fs-writeback.c (082439004b31adc146e96e5f1c574dd2b57dcd93) fs-writeback.c (455b2864686d3591b3b2f39eb46290c95f76471f)
1/*
2 * fs/fs-writeback.c
3 *
4 * Copyright (C) 2002, Linus Torvalds.
5 *
6 * Contains all the functions related to writing back and waiting
7 * upon dirty inodes against superblocks, and writing back dirty
8 * pages against inodes. ie: data writeback. Writeout of the

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21#include <linux/fs.h>
22#include <linux/mm.h>
23#include <linux/kthread.h>
24#include <linux/freezer.h>
25#include <linux/writeback.h>
26#include <linux/blkdev.h>
27#include <linux/backing-dev.h>
28#include <linux/buffer_head.h>
1/*
2 * fs/fs-writeback.c
3 *
4 * Copyright (C) 2002, Linus Torvalds.
5 *
6 * Contains all the functions related to writing back and waiting
7 * upon dirty inodes against superblocks, and writing back dirty
8 * pages against inodes. ie: data writeback. Writeout of the

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21#include <linux/fs.h>
22#include <linux/mm.h>
23#include <linux/kthread.h>
24#include <linux/freezer.h>
25#include <linux/writeback.h>
26#include <linux/blkdev.h>
27#include <linux/backing-dev.h>
28#include <linux/buffer_head.h>
29#include <linux/tracepoint.h>
29#include "internal.h"
30
30#include "internal.h"
31
31#define inode_to_bdi(inode) ((inode)->i_mapping->backing_dev_info)
32
33/*
32/*
34 * We don't actually have pdflush, but this one is exported though /proc...
35 */
36int nr_pdflush_threads;
37
38/*
39 * Passed into wb_writeback(), essentially a subset of writeback_control
40 */
41struct wb_writeback_work {
42 long nr_pages;
43 struct super_block *sb;
44 enum writeback_sync_modes sync_mode;
45 unsigned int for_kupdate:1;
46 unsigned int range_cyclic:1;
47 unsigned int for_background:1;
48
49 struct list_head list; /* pending work list */
50 struct completion *done; /* set if the caller waits */
51};
52
33 * Passed into wb_writeback(), essentially a subset of writeback_control
34 */
35struct wb_writeback_work {
36 long nr_pages;
37 struct super_block *sb;
38 enum writeback_sync_modes sync_mode;
39 unsigned int for_kupdate:1;
40 unsigned int range_cyclic:1;
41 unsigned int for_background:1;
42
43 struct list_head list; /* pending work list */
44 struct completion *done; /* set if the caller waits */
45};
46
47/*
48 * Include the creation of the trace points after defining the
49 * wb_writeback_work structure so that the definition remains local to this
50 * file.
51 */
52#define CREATE_TRACE_POINTS
53#include <trace/events/writeback.h>
54
55#define inode_to_bdi(inode) ((inode)->i_mapping->backing_dev_info)
56
57/*
58 * We don't actually have pdflush, but this one is exported though /proc...
59 */
60int nr_pdflush_threads;
61
53/**
54 * writeback_in_progress - determine whether there is writeback in progress
55 * @bdi: the device's backing_dev_info structure.
56 *
57 * Determine whether there is writeback waiting to be handled against a
58 * backing device.
59 */
60int writeback_in_progress(struct backing_dev_info *bdi)
61{
62 return !list_empty(&bdi->work_list);
63}
64
65static void bdi_queue_work(struct backing_dev_info *bdi,
66 struct wb_writeback_work *work)
67{
62/**
63 * writeback_in_progress - determine whether there is writeback in progress
64 * @bdi: the device's backing_dev_info structure.
65 *
66 * Determine whether there is writeback waiting to be handled against a
67 * backing device.
68 */
69int writeback_in_progress(struct backing_dev_info *bdi)
70{
71 return !list_empty(&bdi->work_list);
72}
73
74static void bdi_queue_work(struct backing_dev_info *bdi,
75 struct wb_writeback_work *work)
76{
77 trace_writeback_queue(bdi, work);
78
68 spin_lock(&bdi->wb_lock);
69 list_add_tail(&work->list, &bdi->work_list);
70 spin_unlock(&bdi->wb_lock);
71
72 /*
73 * If the default thread isn't there, make sure we add it. When
74 * it gets created and wakes up, we'll run this work.
75 */
76 if (unlikely(!bdi->wb.task)) {
79 spin_lock(&bdi->wb_lock);
80 list_add_tail(&work->list, &bdi->work_list);
81 spin_unlock(&bdi->wb_lock);
82
83 /*
84 * If the default thread isn't there, make sure we add it. When
85 * it gets created and wakes up, we'll run this work.
86 */
87 if (unlikely(!bdi->wb.task)) {
88 trace_writeback_nothread(bdi, work);
77 wake_up_process(default_backing_dev_info.wb.task);
78 } else {
79 struct bdi_writeback *wb = &bdi->wb;
80
81 if (wb->task)
82 wake_up_process(wb->task);
83 }
84}

