 6091da177e4SLinus Torvalds } 6101da177e4SLinus Torvalds 61184a89245SWu Fengguang if (inode->i_state & (I_NEW | I_WILL_FREE)) { 6127ef0d737SNick Piggin requeue_io(inode); 6137ef0d737SNick Piggin continue; 6147ef0d737SNick Piggin } 6157ef0d737SNick Piggin 61603ba3782SJens Axboe if (wbc->nonblocking && bdi_write_congested(wb->bdi)) { 6171da177e4SLinus Torvalds wbc->encountered_congestion = 1; 61866f3b8e2SJens Axboe if (!is_blkdev_sb) 6191da177e4SLinus Torvalds break; /* Skip a congested fs */ 6200e0f4fc2SKen Chen requeue_io(inode); 6211da177e4SLinus Torvalds continue; /* Skip a congested blockdev */ 6221da177e4SLinus Torvalds } 6231da177e4SLinus Torvalds 624d2caa3c5SJeff Layton /* 625d2caa3c5SJeff Layton * Was this inode dirtied after sync_sb_inodes was called? 626d2caa3c5SJeff Layton * This keeps sync from extra jobs and livelock. 627d2caa3c5SJeff Layton */ 628d2caa3c5SJeff Layton if (inode_dirtied_after(inode, start)) 6291da177e4SLinus Torvalds break; 6301da177e4SLinus Torvalds 63103ba3782SJens Axboe if (pin_sb_for_writeback(wbc, inode)) { 63203ba3782SJens Axboe requeue_io(inode); 63303ba3782SJens Axboe continue; 63403ba3782SJens Axboe } 6351da177e4SLinus Torvalds 63684a89245SWu Fengguang BUG_ON(inode->i_state & (I_FREEING | I_CLEAR)); 6371da177e4SLinus Torvalds __iget(inode); 6381da177e4SLinus Torvalds pages_skipped = wbc->pages_skipped; 63901c03194SChristoph Hellwig writeback_single_inode(inode, wbc); 64003ba3782SJens Axboe unpin_sb_for_writeback(wbc, inode); 6411da177e4SLinus Torvalds if (wbc->pages_skipped != pages_skipped) { 6421da177e4SLinus Torvalds /* 6431da177e4SLinus Torvalds * writeback is not making progress due to locked 6441da177e4SLinus Torvalds * buffers. Skip this inode for now. 6451da177e4SLinus Torvalds */ 646f57b9b7bSAndrew Morton redirty_tail(inode); 6471da177e4SLinus Torvalds } 6481da177e4SLinus Torvalds spin_unlock(&inode_lock); 6491da177e4SLinus Torvalds iput(inode); 6504ffc8444SOGAWA Hirofumi cond_resched(); 6511da177e4SLinus Torvalds spin_lock(&inode_lock); 6528bc3be27SFengguang Wu if (wbc->nr_to_write <= 0) { 6538bc3be27SFengguang Wu wbc->more_io = 1; 6541da177e4SLinus Torvalds break; 6551da177e4SLinus Torvalds } 65603ba3782SJens Axboe if (!list_empty(&wb->b_more_io)) 6578bc3be27SFengguang Wu wbc->more_io = 1; 6588bc3be27SFengguang Wu } 65938f21977SNick Piggin 66066f3b8e2SJens Axboe spin_unlock(&inode_lock); 66166f3b8e2SJens Axboe /* Leave any unwritten inodes on b_io */ 66266f3b8e2SJens Axboe } 66366f3b8e2SJens Axboe 66403ba3782SJens Axboe void writeback_inodes_wbc(struct writeback_control *wbc) 66503ba3782SJens Axboe { 66603ba3782SJens Axboe struct backing_dev_info *bdi = wbc->bdi; 66703ba3782SJens Axboe 66803ba3782SJens Axboe writeback_inodes_wb(&bdi->wb, wbc); 66903ba3782SJens Axboe } 67003ba3782SJens Axboe 67103ba3782SJens Axboe /* 67203ba3782SJens Axboe * The maximum number of pages to writeout in a single bdi flush/kupdate 67303ba3782SJens Axboe * operation. We do this so we don't hold I_SYNC against an inode for 67403ba3782SJens Axboe * enormous amounts of time, which would block a userspace task which has 67503ba3782SJens Axboe * been forced to throttle against that inode. Also, the code reevaluates 67603ba3782SJens Axboe * the dirty each time it has written this many pages. 67703ba3782SJens Axboe */ 67803ba3782SJens Axboe #define MAX_WRITEBACK_PAGES 1024 67903ba3782SJens Axboe 68003ba3782SJens Axboe static inline bool over_bground_thresh(void) 68103ba3782SJens Axboe { 68203ba3782SJens Axboe unsigned long background_thresh, dirty_thresh; 68303ba3782SJens Axboe 68403ba3782SJens Axboe get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL); 68503ba3782SJens Axboe 68603ba3782SJens Axboe return (global_page_state(NR_FILE_DIRTY) + 68703ba3782SJens Axboe global_page_state(NR_UNSTABLE_NFS) >= background_thresh); 68803ba3782SJens Axboe } 68903ba3782SJens Axboe 