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> 2503ba3782SJens Axboe #include <linux/freezer.h> 261da177e4SLinus Torvalds #include <linux/writeback.h> 271da177e4SLinus Torvalds #include <linux/blkdev.h> 281da177e4SLinus Torvalds #include <linux/backing-dev.h> 29455b2864SDave Chinner #include <linux/tracepoint.h> 3007f3f05cSDavid Howells #include "internal.h" 311da177e4SLinus Torvalds 32d0bceac7SJens Axboe /* 33bc31b86aSWu Fengguang * 4MB minimal write chunk size 34bc31b86aSWu Fengguang */ 35bc31b86aSWu Fengguang #define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_CACHE_SHIFT - 10)) 36bc31b86aSWu Fengguang 37bc31b86aSWu Fengguang /* 38c4a77a6cSJens Axboe * Passed into wb_writeback(), essentially a subset of writeback_control 39c4a77a6cSJens Axboe */ 4083ba7b07SChristoph Hellwig struct wb_writeback_work { 41c4a77a6cSJens Axboe long nr_pages; 42c4a77a6cSJens Axboe struct super_block *sb; 43d46db3d5SWu Fengguang unsigned long *older_than_this; 44c4a77a6cSJens Axboe enum writeback_sync_modes sync_mode; 456e6938b6SWu Fengguang unsigned int tagged_writepages:1; 4652957fe1SH Hartley Sweeten unsigned int for_kupdate:1; 4752957fe1SH Hartley Sweeten unsigned int range_cyclic:1; 4852957fe1SH Hartley Sweeten unsigned int for_background:1; 490e175a18SCurt Wohlgemuth enum wb_reason reason; /* why was writeback initiated? */ 50c4a77a6cSJens Axboe 518010c3b6SJens Axboe struct list_head list; /* pending work list */ 5283ba7b07SChristoph Hellwig struct completion *done; /* set if the caller waits */ 5303ba3782SJens Axboe }; 5403ba3782SJens Axboe 55455b2864SDave Chinner /* 56455b2864SDave Chinner * We don't actually have pdflush, but this one is exported though /proc... 57455b2864SDave Chinner */ 58455b2864SDave Chinner int nr_pdflush_threads; 59455b2864SDave Chinner 60f11b00f3SAdrian Bunk /** 61f11b00f3SAdrian Bunk * writeback_in_progress - determine whether there is writeback in progress 62f11b00f3SAdrian Bunk * @bdi: the device's backing_dev_info structure. 63f11b00f3SAdrian Bunk * 6403ba3782SJens Axboe * Determine whether there is writeback waiting to be handled against a 6503ba3782SJens Axboe * backing device. 66f11b00f3SAdrian Bunk */ 67f11b00f3SAdrian Bunk int writeback_in_progress(struct backing_dev_info *bdi) 68f11b00f3SAdrian Bunk { 6981d73a32SJan Kara return test_bit(BDI_writeback_running, &bdi->state); 70f11b00f3SAdrian Bunk } 71f11b00f3SAdrian Bunk 72692ebd17SJan Kara static inline struct backing_dev_info *inode_to_bdi(struct inode *inode) 73692ebd17SJan Kara { 74692ebd17SJan Kara struct super_block *sb = inode->i_sb; 75692ebd17SJan Kara 76aaead25bSChristoph Hellwig if (strcmp(sb->s_type->name, "bdev") == 0) 77aaead25bSChristoph Hellwig return inode->i_mapping->backing_dev_info; 78aaead25bSChristoph Hellwig 79692ebd17SJan Kara return sb->s_bdi; 80692ebd17SJan Kara } 81692ebd17SJan Kara 827ccf19a8SNick Piggin static inline struct inode *wb_inode(struct list_head *head) 837ccf19a8SNick Piggin { 847ccf19a8SNick Piggin return list_entry(head, struct inode, i_wb_list); 857ccf19a8SNick Piggin } 867ccf19a8SNick Piggin 8715eb77a0SWu Fengguang /* 8815eb77a0SWu Fengguang * Include the creation of the trace points after defining the 8915eb77a0SWu Fengguang * wb_writeback_work structure and inline functions so that the definition 9015eb77a0SWu Fengguang * remains local to this file. 9115eb77a0SWu Fengguang */ 9215eb77a0SWu Fengguang #define CREATE_TRACE_POINTS 9315eb77a0SWu Fengguang #include <trace/events/writeback.h> 9415eb77a0SWu Fengguang 956585027aSJan Kara /* Wakeup flusher thread or forker thread to fork it. Requires bdi->wb_lock. */ 966585027aSJan Kara static void bdi_wakeup_flusher(struct backing_dev_info *bdi) 974195f73dSNick Piggin { 98fff5b85aSArtem Bityutskiy if (bdi->wb.task) { 99fff5b85aSArtem Bityutskiy wake_up_process(bdi->wb.task); 100fff5b85aSArtem Bityutskiy } else { 1011da177e4SLinus Torvalds /* 102fff5b85aSArtem Bityutskiy * The bdi thread isn't there, wake up the forker thread which 103fff5b85aSArtem Bityutskiy * will create and run it. 1041da177e4SLinus Torvalds */ 10503ba3782SJens Axboe wake_up_process(default_backing_dev_info.wb.task); 1061da177e4SLinus Torvalds } 1076585027aSJan Kara } 1086585027aSJan Kara 1096585027aSJan Kara static void bdi_queue_work(struct backing_dev_info *bdi, 1106585027aSJan Kara struct wb_writeback_work *work) 1116585027aSJan Kara { 1126585027aSJan Kara trace_writeback_queue(bdi, work); 1136585027aSJan Kara 1146585027aSJan Kara spin_lock_bh(&bdi->wb_lock); 1156585027aSJan Kara list_add_tail(&work->list, &bdi->work_list); 1166585027aSJan Kara if (!bdi->wb.task) 1176585027aSJan Kara trace_writeback_nothread(bdi, work); 1186585027aSJan Kara bdi_wakeup_flusher(bdi); 1196467716aSArtem Bityutskiy spin_unlock_bh(&bdi->wb_lock); 12003ba3782SJens Axboe } 1211da177e4SLinus Torvalds 12283ba7b07SChristoph Hellwig static void 12383ba7b07SChristoph Hellwig __bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, 1240e175a18SCurt Wohlgemuth bool range_cyclic, enum wb_reason reason) 1251da177e4SLinus Torvalds { 12683ba7b07SChristoph Hellwig struct wb_writeback_work *work; 12703ba3782SJens Axboe 128bcddc3f0SJens Axboe /* 129bcddc3f0SJens Axboe * This is WB_SYNC_NONE writeback, so if allocation fails just 130bcddc3f0SJens Axboe * wakeup the thread for old dirty data writeback 131bcddc3f0SJens Axboe */ 13283ba7b07SChristoph Hellwig work = kzalloc(sizeof(*work), GFP_ATOMIC); 13383ba7b07SChristoph Hellwig if (!work) { 134455b2864SDave Chinner if (bdi->wb.task) { 135455b2864SDave Chinner trace_writeback_nowork(bdi); 13683ba7b07SChristoph Hellwig wake_up_process(bdi->wb.task); 137455b2864SDave Chinner } 13883ba7b07SChristoph Hellwig return; 13983ba7b07SChristoph Hellwig } 14083ba7b07SChristoph Hellwig 14183ba7b07SChristoph Hellwig work->sync_mode = WB_SYNC_NONE; 14283ba7b07SChristoph Hellwig work->nr_pages = nr_pages; 14383ba7b07SChristoph Hellwig work->range_cyclic = range_cyclic; 1440e175a18SCurt Wohlgemuth work->reason = reason; 14583ba7b07SChristoph Hellwig 146f11fcae8SJens Axboe bdi_queue_work(bdi, work); 14703ba3782SJens Axboe } 148b6e51316SJens Axboe 149b6e51316SJens Axboe /** 150b6e51316SJens Axboe * bdi_start_writeback - start writeback 151b6e51316SJens Axboe * @bdi: the backing device to write from 152b6e51316SJens Axboe * @nr_pages: the number of pages to write 153786228abSMarcos Paulo de Souza * @reason: reason why some writeback work was initiated 154b6e51316SJens Axboe * 155b6e51316SJens Axboe * Description: 156b6e51316SJens Axboe * This does WB_SYNC_NONE opportunistic writeback. The IO is only 15725985edcSLucas De Marchi * started when this function returns, we make no guarantees on 1580e3c9a22SJens Axboe * completion. Caller need not hold sb s_umount semaphore. 159b6e51316SJens Axboe * 160b6e51316SJens Axboe */ 1610e175a18SCurt Wohlgemuth void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, 1620e175a18SCurt Wohlgemuth enum wb_reason reason) 163b6e51316SJens Axboe { 1640e175a18SCurt Wohlgemuth __bdi_start_writeback(bdi, nr_pages, true, reason); 165d3ddec76SWu Fengguang } 166d3ddec76SWu Fengguang 167c5444198SChristoph Hellwig /** 168c5444198SChristoph Hellwig * bdi_start_background_writeback - start background writeback 169c5444198SChristoph Hellwig * @bdi: the backing device to write from 170c5444198SChristoph Hellwig * 171c5444198SChristoph Hellwig * Description: 1726585027aSJan Kara * This makes sure WB_SYNC_NONE background writeback happens. When 1736585027aSJan Kara * this function returns, it is only guaranteed that for given BDI 1746585027aSJan Kara * some IO is happening if we are over background dirty threshold. 1756585027aSJan Kara * Caller need not hold sb s_umount semaphore. 176c5444198SChristoph Hellwig */ 177c5444198SChristoph Hellwig void bdi_start_background_writeback(struct backing_dev_info *bdi) 178c5444198SChristoph Hellwig { 1796585027aSJan Kara /* 1806585027aSJan Kara * We just wake up the flusher thread. It will perform background 1816585027aSJan Kara * writeback as soon as there is no other work to do. 1826585027aSJan Kara */ 18371927e84SWu Fengguang trace_writeback_wake_background(bdi); 1846585027aSJan Kara spin_lock_bh(&bdi->wb_lock); 1856585027aSJan Kara bdi_wakeup_flusher(bdi); 1866585027aSJan Kara spin_unlock_bh(&bdi->wb_lock); 1871da177e4SLinus Torvalds } 1881da177e4SLinus Torvalds 1891da177e4SLinus Torvalds /* 190a66979abSDave Chinner * Remove the inode from the writeback list it is on. 191a66979abSDave Chinner */ 192a66979abSDave Chinner void inode_wb_list_del(struct inode *inode) 193a66979abSDave Chinner { 194f758eeabSChristoph Hellwig struct backing_dev_info *bdi = inode_to_bdi(inode); 195a66979abSDave Chinner 196f758eeabSChristoph Hellwig spin_lock(&bdi->wb.list_lock); 197f758eeabSChristoph Hellwig list_del_init(&inode->i_wb_list); 198f758eeabSChristoph Hellwig spin_unlock(&bdi->wb.list_lock); 199f758eeabSChristoph Hellwig } 200a66979abSDave Chinner 201a66979abSDave Chinner /* 2026610a0bcSAndrew Morton * Redirty an inode: set its when-it-was dirtied timestamp and move it to the 2036610a0bcSAndrew Morton * furthest end of its superblock's dirty-inode list. 2046610a0bcSAndrew Morton * 2056610a0bcSAndrew Morton * Before stamping the inode's ->dirtied_when, we check to see whether it is 20666f3b8e2SJens Axboe * already the most-recently-dirtied inode on the b_dirty list. If that is 2076610a0bcSAndrew Morton * the case then the inode must have been redirtied while it was being written 2086610a0bcSAndrew Morton * out and we don't reset its dirtied_when. 2096610a0bcSAndrew Morton */ 210f758eeabSChristoph Hellwig static void redirty_tail(struct inode *inode, struct bdi_writeback *wb) 2116610a0bcSAndrew Morton { 212f758eeabSChristoph Hellwig assert_spin_locked(&wb->list_lock); 21303ba3782SJens Axboe if (!list_empty(&wb->b_dirty)) { 21466f3b8e2SJens Axboe struct inode *tail; 2156610a0bcSAndrew Morton 2167ccf19a8SNick Piggin tail = wb_inode(wb->b_dirty.next); 21766f3b8e2SJens Axboe if (time_before(inode->dirtied_when, tail->dirtied_when)) 2186610a0bcSAndrew Morton inode->dirtied_when = jiffies; 2196610a0bcSAndrew Morton } 2207ccf19a8SNick Piggin list_move(&inode->i_wb_list, &wb->b_dirty); 2216610a0bcSAndrew Morton } 2226610a0bcSAndrew Morton 2236610a0bcSAndrew Morton /* 22466f3b8e2SJens Axboe * requeue inode for re-scanning after bdi->b_io list is exhausted. 