![Linus Torvalds](/assets/img/avatar_default.png)
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/writeback: (27 commits) mm: properly reflect task dirty limits in dirty_exceeded logic writeback: don't busy retry writeback on new/freeing inodes writeback: scale IO chunk size up to half device bandwidth writeback: trace global_dirty_state writeback: introduce max-pause and pass-good dirty limits writeback: introduce smoothed global dirty limit writeback: consolidate variable names in balance_dirty_pages() writeback: show bdi write bandwidth in debugfs writeback: bdi write bandwidth estimation writeback: account per-bdi accumulated written pages writeback: make writeback_control.nr_to_write straight writeback: skip tmpfs early in balance_dirty_pages_ratelimited_nr() writeback: trace event writeback_queue_io writeback: trace event writeback_single_inode writeback: remove .nonblocking and .encountered_congestion writeback: remove writeback_control.more_io writeback: skip balance_dirty_pages() for in-memory fs writeback: add bdi_dirty_limit() kernel-doc writeback: avoid extra sync work at enqueue time writeback: elevate queue_io() into wb_writeback() ... Fix up trivial conflicts in fs/fs-writeback.c and mm/filemap.c
1379 lines
36 KiB
C
1379 lines
36 KiB
C
/*
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* fs/fs-writeback.c
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*
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* Copyright (C) 2002, Linus Torvalds.
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*
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* Contains all the functions related to writing back and waiting
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* upon dirty inodes against superblocks, and writing back dirty
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* pages against inodes. ie: data writeback. Writeout of the
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* inode itself is not handled here.
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*
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* 10Apr2002 Andrew Morton
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* Split out of fs/inode.c
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* Additions for address_space-based writeback
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/spinlock.h>
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#include <linux/slab.h>
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#include <linux/sched.h>
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/kthread.h>
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#include <linux/freezer.h>
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#include <linux/writeback.h>
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#include <linux/blkdev.h>
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#include <linux/backing-dev.h>
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#include <linux/buffer_head.h>
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#include <linux/tracepoint.h>
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#include "internal.h"
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/*
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* Passed into wb_writeback(), essentially a subset of writeback_control
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*/
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struct wb_writeback_work {
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long nr_pages;
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struct super_block *sb;
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unsigned long *older_than_this;
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enum writeback_sync_modes sync_mode;
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unsigned int tagged_writepages:1;
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unsigned int for_kupdate:1;
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unsigned int range_cyclic:1;
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unsigned int for_background:1;
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struct list_head list; /* pending work list */
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struct completion *done; /* set if the caller waits */
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};
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/*
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* Include the creation of the trace points after defining the
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* wb_writeback_work structure so that the definition remains local to this
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* file.
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*/
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#define CREATE_TRACE_POINTS
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#include <trace/events/writeback.h>
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/*
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* We don't actually have pdflush, but this one is exported though /proc...
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*/
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int nr_pdflush_threads;
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/**
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* writeback_in_progress - determine whether there is writeback in progress
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* @bdi: the device's backing_dev_info structure.
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*
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* Determine whether there is writeback waiting to be handled against a
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* backing device.
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*/
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int writeback_in_progress(struct backing_dev_info *bdi)
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{
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return test_bit(BDI_writeback_running, &bdi->state);
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}
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static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
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{
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struct super_block *sb = inode->i_sb;
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if (strcmp(sb->s_type->name, "bdev") == 0)
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return inode->i_mapping->backing_dev_info;
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return sb->s_bdi;
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}
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static inline struct inode *wb_inode(struct list_head *head)
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{
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return list_entry(head, struct inode, i_wb_list);
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}
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/* Wakeup flusher thread or forker thread to fork it. Requires bdi->wb_lock. */
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static void bdi_wakeup_flusher(struct backing_dev_info *bdi)
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{
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if (bdi->wb.task) {
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wake_up_process(bdi->wb.task);
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} else {
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/*
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* The bdi thread isn't there, wake up the forker thread which
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* will create and run it.
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*/
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wake_up_process(default_backing_dev_info.wb.task);
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}
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}
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static void bdi_queue_work(struct backing_dev_info *bdi,
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struct wb_writeback_work *work)
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{
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trace_writeback_queue(bdi, work);
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spin_lock_bh(&bdi->wb_lock);
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list_add_tail(&work->list, &bdi->work_list);
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if (!bdi->wb.task)
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trace_writeback_nothread(bdi, work);
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bdi_wakeup_flusher(bdi);
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spin_unlock_bh(&bdi->wb_lock);
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}
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static void
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__bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
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bool range_cyclic)
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{
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struct wb_writeback_work *work;
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/*
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* This is WB_SYNC_NONE writeback, so if allocation fails just
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* wakeup the thread for old dirty data writeback
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*/
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work = kzalloc(sizeof(*work), GFP_ATOMIC);
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if (!work) {
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if (bdi->wb.task) {
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trace_writeback_nowork(bdi);
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wake_up_process(bdi->wb.task);
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}
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return;
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}
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work->sync_mode = WB_SYNC_NONE;
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work->nr_pages = nr_pages;
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work->range_cyclic = range_cyclic;
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bdi_queue_work(bdi, work);
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}
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/**
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* bdi_start_writeback - start writeback
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* @bdi: the backing device to write from
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* @nr_pages: the number of pages to write
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*
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* Description:
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* This does WB_SYNC_NONE opportunistic writeback. The IO is only
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* started when this function returns, we make no guarantees on
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* completion. Caller need not hold sb s_umount semaphore.
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*
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*/
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void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages)
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{
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__bdi_start_writeback(bdi, nr_pages, true);
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}
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/**
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* bdi_start_background_writeback - start background writeback
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* @bdi: the backing device to write from
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*
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* Description:
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* This makes sure WB_SYNC_NONE background writeback happens. When
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* this function returns, it is only guaranteed that for given BDI
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* some IO is happening if we are over background dirty threshold.
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* Caller need not hold sb s_umount semaphore.
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*/
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void bdi_start_background_writeback(struct backing_dev_info *bdi)
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{
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/*
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* We just wake up the flusher thread. It will perform background
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* writeback as soon as there is no other work to do.