69003ba3782SJens Axboe /* 69103ba3782SJens Axboe * Explicit flushing or periodic writeback of "old" data. 69203ba3782SJens Axboe * 69303ba3782SJens Axboe * Define "old": the first time one of an inode's pages is dirtied, we mark the 69403ba3782SJens Axboe * dirtying-time in the inode's address_space. So this periodic writeback code 69503ba3782SJens Axboe * just walks the superblock inode list, writing back any inodes which are 69603ba3782SJens Axboe * older than a specific point in time. 69703ba3782SJens Axboe * 69803ba3782SJens Axboe * Try to run once per dirty_writeback_interval. But if a writeback event 69903ba3782SJens Axboe * takes longer than a dirty_writeback_interval interval, then leave a 70003ba3782SJens Axboe * one-second gap. 70103ba3782SJens Axboe * 70203ba3782SJens Axboe * older_than_this takes precedence over nr_to_write. So we'll only write back 70303ba3782SJens Axboe * all dirty pages if they are all attached to "old" mappings. 70403ba3782SJens Axboe */ 705c4a77a6cSJens Axboe static long wb_writeback(struct bdi_writeback *wb, 706c4a77a6cSJens Axboe struct wb_writeback_args *args) 70703ba3782SJens Axboe { 70803ba3782SJens Axboe struct writeback_control wbc = { 70903ba3782SJens Axboe .bdi = wb->bdi, 710c4a77a6cSJens Axboe .sb = args->sb, 711c4a77a6cSJens Axboe .sync_mode = args->sync_mode, 71203ba3782SJens Axboe .older_than_this = NULL, 713c4a77a6cSJens Axboe .for_kupdate = args->for_kupdate, 714c4a77a6cSJens Axboe .range_cyclic = args->range_cyclic, 71503ba3782SJens Axboe }; 71603ba3782SJens Axboe unsigned long oldest_jif; 71703ba3782SJens Axboe long wrote = 0; 718a5989bdcSJan Kara struct inode *inode; 71903ba3782SJens Axboe 72003ba3782SJens Axboe if (wbc.for_kupdate) { 72103ba3782SJens Axboe wbc.older_than_this = &oldest_jif; 72203ba3782SJens Axboe oldest_jif = jiffies - 72303ba3782SJens Axboe msecs_to_jiffies(dirty_expire_interval * 10); 72403ba3782SJens Axboe } 725c4a77a6cSJens Axboe if (!wbc.range_cyclic) { 726c4a77a6cSJens Axboe wbc.range_start = 0; 727c4a77a6cSJens Axboe wbc.range_end = LLONG_MAX; 728c4a77a6cSJens Axboe } 72903ba3782SJens Axboe 73003ba3782SJens Axboe for (;;) { 73103ba3782SJens Axboe /* 732d3ddec76SWu Fengguang * Stop writeback when nr_pages has been consumed 73303ba3782SJens Axboe */ 734d3ddec76SWu Fengguang if (args->nr_pages <= 0) 73503ba3782SJens Axboe break; 73603ba3782SJens Axboe 73703ba3782SJens Axboe /* 738d3ddec76SWu Fengguang * For background writeout, stop when we are below the 739d3ddec76SWu Fengguang * background dirty threshold 74003ba3782SJens Axboe */ 741d3ddec76SWu Fengguang if (args->for_background && !over_bground_thresh()) 74203ba3782SJens Axboe break; 74303ba3782SJens Axboe 74403ba3782SJens Axboe wbc.more_io = 0; 74503ba3782SJens Axboe wbc.encountered_congestion = 0; 74603ba3782SJens Axboe wbc.nr_to_write = MAX_WRITEBACK_PAGES; 74703ba3782SJens Axboe wbc.pages_skipped = 0; 74803ba3782SJens Axboe writeback_inodes_wb(wb, &wbc); 749c4a77a6cSJens Axboe args->nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; 75003ba3782SJens Axboe wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write; 75103ba3782SJens Axboe 75203ba3782SJens Axboe /* 75303ba3782SJens Axboe * If we ran out of stuff to write, bail unless more_io got set 75403ba3782SJens Axboe */ 7557fbdea32SWu Fengguang if (wbc.nr_to_write > 0) { 7567fbdea32SWu Fengguang if (wbc.more_io) { 757a5989bdcSJan Kara if (wbc.nr_to_write < MAX_WRITEBACK_PAGES) 75803ba3782SJens Axboe continue; 759a5989bdcSJan Kara /* 760a5989bdcSJan Kara * Nothing written. Wait for some inode to 761a5989bdcSJan Kara * become available for writeback. Otherwise 762a5989bdcSJan Kara * we'll just busyloop. 