| |
| #include <linux/wait.h> |
| #include <linux/backing-dev.h> |
| #include <linux/kthread.h> |
| #include <linux/freezer.h> |
| #include <linux/fs.h> |
| #include <linux/pagemap.h> |
| #include <linux/mm.h> |
| #include <linux/sched.h> |
| #include <linux/module.h> |
| #include <linux/writeback.h> |
| #include <linux/device.h> |
| #include <trace/events/writeback.h> |
| |
| static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0); |
| |
| struct backing_dev_info default_backing_dev_info = { |
| .name = "default", |
| .ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE, |
| .state = 0, |
| .capabilities = BDI_CAP_MAP_COPY, |
| }; |
| EXPORT_SYMBOL_GPL(default_backing_dev_info); |
| |
| struct backing_dev_info noop_backing_dev_info = { |
| .name = "noop", |
| .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
| }; |
| EXPORT_SYMBOL_GPL(noop_backing_dev_info); |
| |
| static struct class *bdi_class; |
| |
| /* |
| * bdi_lock protects updates to bdi_list and bdi_pending_list, as well as |
| * reader side protection for bdi_pending_list. bdi_list has RCU reader side |
| * locking. |
| */ |
| DEFINE_SPINLOCK(bdi_lock); |
| LIST_HEAD(bdi_list); |
| LIST_HEAD(bdi_pending_list); |
| |
| static struct task_struct *sync_supers_tsk; |
| static struct timer_list sync_supers_timer; |
| |
| static int bdi_sync_supers(void *); |
| static void sync_supers_timer_fn(unsigned long); |
| |
| void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2) |
| { |
| if (wb1 < wb2) { |
| spin_lock(&wb1->list_lock); |
| spin_lock_nested(&wb2->list_lock, 1); |
| } else { |
| spin_lock(&wb2->list_lock); |
| spin_lock_nested(&wb1->list_lock, 1); |
| } |
| } |
| |
| #ifdef CONFIG_DEBUG_FS |
| #include <linux/debugfs.h> |
| #include <linux/seq_file.h> |
| |
| static struct dentry *bdi_debug_root; |
| |
| static void bdi_debug_init(void) |
| { |
| bdi_debug_root = debugfs_create_dir("bdi", NULL); |
| } |
| |
| static int bdi_debug_stats_show(struct seq_file *m, void *v) |
| { |
| struct backing_dev_info *bdi = m->private; |
| struct bdi_writeback *wb = &bdi->wb; |
| unsigned long background_thresh; |
| unsigned long dirty_thresh; |
| unsigned long bdi_thresh; |
| unsigned long nr_dirty, nr_io, nr_more_io; |
| struct inode *inode; |
| |
| nr_dirty = nr_io = nr_more_io = 0; |
| spin_lock(&wb->list_lock); |
| list_for_each_entry(inode, &wb->b_dirty, i_wb_list) |
| nr_dirty++; |
| list_for_each_entry(inode, &wb->b_io, i_wb_list) |
| nr_io++; |
| list_for_each_entry(inode, &wb->b_more_io, i_wb_list) |
| nr_more_io++; |
| spin_unlock(&wb->list_lock); |
| |
| global_dirty_limits(&background_thresh, &dirty_thresh); |
| bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh); |
| |
| #define K(x) ((x) << (PAGE_SHIFT - 10)) |
| seq_printf(m, |
| "BdiWriteback: %10lu kB\n" |
| "BdiReclaimable: %10lu kB\n" |
| "BdiDirtyThresh: %10lu kB\n" |
| "DirtyThresh: %10lu kB\n" |
| "BackgroundThresh: %10lu kB\n" |
| "BdiDirtied: %10lu kB\n" |
| "BdiWritten: %10lu kB\n" |
| "BdiWriteBandwidth: %10lu kBps\n" |
| "b_dirty: %10lu\n" |
| "b_io: %10lu\n" |
| "b_more_io: %10lu\n" |
| "bdi_list: %10u\n" |
| "state: %10lx\n", |
| (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)), |
| (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)), |
| K(bdi_thresh), |
| K(dirty_thresh), |
| K(background_thresh), |
| (unsigned long) K(bdi_stat(bdi, BDI_DIRTIED)), |
| (unsigned long) K(bdi_stat(bdi, BDI_WRITTEN)), |
| (unsigned long) K(bdi->write_bandwidth), |
| nr_dirty, |
| nr_io, |
