| |
| #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> |
| |
| 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. bdi_list has RCU reader side |
| * locking. |
| */ |
| DEFINE_SPINLOCK(bdi_lock); |
| LIST_HEAD(bdi_list); |
| |
| /* bdi_wq serves all asynchronous writeback tasks */ |
| struct workqueue_struct *bdi_wq; |
| |
| #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 wb_thresh; |
| unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time; |
| struct inode *inode; |
| |
| nr_dirty = nr_io = nr_more_io = nr_dirty_time = 0; |
| spin_lock(&wb->list_lock); |
| list_for_each_entry(inode, &wb->b_dirty, i_io_list) |
| nr_dirty++; |
| list_for_each_entry(inode, &wb->b_io, i_io_list) |
| nr_io++; |
| list_for_each_entry(inode, &wb->b_more_io, i_io_list) |
| nr_more_io++; |
| list_for_each_entry(inode, &wb->b_dirty_time, i_io_list) |
| if (inode->i_state & I_DIRTY_TIME) |
| nr_dirty_time++; |
| spin_unlock(&wb->list_lock); |
| |
| global_dirty_limits(&background_thresh, &dirty_thresh); |
| wb_thresh = wb_calc_thresh(wb, 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" |
| "b_dirty_time: %10lu\n" |
| "bdi_list: %10u\n" |
| "state: %10lx\n", |
| (unsigned long) K(wb_stat(wb, WB_WRITEBACK)), |
| (unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)), |
| K(wb_thresh), |
| K(dirty_thresh), |
| K(background_thresh), |
| (unsigned long) K(wb_stat(wb, WB_DIRTIED)), |
| (unsigned long) K(wb_stat(wb, WB_WRITTEN)), |
| (unsigned long) K(wb->write_bandwidth), |
| nr_dirty, |
| nr_io, |
| nr_more_io, |
| nr_dirty_time, |
| !list_empty(&bdi->bdi_list), bdi->wb.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 int bdi_debug_register(struct backing_dev_info *bdi, const char *name) |
| { |
| if (!bdi_debug_root) |
| return -ENOMEM; |
| |
| bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root); |
| if (!bdi->debug_dir) |
| return -ENOMEM; |
| |
| bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir, |
| bdi, &bdi_debug_stats_fops); |
| if (!bdi->debug_stats) { |
| debugfs_remove(bdi->debug_dir); |
| return -ENOMEM; |
| } |
| |
| return 0; |
| } |
| |
| 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 int bdi_debug_register(struct backing_dev_info *bdi, |
| const char *name) |
| { |
| return 0; |
| } |
| 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); |
| unsigned long read_ahead_kb; |
| ssize_t ret; |
| |
| ret = kstrtoul(buf, 10, &read_ahead_kb); |
| if (ret < 0) |
| return ret; |
| |
| bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10); |
| |
| return count; |
| } |
| |
| #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); \ |
| } \ |
| static DEVICE_ATTR_RW(name); |
| |
| 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); |
| unsigned int ratio; |
| ssize_t ret; |
| |
| ret = kstrtouint(buf, 10, &ratio); |
| if (ret < 0) |
| return ret; |
| |
| 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); |
| unsigned int ratio; |
| ssize_t ret; |
| |
| ret = kstrtouint(buf, 10, &ratio); |
| if (ret < 0) |
| return ret; |
| |
| ret = bdi_set_max_ratio(bdi, ratio); |
| if (!ret) |
| ret = count; |
| |
| return ret; |
| } |
| BDI_SHOW(max_ratio, bdi->max_ratio) |
| |
| static ssize_t stable_pages_required_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, "%d\n", |
| bdi_cap_stable_pages_required(bdi) ? 1 : 0); |
| } |
| static DEVICE_ATTR_RO(stable_pages_required); |
| |
| static struct attribute *bdi_dev_attrs[] = { |
| &dev_attr_read_ahead_kb.attr, |
| &dev_attr_min_ratio.attr, |
| &dev_attr_max_ratio.attr, |
| &dev_attr_stable_pages_required.attr, |
| NULL, |
| }; |
| ATTRIBUTE_GROUPS(bdi_dev); |
| |
| 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_groups = bdi_dev_groups; |
| bdi_debug_init(); |
| |
| return 0; |
| } |