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*/
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trace_writeback_wake_background(bdi);
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spin_lock_bh(&bdi->wb_lock);
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bdi_wakeup_flusher(bdi);
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spin_unlock_bh(&bdi->wb_lock);
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}
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/*
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* Remove the inode from the writeback list it is on.
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*/
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void inode_wb_list_del(struct inode *inode)
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{
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struct backing_dev_info *bdi = inode_to_bdi(inode);
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spin_lock(&bdi->wb.list_lock);
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list_del_init(&inode->i_wb_list);
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spin_unlock(&bdi->wb.list_lock);
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}
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/*
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* Redirty an inode: set its when-it-was dirtied timestamp and move it to the
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* furthest end of its superblock's dirty-inode list.
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*
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* Before stamping the inode's ->dirtied_when, we check to see whether it is
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* already the most-recently-dirtied inode on the b_dirty list. If that is
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* the case then the inode must have been redirtied while it was being written
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* out and we don't reset its dirtied_when.
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*/
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static void redirty_tail(struct inode *inode, struct bdi_writeback *wb)
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{
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assert_spin_locked(&wb->list_lock);
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if (!list_empty(&wb->b_dirty)) {
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struct inode *tail;
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tail = wb_inode(wb->b_dirty.next);
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if (time_before(inode->dirtied_when, tail->dirtied_when))
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inode->dirtied_when = jiffies;
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}
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list_move(&inode->i_wb_list, &wb->b_dirty);
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}
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/*
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* requeue inode for re-scanning after bdi->b_io list is exhausted.
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*/
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static void requeue_io(struct inode *inode, struct bdi_writeback *wb)
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{
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assert_spin_locked(&wb->list_lock);
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list_move(&inode->i_wb_list, &wb->b_more_io);
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}
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static void inode_sync_complete(struct inode *inode)
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{
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/*
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* Prevent speculative execution through
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* spin_unlock(&wb->list_lock);
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*/
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smp_mb();
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wake_up_bit(&inode->i_state, __I_SYNC);
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}
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static bool inode_dirtied_after(struct inode *inode, unsigned long t)
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{
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bool ret = time_after(inode->dirtied_when, t);
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#ifndef CONFIG_64BIT
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/*
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* For inodes being constantly redirtied, dirtied_when can get stuck.
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* It _appears_ to be in the future, but is actually in distant past.
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* This test is necessary to prevent such wrapped-around relative times
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* from permanently stopping the whole bdi writeback.
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*/
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ret = ret && time_before_eq(inode->dirtied_when, jiffies);
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#endif
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return ret;
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}
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/*
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* Move expired dirty inodes from @delaying_queue to @dispatch_queue.
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*/
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static int move_expired_inodes(struct list_head *delaying_queue,
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struct list_head *dispatch_queue,
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unsigned long *older_than_this)
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{
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LIST_HEAD(tmp);
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struct list_head *pos, *node;
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struct super_block *sb = NULL;
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struct inode *inode;
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int do_sb_sort = 0;
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int moved = 0;
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while (!list_empty(delaying_queue)) {
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inode = wb_inode(delaying_queue->prev);
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if (older_than_this &&
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inode_dirtied_after(inode, *older_than_this))
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break;
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if (sb && sb != inode->i_sb)
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do_sb_sort = 1;
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sb = inode->i_sb;
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list_move(&inode->i_wb_list, &tmp);
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moved++;
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}
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/* just one sb in list, splice to dispatch_queue and we're done */
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if (!do_sb_sort) {
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list_splice(&tmp, dispatch_queue);
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goto out;
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}
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/* Move inodes from one superblock together */
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while (!list_empty(&tmp)) {
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sb = wb_inode(tmp.prev)->i_sb;
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list_for_each_prev_safe(pos, node, &tmp) {
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inode = wb_inode(pos);
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if (inode->i_sb == sb)
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list_move(&inode->i_wb_list, dispatch_queue);
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}
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}
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out:
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return moved;
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}
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/*
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* Queue all expired dirty inodes for io, eldest first.
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* Before
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* newly dirtied b_dirty b_io b_more_io
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* =============> gf edc BA
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* After
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* newly dirtied b_dirty b_io b_more_io
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* =============> g fBAedc
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* |
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* +--> dequeue for IO
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*/
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static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this)
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{
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int moved;
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assert_spin_locked(&wb->list_lock);
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list_splice_init(&wb->b_more_io, &wb->b_io);
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moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this);
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trace_writeback_queue_io(wb, older_than_this, moved);
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}
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static int write_inode(struct inode *inode, struct writeback_control *wbc)
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{
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if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode))
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return inode->i_sb->s_op->write_inode(inode, wbc);
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return 0;
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}
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/*
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* Wait for writeback on an inode to complete.
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*/
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static void inode_wait_for_writeback(struct inode *inode,
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struct bdi_writeback *wb)
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{
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DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC);
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wait_queue_head_t *wqh;
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wqh = bit_waitqueue(&inode->i_state, __I_SYNC);
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while (inode->i_state & I_SYNC) {
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spin_unlock(&inode->i_lock);
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spin_unlock(&wb->list_lock);
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__wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE);
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spin_lock(&wb->list_lock);
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spin_lock(&inode->i_lock);
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}
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}
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/*
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* Write out an inode's dirty pages. Called under wb->list_lock and
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* inode->i_lock. Either the caller has an active reference on the inode or
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* the inode has I_WILL_FREE set.
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*
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* If `wait' is set, wait on the writeout.
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*
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* The whole writeout design is quite complex and fragile. We want to avoid
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* starvation of particular inodes when others are being redirtied, prevent
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* livelocks, etc.
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*/
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static int
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writeback_single_inode(struct inode *inode, struct bdi_writeback *wb,
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struct writeback_control *wbc)
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{
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struct address_space *mapping = inode->i_mapping;
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long nr_to_write = wbc->nr_to_write;
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unsigned dirty;
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int ret;
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assert_spin_locked(&wb->list_lock);
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assert_spin_locked(&inode->i_lock);
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if (!atomic_read(&inode->i_count))
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WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING)));
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else
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WARN_ON(inode->i_state & I_WILL_FREE);
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if (inode->i_state & I_SYNC) {
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/*
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* If this inode is locked for writeback and we are not doing
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* writeback-for-data-integrity, move it to b_more_io so that
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* writeback can proceed with the other inodes on s_io.