| nr_more_io, |
| !list_empty(&bdi->bdi_list), bdi->state); |
| #undef K |
| |
| return 0; |
| } |
| |
| static int bdi_debug_stats_open(struct inode *inode, struct file *file) |
| { |
| return single_open(file, bdi_debug_stats_show, inode->i_private); |
| } |
| |
| static const struct file_operations bdi_debug_stats_fops = { |
| .open = bdi_debug_stats_open, |
| .read = seq_read, |
| .llseek = seq_lseek, |
| .release = single_release, |
| }; |
| |
| static void bdi_debug_register(struct backing_dev_info *bdi, const char *name) |
| { |
| bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root); |
| bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir, |
| bdi, &bdi_debug_stats_fops); |
| } |
| |
| static void bdi_debug_unregister(struct backing_dev_info *bdi) |
| { |
| debugfs_remove(bdi->debug_stats); |
| debugfs_remove(bdi->debug_dir); |
| } |
| #else |
| static inline void bdi_debug_init(void) |
| { |
| } |
| static inline void bdi_debug_register(struct backing_dev_info *bdi, |
| const char *name) |
| { |
| } |
| static inline void bdi_debug_unregister(struct backing_dev_info *bdi) |
| { |
| } |
| #endif |
| |
| static ssize_t read_ahead_kb_store(struct device *dev, |
| struct device_attribute *attr, |
| const char *buf, size_t count) |
| { |
| struct backing_dev_info *bdi = dev_get_drvdata(dev); |
| char *end; |
| unsigned long read_ahead_kb; |
| ssize_t ret = -EINVAL; |
| |
| read_ahead_kb = simple_strtoul(buf, &end, 10); |
| if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { |
| bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10); |
| ret = count; |
| } |
| return ret; |
| } |
| |
| #define K(pages) ((pages) << (PAGE_SHIFT - 10)) |
| |
| #define BDI_SHOW(name, expr) \ |
| static ssize_t name##_show(struct device *dev, \ |
| struct device_attribute *attr, char *page) \ |
| { \ |
| struct backing_dev_info *bdi = dev_get_drvdata(dev); \ |
| \ |
| return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \ |
| } |
| |
| BDI_SHOW(read_ahead_kb, K(bdi->ra_pages)) |
| |
| static ssize_t min_ratio_store(struct device *dev, |
| struct device_attribute *attr, const char *buf, size_t count) |
| { |
| struct backing_dev_info *bdi = dev_get_drvdata(dev); |
| char *end; |
| unsigned int ratio; |
| ssize_t ret = -EINVAL; |
| |
| ratio = simple_strtoul(buf, &end, 10); |
| if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { |
| ret = bdi_set_min_ratio(bdi, ratio); |
| if (!ret) |
| ret = count; |
| } |
| return ret; |
| } |
| BDI_SHOW(min_ratio, bdi->min_ratio) |
| |
| static ssize_t max_ratio_store(struct device *dev, |
| struct device_attribute *attr, const char *buf, size_t count) |
| { |
| struct backing_dev_info *bdi = dev_get_drvdata(dev); |
| char *end; |
| unsigned int ratio; |
| ssize_t ret = -EINVAL; |
| |
| ratio = simple_strtoul(buf, &end, 10); |
| if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { |
| ret = bdi_set_max_ratio(bdi, ratio); |
| if (!ret) |
| ret = count; |
| } |
| return ret; |
| } |
| BDI_SHOW(max_ratio, bdi->max_ratio) |
| |
| #define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store) |
| |
| static struct device_attribute bdi_dev_attrs[] = { |
| __ATTR_RW(read_ahead_kb), |
| __ATTR_RW(min_ratio), |
| __ATTR_RW(max_ratio), |
| __ATTR_NULL, |
| }; |
| |
| static __init int bdi_class_init(void) |
| { |
| bdi_class = class_create(THIS_MODULE, "bdi"); |
| if (IS_ERR(bdi_class)) |
| return PTR_ERR(bdi_class); |
| |
| bdi_class->dev_attrs = bdi_dev_attrs; |
| bdi_debug_init(); |