225c986d1e2SAndrew Morton */ 226f758eeabSChristoph Hellwig static void requeue_io(struct inode *inode, struct bdi_writeback *wb) 227c986d1e2SAndrew Morton { 228f758eeabSChristoph Hellwig assert_spin_locked(&wb->list_lock); 2297ccf19a8SNick Piggin list_move(&inode->i_wb_list, &wb->b_more_io); 230c986d1e2SAndrew Morton } 231c986d1e2SAndrew Morton 2321c0eeaf5SJoern Engel static void inode_sync_complete(struct inode *inode) 2331c0eeaf5SJoern Engel { 234365b94aeSJan Kara inode->i_state &= ~I_SYNC; 235365b94aeSJan Kara /* Waiters must see I_SYNC cleared before being woken up */ 2361c0eeaf5SJoern Engel smp_mb(); 2371c0eeaf5SJoern Engel wake_up_bit(&inode->i_state, __I_SYNC); 2381c0eeaf5SJoern Engel } 2391c0eeaf5SJoern Engel 240d2caa3c5SJeff Layton static bool inode_dirtied_after(struct inode *inode, unsigned long t) 241d2caa3c5SJeff Layton { 242d2caa3c5SJeff Layton bool ret = time_after(inode->dirtied_when, t); 243d2caa3c5SJeff Layton #ifndef CONFIG_64BIT 244d2caa3c5SJeff Layton /* 245d2caa3c5SJeff Layton * For inodes being constantly redirtied, dirtied_when can get stuck. 246d2caa3c5SJeff Layton * It _appears_ to be in the future, but is actually in distant past. 247d2caa3c5SJeff Layton * This test is necessary to prevent such wrapped-around relative times 2485b0830cbSJens Axboe * from permanently stopping the whole bdi writeback. 249d2caa3c5SJeff Layton */ 250d2caa3c5SJeff Layton ret = ret && time_before_eq(inode->dirtied_when, jiffies); 251d2caa3c5SJeff Layton #endif 252d2caa3c5SJeff Layton return ret; 253d2caa3c5SJeff Layton } 254d2caa3c5SJeff Layton 255c986d1e2SAndrew Morton /* 256697e6fedSJan Kara * Move expired (dirtied after work->older_than_this) dirty inodes from 257697e6fedSJan Kara * @delaying_queue to @dispatch_queue. 2582c136579SFengguang Wu */ 259e84d0a4fSWu Fengguang static int move_expired_inodes(struct list_head *delaying_queue, 2602c136579SFengguang Wu struct list_head *dispatch_queue, 261ad4e38ddSCurt Wohlgemuth struct wb_writeback_work *work) 2622c136579SFengguang Wu { 2635c03449dSShaohua Li LIST_HEAD(tmp); 2645c03449dSShaohua Li struct list_head *pos, *node; 265cf137307SJens Axboe struct super_block *sb = NULL; 2665c03449dSShaohua Li struct inode *inode; 267cf137307SJens Axboe int do_sb_sort = 0; 268e84d0a4fSWu Fengguang int moved = 0; 2695c03449dSShaohua Li 2702c136579SFengguang Wu while (!list_empty(delaying_queue)) { 2717ccf19a8SNick Piggin inode = wb_inode(delaying_queue->prev); 272ad4e38ddSCurt Wohlgemuth if (work->older_than_this && 273ad4e38ddSCurt Wohlgemuth inode_dirtied_after(inode, *work->older_than_this)) 2742c136579SFengguang Wu break; 275cf137307SJens Axboe if (sb && sb != inode->i_sb) 276cf137307SJens Axboe do_sb_sort = 1; 277cf137307SJens Axboe sb = inode->i_sb; 2787ccf19a8SNick Piggin list_move(&inode->i_wb_list, &tmp); 279e84d0a4fSWu Fengguang moved++; 2805c03449dSShaohua Li } 2815c03449dSShaohua Li 282cf137307SJens Axboe /* just one sb in list, splice to dispatch_queue and we're done */ 283cf137307SJens Axboe if (!do_sb_sort) { 284cf137307SJens Axboe list_splice(&tmp, dispatch_queue); 285e84d0a4fSWu Fengguang goto out; 286cf137307SJens Axboe } 287cf137307SJens Axboe 2885c03449dSShaohua Li /* Move inodes from one superblock together */ 2895c03449dSShaohua Li while (!list_empty(&tmp)) { 2907ccf19a8SNick Piggin sb = wb_inode(tmp.prev)->i_sb; 2915c03449dSShaohua Li list_for_each_prev_safe(pos, node, &tmp) { 2927ccf19a8SNick Piggin inode = wb_inode(pos); 2935c03449dSShaohua Li if (inode->i_sb == sb) 2947ccf19a8SNick Piggin list_move(&inode->i_wb_list, dispatch_queue); 2952c136579SFengguang Wu } 2962c136579SFengguang Wu } 297e84d0a4fSWu Fengguang out: 298e84d0a4fSWu Fengguang return moved; 2995c03449dSShaohua Li } 3002c136579SFengguang Wu 3012c136579SFengguang Wu /* 3022c136579SFengguang Wu * Queue all expired dirty inodes for io, eldest first. 3034ea879b9SWu Fengguang * Before 3044ea879b9SWu Fengguang * newly dirtied b_dirty b_io b_more_io 3054ea879b9SWu Fengguang * =============> gf edc BA 3064ea879b9SWu Fengguang * After 3074ea879b9SWu Fengguang * newly dirtied b_dirty b_io b_more_io 3084ea879b9SWu Fengguang * =============> g fBAedc 3094ea879b9SWu Fengguang * | 3104ea879b9SWu Fengguang * +--> dequeue for IO 3112c136579SFengguang Wu */ 312ad4e38ddSCurt Wohlgemuth static void queue_io(struct bdi_writeback *wb, struct wb_writeback_work *work) 3132c136579SFengguang Wu { 314e84d0a4fSWu Fengguang int moved; 315f758eeabSChristoph Hellwig assert_spin_locked(&wb->list_lock); 3164ea879b9SWu Fengguang list_splice_init(&wb->b_more_io, &wb->b_io); 317ad4e38ddSCurt Wohlgemuth moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, work); 318ad4e38ddSCurt Wohlgemuth trace_writeback_queue_io(wb, work, moved); 31966f3b8e2SJens Axboe } 32066f3b8e2SJens Axboe 321a9185b41SChristoph Hellwig static int write_inode(struct inode *inode, struct writeback_control *wbc) 32266f3b8e2SJens Axboe { 32303ba3782SJens Axboe if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) 324a9185b41SChristoph Hellwig return inode->i_sb->s_op->write_inode(inode, wbc); 32503ba3782SJens Axboe return 0; 32666f3b8e2SJens Axboe } 32708d8e974SFengguang Wu 3282c136579SFengguang Wu /* 329169ebd90SJan Kara * Wait for writeback on an inode to complete. Called with i_lock held. 330169ebd90SJan Kara * Caller must make sure inode cannot go away when we drop i_lock. 33101c03194SChristoph Hellwig */ 332169ebd90SJan Kara static void __inode_wait_for_writeback(struct inode *inode) 333169ebd90SJan Kara __releases(inode->i_lock) 334169ebd90SJan Kara __acquires(inode->i_lock) 33501c03194SChristoph Hellwig { 33601c03194SChristoph Hellwig DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); 33701c03194SChristoph Hellwig wait_queue_head_t *wqh; 33801c03194SChristoph Hellwig 33901c03194SChristoph Hellwig wqh = bit_waitqueue(&inode->i_state, __I_SYNC); 34058a9d3d8SRichard Kennedy while (inode->i_state & I_SYNC) { 341250df6edSDave Chinner spin_unlock(&inode->i_lock); 34201c03194SChristoph Hellwig __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); 343250df6edSDave Chinner spin_lock(&inode->i_lock); 34458a9d3d8SRichard Kennedy } 34501c03194SChristoph Hellwig } 34601c03194SChristoph Hellwig 34701c03194SChristoph Hellwig /* 348169ebd90SJan Kara * Wait for writeback on an inode to complete. Caller must have inode pinned. 349169ebd90SJan Kara */ 350169ebd90SJan Kara void inode_wait_for_writeback(struct inode *inode) 351169ebd90SJan Kara { 352169ebd90SJan Kara spin_lock(&inode->i_lock); 353169ebd90SJan Kara __inode_wait_for_writeback(inode); 354169ebd90SJan Kara spin_unlock(&inode->i_lock); 355169ebd90SJan Kara } 356169ebd90SJan Kara 357169ebd90SJan Kara /* 358169ebd90SJan Kara * Sleep until I_SYNC is cleared. This function must be called with i_lock 359169ebd90SJan Kara * held and drops it. It is aimed for callers not holding any inode reference 360169ebd90SJan Kara * so once i_lock is dropped, inode can go away. 361169ebd90SJan Kara */ 362169ebd90SJan Kara static void inode_sleep_on_writeback(struct inode *inode) 363169ebd90SJan Kara __releases(inode->i_lock) 364169ebd90SJan Kara { 365169ebd90SJan Kara DEFINE_WAIT(wait); 366169ebd90SJan Kara wait_queue_head_t *wqh = bit_waitqueue(&inode->i_state, __I_SYNC); 367169ebd90SJan Kara int sleep; 368169ebd90SJan Kara 369169ebd90SJan Kara prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); 370169ebd90SJan Kara sleep = inode->i_state & I_SYNC; 371169ebd90SJan Kara spin_unlock(&inode->i_lock); 372169ebd90SJan Kara if (sleep) 373169ebd90SJan Kara schedule(); 374169ebd90SJan Kara finish_wait(wqh, &wait); 375169ebd90SJan Kara } 376169ebd90SJan Kara 377169ebd90SJan Kara /* 378ccb26b5aSJan Kara * Find proper writeback list for the inode depending on its current state and 379ccb26b5aSJan Kara * possibly also change of its state while we were doing writeback. Here we 380ccb26b5aSJan Kara * handle things such as livelock prevention or fairness of writeback among 381ccb26b5aSJan Kara * inodes. This function can be called only by flusher thread - noone else 382ccb26b5aSJan Kara * processes all inodes in writeback lists and requeueing inodes behind flusher 383ccb26b5aSJan Kara * thread's back can have unexpected consequences. 