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*
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* We'll have another go at writing back this inode when we
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* completed a full scan of b_io.
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*/
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if (wbc->sync_mode != WB_SYNC_ALL) {
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requeue_io(inode, wb);
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trace_writeback_single_inode_requeue(inode, wbc,
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nr_to_write);
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return 0;
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}
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/*
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* It's a data-integrity sync. We must wait.
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*/
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inode_wait_for_writeback(inode, wb);
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}
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BUG_ON(inode->i_state & I_SYNC);
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/* Set I_SYNC, reset I_DIRTY_PAGES */
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inode->i_state |= I_SYNC;
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inode->i_state &= ~I_DIRTY_PAGES;
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spin_unlock(&inode->i_lock);
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spin_unlock(&wb->list_lock);
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ret = do_writepages(mapping, wbc);
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/*
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* Make sure to wait on the data before writing out the metadata.
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* This is important for filesystems that modify metadata on data
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* I/O completion.
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*/
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if (wbc->sync_mode == WB_SYNC_ALL) {
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int err = filemap_fdatawait(mapping);
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if (ret == 0)
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ret = err;
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}
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/*
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* Some filesystems may redirty the inode during the writeback
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* due to delalloc, clear dirty metadata flags right before
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* write_inode()
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*/
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spin_lock(&inode->i_lock);
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dirty = inode->i_state & I_DIRTY;
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inode->i_state &= ~(I_DIRTY_SYNC | I_DIRTY_DATASYNC);
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spin_unlock(&inode->i_lock);
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/* Don't write the inode if only I_DIRTY_PAGES was set */
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if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) {
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int err = write_inode(inode, wbc);
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if (ret == 0)
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ret = err;
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}
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spin_lock(&wb->list_lock);
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spin_lock(&inode->i_lock);
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inode->i_state &= ~I_SYNC;
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if (!(inode->i_state & I_FREEING)) {
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/*
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* Sync livelock prevention. Each inode is tagged and synced in
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* one shot. If still dirty, it will be redirty_tail()'ed below.
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* Update the dirty time to prevent enqueue and sync it again.
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*/
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if ((inode->i_state & I_DIRTY) &&
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(wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages))
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inode->dirtied_when = jiffies;
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if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
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/*
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* We didn't write back all the pages. nfs_writepages()
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* sometimes bales out without doing anything.
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*/
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inode->i_state |= I_DIRTY_PAGES;
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if (wbc->nr_to_write <= 0) {
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/*
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* slice used up: queue for next turn
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*/
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requeue_io(inode, wb);
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} else {
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/*
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* Writeback blocked by something other than
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* congestion. Delay the inode for some time to
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* avoid spinning on the CPU (100% iowait)
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* retrying writeback of the dirty page/inode
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* that cannot be performed immediately.
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*/
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redirty_tail(inode, wb);
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}
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} else if (inode->i_state & I_DIRTY) {
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/*
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* Filesystems can dirty the inode during writeback
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* operations, such as delayed allocation during
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* submission or metadata updates after data IO
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* completion.
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*/
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redirty_tail(inode, wb);
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} else {
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/*
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* The inode is clean. At this point we either have
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* a reference to the inode or it's on it's way out.
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* No need to add it back to the LRU.
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*/
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list_del_init(&inode->i_wb_list);
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}
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}
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inode_sync_complete(inode);
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trace_writeback_single_inode(inode, wbc, nr_to_write);
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return ret;
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}
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|
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static long writeback_chunk_size(struct backing_dev_info *bdi,
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struct wb_writeback_work *work)
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{
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long pages;
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/*
|
|
* WB_SYNC_ALL mode does livelock avoidance by syncing dirty
|
|
* inodes/pages in one big loop. Setting wbc.nr_to_write=LONG_MAX
|
|
* here avoids calling into writeback_inodes_wb() more than once.
|
|
*
|
|
* The intended call sequence for WB_SYNC_ALL writeback is:
|
|
*
|
|
* wb_writeback()
|
|
* writeback_sb_inodes() <== called only once
|
|
* write_cache_pages() <== called once for each inode
|
|
* (quickly) tag currently dirty pages
|
|
* (maybe slowly) sync all tagged pages
|
|
*/
|
|
if (work->sync_mode == WB_SYNC_ALL || work->tagged_writepages)
|
|
pages = LONG_MAX;
|
|
else {
|
|
pages = min(bdi->avg_write_bandwidth / 2,
|
|
global_dirty_limit / DIRTY_SCOPE);
|
|
pages = min(pages, work->nr_pages);
|
|
pages = round_down(pages + MIN_WRITEBACK_PAGES,
|
|
MIN_WRITEBACK_PAGES);
|
|
}
|
|
|
|
return pages;
|
|
}
|
|
|
|
/*
|
|
* Write a portion of b_io inodes which belong to @sb.
|
|
*
|
|
* If @only_this_sb is true, then find and write all such
|
|
* inodes. Otherwise write only ones which go sequentially
|
|
* in reverse order.
|
|
*
|
|
* Return the number of pages and/or inodes written.
|
|
*/
|
|
static long writeback_sb_inodes(struct super_block *sb,
|
|
struct bdi_writeback *wb,
|
|
struct wb_writeback_work *work)
|
|
{
|
|
struct writeback_control wbc = {
|
|
.sync_mode = work->sync_mode,
|
|
.tagged_writepages = work->tagged_writepages,
|
|
.for_kupdate = work->for_kupdate,
|
|
.for_background = work->for_background,
|
|
.range_cyclic = work->range_cyclic,
|
|
.range_start = 0,
|
|
.range_end = LLONG_MAX,
|
|
};
|
|
unsigned long start_time = jiffies;
|
|
long write_chunk;
|
|
long wrote = 0; /* count both pages and inodes */
|
|
|
|
while (!list_empty(&wb->b_io)) {
|
|
struct inode *inode = wb_inode(wb->b_io.prev);
|
|
|
|
if (inode->i_sb != sb) {
|
|
if (work->sb) {
|
|
/*
|
|
* We only want to write back data for this
|
|
* superblock, move all inodes not belonging
|
|
* to it back onto the dirty list.