763a5989bdcSJan Kara */ 764a5989bdcSJan Kara spin_lock(&inode_lock); 765a5989bdcSJan Kara if (!list_empty(&wb->b_more_io)) { 766a5989bdcSJan Kara inode = list_entry( 767a5989bdcSJan Kara wb->b_more_io.prev, 768a5989bdcSJan Kara struct inode, i_list); 769a5989bdcSJan Kara inode_wait_for_writeback(inode); 770a5989bdcSJan Kara } 771a5989bdcSJan Kara spin_unlock(&inode_lock); 772a5989bdcSJan Kara continue; 773a5989bdcSJan Kara } 77403ba3782SJens Axboe break; 77503ba3782SJens Axboe } 77603ba3782SJens Axboe } 77703ba3782SJens Axboe 77803ba3782SJens Axboe return wrote; 77903ba3782SJens Axboe } 78003ba3782SJens Axboe 78103ba3782SJens Axboe /* 78203ba3782SJens Axboe * Return the next bdi_work struct that hasn't been processed by this 7838010c3b6SJens Axboe * wb thread yet. ->seen is initially set for each thread that exists 7848010c3b6SJens Axboe * for this device, when a thread first notices a piece of work it 7858010c3b6SJens Axboe * clears its bit. Depending on writeback type, the thread will notify 7868010c3b6SJens Axboe * completion on either receiving the work (WB_SYNC_NONE) or after 7878010c3b6SJens Axboe * it is done (WB_SYNC_ALL). 78803ba3782SJens Axboe */ 78903ba3782SJens Axboe static struct bdi_work *get_next_work_item(struct backing_dev_info *bdi, 79003ba3782SJens Axboe struct bdi_writeback *wb) 79103ba3782SJens Axboe { 79203ba3782SJens Axboe struct bdi_work *work, *ret = NULL; 79303ba3782SJens Axboe 79403ba3782SJens Axboe rcu_read_lock(); 79503ba3782SJens Axboe 79603ba3782SJens Axboe list_for_each_entry_rcu(work, &bdi->work_list, list) { 79777fad5e6SNick Piggin if (!test_bit(wb->nr, &work->seen)) 79803ba3782SJens Axboe continue; 79977fad5e6SNick Piggin clear_bit(wb->nr, &work->seen); 80003ba3782SJens Axboe 80103ba3782SJens Axboe ret = work; 80203ba3782SJens Axboe break; 80303ba3782SJens Axboe } 80403ba3782SJens Axboe 80503ba3782SJens Axboe rcu_read_unlock(); 80603ba3782SJens Axboe return ret; 80703ba3782SJens Axboe } 80803ba3782SJens Axboe 80903ba3782SJens Axboe static long wb_check_old_data_flush(struct bdi_writeback *wb) 81003ba3782SJens Axboe { 81103ba3782SJens Axboe unsigned long expired; 81203ba3782SJens Axboe long nr_pages; 81303ba3782SJens Axboe 81403ba3782SJens Axboe expired = wb->last_old_flush + 81503ba3782SJens Axboe msecs_to_jiffies(dirty_writeback_interval * 10); 81603ba3782SJens Axboe if (time_before(jiffies, expired)) 81703ba3782SJens Axboe return 0; 81803ba3782SJens Axboe 81903ba3782SJens Axboe wb->last_old_flush = jiffies; 82003ba3782SJens Axboe nr_pages = global_page_state(NR_FILE_DIRTY) + 82103ba3782SJens Axboe global_page_state(NR_UNSTABLE_NFS) + 82203ba3782SJens Axboe (inodes_stat.nr_inodes - inodes_stat.nr_unused); 82303ba3782SJens Axboe 824c4a77a6cSJens Axboe if (nr_pages) { 825c4a77a6cSJens Axboe struct wb_writeback_args args = { 826c4a77a6cSJens Axboe .nr_pages = nr_pages, 827c4a77a6cSJens Axboe .sync_mode = WB_SYNC_NONE, 828c4a77a6cSJens Axboe .for_kupdate = 1, 829c4a77a6cSJens Axboe .range_cyclic = 1, 830c4a77a6cSJens Axboe }; 831c4a77a6cSJens Axboe 832c4a77a6cSJens Axboe return wb_writeback(wb, &args); 833c4a77a6cSJens Axboe } 83403ba3782SJens Axboe 83503ba3782SJens Axboe return 0; 83603ba3782SJens Axboe } 83703ba3782SJens Axboe 83803ba3782SJens Axboe /* 83903ba3782SJens Axboe * Retrieve work items and do the writeback they describe 84003ba3782SJens Axboe */ 84103ba3782SJens Axboe long wb_do_writeback(struct bdi_writeback *wb, int force_wait) 84203ba3782SJens Axboe { 84303ba3782SJens Axboe struct backing_dev_info *bdi = wb->bdi; 84403ba3782SJens Axboe struct bdi_work *work; 845c4a77a6cSJens Axboe long wrote = 0; 84603ba3782SJens Axboe 84703ba3782SJens Axboe while ((work = get_next_work_item(bdi, wb)) != NULL) { 848c4a77a6cSJens Axboe struct wb_writeback_args args = work->args; 84903ba3782SJens Axboe 85003ba3782SJens Axboe /* 85103ba3782SJens Axboe * Override sync mode, in case we must wait for completion 85203ba3782SJens Axboe */ 85303ba3782SJens Axboe if (force_wait) 854c4a77a6cSJens Axboe work->args.sync_mode = args.sync_mode = WB_SYNC_ALL; 85503ba3782SJens Axboe 