| return 0; |
| } |
| postcore_initcall(bdi_class_init); |
| |
| static int __init default_bdi_init(void) |
| { |
| int err; |
| |
| sync_supers_tsk = kthread_run(bdi_sync_supers, NULL, "sync_supers"); |
| BUG_ON(IS_ERR(sync_supers_tsk)); |
| |
| setup_timer(&sync_supers_timer, sync_supers_timer_fn, 0); |
| bdi_arm_supers_timer(); |
| |
| err = bdi_init(&default_backing_dev_info); |
| if (!err) |
| bdi_register(&default_backing_dev_info, NULL, "default"); |
| err = bdi_init(&noop_backing_dev_info); |
| |
| return err; |
| } |
| subsys_initcall(default_bdi_init); |
| |
| int bdi_has_dirty_io(struct backing_dev_info *bdi) |
| { |
| return wb_has_dirty_io(&bdi->wb); |
| } |
| |
| /* |
| * kupdated() used to do this. We cannot do it from the bdi_forker_thread() |
| * or we risk deadlocking on ->s_umount. The longer term solution would be |
| * to implement sync_supers_bdi() or similar and simply do it from the |
| * bdi writeback thread individually. |
| */ |
| static int bdi_sync_supers(void *unused) |
| { |
| set_user_nice(current, 0); |
| |
| while (!kthread_should_stop()) { |
| set_current_state(TASK_INTERRUPTIBLE); |
| schedule(); |
| |
| /* |
| * Do this periodically, like kupdated() did before. |
| */ |
| sync_supers(); |
| } |
| |
| return 0; |
| } |
| |
| void bdi_arm_supers_timer(void) |
| { |
| unsigned long next; |
| |
| if (!dirty_writeback_interval) |
| return; |
| |
| next = msecs_to_jiffies(dirty_writeback_interval * 10) + jiffies; |
| mod_timer(&sync_supers_timer, round_jiffies_up(next)); |
| } |
| |
| static void sync_supers_timer_fn(unsigned long unused) |
| { |
| wake_up_process(sync_supers_tsk); |
| bdi_arm_supers_timer(); |
| } |
| |
| static void wakeup_timer_fn(unsigned long data) |
| { |
| struct backing_dev_info *bdi = (struct backing_dev_info *)data; |
| |
| spin_lock_bh(&bdi->wb_lock); |
| if (bdi->wb.task) { |
| trace_writeback_wake_thread(bdi); |
| wake_up_process(bdi->wb.task); |
| } else { |
| /* |
| * When bdi tasks are inactive for long time, they are killed. |
| * In this case we have to wake-up the forker thread which |
| * should create and run the bdi thread. |
| */ |
| trace_writeback_wake_forker_thread(bdi); |
| wake_up_process(default_backing_dev_info.wb.task); |
| } |
| spin_unlock_bh(&bdi->wb_lock); |
| } |
| |
| /* |
| * This function is used when the first inode for this bdi is marked dirty. It |
| * wakes-up the corresponding bdi thread which should then take care of the |
| * periodic background write-out of dirty inodes. Since the write-out would |
| * starts only 'dirty_writeback_interval' centisecs from now anyway, we just |
| * set up a timer which wakes the bdi thread up later. |
| * |
| * Note, we wouldn't bother setting up the timer, but this function is on the |
| * fast-path (used by '__mark_inode_dirty()'), so we save few context switches |
| * by delaying the wake-up. |
| */ |
| void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi) |
| { |
| unsigned long timeout; |
| |
| timeout = msecs_to_jiffies(dirty_writeback_interval * 10); |
| mod_timer(&bdi->wb.wakeup_timer, jiffies + timeout); |
| } |
| |
| /* |
| * Calculate the longest interval (jiffies) bdi threads are allowed to be |
| * inactive. |
| */ |
| static unsigned long bdi_longest_inactive(void) |
| { |
| unsigned long interval; |
| |
| interval = msecs_to_jiffies(dirty_writeback_interval * 10); |
| return max(5UL * 60 * HZ, interval); |
| } |
| |
| /* |
| * Clear pending bit and wakeup anybody waiting for flusher thread creation or |