|
|
*/
|
|
redirty_tail(inode, wb);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* The inode belongs to a different superblock.
|
|
* Bounce back to the caller to unpin this and
|
|
* pin the next superblock.
|
|
*/
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Don't bother with new inodes or inodes beeing freed, first
|
|
* kind does not need peridic writeout yet, and for the latter
|
|
* kind writeout is handled by the freer.
|
|
*/
|
|
spin_lock(&inode->i_lock);
|
|
if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) {
|
|
spin_unlock(&inode->i_lock);
|
|
redirty_tail(inode, wb);
|
|
continue;
|
|
}
|
|
__iget(inode);
|
|
write_chunk = writeback_chunk_size(wb->bdi, work);
|
|
wbc.nr_to_write = write_chunk;
|
|
wbc.pages_skipped = 0;
|
|
|
|
writeback_single_inode(inode, wb, &wbc);
|
|
|
|
work->nr_pages -= write_chunk - wbc.nr_to_write;
|
|
wrote += write_chunk - wbc.nr_to_write;
|
|
if (!(inode->i_state & I_DIRTY))
|
|
wrote++;
|
|
if (wbc.pages_skipped) {
|
|
/*
|
|
* writeback is not making progress due to locked
|
|
* buffers. Skip this inode for now.
|
|
*/
|
|
redirty_tail(inode, wb);
|
|
}
|
|
spin_unlock(&inode->i_lock);
|
|
spin_unlock(&wb->list_lock);
|
|
iput(inode);
|
|
cond_resched();
|
|
spin_lock(&wb->list_lock);
|
|
/*
|
|
* bail out to wb_writeback() often enough to check
|
|
* background threshold and other termination conditions.
|
|
*/
|
|
if (wrote) {
|
|
if (time_is_before_jiffies(start_time + HZ / 10UL))
|
|
break;
|
|
if (work->nr_pages <= 0)
|
|
break;
|
|
}
|
|
}
|
|
return wrote;
|
|
}
|
|
|
|
static long __writeback_inodes_wb(struct bdi_writeback *wb,
|
|
struct wb_writeback_work *work)
|
|
{
|
|
unsigned long start_time = jiffies;
|
|
long wrote = 0;
|
|
|
|
while (!list_empty(&wb->b_io)) {
|
|
struct inode *inode = wb_inode(wb->b_io.prev);
|
|
struct super_block *sb = inode->i_sb;
|
|
|
|
if (!grab_super_passive(sb)) {
|
|
requeue_io(inode, wb);
|
|
continue;
|
|
}
|
|
wrote += writeback_sb_inodes(sb, wb, work);
|
|
drop_super(sb);
|
|
|
|
/* refer to the same tests at the end of writeback_sb_inodes */
|
|
if (wrote) {
|
|
if (time_is_before_jiffies(start_time + HZ / 10UL))
|
|
break;
|
|
if (work->nr_pages <= 0)
|
|
break;
|
|
}
|
|
}
|
|
/* Leave any unwritten inodes on b_io */
|
|
return wrote;
|
|
}
|
|
|
|
long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages)
|
|
{
|
|
struct wb_writeback_work work = {
|
|
.nr_pages = nr_pages,
|
|
.sync_mode = WB_SYNC_NONE,
|
|
.range_cyclic = 1,
|
|
};
|
|
|
|
spin_lock(&wb->list_lock);
|
|
if (list_empty(&wb->b_io))
|
|
queue_io(wb, NULL);
|
|
__writeback_inodes_wb(wb, &work);
|
|
spin_unlock(&wb->list_lock);
|
|
|
|
return nr_pages - work.nr_pages;
|
|
}
|
|
|
|
static inline bool over_bground_thresh(void)
|
|
{
|
|
unsigned long background_thresh, dirty_thresh;
|
|
|
|
global_dirty_limits(&background_thresh, &dirty_thresh);
|
|
|
|
return (global_page_state(NR_FILE_DIRTY) +
|
|
global_page_state(NR_UNSTABLE_NFS) > background_thresh);
|
|
}
|
|
|
|
/*
|
|
* Called under wb->list_lock. If there are multiple wb per bdi,
|
|
* only the flusher working on the first wb should do it.
|
|
*/
|
|
static void wb_update_bandwidth(struct bdi_writeback *wb,
|
|
unsigned long start_time)
|
|
{
|
|
__bdi_update_bandwidth(wb->bdi, 0, 0, 0, 0, start_time);
|
|
}
|
|
|
|
/*
|
|
* Explicit flushing or periodic writeback of "old" data.
|
|
*
|
|
* Define "old": the first time one of an inode's pages is dirtied, we mark the
|
|
* dirtying-time in the inode's address_space. So this periodic writeback code
|
|
* just walks the superblock inode list, writing back any inodes which are
|
|
* older than a specific point in time.
|
|
*
|
|
* Try to run once per dirty_writeback_interval. But if a writeback event
|
|
* takes longer than a dirty_writeback_interval interval, then leave a
|
|
* one-second gap.
|
|
*
|
|
* older_than_this takes precedence over nr_to_write. So we'll only write back
|
|
* all dirty pages if they are all attached to "old" mappings.
|
|
*/
|
|
static long wb_writeback(struct bdi_writeback *wb,
|
|
struct wb_writeback_work *work)
|
|
{
|
|
unsigned long wb_start = jiffies;
|
|
long nr_pages = work->nr_pages;
|
|
unsigned long oldest_jif;
|
|
struct inode *inode;
|
|
long progress;
|
|
|
|
oldest_jif = jiffies;
|
|
work->older_than_this = &oldest_jif;
|
|
|
|
spin_lock(&wb->list_lock);
|
|
for (;;) {
|
|
/*
|
|
* Stop writeback when nr_pages has been consumed
|
|
*/
|
|
if (work->nr_pages <= 0)
|
|
break;
|
|
|
|
/*
|
|
* Background writeout and kupdate-style writeback may
|
|
* run forever. Stop them if there is other work to do
|
|
* so that e.g. sync can proceed. They'll be restarted
|
|
* after the other works are all done.