85603ba3782SJens Axboe /* 85703ba3782SJens Axboe * If this isn't a data integrity operation, just notify 85803ba3782SJens Axboe * that we have seen this work and we are now starting it. 85903ba3782SJens Axboe */ 860c4a77a6cSJens Axboe if (args.sync_mode == WB_SYNC_NONE) 86103ba3782SJens Axboe wb_clear_pending(wb, work); 86203ba3782SJens Axboe 863c4a77a6cSJens Axboe wrote += wb_writeback(wb, &args); 86403ba3782SJens Axboe 86503ba3782SJens Axboe /* 86603ba3782SJens Axboe * This is a data integrity writeback, so only do the 86703ba3782SJens Axboe * notification when we have completed the work. 86803ba3782SJens Axboe */ 869c4a77a6cSJens Axboe if (args.sync_mode == WB_SYNC_ALL) 87003ba3782SJens Axboe wb_clear_pending(wb, work); 87103ba3782SJens Axboe } 87203ba3782SJens Axboe 87303ba3782SJens Axboe /* 87403ba3782SJens Axboe * Check for periodic writeback, kupdated() style 87503ba3782SJens Axboe */ 87603ba3782SJens Axboe wrote += wb_check_old_data_flush(wb); 87703ba3782SJens Axboe 87803ba3782SJens Axboe return wrote; 87903ba3782SJens Axboe } 88003ba3782SJens Axboe 88103ba3782SJens Axboe /* 88203ba3782SJens Axboe * Handle writeback of dirty data for the device backed by this bdi. Also 88303ba3782SJens Axboe * wakes up periodically and does kupdated style flushing. 88403ba3782SJens Axboe */ 88503ba3782SJens Axboe int bdi_writeback_task(struct bdi_writeback *wb) 88603ba3782SJens Axboe { 88703ba3782SJens Axboe unsigned long last_active = jiffies; 88803ba3782SJens Axboe unsigned long wait_jiffies = -1UL; 88903ba3782SJens Axboe long pages_written; 89003ba3782SJens Axboe 89103ba3782SJens Axboe while (!kthread_should_stop()) { 89203ba3782SJens Axboe pages_written = wb_do_writeback(wb, 0); 89303ba3782SJens Axboe 89403ba3782SJens Axboe if (pages_written) 89503ba3782SJens Axboe last_active = jiffies; 89603ba3782SJens Axboe else if (wait_jiffies != -1UL) { 89703ba3782SJens Axboe unsigned long max_idle; 89803ba3782SJens Axboe 89903ba3782SJens Axboe /* 90003ba3782SJens Axboe * Longest period of inactivity that we tolerate. If we 90103ba3782SJens Axboe * see dirty data again later, the task will get 90203ba3782SJens Axboe * recreated automatically. 90303ba3782SJens Axboe */ 90403ba3782SJens Axboe max_idle = max(5UL * 60 * HZ, wait_jiffies); 90503ba3782SJens Axboe if (time_after(jiffies, max_idle + last_active)) 90603ba3782SJens Axboe break; 90703ba3782SJens Axboe } 90803ba3782SJens Axboe 90903ba3782SJens Axboe wait_jiffies = msecs_to_jiffies(dirty_writeback_interval * 10); 91049db0414SJens Axboe schedule_timeout_interruptible(wait_jiffies); 91103ba3782SJens Axboe try_to_freeze(); 91203ba3782SJens Axboe } 91303ba3782SJens Axboe 91403ba3782SJens Axboe return 0; 91503ba3782SJens Axboe } 91603ba3782SJens Axboe 91703ba3782SJens Axboe /* 918b6e51316SJens Axboe * Schedule writeback for all backing devices. This does WB_SYNC_NONE 919b6e51316SJens Axboe * writeback, for integrity writeback see bdi_sync_writeback(). 92003ba3782SJens Axboe */ 921b6e51316SJens Axboe static void bdi_writeback_all(struct super_block *sb, long nr_pages) 92203ba3782SJens Axboe { 923b6e51316SJens Axboe struct wb_writeback_args args = { 924b6e51316SJens Axboe .sb = sb, 925b6e51316SJens Axboe .nr_pages = nr_pages, 926b6e51316SJens Axboe .sync_mode = WB_SYNC_NONE, 927b6e51316SJens Axboe }; 92803ba3782SJens Axboe struct backing_dev_info *bdi; 92903ba3782SJens Axboe 930cfc4ba53SJens Axboe rcu_read_lock(); 93103ba3782SJens Axboe 932cfc4ba53SJens Axboe list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { 93303ba3782SJens Axboe if (!bdi_has_dirty_io(bdi)) 93403ba3782SJens Axboe continue; 93503ba3782SJens Axboe 936b6e51316SJens Axboe bdi_alloc_queue_work(bdi, &args); 93703ba3782SJens Axboe } 93803ba3782SJens Axboe 939cfc4ba53SJens Axboe rcu_read_unlock(); 94003ba3782SJens Axboe } 94103ba3782SJens Axboe 94203ba3782SJens Axboe /* 94303ba3782SJens Axboe * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back 94403ba3782SJens Axboe * the whole world. 