| * shutdown |
| */ |
| static void bdi_clear_pending(struct backing_dev_info *bdi) |
| { |
| clear_bit(BDI_pending, &bdi->state); |
| smp_mb__after_clear_bit(); |
| wake_up_bit(&bdi->state, BDI_pending); |
| } |
| |
| static int bdi_forker_thread(void *ptr) |
| { |
| struct bdi_writeback *me = ptr; |
| |
| current->flags |= PF_SWAPWRITE; |
| set_freezable(); |
| |
| /* |
| * Our parent may run at a different priority, just set us to normal |
| */ |
| set_user_nice(current, 0); |
| |
| for (;;) { |
| struct task_struct *task = NULL; |
| struct backing_dev_info *bdi; |
| enum { |
| NO_ACTION, /* Nothing to do */ |
| FORK_THREAD, /* Fork bdi thread */ |
| KILL_THREAD, /* Kill inactive bdi thread */ |
| } action = NO_ACTION; |
| |
| /* |
| * Temporary measure, we want to make sure we don't see |
| * dirty data on the default backing_dev_info |
| */ |
| if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list)) { |
| del_timer(&me->wakeup_timer); |
| wb_do_writeback(me, 0); |
| } |
| |
| spin_lock_bh(&bdi_lock); |
| /* |
| * In the following loop we are going to check whether we have |
| * some work to do without any synchronization with tasks |
| * waking us up to do work for them. So we have to set task |
| * state already here so that we don't miss wakeups coming |
| * after we verify some condition. |
| */ |
| set_current_state(TASK_INTERRUPTIBLE); |
| |
| list_for_each_entry(bdi, &bdi_list, bdi_list) { |
| bool have_dirty_io; |
| |
| if (!bdi_cap_writeback_dirty(bdi) || |
| bdi_cap_flush_forker(bdi)) |
| continue; |
| |
| WARN(!test_bit(BDI_registered, &bdi->state), |
| "bdi %p/%s is not registered!\n", bdi, bdi->name); |
| |
| have_dirty_io = !list_empty(&bdi->work_list) || |
| wb_has_dirty_io(&bdi->wb); |
| |
| /* |
| * If the bdi has work to do, but the thread does not |
| * exist - create it. |
| */ |
| if (!bdi->wb.task && have_dirty_io) { |
| /* |
| * Set the pending bit - if someone will try to |
| * unregister this bdi - it'll wait on this bit. |
| */ |
| set_bit(BDI_pending, &bdi->state); |
| action = FORK_THREAD; |
| break; |
| } |
| |
| spin_lock(&bdi->wb_lock); |
| |
| /* |
| * If there is no work to do and the bdi thread was |
| * inactive long enough - kill it. The wb_lock is taken |
| * to make sure no-one adds more work to this bdi and |
| * wakes the bdi thread up. |
| */ |
| if (bdi->wb.task && !have_dirty_io && |
| time_after(jiffies, bdi->wb.last_active + |
| bdi_longest_inactive())) { |
| task = bdi->wb.task; |
| bdi->wb.task = NULL; |
| spin_unlock(&bdi->wb_lock); |
| set_bit(BDI_pending, &bdi->state); |
| action = KILL_THREAD; |
| break; |
| } |
| spin_unlock(&bdi->wb_lock); |
| } |
| spin_unlock_bh(&bdi_lock); |
| |
| /* Keep working if default bdi still has things to do */ |
| if (!list_empty(&me->bdi->work_list)) |
| __set_current_state(TASK_RUNNING); |
| |
| switch (action) { |
| case FORK_THREAD: |
| __set_current_state(TASK_RUNNING); |
| task = kthread_create(bdi_writeback_thread, &bdi->wb, |
| "flush-%s", dev_name(bdi->dev)); |
| if (IS_ERR(task)) { |
| /* |
| * If thread creation fails, force writeout of |
| * the bdi from the thread. Hopefully 1024 is |
| * large enough for efficient IO. |
| */ |
| writeback_inodes_wb(&bdi->wb, 1024); |
| } else { |
| /* |
| * The spinlock makes sure we do not lose |
| * wake-ups when racing with 'bdi_queue_work()'. |
| * And as soon as the bdi thread is visible, we |
| * can start it. |
| */ |
| spin_lock_bh(&bdi->wb_lock); |
| bdi->wb.task = task; |