384ccb26b5aSJan Kara */ 385ccb26b5aSJan Kara static void requeue_inode(struct inode *inode, struct bdi_writeback *wb, 386ccb26b5aSJan Kara struct writeback_control *wbc) 387ccb26b5aSJan Kara { 388ccb26b5aSJan Kara if (inode->i_state & I_FREEING) 389ccb26b5aSJan Kara return; 390ccb26b5aSJan Kara 391ccb26b5aSJan Kara /* 392ccb26b5aSJan Kara * Sync livelock prevention. Each inode is tagged and synced in one 393ccb26b5aSJan Kara * shot. If still dirty, it will be redirty_tail()'ed below. Update 394ccb26b5aSJan Kara * the dirty time to prevent enqueue and sync it again. 395ccb26b5aSJan Kara */ 396ccb26b5aSJan Kara if ((inode->i_state & I_DIRTY) && 397ccb26b5aSJan Kara (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)) 398ccb26b5aSJan Kara inode->dirtied_when = jiffies; 399ccb26b5aSJan Kara 4004f8ad655SJan Kara if (wbc->pages_skipped) { 4014f8ad655SJan Kara /* 4024f8ad655SJan Kara * writeback is not making progress due to locked 4034f8ad655SJan Kara * buffers. Skip this inode for now. 4044f8ad655SJan Kara */ 4054f8ad655SJan Kara redirty_tail(inode, wb); 4064f8ad655SJan Kara return; 4074f8ad655SJan Kara } 4084f8ad655SJan Kara 409ccb26b5aSJan Kara if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) { 410ccb26b5aSJan Kara /* 411ccb26b5aSJan Kara * We didn't write back all the pages. nfs_writepages() 412ccb26b5aSJan Kara * sometimes bales out without doing anything. 413ccb26b5aSJan Kara */ 414ccb26b5aSJan Kara if (wbc->nr_to_write <= 0) { 415ccb26b5aSJan Kara /* Slice used up. Queue for next turn. */ 416ccb26b5aSJan Kara requeue_io(inode, wb); 417ccb26b5aSJan Kara } else { 418ccb26b5aSJan Kara /* 419ccb26b5aSJan Kara * Writeback blocked by something other than 420ccb26b5aSJan Kara * congestion. Delay the inode for some time to 421ccb26b5aSJan Kara * avoid spinning on the CPU (100% iowait) 422ccb26b5aSJan Kara * retrying writeback of the dirty page/inode 423ccb26b5aSJan Kara * that cannot be performed immediately. 424ccb26b5aSJan Kara */ 425ccb26b5aSJan Kara redirty_tail(inode, wb); 426ccb26b5aSJan Kara } 427ccb26b5aSJan Kara } else if (inode->i_state & I_DIRTY) { 428ccb26b5aSJan Kara /* 429ccb26b5aSJan Kara * Filesystems can dirty the inode during writeback operations, 430ccb26b5aSJan Kara * such as delayed allocation during submission or metadata 431ccb26b5aSJan Kara * updates after data IO completion. 432ccb26b5aSJan Kara */ 433ccb26b5aSJan Kara redirty_tail(inode, wb); 434ccb26b5aSJan Kara } else { 435ccb26b5aSJan Kara /* The inode is clean. Remove from writeback lists. */ 436ccb26b5aSJan Kara list_del_init(&inode->i_wb_list); 437ccb26b5aSJan Kara } 438ccb26b5aSJan Kara } 439ccb26b5aSJan Kara 440ccb26b5aSJan Kara /* 4414f8ad655SJan Kara * Write out an inode and its dirty pages. Do not update the writeback list 4424f8ad655SJan Kara * linkage. That is left to the caller. The caller is also responsible for 4434f8ad655SJan Kara * setting I_SYNC flag and calling inode_sync_complete() to clear it. 4441da177e4SLinus Torvalds */ 4451da177e4SLinus Torvalds static int 4464f8ad655SJan Kara __writeback_single_inode(struct inode *inode, struct bdi_writeback *wb, 447f758eeabSChristoph Hellwig struct writeback_control *wbc) 4481da177e4SLinus Torvalds { 4491da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 450251d6a47SWu Fengguang long nr_to_write = wbc->nr_to_write; 45101c03194SChristoph Hellwig unsigned dirty; 4521da177e4SLinus Torvalds int ret; 4531da177e4SLinus Torvalds 4544f8ad655SJan Kara WARN_ON(!(inode->i_state & I_SYNC)); 4551da177e4SLinus Torvalds 4561da177e4SLinus Torvalds ret = do_writepages(mapping, wbc); 4571da177e4SLinus Torvalds 45826821ed4SChristoph Hellwig /* 45926821ed4SChristoph Hellwig * Make sure to wait on the data before writing out the metadata. 46026821ed4SChristoph Hellwig * This is important for filesystems that modify metadata on data 46126821ed4SChristoph Hellwig * I/O completion. 46226821ed4SChristoph Hellwig */ 463a9185b41SChristoph Hellwig if (wbc->sync_mode == WB_SYNC_ALL) { 46426821ed4SChristoph Hellwig int err = filemap_fdatawait(mapping); 4651da177e4SLinus Torvalds if (ret == 0) 4661da177e4SLinus Torvalds ret = err; 4671da177e4SLinus Torvalds } 4681da177e4SLinus Torvalds 4695547e8aaSDmitry Monakhov /* 4705547e8aaSDmitry Monakhov * Some filesystems may redirty the inode during the writeback 4715547e8aaSDmitry Monakhov * due to delalloc, clear dirty metadata flags right before 4725547e8aaSDmitry Monakhov * write_inode() 4735547e8aaSDmitry Monakhov */ 474250df6edSDave Chinner spin_lock(&inode->i_lock); 4756290be1cSJan Kara /* Clear I_DIRTY_PAGES if we've written out all dirty pages */ 4766290be1cSJan Kara if (!mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) 4776290be1cSJan Kara inode->i_state &= ~I_DIRTY_PAGES; 4785547e8aaSDmitry Monakhov dirty = inode->i_state & I_DIRTY; 4795547e8aaSDmitry Monakhov inode->i_state &= ~(I_DIRTY_SYNC | I_DIRTY_DATASYNC); 480250df6edSDave Chinner spin_unlock(&inode->i_lock); 48126821ed4SChristoph Hellwig /* Don't write the inode if only I_DIRTY_PAGES was set */ 48226821ed4SChristoph Hellwig if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { 483a9185b41SChristoph Hellwig int err = write_inode(inode, wbc); 4841da177e4SLinus Torvalds if (ret == 0) 4851da177e4SLinus Torvalds ret = err; 4861da177e4SLinus Torvalds } 4874f8ad655SJan Kara trace_writeback_single_inode(inode, wbc, nr_to_write); 4884f8ad655SJan Kara return ret; 4894f8ad655SJan Kara } 4904f8ad655SJan Kara 4914f8ad655SJan Kara /* 4924f8ad655SJan Kara * Write out an inode's dirty pages. Either the caller has an active reference 4934f8ad655SJan Kara * on the inode or the inode has I_WILL_FREE set. 4944f8ad655SJan Kara * 4954f8ad655SJan Kara * This function is designed to be called for writing back one inode which 4964f8ad655SJan Kara * we go e.g. from filesystem. Flusher thread uses __writeback_single_inode() 4974f8ad655SJan Kara * and does more profound writeback list handling in writeback_sb_inodes(). 4984f8ad655SJan Kara */ 4994f8ad655SJan Kara static int 5004f8ad655SJan Kara writeback_single_inode(struct inode *inode, struct bdi_writeback *wb, 5014f8ad655SJan Kara struct writeback_control *wbc) 5024f8ad655SJan Kara { 5034f8ad655SJan Kara int ret = 0; 5044f8ad655SJan Kara 5054f8ad655SJan Kara spin_lock(&inode->i_lock); 5064f8ad655SJan Kara if (!atomic_read(&inode->i_count)) 5074f8ad655SJan Kara WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); 5084f8ad655SJan Kara else 5094f8ad655SJan Kara WARN_ON(inode->i_state & I_WILL_FREE); 5104f8ad655SJan Kara 5114f8ad655SJan Kara if (inode->i_state & I_SYNC) { 5124f8ad655SJan Kara if (wbc->sync_mode != WB_SYNC_ALL) 5134f8ad655SJan Kara goto out; 5144f8ad655SJan Kara /* 515169ebd90SJan Kara * It's a data-integrity sync. We must wait. Since callers hold 516169ebd90SJan Kara * inode reference or inode has I_WILL_FREE set, it cannot go 517169ebd90SJan Kara * away under us. 5184f8ad655SJan Kara */ 519169ebd90SJan Kara __inode_wait_for_writeback(inode); 5204f8ad655SJan Kara } 5214f8ad655SJan Kara WARN_ON(inode->i_state & I_SYNC); 5224f8ad655SJan Kara /* 5234f8ad655SJan Kara * Skip inode if it is clean. We don't want to mess with writeback 5244f8ad655SJan Kara * lists in this function since flusher thread may be doing for example 5254f8ad655SJan Kara * sync in parallel and if we move the inode, it could get skipped. So 5264f8ad655SJan Kara * here we make sure inode is on some writeback list and leave it there 5274f8ad655SJan Kara * unless we have completely cleaned the inode. 5284f8ad655SJan Kara */ 5294f8ad655SJan Kara if (!(inode->i_state & I_DIRTY)) 5304f8ad655SJan Kara goto out; 5314f8ad655SJan Kara inode->i_state |= I_SYNC; 5324f8ad655SJan Kara spin_unlock(&inode->i_lock); 5334f8ad655SJan Kara 5344f8ad655SJan Kara ret = __writeback_single_inode(inode, wb, wbc); 5351da177e4SLinus Torvalds 536f758eeabSChristoph Hellwig spin_lock(&wb->list_lock); 537250df6edSDave Chinner spin_lock(&inode->i_lock); 5384f8ad655SJan Kara /* 5394f8ad655SJan Kara * If inode is clean, remove it from writeback lists. Otherwise don't 5404f8ad655SJan Kara * touch it. See comment above for explanation. 5414f8ad655SJan Kara */ 5424f8ad655SJan Kara if (!