94503ba3782SJens Axboe */ 94603ba3782SJens Axboe void wakeup_flusher_threads(long nr_pages) 94703ba3782SJens Axboe { 94803ba3782SJens Axboe if (nr_pages == 0) 94903ba3782SJens Axboe nr_pages = global_page_state(NR_FILE_DIRTY) + 95003ba3782SJens Axboe global_page_state(NR_UNSTABLE_NFS); 951b6e51316SJens Axboe bdi_writeback_all(NULL, nr_pages); 95203ba3782SJens Axboe } 95303ba3782SJens Axboe 95403ba3782SJens Axboe static noinline void block_dump___mark_inode_dirty(struct inode *inode) 95503ba3782SJens Axboe { 95603ba3782SJens Axboe if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { 95703ba3782SJens Axboe struct dentry *dentry; 95803ba3782SJens Axboe const char *name = "?"; 95903ba3782SJens Axboe 96003ba3782SJens Axboe dentry = d_find_alias(inode); 96103ba3782SJens Axboe if (dentry) { 96203ba3782SJens Axboe spin_lock(&dentry->d_lock); 96303ba3782SJens Axboe name = (const char *) dentry->d_name.name; 96403ba3782SJens Axboe } 96503ba3782SJens Axboe printk(KERN_DEBUG 96603ba3782SJens Axboe "%s(%d): dirtied inode %lu (%s) on %s\n", 96703ba3782SJens Axboe current->comm, task_pid_nr(current), inode->i_ino, 96803ba3782SJens Axboe name, inode->i_sb->s_id); 96903ba3782SJens Axboe if (dentry) { 97003ba3782SJens Axboe spin_unlock(&dentry->d_lock); 97103ba3782SJens Axboe dput(dentry); 97203ba3782SJens Axboe } 97303ba3782SJens Axboe } 97403ba3782SJens Axboe } 97503ba3782SJens Axboe 97603ba3782SJens Axboe /** 97703ba3782SJens Axboe * __mark_inode_dirty - internal function 97803ba3782SJens Axboe * @inode: inode to mark 97903ba3782SJens Axboe * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) 98003ba3782SJens Axboe * Mark an inode as dirty. Callers should use mark_inode_dirty or 98103ba3782SJens Axboe * mark_inode_dirty_sync. 98203ba3782SJens Axboe * 98303ba3782SJens Axboe * Put the inode on the super block's dirty list. 98403ba3782SJens Axboe * 98503ba3782SJens Axboe * CAREFUL! We mark it dirty unconditionally, but move it onto the 98603ba3782SJens Axboe * dirty list only if it is hashed or if it refers to a blockdev. 98703ba3782SJens Axboe * If it was not hashed, it will never be added to the dirty list 98803ba3782SJens Axboe * even if it is later hashed, as it will have been marked dirty already. 98903ba3782SJens Axboe * 99003ba3782SJens Axboe * In short, make sure you hash any inodes _before_ you start marking 99103ba3782SJens Axboe * them dirty. 99203ba3782SJens Axboe * 99303ba3782SJens Axboe * This function *must* be atomic for the I_DIRTY_PAGES case - 99403ba3782SJens Axboe * set_page_dirty() is called under spinlock in several places. 99503ba3782SJens Axboe * 99603ba3782SJens Axboe * Note that for blockdevs, inode->dirtied_when represents the dirtying time of 99703ba3782SJens Axboe * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of 99803ba3782SJens Axboe * the kernel-internal blockdev inode represents the dirtying time of the 99903ba3782SJens Axboe * blockdev's pages. This is why for I_DIRTY_PAGES we always use 100003ba3782SJens Axboe * page->mapping->host, so the page-dirtying time is recorded in the internal 100103ba3782SJens Axboe * blockdev inode. 100203ba3782SJens Axboe */ 100303ba3782SJens Axboe void __mark_inode_dirty(struct inode *inode, int flags) 100403ba3782SJens Axboe { 100503ba3782SJens Axboe struct super_block *sb = inode->i_sb; 100603ba3782SJens Axboe 100703ba3782SJens Axboe /* 100803ba3782SJens Axboe * Don't do this for I_DIRTY_PAGES - that doesn't actually 100903ba3782SJens Axboe * dirty the inode itself 101003ba3782SJens Axboe */ 101103ba3782SJens Axboe if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { 101203ba3782SJens Axboe if (sb->s_op->dirty_inode) 101303ba3782SJens Axboe sb->s_op->dirty_inode(inode); 101403ba3782SJens Axboe } 101503ba3782SJens Axboe 101603ba3782SJens