| spin_unlock_bh(&bdi->wb_lock); |
| wake_up_process(task); |
| } |
| bdi_clear_pending(bdi); |
| break; |
| |
| case KILL_THREAD: |
| __set_current_state(TASK_RUNNING); |
| kthread_stop(task); |
| bdi_clear_pending(bdi); |
| break; |
| |
| case NO_ACTION: |
| if (!wb_has_dirty_io(me) || !dirty_writeback_interval) |
| /* |
| * There are no dirty data. The only thing we |
| * should now care about is checking for |
| * inactive bdi threads and killing them. Thus, |
| * let's sleep for longer time, save energy and |
| * be friendly for battery-driven devices. |
| */ |
| schedule_timeout(bdi_longest_inactive()); |
| else |
| schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10)); |
| try_to_freeze(); |
| break; |
| } |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * Remove bdi from bdi_list, and ensure that it is no longer visible |
| */ |
| static void bdi_remove_from_list(struct backing_dev_info *bdi) |
| { |
| spin_lock_bh(&bdi_lock); |
| list_del_rcu(&bdi->bdi_list); |
| spin_unlock_bh(&bdi_lock); |
| |
| synchronize_rcu_expedited(); |
| } |
| |
| int bdi_register(struct backing_dev_info *bdi, struct device *parent, |
| const char *fmt, ...) |
| { |
| va_list args; |
| struct device *dev; |
| |
| if (bdi->dev) /* The driver needs to use separate queues per device */ |
| return 0; |
| |
| va_start(args, fmt); |
| dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args); |
| va_end(args); |
| if (IS_ERR(dev)) |
| return PTR_ERR(dev); |
| |
| bdi->dev = dev; |
| |
| /* |
| * Just start the forker thread for our default backing_dev_info, |
| * and add other bdi's to the list. They will get a thread created |
| * on-demand when they need it. |
| */ |
| if (bdi_cap_flush_forker(bdi)) { |
| struct bdi_writeback *wb = &bdi->wb; |
| |
| wb->task = kthread_run(bdi_forker_thread, wb, "bdi-%s", |
| dev_name(dev)); |
| if (IS_ERR(wb->task)) |
| return PTR_ERR(wb->task); |
| } |
| |
| bdi_debug_register(bdi, dev_name(dev)); |
| set_bit(BDI_registered, &bdi->state); |
| |
| spin_lock_bh(&bdi_lock); |
| list_add_tail_rcu(&bdi->bdi_list, &bdi_list); |
| spin_unlock_bh(&bdi_lock); |
| |
| trace_writeback_bdi_register(bdi); |
| return 0; |
| } |
| EXPORT_SYMBOL(bdi_register); |
| |
| int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev) |
| { |
| return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev)); |
| } |
| EXPORT_SYMBOL(bdi_register_dev); |
| |
| /* |
| * Remove bdi from the global list and shutdown any threads we have running |
| */ |
| static void bdi_wb_shutdown(struct backing_dev_info *bdi) |
| { |
| if (!bdi_cap_writeback_dirty(bdi)) |
| return; |
| |
| /* |
| * Make sure nobody finds us on the bdi_list anymore |
| */ |
| bdi_remove_from_list(bdi); |
| |
| /* |
| * If setup is pending, wait for that to complete first |
| */ |
| wait_on_bit(&bdi->state, BDI_pending, bdi_sched_wait, |
| TASK_UNINTERRUPTIBLE); |
| |
| /* |
| * Finally, kill the kernel thread. We don't need to be RCU |
| * safe anymore, since the bdi is gone from visibility. Force |
| * unfreeze of the thread before calling kthread_stop(), otherwise |
| * it would never exet if it is currently stuck in the refrigerator. |
| */ |
| if (bdi->wb.task) { |
| thaw_process(bdi->wb.task); |
| kthread_stop(bdi->wb.task); |
| } |
| } |
| |
| /* |
| * This bdi is going away now, make sure that no super_blocks point to it |
| */ |
| static void bdi_prune_sb(struct backing_dev_info *bdi) |
| { |
| struct super_block *sb; |
| |
| spin_lock(&sb_lock); |