(inode->i_state & I_DIRTY)) 5434f8ad655SJan Kara list_del_init(&inode->i_wb_list); 5444f8ad655SJan Kara spin_unlock(&wb->list_lock); 5451c0eeaf5SJoern Engel inode_sync_complete(inode); 5464f8ad655SJan Kara out: 5474f8ad655SJan Kara spin_unlock(&inode->i_lock); 5481da177e4SLinus Torvalds return ret; 5491da177e4SLinus Torvalds } 5501da177e4SLinus Torvalds 5511a12d8bdSWu Fengguang static long writeback_chunk_size(struct backing_dev_info *bdi, 5521a12d8bdSWu Fengguang struct wb_writeback_work *work) 553d46db3d5SWu Fengguang { 554d46db3d5SWu Fengguang long pages; 555d46db3d5SWu Fengguang 556d46db3d5SWu Fengguang /* 557d46db3d5SWu Fengguang * WB_SYNC_ALL mode does livelock avoidance by syncing dirty 558d46db3d5SWu Fengguang * inodes/pages in one big loop. Setting wbc.nr_to_write=LONG_MAX 559d46db3d5SWu Fengguang * here avoids calling into writeback_inodes_wb() more than once. 560d46db3d5SWu Fengguang * 561d46db3d5SWu Fengguang * The intended call sequence for WB_SYNC_ALL writeback is: 562d46db3d5SWu Fengguang * 563d46db3d5SWu Fengguang * wb_writeback() 564d46db3d5SWu Fengguang * writeback_sb_inodes() <== called only once 565d46db3d5SWu Fengguang * write_cache_pages() <== called once for each inode 566d46db3d5SWu Fengguang * (quickly) tag currently dirty pages 567d46db3d5SWu Fengguang * (maybe slowly) sync all tagged pages 568d46db3d5SWu Fengguang */ 569d46db3d5SWu Fengguang if (work->sync_mode == WB_SYNC_ALL || work->tagged_writepages) 570d46db3d5SWu Fengguang pages = LONG_MAX; 5711a12d8bdSWu Fengguang else { 5721a12d8bdSWu Fengguang pages = min(bdi->avg_write_bandwidth / 2, 5731a12d8bdSWu Fengguang global_dirty_limit / DIRTY_SCOPE); 5741a12d8bdSWu Fengguang pages = min(pages, work->nr_pages); 5751a12d8bdSWu Fengguang pages = round_down(pages + MIN_WRITEBACK_PAGES, 5761a12d8bdSWu Fengguang MIN_WRITEBACK_PAGES); 5771a12d8bdSWu Fengguang } 578d46db3d5SWu Fengguang 579d46db3d5SWu Fengguang return pages; 580d46db3d5SWu Fengguang } 581d46db3d5SWu Fengguang 58203ba3782SJens Axboe /* 583f11c9c5cSEdward Shishkin * Write a portion of b_io inodes which belong to @sb. 584edadfb10SChristoph Hellwig * 585edadfb10SChristoph Hellwig * If @only_this_sb is true, then find and write all such 586f11c9c5cSEdward Shishkin * inodes. Otherwise write only ones which go sequentially 587f11c9c5cSEdward Shishkin * in reverse order. 588edadfb10SChristoph Hellwig * 589d46db3d5SWu Fengguang * Return the number of pages and/or inodes written. 590f11c9c5cSEdward Shishkin */ 591d46db3d5SWu Fengguang static long writeback_sb_inodes(struct super_block *sb, 592d46db3d5SWu Fengguang struct bdi_writeback *wb, 593d46db3d5SWu Fengguang struct wb_writeback_work *work) 59403ba3782SJens Axboe { 595d46db3d5SWu Fengguang struct writeback_control wbc = { 596d46db3d5SWu Fengguang .sync_mode = work->sync_mode, 597d46db3d5SWu Fengguang .tagged_writepages = work->tagged_writepages, 598d46db3d5SWu Fengguang .for_kupdate = work->for_kupdate, 599d46db3d5SWu Fengguang .for_background = work->for_background, 600d46db3d5SWu Fengguang .range_cyclic = work->range_cyclic, 601d46db3d5SWu Fengguang .range_start = 0, 602d46db3d5SWu Fengguang .range_end = LLONG_MAX, 603d46db3d5SWu Fengguang }; 604d46db3d5SWu Fengguang unsigned long start_time = jiffies; 605d46db3d5SWu Fengguang long write_chunk; 606d46db3d5SWu Fengguang long wrote = 0; /* count both pages and inodes */ 607d46db3d5SWu Fengguang 60803ba3782SJens Axboe while (!list_empty(&wb->b_io)) { 6097ccf19a8SNick Piggin struct inode *inode = wb_inode(wb->b_io.prev); 610edadfb10SChristoph Hellwig 611edadfb10SChristoph Hellwig if (inode->i_sb != sb) { 612d46db3d5SWu Fengguang if (work->sb) { 613edadfb10SChristoph Hellwig /* 614edadfb10SChristoph Hellwig * We only want to write back data for this 615edadfb10SChristoph Hellwig * superblock, move all inodes not belonging 616edadfb10SChristoph Hellwig * to it back onto the dirty list. 617edadfb10SChristoph Hellwig */ 618f758eeabSChristoph Hellwig redirty_tail(inode, wb); 61966f3b8e2SJens Axboe continue; 62066f3b8e2SJens Axboe } 621edadfb10SChristoph Hellwig 622edadfb10SChristoph Hellwig /* 623edadfb10SChristoph Hellwig * The inode belongs to a different superblock. 624edadfb10SChristoph Hellwig * Bounce back to the caller to unpin this and 625edadfb10SChristoph Hellwig * pin the next superblock. 626edadfb10SChristoph Hellwig */ 627d46db3d5SWu Fengguang break; 628edadfb10SChristoph Hellwig } 629edadfb10SChristoph Hellwig 6309843b76aSChristoph Hellwig /* 6319843b76aSChristoph Hellwig * Don't bother with new inodes or inodes beeing freed, first 6329843b76aSChristoph Hellwig * kind does not need peridic writeout yet, and for the latter 6339843b76aSChristoph Hellwig * kind writeout is handled by the freer. 6349843b76aSChristoph Hellwig */ 635250df6edSDave Chinner spin_lock(&inode->i_lock); 6369843b76aSChristoph Hellwig if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { 637250df6edSDave Chinner spin_unlock(&inode->i_lock); 638fcc5c222SWu Fengguang redirty_tail(inode, wb); 6397ef0d737SNick Piggin continue; 6407ef0d737SNick Piggin } 641cc1676d9SJan Kara if ((inode->i_state & I_SYNC) && wbc.sync_mode != WB_SYNC_ALL) { 642cc1676d9SJan Kara /* 643cc1676d9SJan Kara * If this inode is locked for writeback and we are not 644cc1676d9SJan Kara * doing writeback-for-data-integrity, move it to 645cc1676d9SJan Kara * b_more_io so that writeback can proceed with the 646cc1676d9SJan Kara * other inodes on s_io. 647cc1676d9SJan Kara * 648cc1676d9SJan Kara * We'll have another go at writing back this inode 649cc1676d9SJan Kara * when we completed a full scan of b_io. 650cc1676d9SJan Kara */ 651cc1676d9SJan Kara spin_unlock(&inode->i_lock); 652cc1676d9SJan Kara requeue_io(inode, wb); 653cc1676d9SJan Kara trace_writeback_sb_inodes_requeue(inode); 654cc1676d9SJan Kara continue; 655cc1676d9SJan Kara } 656f0d07b7fSJan Kara spin_unlock(&wb->list_lock); 657f0d07b7fSJan Kara 6584f8ad655SJan Kara /* 6594f8ad655SJan Kara * We already requeued the inode if it had I_SYNC set and we 6604f8ad655SJan Kara * are doing WB_SYNC_NONE writeback. So this catches only the 6614f8ad655SJan Kara * WB_SYNC_ALL case. 6624f8ad655SJan Kara */ 663169ebd90SJan Kara if (inode->i_state & I_SYNC) { 664169ebd90SJan Kara /* Wait for I_SYNC. This function drops i_lock... */ 665169ebd90SJan Kara inode_sleep_on_writeback(inode); 666169ebd90SJan Kara /* Inode may be gone, start again */ 667169ebd90SJan Kara continue; 668169ebd90SJan Kara } 6694f8ad655SJan Kara inode->i_state |= I_SYNC; 6704f8ad655SJan Kara spin_unlock(&inode->i_lock); 671169ebd90SJan Kara 6721a12d8bdSWu Fengguang write_chunk = writeback_chunk_size(wb->bdi, work); 673d46db3d5SWu Fengguang wbc.nr_to_write = write_chunk; 674d46db3d5SWu Fengguang wbc.pages_skipped = 0; 675250df6edSDave Chinner 676169ebd90SJan Kara /* 677169ebd90SJan Kara * We use I_SYNC to pin the inode in memory. While it is set 678169ebd90SJan Kara * evict_inode() will wait so the inode cannot be freed. 679169ebd90SJan Kara */ 6804f8ad655SJan Kara __writeback_single_inode(inode, wb, &wbc); 681d46db3d5SWu Fengguang 682d46db3d5SWu Fengguang work->nr_pages -= write_chunk - wbc.nr_to_write; 683d46db3d5SWu Fengguang wrote += write_chunk - wbc.nr_to_write; 6844f8ad655SJan Kara spin_lock(&wb->list_lock); 6854f8ad655SJan Kara spin_lock(&inode->i_lock); 686d46db3d5SWu Fengguang if (!(inode->i_state & I_DIRTY)) 687d46db3d5SWu Fengguang wrote++; 6884f8ad655SJan Kara requeue_inode(inode, wb, &wbc); 6894f8ad655SJan Kara inode_sync_complete(inode); 6900f1b1fd8SDave Chinner spin_unlock(&inode->i_lock); 691169ebd90SJan Kara cond_resched_lock(&wb->list_lock); 692d46db3d5SWu Fengguang /* 693d46db3d5SWu Fengguang * bail out to wb_writeback() often enough to check 694d46db3d5SWu Fengguang * background threshold and other termination conditions. 695d46db3d5SWu Fengguang */ 696d46db3d5SWu Fengguang if (wrote) { 697d46db3d5SWu Fengguang if (time_is_before_jiffies(start_time + HZ / 10UL)) 698d46db3d5SWu Fengguang break; 699d46db3d5SWu Fengguang if (work->nr_pages <= 0) 700d46db3d5SWu Fengguang break; 7011da177e4SLinus Torvalds } 7028bc3be27SFengguang Wu } 703d46db3d5SWu Fengguang return wrote; 704f11c9c5cSEdward Shishkin } 70538f21977SNick Piggin 706d46db3d5SWu Fengguang static long __writeback_inodes_wb(struct bdi_writeback *wb, 707d46db3d5SWu Fengguang struct wb_writeback_work *work) 708f11c9c5cSEdward Shishkin { 709d46db3d5SWu Fengguang unsigned long start_time = jiffies; 710d46db3d5SWu Fengguang long wrote = 0; 711f11c9c5cSEdward Shishkin 712f11c9c5cSEdward Shishkin while (!list_empty(&wb->b_io)) { 7137ccf19a8SNick Piggin struct inode *inode = wb_inode(wb->b_io.prev); 714f11c9c5cSEdward Shishkin struct super_block *sb = inode->i_sb; 715f11c9c5cSEdward Shishkin 71612ad3ab6SDave Chinner if (!grab_super_passive(sb)) { 7170e995816SWu Fengguang /* 7180e995816SWu Fengguang * grab_super_passive() may fail consistently due to 7190e995816SWu Fengguang * s_umount being grabbed by someone else. Don't use 7200e995816SWu Fengguang * requeue_io() to avoid busy retrying the inode/sb. 7210e995816SWu Fengguang */ 7220e995816SWu Fengguang redirty_tail(inode, wb); 723d19de7edSChristoph Hellwig continue; 724334132aeSChristoph Hellwig } 725d46db3d5SWu Fengguang wrote += writeback_sb_inodes(sb, wb, work); 726d19de7edSChristoph Hellwig drop_super(sb); 727f11c9c5cSEdward Shishkin 728d46db3d5SWu Fengguang /* refer to the same tests at the end of writeback_sb_inodes */ 729d46db3d5SWu Fengguang if (wrote) { 730d46db3d5SWu Fengguang if (time_is_before_jiffies(start_time + HZ / 10UL)) 731d46db3d5SWu Fengguang break; 732d46db3d5SWu Fengguang if (work->nr_pages <= 0) 733f11c9c5cSEdward Shishkin break; 734f11c9c5cSEdward Shishkin } 735d46db3d5SWu Fengguang } 73666f3b8e2SJens Axboe /* Leave any unwritten inodes on b_io */ 737d46db3d5SWu Fengguang return wrote; 73866f3b8e2SJens Axboe } 73966f3b8e2SJens Axboe 7400e175a18SCurt Wohlgemuth long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, 7410e175a18SCurt Wohlgemuth enum wb_reason reason) 742edadfb10SChristoph Hellwig { 743d46db3d5SWu Fengguang struct wb_writeback_work