|
|
*/
|
|
if ((work->for_background || work->for_kupdate) &&
|
|
!list_empty(&wb->bdi->work_list))
|
|
break;
|
|
|
|
/*
|
|
* For background writeout, stop when we are below the
|
|
* background dirty threshold
|
|
*/
|
|
if (work->for_background && !over_bground_thresh())
|
|
break;
|
|
|
|
if (work->for_kupdate) {
|
|
oldest_jif = jiffies -
|
|
msecs_to_jiffies(dirty_expire_interval * 10);
|
|
work->older_than_this = &oldest_jif;
|
|
}
|
|
|
|
trace_writeback_start(wb->bdi, work);
|
|
if (list_empty(&wb->b_io))
|
|
queue_io(wb, work->older_than_this);
|
|
if (work->sb)
|
|
progress = writeback_sb_inodes(work->sb, wb, work);
|
|
else
|
|
progress = __writeback_inodes_wb(wb, work);
|
|
trace_writeback_written(wb->bdi, work);
|
|
|
|
wb_update_bandwidth(wb, wb_start);
|
|
|
|
/*
|
|
* Did we write something? Try for more
|
|
*
|
|
* Dirty inodes are moved to b_io for writeback in batches.
|
|
* The completion of the current batch does not necessarily
|
|
* mean the overall work is done. So we keep looping as long
|
|
* as made some progress on cleaning pages or inodes.
|
|
*/
|
|
if (progress)
|
|
continue;
|
|
/*
|
|
* No more inodes for IO, bail
|
|
*/
|
|
if (list_empty(&wb->b_more_io))
|
|
break;
|
|
/*
|
|
* Nothing written. Wait for some inode to
|
|
* become available for writeback. Otherwise
|
|
* we'll just busyloop.
|
|
*/
|
|
if (!list_empty(&wb->b_more_io)) {
|
|
trace_writeback_wait(wb->bdi, work);
|
|
inode = wb_inode(wb->b_more_io.prev);
|
|
spin_lock(&inode->i_lock);
|
|
inode_wait_for_writeback(inode, wb);
|
|
spin_unlock(&inode->i_lock);
|
|
}
|
|
}
|
|
spin_unlock(&wb->list_lock);
|
|
|
|
return nr_pages - work->nr_pages;
|
|
}
|
|
|
|
/*
|
|
* Return the next wb_writeback_work struct that hasn't been processed yet.
|
|
*/
|
|
static struct wb_writeback_work *
|
|
get_next_work_item(struct backing_dev_info *bdi)
|
|
{
|
|
struct wb_writeback_work *work = NULL;
|
|
|
|
spin_lock_bh(&bdi->wb_lock);
|
|
if (!list_empty(&bdi->work_list)) {
|
|
work = list_entry(bdi->work_list.next,
|
|
struct wb_writeback_work, list);
|
|
list_del_init(&work->list);
|
|
}
|
|
spin_unlock_bh(&bdi->wb_lock);
|
|
return work;
|
|
}
|
|
|
|
/*
|
|
* Add in the number of potentially dirty inodes, because each inode
|
|
* write can dirty pagecache in the underlying blockdev.
|
|
*/
|
|
static unsigned long get_nr_dirty_pages(void)
|
|
{
|
|
return global_page_state(NR_FILE_DIRTY) +
|
|
global_page_state(NR_UNSTABLE_NFS) +
|
|
get_nr_dirty_inodes();
|
|
}
|
|
|
|
static long wb_check_background_flush(struct bdi_writeback *wb)
|
|
{
|
|
if (over_bground_thresh()) {
|
|
|
|
struct wb_writeback_work work = {
|
|
.nr_pages = LONG_MAX,
|
|
.sync_mode = WB_SYNC_NONE,
|
|
.for_background = 1,
|
|
.range_cyclic = 1,
|
|
};
|
|
|
|
return wb_writeback(wb, &work);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static long wb_check_old_data_flush(struct bdi_writeback *wb)
|
|
{
|
|
unsigned long expired;
|
|
long nr_pages;
|
|
|
|
/*
|
|
* When set to zero, disable periodic writeback
|
|
*/
|
|
if (!dirty_writeback_interval)
|
|
return 0;
|
|
|
|
expired = wb->last_old_flush +
|
|
msecs_to_jiffies(dirty_writeback_interval * 10);
|
|
if (time_before(jiffies, expired))
|
|
return 0;
|
|
|
|
wb->last_old_flush = jiffies;
|
|
nr_pages = get_nr_dirty_pages();
|
|
|
|
if (nr_pages) {
|
|
struct wb_writeback_work work = {
|
|
.nr_pages = nr_pages,
|
|
.sync_mode = WB_SYNC_NONE,
|
|
.for_kupdate = 1,
|
|
.range_cyclic = 1,
|
|
};
|
|
|
|
return wb_writeback(wb, &work);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Retrieve work items and do the writeback they describe
|
|
*/
|
|
long wb_do_writeback(struct bdi_writeback *wb, int force_wait)
|
|
{
|
|
struct backing_dev_info *bdi = wb->bdi;
|
|
struct wb_writeback_work *work;
|
|
long wrote = 0;
|
|
|
|
set_bit(BDI_writeback_running, &wb->bdi->state);
|
|
while ((work = get_next_work_item(bdi)) != NULL) {
|
|
/*
|
|
* Override sync mode, in case we must wait for completion
|
|
* because this thread is exiting now.
|
|
*/
|
|
if (force_wait)
|
|
work->sync_mode = WB_SYNC_ALL;
|
|
|
|
trace_writeback_exec(bdi, work);
|
|
|
|
wrote += wb_writeback(wb, work);
|
|
|
|
/*
|
|
* Notify the caller of completion if this is a synchronous
|
|
* work item, otherwise just free it.