| list_for_each_entry(sb, &super_blocks, s_list) { |
| if (sb->s_bdi == bdi) |
| sb->s_bdi = &default_backing_dev_info; |
| } |
| spin_unlock(&sb_lock); |
| } |
| |
| void bdi_unregister(struct backing_dev_info *bdi) |
| { |
| if (bdi->dev) { |
| bdi_set_min_ratio(bdi, 0); |
| trace_writeback_bdi_unregister(bdi); |
| bdi_prune_sb(bdi); |
| del_timer_sync(&bdi->wb.wakeup_timer); |
| |
| if (!bdi_cap_flush_forker(bdi)) |
| bdi_wb_shutdown(bdi); |
| bdi_debug_unregister(bdi); |
| device_unregister(bdi->dev); |
| bdi->dev = NULL; |
| } |
| } |
| EXPORT_SYMBOL(bdi_unregister); |
| |
| static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi) |
| { |
| memset(wb, 0, sizeof(*wb)); |
| |
| wb->bdi = bdi; |
| wb->last_old_flush = jiffies; |
| INIT_LIST_HEAD(&wb->b_dirty); |
| INIT_LIST_HEAD(&wb->b_io); |
| INIT_LIST_HEAD(&wb->b_more_io); |
| spin_lock_init(&wb->list_lock); |
| setup_timer(&wb->wakeup_timer, wakeup_timer_fn, (unsigned long)bdi); |
| } |
| |
| /* |
| * Initial write bandwidth: 100 MB/s |
| */ |
| #define INIT_BW (100 << (20 - PAGE_SHIFT)) |
| |
| int bdi_init(struct backing_dev_info *bdi) |
| { |
| int i, err; |
| |
| bdi->dev = NULL; |
| |
| bdi->min_ratio = 0; |
| bdi->max_ratio = 100; |
| bdi->max_prop_frac = PROP_FRAC_BASE; |
| spin_lock_init(&bdi->wb_lock); |
| INIT_LIST_HEAD(&bdi->bdi_list); |
| INIT_LIST_HEAD(&bdi->work_list); |
| |
| bdi_wb_init(&bdi->wb, bdi); |
| |
| for (i = 0; i < NR_BDI_STAT_ITEMS; i++) { |
| err = percpu_counter_init(&bdi->bdi_stat[i], 0); |
| if (err) |
| goto err; |
| } |
| |
| bdi->dirty_exceeded = 0; |
| |
| bdi->bw_time_stamp = jiffies; |
| bdi->written_stamp = 0; |
| |
| bdi->dirty_ratelimit = INIT_BW; |
| bdi->write_bandwidth = INIT_BW; |
| bdi->avg_write_bandwidth = INIT_BW; |
| |
| err = prop_local_init_percpu(&bdi->completions); |
| |
| if (err) { |
| err: |
| while (i--) |
| percpu_counter_destroy(&bdi->bdi_stat[i]); |
| } |
| |
| return err; |
| } |
| EXPORT_SYMBOL(bdi_init); |
| |
| void bdi_destroy(struct backing_dev_info *bdi) |
| { |
| int i; |
| |
| /* |
| * Splice our entries to the default_backing_dev_info, if this |
| * bdi disappears |
| */ |
| if (bdi_has_dirty_io(bdi)) { |
| struct bdi_writeback *dst = &default_backing_dev_info.wb; |
| |
| bdi_lock_two(&bdi->wb, dst); |
| list_splice(&bdi->wb.b_dirty, &dst->b_dirty); |
| list_splice(&bdi->wb.b_io, &dst->b_io); |
| list_splice(&bdi->wb.b_more_io, &dst->b_more_io); |
| spin_unlock(&bdi->wb.list_lock); |
| spin_unlock(&dst->list_lock); |
| } |
| |
| bdi_unregister(bdi); |
| |
| for (i = 0; i < NR_BDI_STAT_ITEMS; i++) |
| percpu_counter_destroy(&bdi->bdi_stat[i]); |
| |
| prop_local_destroy_percpu(&bdi->completions); |
| } |
| EXPORT_SYMBOL(bdi_destroy); |
| |
| /* |
| * For use from filesystems to quickly init and register a bdi associated |
| * with dirty writeback |
| */ |
| int bdi_setup_and_register(struct backing_dev_info *bdi, char *name, |
| unsigned int cap) |
| { |
| char tmp[32]; |
| int err; |
| |
| bdi->name = name; |
| bdi->capabilities = cap; |
| err = bdi_init(bdi); |
| if (err) |
| return err; |
| |
| sprintf(tmp, "%.28s%s", name, "-%d"); |
| err = bdi_register(bdi, NULL, tmp, atomic_long_inc_return(&bdi_seq)); |
| if (err) { |
| bdi_destroy(bdi); |
| return err; |
| } |
| |
| return 0; |
| } |
| EXPORT_SYMBOL(bdi_setup_and_register); |
| |
| static wait_queue_head_t congestion_wqh[2] = { |
| __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), |
| __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) |
| }; |