work = { 744d46db3d5SWu Fengguang .nr_pages = nr_pages, 745d46db3d5SWu Fengguang .sync_mode = WB_SYNC_NONE, 746d46db3d5SWu Fengguang .range_cyclic = 1, 7470e175a18SCurt Wohlgemuth .reason = reason, 748d46db3d5SWu Fengguang }; 749edadfb10SChristoph Hellwig 750f758eeabSChristoph Hellwig spin_lock(&wb->list_lock); 751424b351fSWu Fengguang if (list_empty(&wb->b_io)) 752ad4e38ddSCurt Wohlgemuth queue_io(wb, &work); 753d46db3d5SWu Fengguang __writeback_inodes_wb(wb, &work); 754f758eeabSChristoph Hellwig spin_unlock(&wb->list_lock); 755edadfb10SChristoph Hellwig 756d46db3d5SWu Fengguang return nr_pages - work.nr_pages; 75766f3b8e2SJens Axboe } 75866f3b8e2SJens Axboe 759b00949aaSWu Fengguang static bool over_bground_thresh(struct backing_dev_info *bdi) 76003ba3782SJens Axboe { 76103ba3782SJens Axboe unsigned long background_thresh, dirty_thresh; 76203ba3782SJens Axboe 76316c4042fSWu Fengguang global_dirty_limits(&background_thresh, &dirty_thresh); 76403ba3782SJens Axboe 765b00949aaSWu Fengguang if (global_page_state(NR_FILE_DIRTY) + 766b00949aaSWu Fengguang global_page_state(NR_UNSTABLE_NFS) > background_thresh) 767b00949aaSWu Fengguang return true; 768b00949aaSWu Fengguang 769b00949aaSWu Fengguang if (bdi_stat(bdi, BDI_RECLAIMABLE) > 770b00949aaSWu Fengguang bdi_dirty_limit(bdi, background_thresh)) 771b00949aaSWu Fengguang return true; 772b00949aaSWu Fengguang 773b00949aaSWu Fengguang return false; 77403ba3782SJens Axboe } 77503ba3782SJens Axboe 77603ba3782SJens Axboe /* 777e98be2d5SWu Fengguang * Called under wb->list_lock. If there are multiple wb per bdi, 778e98be2d5SWu Fengguang * only the flusher working on the first wb should do it. 779e98be2d5SWu Fengguang */ 780e98be2d5SWu Fengguang static void wb_update_bandwidth(struct bdi_writeback *wb, 781e98be2d5SWu Fengguang unsigned long start_time) 782e98be2d5SWu Fengguang { 783af6a3113SWu Fengguang __bdi_update_bandwidth(wb->bdi, 0, 0, 0, 0, 0, start_time); 784e98be2d5SWu Fengguang } 785e98be2d5SWu Fengguang 786e98be2d5SWu Fengguang /* 78703ba3782SJens Axboe * Explicit flushing or periodic writeback of "old" data. 78803ba3782SJens Axboe * 78903ba3782SJens Axboe * Define "old": the first time one of an inode's pages is dirtied, we mark the 79003ba3782SJens Axboe * dirtying-time in the inode's address_space. So this periodic writeback code 79103ba3782SJens Axboe * just walks the superblock inode list, writing back any inodes which are 79203ba3782SJens Axboe * older than a specific point in time. 79303ba3782SJens Axboe * 79403ba3782SJens Axboe * Try to run once per dirty_writeback_interval. But if a writeback event 79503ba3782SJens Axboe * takes longer than a dirty_writeback_interval interval, then leave a 79603ba3782SJens Axboe * one-second gap. 79703ba3782SJens Axboe * 79803ba3782SJens Axboe * older_than_this takes precedence over nr_to_write. So we'll only write back 79903ba3782SJens Axboe * all dirty pages if they are all attached to "old" mappings. 80003ba3782SJens Axboe */ 801c4a77a6cSJens Axboe static long wb_writeback(struct bdi_writeback *wb, 80283ba7b07SChristoph Hellwig struct wb_writeback_work *work) 80303ba3782SJens Axboe { 804e98be2d5SWu Fengguang unsigned long wb_start = jiffies; 805d46db3d5SWu Fengguang long nr_pages = work->nr_pages; 80603ba3782SJens Axboe unsigned long oldest_jif; 807a5989bdcSJan Kara struct inode *inode; 808d46db3d5SWu Fengguang long progress; 80903ba3782SJens Axboe 810e185dda8SWu Fengguang oldest_jif = jiffies; 811d46db3d5SWu Fengguang work->older_than_this = &oldest_jif; 81203ba3782SJens Axboe 813e8dfc305SWu Fengguang spin_lock(&wb->list_lock); 81403ba3782SJens Axboe for (;;) { 81503ba3782SJens Axboe /* 816d3ddec76SWu Fengguang * Stop writeback when nr_pages has been consumed 81703ba3782SJens Axboe */ 81883ba7b07SChristoph Hellwig if (work->nr_pages <= 0) 81903ba3782SJens Axboe break; 82003ba3782SJens Axboe 82103ba3782SJens Axboe /* 822aa373cf5SJan Kara * Background writeout and kupdate-style writeback may 823aa373cf5SJan Kara * run forever. Stop them if there is other work to do 824aa373cf5SJan Kara * so that e.g. sync can proceed. They'll be restarted 825aa373cf5SJan Kara * after the other works are all done. 826aa373cf5SJan Kara */ 827aa373cf5SJan Kara if ((work->for_background || work->for_kupdate) && 828aa373cf5SJan Kara !list_empty(&wb->bdi->work_list)) 829aa373cf5SJan Kara break; 830aa373cf5SJan Kara 831aa373cf5SJan Kara /* 832d3ddec76SWu Fengguang * For background writeout, stop when we are below the 833d3ddec76SWu Fengguang * background dirty threshold 83403ba3782SJens Axboe */ 835b00949aaSWu Fengguang if (work->for_background && !over_bground_thresh(wb->bdi)) 83603ba3782SJens Axboe break; 83703ba3782SJens Axboe 8381bc36b64SJan Kara /* 8391bc36b64SJan Kara * Kupdate and background works are special and we want to 8401bc36b64SJan Kara * include all inodes that need writing. Livelock avoidance is 8411bc36b64SJan Kara * handled by these works yielding to any other work so we are 8421bc36b64SJan Kara * safe. 8431bc36b64SJan Kara */ 844ba9aa839SWu Fengguang if (work->for_kupdate) { 845ba9aa839SWu Fengguang oldest_jif = jiffies - 846ba9aa839SWu Fengguang msecs_to_jiffies(dirty_expire_interval * 10); 8471bc36b64SJan Kara } else if (work->for_background) 8481bc36b64SJan Kara oldest_jif = jiffies; 849028c2dd1SDave Chinner 850d46db3d5SWu Fengguang trace_writeback_start(wb->bdi, work); 851e8dfc305SWu Fengguang if (list_empty(&wb->b_io)) 852ad4e38ddSCurt Wohlgemuth queue_io(wb, work); 85383ba7b07SChristoph Hellwig if (work->sb) 854d46db3d5SWu Fengguang progress = writeback_sb_inodes(work->sb, wb, work); 855edadfb10SChristoph Hellwig else 856d46db3d5SWu Fengguang progress = __writeback_inodes_wb(wb, work); 857d46db3d5SWu Fengguang trace_writeback_written(wb->bdi, work); 858028c2dd1SDave Chinner 859e98be2d5SWu Fengguang wb_update_bandwidth(wb, wb_start); 86003ba3782SJens Axboe 86103ba3782SJens Axboe /* 86271fd05a8SJens Axboe * Did we write something? Try for more 863e6fb6da2SWu Fengguang * 864e6fb6da2SWu Fengguang * Dirty inodes are moved to b_io for writeback in batches. 865e6fb6da2SWu Fengguang * The completion of the current batch does not necessarily 866e6fb6da2SWu Fengguang * mean the overall work is done. So we keep looping as long 867e6fb6da2SWu Fengguang * as made some progress on cleaning pages or inodes. 86871fd05a8SJens Axboe */ 869d46db3d5SWu Fengguang if (progress) 87003ba3782SJens Axboe continue; 871a5989bdcSJan Kara /* 872e6fb6da2SWu Fengguang * No more inodes for IO, bail 873a5989bdcSJan Kara */ 874b7a2441fSWu Fengguang if (list_empty(&wb->b_more_io)) 87503ba3782SJens Axboe break; 87603ba3782SJens Axboe /* 8778010c3b6SJens Axboe * Nothing written. Wait for some inode to 8788010c3b6SJens Axboe * become available for writeback. Otherwise 8798010c3b6SJens Axboe * we'll just busyloop. 88003ba3782SJens Axboe */ 88103ba3782SJens Axboe if (!list_empty(&wb->b_more_io)) { 882d46db3d5SWu Fengguang trace_writeback_wait(wb->bdi, work); 88303ba3782SJens Axboe inode = wb_inode(wb->b_more_io.prev); 884250df6edSDave Chinner spin_lock(&inode->i_lock); 885f0d07b7fSJan Kara spin_unlock(&wb->list_lock); 886169ebd90SJan Kara /* This function drops i_lock... */ 887169ebd90SJan Kara inode_sleep_on_writeback(inode); 888f0d07b7fSJan Kara spin_lock(&wb->list_lock); 88903ba3782SJens Axboe } 89003ba3782SJens Axboe } 891e8dfc305SWu Fengguang spin_unlock(&wb->list_lock); 89203ba3782SJens Axboe 893d46db3d5SWu Fengguang return nr_pages - work->nr_pages; 89403ba3782SJens Axboe } 89503ba3782SJens Axboe 89603ba3782SJens Axboe /* 89783ba7b07SChristoph Hellwig * Return the next wb_writeback_work struct that hasn't been processed yet. 89803ba3782SJens Axboe */ 89983ba7b07SChristoph Hellwig static struct wb_writeback_work * 90008852b6dSMinchan Kim get_next_work_item(struct backing_dev_info *bdi) 90103ba3782SJens Axboe { 90283ba7b07SChristoph Hellwig struct wb_writeback_work *work = NULL; 90303ba3782SJens Axboe 9046467716aSArtem Bityutskiy spin_lock_bh(&bdi->wb_lock); 90583ba7b07SChristoph Hellwig if (!list_empty(&bdi->work_list)) { 90683ba7b07SChristoph Hellwig work = list_entry(bdi->work_list.next, 90783ba7b07SChristoph Hellwig struct wb_writeback_work, list); 90883ba7b07SChristoph Hellwig list_del_init(&work->list); 90903ba3782SJens Axboe } 9106467716aSArtem Bityutskiy spin_unlock_bh(&bdi->wb_lock); 91183ba7b07SChristoph Hellwig return work; 91203ba3782SJens Axboe } 91303ba3782SJens Axboe 914cdf01dd5SLinus Torvalds /* 915cdf01dd5SLinus Torvalds * Add in the number of potentially dirty inodes, because each inode 916cdf01dd5SLinus Torvalds * write can dirty pagecache in the underlying blockdev. 