|
|
*/
|
|
if (work->done)
|
|
complete(work->done);
|
|
else
|
|
kfree(work);
|
|
}
|
|
|
|
/*
|
|
* Check for periodic writeback, kupdated() style
|
|
*/
|
|
wrote += wb_check_old_data_flush(wb);
|
|
wrote += wb_check_background_flush(wb);
|
|
clear_bit(BDI_writeback_running, &wb->bdi->state);
|
|
|
|
return wrote;
|
|
}
|
|
|
|
/*
|
|
* Handle writeback of dirty data for the device backed by this bdi. Also
|
|
* wakes up periodically and does kupdated style flushing.
|
|
*/
|
|
int bdi_writeback_thread(void *data)
|
|
{
|
|
struct bdi_writeback *wb = data;
|
|
struct backing_dev_info *bdi = wb->bdi;
|
|
long pages_written;
|
|
|
|
current->flags |= PF_SWAPWRITE;
|
|
set_freezable();
|
|
wb->last_active = jiffies;
|
|
|
|
/*
|
|
* Our parent may run at a different priority, just set us to normal
|
|
*/
|
|
set_user_nice(current, 0);
|
|
|
|
trace_writeback_thread_start(bdi);
|
|
|
|
while (!kthread_should_stop()) {
|
|
/*
|
|
* Remove own delayed wake-up timer, since we are already awake
|
|
* and we'll take care of the preriodic write-back.
|
|
*/
|
|
del_timer(&wb->wakeup_timer);
|
|
|
|
pages_written = wb_do_writeback(wb, 0);
|
|
|
|
trace_writeback_pages_written(pages_written);
|
|
|
|
if (pages_written)
|
|
wb->last_active = jiffies;
|
|
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
if (!list_empty(&bdi->work_list) || kthread_should_stop()) {
|
|
__set_current_state(TASK_RUNNING);
|
|
continue;
|
|
}
|
|
|
|
if (wb_has_dirty_io(wb) && dirty_writeback_interval)
|
|
schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10));
|
|
else {
|
|
/*
|
|
* We have nothing to do, so can go sleep without any
|
|
* timeout and save power. When a work is queued or
|
|
* something is made dirty - we will be woken up.
|
|
*/
|
|
schedule();
|
|
}
|
|
|
|
try_to_freeze();
|
|
}
|
|
|
|
/* Flush any work that raced with us exiting */
|
|
if (!list_empty(&bdi->work_list))
|
|
wb_do_writeback(wb, 1);
|
|
|
|
trace_writeback_thread_stop(bdi);
|
|
return 0;
|
|
}
|
|
|
|
|
|
/*
|
|
* Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back
|
|
* the whole world.
|
|
*/
|
|
void wakeup_flusher_threads(long nr_pages)
|
|
{
|
|
struct backing_dev_info *bdi;
|
|
|
|
if (!nr_pages) {
|
|
nr_pages = global_page_state(NR_FILE_DIRTY) +
|
|
global_page_state(NR_UNSTABLE_NFS);
|
|
}
|
|
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) {
|
|
if (!bdi_has_dirty_io(bdi))
|
|
continue;
|
|
__bdi_start_writeback(bdi, nr_pages, false);
|
|
}
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
static noinline void block_dump___mark_inode_dirty(struct inode *inode)
|
|
{
|
|
if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) {
|
|
struct dentry *dentry;
|
|
const char *name = "?";
|
|
|
|
dentry = d_find_alias(inode);
|
|
if (dentry) {
|
|
spin_lock(&dentry->d_lock);
|
|
name = (const char *) dentry->d_name.name;
|
|
}
|
|
printk(KERN_DEBUG
|
|
"%s(%d): dirtied inode %lu (%s) on %s\n",
|
|
current->comm, task_pid_nr(current), inode->i_ino,
|
|
name, inode->i_sb->s_id);
|
|
if (dentry) {
|
|
spin_unlock(&dentry->d_lock);
|
|
dput(dentry);
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* __mark_inode_dirty - internal function
|
|
* @inode: inode to mark
|
|
* @flags: what kind of dirty (i.e. I_DIRTY_SYNC)
|
|
* Mark an inode as dirty. Callers should use mark_inode_dirty or
|
|
* mark_inode_dirty_sync.
|
|
*
|
|
* Put the inode on the super block's dirty list.
|
|
*
|
|
* CAREFUL! We mark it dirty unconditionally, but move it onto the
|
|
* dirty list only if it is hashed or if it refers to a blockdev.
|
|
* If it was not hashed, it will never be added to the dirty list
|
|
* even if it is later hashed, as it will have been marked dirty already.
|
|
*
|
|
* In short, make sure you hash any inodes _before_ you start marking
|
|
* them dirty.
|
|
*
|
|
* Note that for blockdevs, inode->dirtied_when represents the dirtying time of
|
|
* the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of
|
|
* the kernel-internal blockdev inode represents the dirtying time of the
|
|
* blockdev's pages. This is why for I_DIRTY_PAGES we always use
|
|
* page->mapping->host, so the page-dirtying time is recorded in the internal
|
|
* blockdev inode.
|
|
*/
|
|
void __mark_inode_dirty(struct inode *inode, int flags)
|
|
{
|
|
struct super_block *sb = inode->i_sb;
|
|
struct backing_dev_info *bdi = NULL;
|
|
|
|
/*
|
|
* Don't do this for I_DIRTY_PAGES - that doesn't actually
|
|
* dirty the inode itself
|
|
*/
|
|
if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) {
|
|
if (sb->s_op->dirty_inode)
|
|
sb->s_op->dirty_inode(inode, flags);
|
|
}
|
|
|
|
/*
|
|
* make sure that changes are seen by all cpus before we test i_state
|
|
* -- mikulas
|
|
*/
|
|
smp_mb();
|
|
|
|
/* avoid the locking if we can */
|
|
if ((inode->i_state & flags) == flags)
|
|
return;
|
|
|
|
if (unlikely(block_dump))
|
|
block_dump___mark_inode_dirty(inode);
|
|
|
|
spin_lock(&inode->i_lock);
|
|
if ((inode->i_state & flags) != flags) {
|
|
const int was_dirty = inode->i_state & I_DIRTY;
|
|
|
|
inode->i_state |= flags;
|
|
|
|
/*
|
|
* If the inode is being synced, just update its dirty state.