Axboe /* 101703ba3782SJens Axboe * make sure that changes are seen by all cpus before we test i_state 101803ba3782SJens Axboe * -- mikulas 101903ba3782SJens Axboe */ 102003ba3782SJens Axboe smp_mb(); 102103ba3782SJens Axboe 102203ba3782SJens Axboe /* avoid the locking if we can */ 102303ba3782SJens Axboe if ((inode->i_state & flags) == flags) 102403ba3782SJens Axboe return; 102503ba3782SJens Axboe 102603ba3782SJens Axboe if (unlikely(block_dump)) 102703ba3782SJens Axboe block_dump___mark_inode_dirty(inode); 102803ba3782SJens Axboe 102903ba3782SJens Axboe spin_lock(&inode_lock); 103003ba3782SJens Axboe if ((inode->i_state & flags) != flags) { 103103ba3782SJens Axboe const int was_dirty = inode->i_state & I_DIRTY; 103203ba3782SJens Axboe 103303ba3782SJens Axboe inode->i_state |= flags; 103403ba3782SJens Axboe 103503ba3782SJens Axboe /* 103603ba3782SJens Axboe * If the inode is being synced, just update its dirty state. 103703ba3782SJens Axboe * The unlocker will place the inode on the appropriate 103803ba3782SJens Axboe * superblock list, based upon its state. 103903ba3782SJens Axboe */ 104003ba3782SJens Axboe if (inode->i_state & I_SYNC) 104103ba3782SJens Axboe goto out; 104203ba3782SJens Axboe 104303ba3782SJens Axboe /* 104403ba3782SJens Axboe * Only add valid (hashed) inodes to the superblock's 104503ba3782SJens Axboe * dirty list. Add blockdev inodes as well. 104603ba3782SJens Axboe */ 104703ba3782SJens Axboe if (!S_ISBLK(inode->i_mode)) { 104803ba3782SJens Axboe if (hlist_unhashed(&inode->i_hash)) 104903ba3782SJens Axboe goto out; 105003ba3782SJens Axboe } 105103ba3782SJens Axboe if (inode->i_state & (I_FREEING|I_CLEAR)) 105203ba3782SJens Axboe goto out; 105303ba3782SJens Axboe 105403ba3782SJens Axboe /* 105503ba3782SJens Axboe * If the inode was already on b_dirty/b_io/b_more_io, don't 105603ba3782SJens Axboe * reposition it (that would break b_dirty time-ordering). 105703ba3782SJens Axboe */ 105803ba3782SJens Axboe if (!was_dirty) { 105903ba3782SJens Axboe struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; 1060500b067cSJens Axboe struct backing_dev_info *bdi = wb->bdi; 1061500b067cSJens Axboe 1062500b067cSJens Axboe if (bdi_cap_writeback_dirty(bdi) && 1063500b067cSJens Axboe !test_bit(BDI_registered, &bdi->state)) { 1064500b067cSJens Axboe WARN_ON(1); 1065500b067cSJens Axboe printk(KERN_ERR "bdi-%s not registered\n", 1066500b067cSJens Axboe bdi->name); 1067500b067cSJens Axboe } 106803ba3782SJens Axboe 106903ba3782SJens Axboe inode->dirtied_when = jiffies; 107003ba3782SJens Axboe list_move(&inode->i_list, &wb->b_dirty); 107103ba3782SJens Axboe } 107203ba3782SJens Axboe } 107303ba3782SJens Axboe out: 107403ba3782SJens Axboe spin_unlock(&inode_lock); 107503ba3782SJens Axboe } 107603ba3782SJens Axboe EXPORT_SYMBOL(__mark_inode_dirty); 107703ba3782SJens Axboe 107866f3b8e2SJens Axboe /* 107966f3b8e2SJens Axboe * Write out a superblock's list of dirty inodes. A wait will be performed 108066f3b8e2SJens Axboe * upon no inodes, all inodes or the final one, depending upon sync_mode. 108166f3b8e2SJens Axboe * 108266f3b8e2SJens Axboe * If older_than_this is non-NULL, then only write out inodes which 108366f3b8e2SJens Axboe * had their first dirtying at a time earlier than *older_than_this. 108466f3b8e2SJens Axboe * 108566f3b8e2SJens Axboe * If we're a pdlfush thread, then implement pdflush collision avoidance 108666f3b8e2SJens Axboe * against the entire list. 108766f3b8e2SJens Axboe * 108866f3b8e2SJens Axboe * If `bdi' is non-zero then we're being asked to writeback a specific queue. 108966f3b8e2SJens Axboe * This function assumes that the blockdev superblock's inodes are backed by 109066f3b8e2SJens Axboe * a variety of queues, so all inodes are searched. For other superblocks, 109166f3b8e2SJens Axboe * assume that all inodes are backed by the same queue. 