917cdf01dd5SLinus Torvalds */ 918cdf01dd5SLinus Torvalds static unsigned long get_nr_dirty_pages(void) 919cdf01dd5SLinus Torvalds { 920cdf01dd5SLinus Torvalds return global_page_state(NR_FILE_DIRTY) + 921cdf01dd5SLinus Torvalds global_page_state(NR_UNSTABLE_NFS) + 922cdf01dd5SLinus Torvalds get_nr_dirty_inodes(); 923cdf01dd5SLinus Torvalds } 924cdf01dd5SLinus Torvalds 9256585027aSJan Kara static long wb_check_background_flush(struct bdi_writeback *wb) 9266585027aSJan Kara { 927b00949aaSWu Fengguang if (over_bground_thresh(wb->bdi)) { 9286585027aSJan Kara 9296585027aSJan Kara struct wb_writeback_work work = { 9306585027aSJan Kara .nr_pages = LONG_MAX, 9316585027aSJan Kara .sync_mode = WB_SYNC_NONE, 9326585027aSJan Kara .for_background = 1, 9336585027aSJan Kara .range_cyclic = 1, 9340e175a18SCurt Wohlgemuth .reason = WB_REASON_BACKGROUND, 9356585027aSJan Kara }; 9366585027aSJan Kara 9376585027aSJan Kara return wb_writeback(wb, &work); 9386585027aSJan Kara } 9396585027aSJan Kara 9406585027aSJan Kara return 0; 9416585027aSJan Kara } 9426585027aSJan Kara 94303ba3782SJens Axboe static long wb_check_old_data_flush(struct bdi_writeback *wb) 94403ba3782SJens Axboe { 94503ba3782SJens Axboe unsigned long expired; 94603ba3782SJens Axboe long nr_pages; 94703ba3782SJens Axboe 94869b62d01SJens Axboe /* 94969b62d01SJens Axboe * When set to zero, disable periodic writeback 95069b62d01SJens Axboe */ 95169b62d01SJens Axboe if (!dirty_writeback_interval) 95269b62d01SJens Axboe return 0; 95369b62d01SJens Axboe 95403ba3782SJens Axboe expired = wb->last_old_flush + 95503ba3782SJens Axboe msecs_to_jiffies(dirty_writeback_interval * 10); 95603ba3782SJens Axboe if (time_before(jiffies, expired)) 95703ba3782SJens Axboe return 0; 95803ba3782SJens Axboe 95903ba3782SJens Axboe wb->last_old_flush = jiffies; 960cdf01dd5SLinus Torvalds nr_pages = get_nr_dirty_pages(); 96103ba3782SJens Axboe 962c4a77a6cSJens Axboe if (nr_pages) { 96383ba7b07SChristoph Hellwig struct wb_writeback_work work = { 964c4a77a6cSJens Axboe .nr_pages = nr_pages, 965c4a77a6cSJens Axboe .sync_mode = WB_SYNC_NONE, 966c4a77a6cSJens Axboe .for_kupdate = 1, 967c4a77a6cSJens Axboe .range_cyclic = 1, 9680e175a18SCurt Wohlgemuth .reason = WB_REASON_PERIODIC, 969c4a77a6cSJens Axboe }; 970c4a77a6cSJens Axboe 97183ba7b07SChristoph Hellwig return wb_writeback(wb, &work); 972c4a77a6cSJens Axboe } 97303ba3782SJens Axboe 97403ba3782SJens Axboe return 0; 97503ba3782SJens Axboe } 97603ba3782SJens Axboe 97703ba3782SJens Axboe /* 97803ba3782SJens Axboe * Retrieve work items and do the writeback they describe 97903ba3782SJens Axboe */ 98003ba3782SJens Axboe long wb_do_writeback(struct bdi_writeback *wb, int force_wait) 98103ba3782SJens Axboe { 98203ba3782SJens Axboe struct backing_dev_info *bdi = wb->bdi; 98383ba7b07SChristoph Hellwig struct wb_writeback_work *work; 984c4a77a6cSJens Axboe long wrote = 0; 98503ba3782SJens Axboe 98681d73a32SJan Kara set_bit(BDI_writeback_running, &wb->bdi->state); 98708852b6dSMinchan Kim while ((work = get_next_work_item(bdi)) != NULL) { 98803ba3782SJens Axboe /* 98903ba3782SJens Axboe * Override sync mode, in case we must wait for completion 99083ba7b07SChristoph Hellwig * because this thread is exiting now. 99103ba3782SJens Axboe */ 99203ba3782SJens Axboe if (force_wait) 99383ba7b07SChristoph Hellwig work->sync_mode = WB_SYNC_ALL; 99483ba7b07SChristoph Hellwig 995455b2864SDave Chinner trace_writeback_exec(bdi, work); 996455b2864SDave Chinner 99783ba7b07SChristoph Hellwig wrote += wb_writeback(wb, work); 99803ba3782SJens Axboe 99903ba3782SJens Axboe /* 100083ba7b07SChristoph Hellwig * Notify the caller of completion if this is a synchronous 100183ba7b07SChristoph Hellwig * work item, otherwise just free it. 100203ba3782SJens Axboe */ 100383ba7b07SChristoph Hellwig if (work->done) 100483ba7b07SChristoph Hellwig complete(work->done); 100583ba7b07SChristoph Hellwig else 100683ba7b07SChristoph Hellwig kfree(work); 100703ba3782SJens Axboe } 100803ba3782SJens Axboe 100903ba3782SJens Axboe /* 101003ba3782SJens Axboe * Check for periodic writeback, kupdated() style 101103ba3782SJens Axboe */ 101203ba3782SJens Axboe wrote += wb_check_old_data_flush(wb); 10136585027aSJan Kara wrote += wb_check_background_flush(wb); 101481d73a32SJan Kara clear_bit(BDI_writeback_running, &wb->bdi->state); 101503ba3782SJens Axboe 101603ba3782SJens Axboe return wrote; 101703ba3782SJens Axboe } 101803ba3782SJens Axboe 101903ba3782SJens Axboe /* 102003ba3782SJens Axboe * Handle writeback of dirty data for the device backed by this bdi. Also 102103ba3782SJens Axboe * wakes up periodically and does kupdated style flushing. 102203ba3782SJens Axboe */ 102308243900SChristoph Hellwig int bdi_writeback_thread(void *data) 102403ba3782SJens Axboe { 102508243900SChristoph Hellwig struct bdi_writeback *wb = data; 102608243900SChristoph Hellwig struct backing_dev_info *bdi = wb->bdi; 102703ba3782SJens Axboe long pages_written; 102803ba3782SJens Axboe 1029766f9164SPeter Zijlstra current->flags |= PF_SWAPWRITE; 103008243900SChristoph Hellwig set_freezable(); 1031ecd58403SArtem Bityutskiy wb->last_active = jiffies; 103203ba3782SJens Axboe 103303ba3782SJens Axboe /* 103408243900SChristoph Hellwig * Our parent may run at a different priority, just set us to normal 103503ba3782SJens Axboe */ 103608243900SChristoph Hellwig set_user_nice(current, 0); 103708243900SChristoph Hellwig 1038455b2864SDave Chinner trace_writeback_thread_start(bdi); 1039455b2864SDave Chinner 10408a32c441STejun Heo while (!kthread_freezable_should_stop(NULL)) { 10416467716aSArtem Bityutskiy /* 10426467716aSArtem Bityutskiy * Remove own delayed wake-up timer, since we are already awake 10436467716aSArtem Bityutskiy * and we'll take care of the preriodic write-back. 10446467716aSArtem Bityutskiy */ 10456467716aSArtem Bityutskiy del_timer(&wb->wakeup_timer); 10466467716aSArtem Bityutskiy 104703ba3782SJens Axboe pages_written = wb_do_writeback(wb, 0); 104803ba3782SJens Axboe 1049455b2864SDave Chinner trace_writeback_pages_written(pages_written); 1050455b2864SDave Chinner 105103ba3782SJens Axboe if (pages_written) 1052ecd58403SArtem Bityutskiy wb->last_active = jiffies; 105303ba3782SJens Axboe 1054297252c8SArtem Bityutskiy set_current_state(TASK_INTERRUPTIBLE); 1055b76b4014SJ. Bruce Fields if (!list_empty(&bdi->work_list) || kthread_should_stop()) { 1056297252c8SArtem Bityutskiy __set_current_state(TASK_RUNNING); 1057297252c8SArtem Bityutskiy continue; 105803ba3782SJens Axboe } 105903ba3782SJens Axboe 1060253c34e9SArtem Bityutskiy if (wb_has_dirty_io(wb) && dirty_writeback_interval) 1061fff5b85aSArtem Bityutskiy schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10)); 1062253c34e9SArtem Bityutskiy else { 1063253c34e9SArtem Bityutskiy /* 1064253c34e9SArtem Bityutskiy * We have nothing to do, so can go sleep without any 1065253c34e9SArtem Bityutskiy * timeout and save power. When a work is queued or 1066253c34e9SArtem Bityutskiy * something is made dirty - we will be woken up. 1067253c34e9SArtem Bityutskiy */ 106869b62d01SJens Axboe schedule(); 1069f9eadbbdSJens Axboe } 107003ba3782SJens Axboe } 107103ba3782SJens Axboe 1072fff5b85aSArtem Bityutskiy /* Flush any work that raced with us exiting */ 107308243900SChristoph Hellwig if (!list_empty(&bdi->work_list)) 107408243900SChristoph Hellwig wb_do_writeback(wb, 1); 1075455b2864SDave Chinner 1076455b2864SDave Chinner trace_writeback_thread_stop(bdi); 107703ba3782SJens Axboe return 0; 107803ba3782SJens Axboe } 107903ba3782SJens Axboe 108008243900SChristoph Hellwig 108103ba3782SJens Axboe /* 108203ba3782SJens Axboe * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back 108303ba3782SJens Axboe * the whole world. 108403ba3782SJens Axboe */ 10850e175a18SCurt Wohlgemuth void wakeup_flusher_threads(long nr_pages, enum wb_reason reason) 108603ba3782SJens Axboe { 1087b8c2f347SChristoph Hellwig struct backing_dev_info *bdi; 1088b8c2f347SChristoph Hellwig 108983ba7b07SChristoph Hellwig if (!nr_pages) { 109083ba7b07SChristoph Hellwig nr_pages = global_page_state(NR_FILE_DIRTY) + 109103ba3782SJens Axboe global_page_state(NR_UNSTABLE_NFS); 1092b8c2f347SChristoph Hellwig } 1093b8c2f347SChristoph Hellwig 1094b8c2f347SChristoph Hellwig rcu_read_lock(); 1095b8c2f347SChristoph Hellwig list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { 1096b8c2f347SChristoph Hellwig if (!bdi_has_dirty_io(bdi)) 1097b8c2f347SChristoph Hellwig continue; 10980e175a18SCurt Wohlgemuth __bdi_start_writeback(bdi, nr_pages, false, reason); 1099b8c2f347SChristoph Hellwig } 1100b8c2f347SChristoph Hellwig rcu_read_unlock(); 110103ba3782SJens Axboe } 110203ba3782SJens Axboe 110303ba3782SJens Axboe static noinline void block_dump___mark_inode_dirty(struct inode *inode) 110403ba3782SJens Axboe { 110503ba3782SJens Axboe if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { 110603ba3782SJens Axboe struct dentry *dentry; 110703ba3782SJens Axboe const char *name = "?"; 110803ba3782SJens Axboe 110903ba3782SJens Axboe dentry = d_find_alias(inode); 111003ba3782SJens Axboe if (dentry) { 111103ba3782SJens Axboe spin_lock(&dentry->d_lock); 111203ba3782SJens Axboe name = (const char *) dentry->d_name.name; 111303ba3782SJens Axboe } 111403ba3782SJens Axboe printk(KERN_DEBUG 111503ba3782SJens Axboe "%s(%d): dirtied inode %lu (%s) on %s\n", 111603ba3782SJens Axboe current->comm, task_pid_nr(current), inode->i_ino, 111703ba3782SJens Axboe name, inode->i_sb->s_id); 111803ba3782SJens Axboe if (dentry) { 111903ba3782SJens Axboe spin_unlock(&dentry->d_lock); 112003ba3782SJens Axboe dput(dentry); 112103ba3782SJens Axboe } 112203ba3782SJens Axboe } 112303ba3782SJens Axboe } 112403ba3782SJens Axboe 112503ba3782SJens Axboe /** 112603ba3782SJens Axboe * __mark_inode_dirty - internal function 112703ba3782SJens Axboe * @inode: inode to mark 112803ba3782SJens Axboe * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) 112903ba3782SJens Axboe * Mark an inode as dirty. Callers should use mark_inode_dirty or 113003ba3782SJens Axboe * mark_inode_dirty_sync. 113103ba3782SJens Axboe * 113203ba3782SJens Axboe * Put the inode on the super block's dirty list. 113303ba3782SJens Axboe * 113403ba3782SJens Axboe * CAREFUL! We mark it dirty unconditionally, but move it onto the 113503ba3782SJens Axboe * dirty list only if it is hashed or if it refers to a blockdev. 