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90 struct wb_writeback_work *work;
91
92 /*
93 * This is WB_SYNC_NONE writeback, so if allocation fails just
94 * wakeup the thread for old dirty data writeback
95 */
96 work = kzalloc(sizeof(*work), GFP_ATOMIC);
97 if (!work) {
89 wake_up_process(default_backing_dev_info.wb.task);
90 } else {
91 struct bdi_writeback *wb = &bdi->wb;
92
93 if (wb->task)
94 wake_up_process(wb->task);
95 }
96}

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102 struct wb_writeback_work *work;
103
104 /*
105 * This is WB_SYNC_NONE writeback, so if allocation fails just
106 * wakeup the thread for old dirty data writeback
107 */
108 work = kzalloc(sizeof(*work), GFP_ATOMIC);
109 if (!work) {
98 if (bdi->wb.task)
110 if (bdi->wb.task) {
111 trace_writeback_nowork(bdi);
99 wake_up_process(bdi->wb.task);
112 wake_up_process(bdi->wb.task);
113 }
100 return;
101 }
102
103 work->sync_mode = WB_SYNC_NONE;
104 work->nr_pages = nr_pages;
105 work->range_cyclic = range_cyclic;
106 work->for_background = for_background;
107

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746 while ((work = get_next_work_item(bdi, wb)) != NULL) {
747 /*
748 * Override sync mode, in case we must wait for completion
749 * because this thread is exiting now.
750 */
751 if (force_wait)
752 work->sync_mode = WB_SYNC_ALL;
753
114 return;
115 }
116
117 work->sync_mode = WB_SYNC_NONE;
118 work->nr_pages = nr_pages;
119 work->range_cyclic = range_cyclic;
120 work->for_background = for_background;
121

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760 while ((work = get_next_work_item(bdi, wb)) != NULL) {
761 /*
762 * Override sync mode, in case we must wait for completion
763 * because this thread is exiting now.
764 */
765 if (force_wait)
766 work->sync_mode = WB_SYNC_ALL;
767
768 trace_writeback_exec(bdi, work);
769
754 wrote += wb_writeback(wb, work);
755
756 /*
757 * Notify the caller of completion if this is a synchronous
758 * work item, otherwise just free it.
759 */
760 if (work->done)
761 complete(work->done);

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800
801 /*
802 * Clear pending bit and wakeup anybody waiting to tear us down
803 */
804 clear_bit(BDI_pending, &bdi->state);
805 smp_mb__after_clear_bit();
806 wake_up_bit(&bdi->state, BDI_pending);
807
770 wrote += wb_writeback(wb, work);
771
772 /*
773 * Notify the caller of completion if this is a synchronous
774 * work item, otherwise just free it.
775 */
776 if (work->done)
777 complete(work->done);

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816
817 /*
818 * Clear pending bit and wakeup anybody waiting to tear us down
819 */
820 clear_bit(BDI_pending, &bdi->state);
821 smp_mb__after_clear_bit();
822 wake_up_bit(&bdi->state, BDI_pending);
823
824 trace_writeback_thread_start(bdi);
825
808 while (!kthread_should_stop()) {
809 pages_written = wb_do_writeback(wb, 0);
810
826 while (!kthread_should_stop()) {
827 pages_written = wb_do_writeback(wb, 0);
828
829 trace_writeback_pages_written(pages_written);
830
811 if (pages_written)
812 last_active = jiffies;
813 else if (wait_jiffies != -1UL) {
814 unsigned long max_idle;
815
816 /*
817 * Longest period of inactivity that we tolerate. If we
818 * see dirty data again later, the task will get

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840 wb->task = NULL;
841
842 /*
843 * Flush any work that raced with us exiting. No new work
844 * will be added, since this bdi isn't discoverable anymore.
845 */
846 if (!list_empty(&bdi->work_list))
847 wb_do_writeback(wb, 1);
831 if (pages_written)
832 last_active = jiffies;
833 else if (wait_jiffies != -1UL) {
834 unsigned long max_idle;
835
836 /*
837 * Longest period of inactivity that we tolerate. If we
838 * see dirty data again later, the task will get

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860 wb->task = NULL;
861
862 /*
863 * Flush any work that raced with us exiting. No new work
864 * will be added, since this bdi isn't discoverable anymore.
865 */
866 if (!list_empty(&bdi->work_list))
867 wb_do_writeback(wb, 1);
868
869 trace_writeback_thread_stop(bdi);
848 return 0;
849}
850
851
852/*
853 * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back
854 * the whole world.
855 */

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871}
872
873
874/*
875 * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back
876 * the whole world.
877 */

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