109266f3b8e2SJens Axboe * 109366f3b8e2SJens Axboe * The inodes to be written are parked on bdi->b_io. They are moved back onto 109466f3b8e2SJens Axboe * bdi->b_dirty as they are selected for writing. This way, none can be missed 109566f3b8e2SJens Axboe * on the writer throttling path, and we get decent balancing between many 109666f3b8e2SJens Axboe * throttled threads: we don't want them all piling up on inode_sync_wait. 109766f3b8e2SJens Axboe */ 1098b6e51316SJens Axboe static void wait_sb_inodes(struct super_block *sb) 109966f3b8e2SJens Axboe { 110038f21977SNick Piggin struct inode *inode, *old_inode = NULL; 110138f21977SNick Piggin 110203ba3782SJens Axboe /* 110303ba3782SJens Axboe * We need to be protected against the filesystem going from 110403ba3782SJens Axboe * r/o to r/w or vice versa. 110503ba3782SJens Axboe */ 1106b6e51316SJens Axboe WARN_ON(!rwsem_is_locked(&sb->s_umount)); 110703ba3782SJens Axboe 110866f3b8e2SJens Axboe spin_lock(&inode_lock); 110966f3b8e2SJens Axboe 111038f21977SNick Piggin /* 111138f21977SNick Piggin * Data integrity sync. Must wait for all pages under writeback, 111238f21977SNick Piggin * because there may have been pages dirtied before our sync 111338f21977SNick Piggin * call, but which had writeout started before we write it out. 111438f21977SNick Piggin * In which case, the inode may not be on the dirty list, but 111538f21977SNick Piggin * we still have to wait for that writeout. 111638f21977SNick Piggin */ 1117b6e51316SJens Axboe list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { 111838f21977SNick Piggin struct address_space *mapping; 111938f21977SNick Piggin 112003ba3782SJens Axboe if (inode->i_state & (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW)) 112138f21977SNick Piggin continue; 112238f21977SNick Piggin mapping = inode->i_mapping; 112338f21977SNick Piggin if (mapping->nrpages == 0) 112438f21977SNick Piggin continue; 112538f21977SNick Piggin __iget(inode); 1126ae8547b0SHans Reiser spin_unlock(&inode_lock); 112738f21977SNick Piggin /* 112838f21977SNick Piggin * We hold a reference to 'inode' so it couldn't have 112938f21977SNick Piggin * been removed from s_inodes list while we dropped the 113038f21977SNick Piggin * inode_lock. We cannot iput the inode now as we can 113138f21977SNick Piggin * be holding the last reference and we cannot iput it 113238f21977SNick Piggin * under inode_lock. So we keep the reference and iput 113338f21977SNick Piggin * it later. 113438f21977SNick Piggin */ 113538f21977SNick Piggin iput(old_inode); 113638f21977SNick Piggin old_inode = inode; 113738f21977SNick Piggin 113838f21977SNick Piggin filemap_fdatawait(mapping); 113938f21977SNick Piggin 114038f21977SNick Piggin cond_resched(); 114138f21977SNick Piggin 114238f21977SNick Piggin spin_lock(&inode_lock); 114338f21977SNick Piggin } 114438f21977SNick Piggin spin_unlock(&inode_lock); 114538f21977SNick Piggin iput(old_inode); 114666f3b8e2SJens Axboe } 11471da177e4SLinus Torvalds 1148d8a8559cSJens Axboe /** 1149d8a8559cSJens Axboe * writeback_inodes_sb - writeback dirty inodes from given super_block 1150d8a8559cSJens Axboe * @sb: the superblock 11511da177e4SLinus Torvalds * 1152d8a8559cSJens Axboe * Start writeback on some inodes on this super_block. No guarantees are made 1153d8a8559cSJens Axboe * on how many (if any) will be written, and this function does not wait 1154d8a8559cSJens Axboe * for IO completion of submitted IO. The number of pages submitted is 1155d8a8559cSJens Axboe * returned. 