113603ba3782SJens Axboe * If it was not hashed, it will never be added to the dirty list 113703ba3782SJens Axboe * even if it is later hashed, as it will have been marked dirty already. 113803ba3782SJens Axboe * 113903ba3782SJens Axboe * In short, make sure you hash any inodes _before_ you start marking 114003ba3782SJens Axboe * them dirty. 114103ba3782SJens Axboe * 114203ba3782SJens Axboe * Note that for blockdevs, inode->dirtied_when represents the dirtying time of 114303ba3782SJens Axboe * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of 114403ba3782SJens Axboe * the kernel-internal blockdev inode represents the dirtying time of the 114503ba3782SJens Axboe * blockdev's pages. This is why for I_DIRTY_PAGES we always use 114603ba3782SJens Axboe * page->mapping->host, so the page-dirtying time is recorded in the internal 114703ba3782SJens Axboe * blockdev inode. 114803ba3782SJens Axboe */ 114903ba3782SJens Axboe void __mark_inode_dirty(struct inode *inode, int flags) 115003ba3782SJens Axboe { 115103ba3782SJens Axboe struct super_block *sb = inode->i_sb; 1152253c34e9SArtem Bityutskiy struct backing_dev_info *bdi = NULL; 115303ba3782SJens Axboe 115403ba3782SJens Axboe /* 115503ba3782SJens Axboe * Don't do this for I_DIRTY_PAGES - that doesn't actually 115603ba3782SJens Axboe * dirty the inode itself 115703ba3782SJens Axboe */ 115803ba3782SJens Axboe if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { 115903ba3782SJens Axboe if (sb->s_op->dirty_inode) 1160aa385729SChristoph Hellwig sb->s_op->dirty_inode(inode, flags); 116103ba3782SJens Axboe } 116203ba3782SJens Axboe 116303ba3782SJens Axboe /* 116403ba3782SJens Axboe * make sure that changes are seen by all cpus before we test i_state 116503ba3782SJens Axboe * -- mikulas 116603ba3782SJens Axboe */ 116703ba3782SJens Axboe smp_mb(); 116803ba3782SJens Axboe 116903ba3782SJens Axboe /* avoid the locking if we can */ 117003ba3782SJens Axboe if ((inode->i_state & flags) == flags) 117103ba3782SJens Axboe return; 117203ba3782SJens Axboe 117303ba3782SJens Axboe if (unlikely(block_dump)) 117403ba3782SJens Axboe block_dump___mark_inode_dirty(inode); 117503ba3782SJens Axboe 1176250df6edSDave Chinner spin_lock(&inode->i_lock); 117703ba3782SJens Axboe if ((inode->i_state & flags) != flags) { 117803ba3782SJens Axboe const int was_dirty = inode->i_state & I_DIRTY; 117903ba3782SJens Axboe 118003ba3782SJens Axboe inode->i_state |= flags; 118103ba3782SJens Axboe 118203ba3782SJens Axboe /* 118303ba3782SJens Axboe * If the inode is being synced, just update its dirty state. 118403ba3782SJens Axboe * The unlocker will place the inode on the appropriate 118503ba3782SJens Axboe * superblock list, based upon its state. 118603ba3782SJens Axboe */ 118703ba3782SJens Axboe if (inode->i_state & I_SYNC) 1188250df6edSDave Chinner goto out_unlock_inode; 118903ba3782SJens Axboe 119003ba3782SJens Axboe /* 119103ba3782SJens Axboe * Only add valid (hashed) inodes to the superblock's 119203ba3782SJens Axboe * dirty list. Add blockdev inodes as well. 119303ba3782SJens Axboe */ 119403ba3782SJens Axboe if (!S_ISBLK(inode->i_mode)) { 11951d3382cbSAl Viro if (inode_unhashed(inode)) 1196250df6edSDave Chinner goto out_unlock_inode; 119703ba3782SJens Axboe } 1198a4ffdde6SAl Viro if (inode->i_state & I_FREEING) 1199250df6edSDave Chinner goto out_unlock_inode; 120003ba3782SJens Axboe 120103ba3782SJens Axboe /* 120203ba3782SJens Axboe * If the inode was already on b_dirty/b_io/b_more_io, don't 120303ba3782SJens Axboe * reposition it (that would break b_dirty time-ordering). 120403ba3782SJens Axboe */ 120503ba3782SJens Axboe if (!was_dirty) { 1206a66979abSDave Chinner bool wakeup_bdi = false; 1207253c34e9SArtem Bityutskiy bdi = inode_to_bdi(inode); 1208500b067cSJens Axboe 1209253c34e9SArtem Bityutskiy if (bdi_cap_writeback_dirty(bdi)) { 1210253c34e9SArtem Bityutskiy WARN(!test_bit(BDI_registered, &bdi->state), 1211253c34e9SArtem Bityutskiy "bdi-%s not registered\n", bdi->name); 1212253c34e9SArtem Bityutskiy 1213253c34e9SArtem Bityutskiy /* 1214253c34e9SArtem Bityutskiy * If this is the first dirty inode for this 1215253c34e9SArtem Bityutskiy * bdi, we have to wake-up the corresponding 1216253c34e9SArtem Bityutskiy * bdi thread to make sure background 1217253c34e9SArtem Bityutskiy * write-back happens later. 1218253c34e9SArtem Bityutskiy */ 1219253c34e9SArtem Bityutskiy if (!wb_has_dirty_io(&bdi->wb)) 1220253c34e9SArtem Bityutskiy wakeup_bdi = true; 1221500b067cSJens Axboe } 122203ba3782SJens Axboe 1223a66979abSDave Chinner spin_unlock(&inode->i_lock); 1224f758eeabSChristoph Hellwig spin_lock(&bdi->wb.list_lock); 122503ba3782SJens Axboe inode->dirtied_when = jiffies; 12267ccf19a8SNick Piggin list_move(&inode->i_wb_list, &bdi->wb.b_dirty); 1227f758eeabSChristoph Hellwig spin_unlock(&bdi->wb.list_lock); 1228253c34e9SArtem Bityutskiy 1229253c34e9SArtem Bityutskiy if (wakeup_bdi) 12306467716aSArtem Bityutskiy bdi_wakeup_thread_delayed(bdi); 1231a66979abSDave Chinner return; 1232a66979abSDave Chinner } 1233a66979abSDave Chinner } 1234a66979abSDave Chinner out_unlock_inode: 1235a66979abSDave Chinner spin_unlock(&inode->i_lock); 1236a66979abSDave Chinner 123703ba3782SJens Axboe } 123803ba3782SJens Axboe EXPORT_SYMBOL(__mark_inode_dirty); 123903ba3782SJens Axboe 1240b6e51316SJens Axboe static void wait_sb_inodes(struct super_block *sb) 124166f3b8e2SJens Axboe { 124238f21977SNick Piggin struct inode *inode, *old_inode = NULL; 124338f21977SNick Piggin 124403ba3782SJens Axboe /* 124503ba3782SJens Axboe * We need to be protected against the filesystem going from 124603ba3782SJens Axboe * r/o to r/w or vice versa. 124703ba3782SJens Axboe */ 1248b6e51316SJens Axboe WARN_ON(!rwsem_is_locked(&sb->s_umount)); 124903ba3782SJens Axboe 125055fa6091SDave Chinner spin_lock(&inode_sb_list_lock); 125166f3b8e2SJens Axboe 125238f21977SNick Piggin /* 125338f21977SNick Piggin * Data integrity sync. Must wait for all pages under writeback, 125438f21977SNick Piggin * because there may have been pages dirtied before our sync 125538f21977SNick Piggin * call, but which had writeout started before we write it out. 125638f21977SNick Piggin * In which case, the inode may not be on the dirty list, but 125738f21977SNick Piggin * we still have to wait for that writeout. 125838f21977SNick Piggin */ 1259b6e51316SJens Axboe list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { 1260250df6edSDave Chinner struct address_space *mapping = inode->i_mapping; 126138f21977SNick Piggin 1262250df6edSDave Chinner spin_lock(&inode->i_lock); 1263250df6edSDave Chinner if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || 1264250df6edSDave Chinner (mapping->nrpages == 0)) { 1265250df6edSDave Chinner spin_unlock(&inode->i_lock); 126638f21977SNick Piggin continue; 1267250df6edSDave Chinner } 126838f21977SNick Piggin __iget(inode); 1269250df6edSDave Chinner spin_unlock(&inode->i_lock); 127055fa6091SDave Chinner spin_unlock(&inode_sb_list_lock); 127155fa6091SDave Chinner 127238f21977SNick Piggin /* 127355fa6091SDave Chinner * We hold a reference to 'inode' so it couldn't have been 127455fa6091SDave Chinner * removed from s_inodes list while we dropped the 127555fa6091SDave Chinner * inode_sb_list_lock. We cannot iput the inode now as we can 127655fa6091SDave Chinner * be holding the last reference and we cannot iput it under 127755fa6091SDave Chinner * inode_sb_list_lock. So we keep the reference and iput it 127855fa6091SDave Chinner * later. 