| static atomic_t nr_bdi_congested[2]; |
| |
| void clear_bdi_congested(struct backing_dev_info *bdi, int sync) |
| { |
| enum bdi_state bit; |
| wait_queue_head_t *wqh = &congestion_wqh[sync]; |
| |
| bit = sync ? BDI_sync_congested : BDI_async_congested; |
| if (test_and_clear_bit(bit, &bdi->state)) |
| atomic_dec(&nr_bdi_congested[sync]); |
| smp_mb__after_clear_bit(); |
| if (waitqueue_active(wqh)) |
| wake_up(wqh); |
| } |
| EXPORT_SYMBOL(clear_bdi_congested); |
| |
| void set_bdi_congested(struct backing_dev_info *bdi, int sync) |
| { |
| enum bdi_state bit; |
| |
| bit = sync ? BDI_sync_congested : BDI_async_congested; |
| if (!test_and_set_bit(bit, &bdi->state)) |
| atomic_inc(&nr_bdi_congested[sync]); |
| } |
| EXPORT_SYMBOL(set_bdi_congested); |
| |
| /** |
| * congestion_wait - wait for a backing_dev to become uncongested |
| * @sync: SYNC or ASYNC IO |
| * @timeout: timeout in jiffies |
| * |
| * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit |
| * write congestion. If no backing_devs are congested then just wait for the |
| * next write to be completed. |
| */ |
| long congestion_wait(int sync, long timeout) |
| { |
| long ret; |
| unsigned long start = jiffies; |
| DEFINE_WAIT(wait); |
| wait_queue_head_t *wqh = &congestion_wqh[sync]; |
| |
| prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); |
| ret = io_schedule_timeout(timeout); |
| finish_wait(wqh, &wait); |
| |
| trace_writeback_congestion_wait(jiffies_to_usecs(timeout), |
| jiffies_to_usecs(jiffies - start)); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL(congestion_wait); |
| |
| /** |
| * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a zone to complete writes |
| * @zone: A zone to check if it is heavily congested |
| * @sync: SYNC or ASYNC IO |
| * @timeout: timeout in jiffies |
| * |
| * In the event of a congested backing_dev (any backing_dev) and the given |
| * @zone has experienced recent congestion, this waits for up to @timeout |
| * jiffies for either a BDI to exit congestion of the given @sync queue |
| * or a write to complete. |
| * |
| * In the absence of zone congestion, cond_resched() is called to yield |
| * the processor if necessary but otherwise does not sleep. |
| * |
| * The return value is 0 if the sleep is for the full timeout. Otherwise, |
| * it is the number of jiffies that were still remaining when the function |
| * returned. return_value == timeout implies the function did not sleep. |
| */ |
| long wait_iff_congested(struct zone *zone, int sync, long timeout) |
| { |
| long ret; |
| unsigned long start = jiffies; |
| DEFINE_WAIT(wait); |
| wait_queue_head_t *wqh = &congestion_wqh[sync]; |
| |
| /* |
| * If there is no congestion, or heavy congestion is not being |
| * encountered in the current zone, yield if necessary instead |
| * of sleeping on the congestion queue |
| */ |
| if (atomic_read(&nr_bdi_congested[sync]) == 0 || |
| !zone_is_reclaim_congested(zone)) { |
| cond_resched(); |
| |
| /* In case we scheduled, work out time remaining */ |
| ret = timeout - (jiffies - start); |
| if (ret < 0) |
| ret = 0; |
| |
| goto out; |
| } |
| |
| /* Sleep until uncongested or a write happens */ |
| prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); |
| ret = io_schedule_timeout(timeout); |
| finish_wait(wqh, &wait); |
| |
| out: |
| trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout), |
| jiffies_to_usecs(jiffies - start)); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL(wait_iff_congested); |