11561da177e4SLinus Torvalds */ 1157b6e51316SJens Axboe void writeback_inodes_sb(struct super_block *sb) 11581da177e4SLinus Torvalds { 1159b1e7a8fdSChristoph Lameter unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY); 1160fd39fc85SChristoph Lameter unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS); 1161d8a8559cSJens Axboe long nr_to_write; 11621da177e4SLinus Torvalds 1163d8a8559cSJens Axboe nr_to_write = nr_dirty + nr_unstable + 116438f21977SNick Piggin (inodes_stat.nr_inodes - inodes_stat.nr_unused); 116538f21977SNick Piggin 1166b6e51316SJens Axboe bdi_writeback_all(sb, nr_to_write); 11671da177e4SLinus Torvalds } 1168d8a8559cSJens Axboe EXPORT_SYMBOL(writeback_inodes_sb); 1169d8a8559cSJens Axboe 1170d8a8559cSJens Axboe /** 1171d8a8559cSJens Axboe * sync_inodes_sb - sync sb inode pages 1172d8a8559cSJens Axboe * @sb: the superblock 1173d8a8559cSJens Axboe * 1174d8a8559cSJens Axboe * This function writes and waits on any dirty inode belonging to this 1175d8a8559cSJens Axboe * super_block. The number of pages synced is returned. 1176d8a8559cSJens Axboe */ 1177b6e51316SJens Axboe void sync_inodes_sb(struct super_block *sb) 1178d8a8559cSJens Axboe { 1179b6e51316SJens Axboe bdi_sync_writeback(sb->s_bdi, sb); 1180b6e51316SJens Axboe wait_sb_inodes(sb); 1181d8a8559cSJens Axboe } 1182d8a8559cSJens Axboe EXPORT_SYMBOL(sync_inodes_sb); 11831da177e4SLinus Torvalds 11841da177e4SLinus Torvalds /** 11851da177e4SLinus Torvalds * write_inode_now - write an inode to disk 11861da177e4SLinus Torvalds * @inode: inode to write to disk 11871da177e4SLinus Torvalds * @sync: whether the write should be synchronous or not 11881da177e4SLinus Torvalds * 11897f04c26dSAndrea Arcangeli * This function commits an inode to disk immediately if it is dirty. This is 11907f04c26dSAndrea Arcangeli * primarily needed by knfsd. 11917f04c26dSAndrea Arcangeli * 11927f04c26dSAndrea Arcangeli * The caller must either have a ref on the inode or must have set I_WILL_FREE. 11931da177e4SLinus Torvalds */ 11941da177e4SLinus Torvalds int write_inode_now(struct inode *inode, int sync) 11951da177e4SLinus Torvalds { 11961da177e4SLinus Torvalds int ret; 11971da177e4SLinus Torvalds struct writeback_control wbc = { 11981da177e4SLinus Torvalds .nr_to_write = LONG_MAX, 119918914b18SMike Galbraith .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, 1200111ebb6eSOGAWA Hirofumi .range_start = 0, 1201111ebb6eSOGAWA Hirofumi .range_end = LLONG_MAX, 12021da177e4SLinus Torvalds }; 12031da177e4SLinus Torvalds 12041da177e4SLinus Torvalds if (!mapping_cap_writeback_dirty(inode->i_mapping)) 120549364ce2SAndrew Morton wbc.nr_to_write = 0; 12061da177e4SLinus Torvalds 12071da177e4SLinus Torvalds might_sleep(); 12081da177e4SLinus Torvalds spin_lock(&inode_lock); 120901c03194SChristoph Hellwig ret = writeback_single_inode(inode, &wbc); 12101da177e4SLinus Torvalds spin_unlock(&inode_lock); 12111da177e4SLinus Torvalds if (sync) 12121c0eeaf5SJoern Engel inode_sync_wait(inode); 12131da177e4SLinus Torvalds return ret; 12141da177e4SLinus Torvalds } 12151da177e4SLinus Torvalds EXPORT_SYMBOL(write_inode_now); 12161da177e4SLinus Torvalds 12171da177e4SLinus Torvalds /** 12181da177e4SLinus Torvalds * sync_inode - write an inode and its pages to disk. 12191da177e4SLinus Torvalds * @inode: the inode to sync 12201da177e4SLinus Torvalds * @wbc: controls the writeback mode 12211da177e4SLinus Torvalds * 12221da177e4SLinus Torvalds * sync_inode() will write an inode and its pages to disk. It will also 12231da177e4SLinus Torvalds * correctly update the inode on its superblock's dirty inode lists and will 12241da177e4SLinus Torvalds * update inode->i_state. 12251da177e4SLinus Torvalds * 12261da177e4SLinus Torvalds * The caller must have a ref on the inode. 12271da177e4SLinus Torvalds */ 12281da177e4SLinus Torvalds int sync_inode(struct inode *inode, struct writeback_control *wbc) 12291da177e4SLinus Torvalds { 12301da177e4SLinus Torvalds int ret; 12311da177e4SLinus Torvalds 12321da177e4SLinus Torvalds spin_lock(&inode_lock); 123301c03194SChristoph Hellwig ret = writeback_single_inode(inode, wbc); 12341da177e4SLinus Torvalds spin_unlock(&inode_lock); 12351da177e4SLinus Torvalds return ret; 12361da177e4SLinus Torvalds } 12371da177e4SLinus Torvalds EXPORT_SYMBOL(sync_inode); 1238