|
|
* The unlocker will place the inode on the appropriate
|
|
* superblock list, based upon its state.
|
|
*/
|
|
if (inode->i_state & I_SYNC)
|
|
goto out_unlock_inode;
|
|
|
|
/*
|
|
* Only add valid (hashed) inodes to the superblock's
|
|
* dirty list. Add blockdev inodes as well.
|
|
*/
|
|
if (!S_ISBLK(inode->i_mode)) {
|
|
if (inode_unhashed(inode))
|
|
goto out_unlock_inode;
|
|
}
|
|
if (inode->i_state & I_FREEING)
|
|
goto out_unlock_inode;
|
|
|
|
/*
|
|
* If the inode was already on b_dirty/b_io/b_more_io, don't
|
|
* reposition it (that would break b_dirty time-ordering).
|
|
*/
|
|
if (!was_dirty) {
|
|
bool wakeup_bdi = false;
|
|
bdi = inode_to_bdi(inode);
|
|
|
|
if (bdi_cap_writeback_dirty(bdi)) {
|
|
WARN(!test_bit(BDI_registered, &bdi->state),
|
|
"bdi-%s not registered\n", bdi->name);
|
|
|
|
/*
|
|
* If this is the first dirty inode for this
|
|
* bdi, we have to wake-up the corresponding
|
|
* bdi thread to make sure background
|
|
* write-back happens later.
|
|
*/
|
|
if (!wb_has_dirty_io(&bdi->wb))
|
|
wakeup_bdi = true;
|
|
}
|
|
|
|
spin_unlock(&inode->i_lock);
|
|
spin_lock(&bdi->wb.list_lock);
|
|
inode->dirtied_when = jiffies;
|
|
list_move(&inode->i_wb_list, &bdi->wb.b_dirty);
|
|
spin_unlock(&bdi->wb.list_lock);
|
|
|
|
if (wakeup_bdi)
|
|
bdi_wakeup_thread_delayed(bdi);
|
|
return;
|
|
}
|
|
}
|
|
out_unlock_inode:
|
|
spin_unlock(&inode->i_lock);
|
|
|
|
}
|
|
EXPORT_SYMBOL(__mark_inode_dirty);
|
|
|
|
/*
|
|
* Write out a superblock's list of dirty inodes. A wait will be performed
|
|
* upon no inodes, all inodes or the final one, depending upon sync_mode.
|
|
*
|
|
* If older_than_this is non-NULL, then only write out inodes which
|
|
* had their first dirtying at a time earlier than *older_than_this.
|
|
*
|
|
* If `bdi' is non-zero then we're being asked to writeback a specific queue.
|
|
* This function assumes that the blockdev superblock's inodes are backed by
|
|
* a variety of queues, so all inodes are searched. For other superblocks,
|
|
* assume that all inodes are backed by the same queue.
|
|
*
|
|
* The inodes to be written are parked on bdi->b_io. They are moved back onto
|
|
* bdi->b_dirty as they are selected for writing. This way, none can be missed
|
|
* on the writer throttling path, and we get decent balancing between many
|
|
* throttled threads: we don't want them all piling up on inode_sync_wait.
|
|
*/
|
|
static void wait_sb_inodes(struct super_block *sb)
|
|
{
|
|
struct inode *inode, *old_inode = NULL;
|
|
|
|
/*
|
|
* We need to be protected against the filesystem going from
|
|
* r/o to r/w or vice versa.
|
|
*/
|
|
WARN_ON(!rwsem_is_locked(&sb->s_umount));
|
|
|
|
spin_lock(&inode_sb_list_lock);
|
|
|
|
/*
|
|
* Data integrity sync. Must wait for all pages under writeback,
|
|
* because there may have been pages dirtied before our sync
|
|
* call, but which had writeout started before we write it out.
|
|
* In which case, the inode may not be on the dirty list, but
|
|
* we still have to wait for that writeout.
|
|
*/
|
|
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
|
|
struct address_space *mapping = inode->i_mapping;
|
|
|
|
spin_lock(&inode->i_lock);
|
|
if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
|
|
(mapping->nrpages == 0)) {
|
|
spin_unlock(&inode->i_lock);
|
|
continue;
|
|
}
|
|
__iget(inode);
|
|
spin_unlock(&inode->i_lock);
|
|
spin_unlock(&inode_sb_list_lock);
|
|
|
|
/*
|
|
* We hold a reference to 'inode' so it couldn't have been
|
|
* removed from s_inodes list while we dropped the
|
|
* inode_sb_list_lock. We cannot iput the inode now as we can
|
|
* be holding the last reference and we cannot iput it under
|
|
* inode_sb_list_lock. So we keep the reference and iput it
|
|
* later.
|
|
*/
|
|
iput(old_inode);
|
|
old_inode = inode;
|
|
|
|
filemap_fdatawait(mapping);
|
|
|
|
cond_resched();
|
|
|
|
spin_lock(&inode_sb_list_lock);
|
|
}
|
|
spin_unlock(&inode_sb_list_lock);
|
|
iput(old_inode);
|
|
}
|
|
|
|
/**
|
|
* writeback_inodes_sb_nr - writeback dirty inodes from given super_block
|
|
* @sb: the superblock
|
|
* @nr: the number of pages to write
|
|
*
|
|
* Start writeback on some inodes on this super_block. No guarantees are made
|
|
* on how many (if any) will be written, and this function does not wait
|
|
* for IO completion of submitted IO.
|
|
*/
|
|
void writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr)
|
|
{
|
|
DECLARE_COMPLETION_ONSTACK(done);
|
|
struct wb_writeback_work work = {
|
|
.sb = sb,
|
|
.sync_mode = WB_SYNC_NONE,
|
|
.tagged_writepages = 1,
|
|
.done = &done,
|
|
.nr_pages = nr,
|
|
};
|
|
|
|
WARN_ON(!rwsem_is_locked(&sb->s_umount));
|
|
bdi_queue_work(sb->s_bdi, &work);
|
|
wait_for_completion(&done);
|
|
}
|
|
EXPORT_SYMBOL(writeback_inodes_sb_nr);
|
|
|
|
/**
|
|
* writeback_inodes_sb - writeback dirty inodes from given super_block
|
|
* @sb: the superblock
|
|
*
|
|
* Start writeback on some inodes on this super_block. No guarantees are made
|
|
* on how many (if any) will be written, and this function does not wait
|
|
* for IO completion of submitted IO.