127938f21977SNick Piggin */ 128038f21977SNick Piggin iput(old_inode); 128138f21977SNick Piggin old_inode = inode; 128238f21977SNick Piggin 128338f21977SNick Piggin filemap_fdatawait(mapping); 128438f21977SNick Piggin 128538f21977SNick Piggin cond_resched(); 128638f21977SNick Piggin 128755fa6091SDave Chinner spin_lock(&inode_sb_list_lock); 128838f21977SNick Piggin } 128955fa6091SDave Chinner spin_unlock(&inode_sb_list_lock); 129038f21977SNick Piggin iput(old_inode); 129166f3b8e2SJens Axboe } 12921da177e4SLinus Torvalds 1293d8a8559cSJens Axboe /** 12943259f8beSChris Mason * writeback_inodes_sb_nr - writeback dirty inodes from given super_block 1295d8a8559cSJens Axboe * @sb: the superblock 12963259f8beSChris Mason * @nr: the number of pages to write 1297786228abSMarcos Paulo de Souza * @reason: reason why some writeback work initiated 12981da177e4SLinus Torvalds * 1299d8a8559cSJens Axboe * Start writeback on some inodes on this super_block. No guarantees are made 1300d8a8559cSJens Axboe * on how many (if any) will be written, and this function does not wait 13013259f8beSChris Mason * for IO completion of submitted IO. 13021da177e4SLinus Torvalds */ 13030e175a18SCurt Wohlgemuth void writeback_inodes_sb_nr(struct super_block *sb, 13040e175a18SCurt Wohlgemuth unsigned long nr, 13050e175a18SCurt Wohlgemuth enum wb_reason reason) 13061da177e4SLinus Torvalds { 130783ba7b07SChristoph Hellwig DECLARE_COMPLETION_ONSTACK(done); 130883ba7b07SChristoph Hellwig struct wb_writeback_work work = { 13093c4d7165SChristoph Hellwig .sb = sb, 13103c4d7165SChristoph Hellwig .sync_mode = WB_SYNC_NONE, 13116e6938b6SWu Fengguang .tagged_writepages = 1, 131283ba7b07SChristoph Hellwig .done = &done, 13133259f8beSChris Mason .nr_pages = nr, 13140e175a18SCurt Wohlgemuth .reason = reason, 13153c4d7165SChristoph Hellwig }; 13160e3c9a22SJens Axboe 1317cf37e972SChristoph Hellwig WARN_ON(!rwsem_is_locked(&sb->s_umount)); 131883ba7b07SChristoph Hellwig bdi_queue_work(sb->s_bdi, &work); 131983ba7b07SChristoph Hellwig wait_for_completion(&done); 13201da177e4SLinus Torvalds } 13213259f8beSChris Mason EXPORT_SYMBOL(writeback_inodes_sb_nr); 13223259f8beSChris Mason 13233259f8beSChris Mason /** 13243259f8beSChris Mason * writeback_inodes_sb - writeback dirty inodes from given super_block 13253259f8beSChris Mason * @sb: the superblock 1326786228abSMarcos Paulo de Souza * @reason: reason why some writeback work was initiated 13273259f8beSChris Mason * 13283259f8beSChris Mason * Start writeback on some inodes on this super_block. No guarantees are made 13293259f8beSChris Mason * on how many (if any) will be written, and this function does not wait 13303259f8beSChris Mason * for IO completion of submitted IO. 13313259f8beSChris Mason */ 13320e175a18SCurt Wohlgemuth void writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) 13333259f8beSChris Mason { 13340e175a18SCurt Wohlgemuth return writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); 13353259f8beSChris Mason } 1336d8a8559cSJens Axboe EXPORT_SYMBOL(writeback_inodes_sb); 1337d8a8559cSJens Axboe 1338d8a8559cSJens Axboe /** 133917bd55d0SEric Sandeen * writeback_inodes_sb_if_idle - start writeback if none underway 134017bd55d0SEric Sandeen * @sb: the superblock 1341786228abSMarcos Paulo de Souza * @reason: reason why some writeback work was initiated 134217bd55d0SEric Sandeen * 134317bd55d0SEric Sandeen * Invoke writeback_inodes_sb if no writeback is currently underway. 134417bd55d0SEric Sandeen * Returns 1 if writeback was started, 0 if not. 134517bd55d0SEric Sandeen */ 13460e175a18SCurt Wohlgemuth int writeback_inodes_sb_if_idle(struct super_block *sb, enum wb_reason reason) 134717bd55d0SEric Sandeen { 134817bd55d0SEric Sandeen if (!writeback_in_progress(sb->s_bdi)) { 1349cf37e972SChristoph Hellwig down_read(&sb->s_umount); 13500e175a18SCurt Wohlgemuth writeback_inodes_sb(sb, reason); 1351cf37e972SChristoph Hellwig up_read(&sb->s_umount); 135217bd55d0SEric Sandeen return 1; 135317bd55d0SEric Sandeen } else 135417bd55d0SEric Sandeen return 0; 135517bd55d0SEric Sandeen } 135617bd55d0SEric Sandeen EXPORT_SYMBOL(writeback_inodes_sb_if_idle); 135717bd55d0SEric Sandeen 135817bd55d0SEric Sandeen /** 1359c097b2caSFengguang Wu * writeback_inodes_sb_nr_if_idle - start writeback if none underway 13603259f8beSChris Mason * @sb: the superblock 13613259f8beSChris Mason * @nr: the number of pages to write 1362786228abSMarcos Paulo de Souza * @reason: reason why some writeback work was initiated 13633259f8beSChris Mason * 13643259f8beSChris Mason * Invoke writeback_inodes_sb if no writeback is currently underway. 13653259f8beSChris Mason * Returns 1 if writeback was started, 0 if not. 13663259f8beSChris Mason */ 13673259f8beSChris Mason int writeback_inodes_sb_nr_if_idle(struct super_block *sb, 13680e175a18SCurt Wohlgemuth unsigned long nr, 13690e175a18SCurt Wohlgemuth enum wb_reason reason) 13703259f8beSChris Mason { 13713259f8beSChris Mason if (!writeback_in_progress(sb->s_bdi)) { 13723259f8beSChris Mason down_read(&sb->s_umount); 13730e175a18SCurt Wohlgemuth writeback_inodes_sb_nr(sb, nr, reason); 13743259f8beSChris Mason up_read(&sb->s_umount); 13753259f8beSChris Mason return 1; 13763259f8beSChris Mason } else 13773259f8beSChris Mason return 0; 13783259f8beSChris Mason } 13793259f8beSChris Mason EXPORT_SYMBOL(writeback_inodes_sb_nr_if_idle); 13803259f8beSChris Mason 13813259f8beSChris Mason /** 1382d8a8559cSJens Axboe * sync_inodes_sb - sync sb inode pages 1383d8a8559cSJens Axboe * @sb: the superblock 1384d8a8559cSJens Axboe * 1385d8a8559cSJens Axboe * This function writes and waits on any dirty inode belonging to this 1386cb9ef8d5SStefan Hajnoczi * super_block. 1387d8a8559cSJens Axboe */ 1388b6e51316SJens Axboe void sync_inodes_sb(struct super_block *sb) 1389d8a8559cSJens Axboe { 139083ba7b07SChristoph Hellwig DECLARE_COMPLETION_ONSTACK(done); 139183ba7b07SChristoph Hellwig struct wb_writeback_work work = { 13923c4d7165SChristoph Hellwig .sb = sb, 13933c4d7165SChristoph Hellwig .sync_mode = WB_SYNC_ALL, 13943c4d7165SChristoph Hellwig .nr_pages = LONG_MAX, 13953c4d7165SChristoph Hellwig .range_cyclic = 0, 139683ba7b07SChristoph Hellwig .done = &done, 13970e175a18SCurt Wohlgemuth .reason = WB_REASON_SYNC, 13983c4d7165SChristoph Hellwig }; 13993c4d7165SChristoph Hellwig 1400cf37e972SChristoph Hellwig WARN_ON(!rwsem_is_locked(&sb->s_umount)); 1401cf37e972SChristoph Hellwig 140283ba7b07SChristoph Hellwig bdi_queue_work(sb->s_bdi, &work); 140383ba7b07SChristoph Hellwig wait_for_completion(&done); 140483ba7b07SChristoph Hellwig 1405b6e51316SJens Axboe wait_sb_inodes(sb); 1406d8a8559cSJens Axboe } 1407d8a8559cSJens Axboe EXPORT_SYMBOL(sync_inodes_sb); 14081da177e4SLinus Torvalds 14091da177e4SLinus Torvalds /** 14101da177e4SLinus Torvalds * write_inode_now - write an inode to disk 14111da177e4SLinus Torvalds * @inode: inode to write to disk 14121da177e4SLinus Torvalds * @sync: whether the write should be synchronous or not 14131da177e4SLinus Torvalds * 14147f04c26dSAndrea Arcangeli * This function commits an inode to disk immediately if it is dirty. This is 14157f04c26dSAndrea Arcangeli * primarily needed by knfsd. 14167f04c26dSAndrea Arcangeli * 14177f04c26dSAndrea Arcangeli * The caller must either have a ref on the inode or must have set I_WILL_FREE. 14181da177e4SLinus Torvalds */ 14191da177e4SLinus Torvalds int write_inode_now(struct inode *inode, int sync) 14201da177e4SLinus Torvalds { 1421f758eeabSChristoph Hellwig struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; 14221da177e4SLinus Torvalds struct writeback_control wbc = { 14231da177e4SLinus Torvalds .nr_to_write = LONG_MAX, 142418914b18SMike Galbraith .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, 1425111ebb6eSOGAWA Hirofumi .range_start = 0, 1426111ebb6eSOGAWA Hirofumi .range_end = LLONG_MAX, 14271da177e4SLinus Torvalds }; 14281da177e4SLinus Torvalds 14291da177e4SLinus Torvalds if (!mapping_cap_writeback_dirty(inode->i_mapping)) 143049364ce2SAndrew Morton wbc.nr_to_write = 0; 14311da177e4SLinus Torvalds 14321da177e4SLinus Torvalds might_sleep(); 14334f8ad655SJan Kara return writeback_single_inode(inode, wb, &wbc); 14341da177e4SLinus Torvalds } 14351da177e4SLinus Torvalds EXPORT_SYMBOL(write_inode_now); 14361da177e4SLinus Torvalds 14371da177e4SLinus Torvalds /** 14381da177e4SLinus Torvalds * sync_inode - write an inode and its pages to disk. 14391da177e4SLinus Torvalds * @inode: the inode to sync 14401da177e4SLinus Torvalds * @wbc: controls the writeback mode 14411da177e4SLinus Torvalds * 14421da177e4SLinus Torvalds * sync_inode() will write an inode and its pages to disk. It will also 14431da177e4SLinus Torvalds * correctly update the inode on its superblock's dirty inode lists and will 14441da177e4SLinus Torvalds * update inode->i_state. 14451da177e4SLinus Torvalds * 14461da177e4SLinus Torvalds * The caller must have a ref on the inode. 14471da177e4SLinus Torvalds */ 14481da177e4SLinus Torvalds int sync_inode(struct inode *inode, struct writeback_control *wbc) 14491da177e4SLinus Torvalds { 14504f8ad655SJan Kara return writeback_single_inode(inode, &inode_to_bdi(inode)->wb, wbc); 14511da177e4SLinus Torvalds } 14521da177e4SLinus Torvalds EXPORT_SYMBOL(sync_inode); 1453c3765016SChristoph Hellwig 1454c3765016SChristoph Hellwig /** 1455c691b9d9SAndrew Morton * sync_inode_metadata - write an inode to disk 1456c3765016SChristoph Hellwig * @inode: the inode to sync 1457c3765016SChristoph Hellwig * @wait: wait for I/O to complete. 1458c3765016SChristoph Hellwig * 1459c691b9d9SAndrew Morton * Write an inode to disk and adjust its dirty state after completion. 1460c3765016SChristoph Hellwig * 1461c3765016SChristoph Hellwig * Note: only writes the actual inode, no associated data or other metadata. 1462c3765016SChristoph Hellwig */ 1463c3765016SChristoph Hellwig int sync_inode_metadata(struct inode *inode, int wait) 1464c3765016SChristoph Hellwig { 1465c3765016SChristoph Hellwig struct writeback_control wbc = { 1466c3765016SChristoph Hellwig .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_NONE, 1467c3765016SChristoph Hellwig .nr_to_write = 0, /* metadata-only */ 1468c3765016SChristoph Hellwig }; 1469c3765016SChristoph Hellwig 1470c3765016SChristoph Hellwig return sync_inode(inode, &wbc); 1471c3765016SChristoph Hellwig } 1472c3765016SChristoph Hellwig EXPORT_SYMBOL(sync_inode_metadata); 1473