|
|
*/
|
|
void writeback_inodes_sb(struct super_block *sb)
|
|
{
|
|
return writeback_inodes_sb_nr(sb, get_nr_dirty_pages());
|
|
}
|
|
EXPORT_SYMBOL(writeback_inodes_sb);
|
|
|
|
/**
|
|
* writeback_inodes_sb_if_idle - start writeback if none underway
|
|
* @sb: the superblock
|
|
*
|
|
* Invoke writeback_inodes_sb if no writeback is currently underway.
|
|
* Returns 1 if writeback was started, 0 if not.
|
|
*/
|
|
int writeback_inodes_sb_if_idle(struct super_block *sb)
|
|
{
|
|
if (!writeback_in_progress(sb->s_bdi)) {
|
|
down_read(&sb->s_umount);
|
|
writeback_inodes_sb(sb);
|
|
up_read(&sb->s_umount);
|
|
return 1;
|
|
} else
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(writeback_inodes_sb_if_idle);
|
|
|
|
/**
|
|
* writeback_inodes_sb_if_idle - start writeback if none underway
|
|
* @sb: the superblock
|
|
* @nr: the number of pages to write
|
|
*
|
|
* Invoke writeback_inodes_sb if no writeback is currently underway.
|
|
* Returns 1 if writeback was started, 0 if not.
|
|
*/
|
|
int writeback_inodes_sb_nr_if_idle(struct super_block *sb,
|
|
unsigned long nr)
|
|
{
|
|
if (!writeback_in_progress(sb->s_bdi)) {
|
|
down_read(&sb->s_umount);
|
|
writeback_inodes_sb_nr(sb, nr);
|
|
up_read(&sb->s_umount);
|
|
return 1;
|
|
} else
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(writeback_inodes_sb_nr_if_idle);
|
|
|
|
/**
|
|
* sync_inodes_sb - sync sb inode pages
|
|
* @sb: the superblock
|
|
*
|
|
* This function writes and waits on any dirty inode belonging to this
|
|
* super_block.
|
|
*/
|
|
void sync_inodes_sb(struct super_block *sb)
|
|
{
|
|
DECLARE_COMPLETION_ONSTACK(done);
|
|
struct wb_writeback_work work = {
|
|
.sb = sb,
|
|
.sync_mode = WB_SYNC_ALL,
|
|
.nr_pages = LONG_MAX,
|
|
.range_cyclic = 0,
|
|
.done = &done,
|
|
};
|
|
|
|
WARN_ON(!rwsem_is_locked(&sb->s_umount));
|
|
|
|
bdi_queue_work(sb->s_bdi, &work);
|
|
wait_for_completion(&done);
|
|
|
|
wait_sb_inodes(sb);
|
|
}
|
|
EXPORT_SYMBOL(sync_inodes_sb);
|
|
|
|
/**
|
|
* write_inode_now - write an inode to disk
|
|
* @inode: inode to write to disk
|
|
* @sync: whether the write should be synchronous or not
|
|
*
|
|
* This function commits an inode to disk immediately if it is dirty. This is
|
|
* primarily needed by knfsd.
|
|
*
|
|
* The caller must either have a ref on the inode or must have set I_WILL_FREE.
|
|
*/
|
|
int write_inode_now(struct inode *inode, int sync)
|
|
{
|
|
struct bdi_writeback *wb = &inode_to_bdi(inode)->wb;
|
|
int ret;
|
|
struct writeback_control wbc = {
|
|
.nr_to_write = LONG_MAX,
|
|
.sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE,
|
|
.range_start = 0,
|
|
.range_end = LLONG_MAX,
|
|
};
|
|
|
|
if (!mapping_cap_writeback_dirty(inode->i_mapping))
|
|
wbc.nr_to_write = 0;
|
|
|
|
might_sleep();
|
|
spin_lock(&wb->list_lock);
|
|
spin_lock(&inode->i_lock);
|
|
ret = writeback_single_inode(inode, wb, &wbc);
|
|
spin_unlock(&inode->i_lock);
|
|
spin_unlock(&wb->list_lock);
|
|
if (sync)
|
|
inode_sync_wait(inode);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(write_inode_now);
|
|
|
|
/**
|
|
* sync_inode - write an inode and its pages to disk.
|
|
* @inode: the inode to sync
|
|
* @wbc: controls the writeback mode
|
|
*
|
|
* sync_inode() will write an inode and its pages to disk. It will also
|
|
* correctly update the inode on its superblock's dirty inode lists and will
|
|
* update inode->i_state.
|
|
*
|
|
* The caller must have a ref on the inode.
|
|
*/
|
|
int sync_inode(struct inode *inode, struct writeback_control *wbc)
|
|
{
|
|
struct bdi_writeback *wb = &inode_to_bdi(inode)->wb;
|
|
int ret;
|
|
|
|
spin_lock(&wb->list_lock);
|
|
spin_lock(&inode->i_lock);
|
|
ret = writeback_single_inode(inode, wb, wbc);
|
|
spin_unlock(&inode->i_lock);
|
|
spin_unlock(&wb->list_lock);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(sync_inode);
|
|
|
|
/**
|
|
* sync_inode_metadata - write an inode to disk
|
|
* @inode: the inode to sync
|
|
* @wait: wait for I/O to complete.
|
|
*
|
|
* Write an inode to disk and adjust its dirty state after completion.
|
|
*
|
|
* Note: only writes the actual inode, no associated data or other metadata.
|
|
*/
|
|
int sync_inode_metadata(struct inode *inode, int wait)
|
|
{
|
|
struct writeback_control wbc = {
|
|
.sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_NONE,
|
|
.nr_to_write = 0, /* metadata-only */
|
|
};
|
|
|
|
return sync_inode(inode, &wbc);
|
|
}
|
|
EXPORT_SYMBOL(sync_inode_metadata);
|