| postcore_initcall(bdi_class_init); |
| |
| static int bdi_init(struct backing_dev_info *bdi); |
| |
| static int __init default_bdi_init(void) |
| { |
| int err; |
| |
| bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_FREEZABLE | |
| WQ_UNBOUND | WQ_SYSFS, 0); |
| if (!bdi_wq) |
| return -ENOMEM; |
| |
| err = bdi_init(&noop_backing_dev_info); |
| |
| return err; |
| } |
| subsys_initcall(default_bdi_init); |
| |
| /* |
| * This function is used when the first inode for this wb 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. |
| * |
| * We have to be careful not to postpone flush work if it is scheduled for |
| * earlier. Thus we use queue_delayed_work(). |
| */ |
| void wb_wakeup_delayed(struct bdi_writeback *wb) |
| { |
| unsigned long timeout; |
| |
| timeout = msecs_to_jiffies(dirty_writeback_interval * 10); |
| spin_lock_bh(&wb->work_lock); |
| if (test_bit(WB_registered, &wb->state)) |
| queue_delayed_work(bdi_wq, &wb->dwork, timeout); |
| spin_unlock_bh(&wb->work_lock); |
| } |
| |
| /* |
| * Initial write bandwidth: 100 MB/s |
| */ |
| #define INIT_BW (100 << (20 - PAGE_SHIFT)) |
| |
| static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi, |
| int blkcg_id, gfp_t gfp) |
| { |
| int i, err; |
| |
| memset(wb, 0, sizeof(*wb)); |
| |
| if (wb != &bdi->wb) |
| bdi_get(bdi); |
| 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); |
| INIT_LIST_HEAD(&wb->b_dirty_time); |
| spin_lock_init(&wb->list_lock); |
| |
| wb->bw_time_stamp = jiffies; |
| wb->balanced_dirty_ratelimit = INIT_BW; |
| wb->dirty_ratelimit = INIT_BW; |
| wb->write_bandwidth = INIT_BW; |
| wb->avg_write_bandwidth = INIT_BW; |
| |
| spin_lock_init(&wb->work_lock); |
| INIT_LIST_HEAD(&wb->work_list); |
| INIT_DELAYED_WORK(&wb->dwork, wb_workfn); |
| wb->dirty_sleep = jiffies; |
| |
| wb->congested = wb_congested_get_create(bdi, blkcg_id, gfp); |
| if (!wb->congested) { |
| err = -ENOMEM; |
| goto out_put_bdi; |
| } |
| |
| err = fprop_local_init_percpu(&wb->completions, gfp); |
| if (err) |
| goto out_put_cong; |
| |
| for (i = 0; i < NR_WB_STAT_ITEMS; i++) { |
| err = percpu_counter_init(&wb->stat[i], 0, gfp); |
| if (err) |
| goto out_destroy_stat; |
| } |
| |
| return 0; |
| |
| out_destroy_stat: |
| while (i--) |
| percpu_counter_destroy(&wb->stat[i]); |
| fprop_local_destroy_percpu(&wb->completions); |
| out_put_cong: |
| wb_congested_put(wb->congested); |
| out_put_bdi: |
| if (wb != &bdi->wb) |
| bdi_put(bdi); |
| return err; |
| } |
| |
| static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb); |
| |
| /* |
| * Remove bdi from the global list and shutdown any threads we have running |
| */ |
| static void wb_shutdown(struct bdi_writeback *wb) |
| { |
| /* Make sure nobody queues further work */ |
| spin_lock_bh(&wb->work_lock); |
| if (!test_and_clear_bit(WB_registered, &wb->state)) { |
| spin_unlock_bh(&wb->work_lock); |
| /* |
| * Wait for wb shutdown to finish if someone else is just |
| * running wb_shutdown(). Otherwise we could proceed to wb / |
| * bdi destruction before wb_shutdown() is finished. |
| */ |
| wait_on_bit(&wb->state, WB_shutting_down, TASK_UNINTERRUPTIBLE); |
| return; |
| } |
| set_bit(WB_shutting_down, &wb->state); |
| spin_unlock_bh(&wb->work_lock); |
| |
| cgwb_remove_from_bdi_list(wb); |
| /* |
| * Drain work list and shutdown the delayed_work. !WB_registered |
| * tells wb_workfn() that @wb is dying and its work_list needs to |
| * be drained no matter what. |
| */ |
| mod_delayed_work(bdi_wq, &wb->dwork, 0); |
| flush_delayed_work(&wb->dwork); |
| WARN_ON(!list_empty(&wb->work_list)); |
| /* |
| * Make sure bit gets cleared after shutdown is finished. Matches with |
| * the barrier provided by test_and_clear_bit() above. |
| */ |
| smp_wmb(); |
| clear_bit(WB_shutting_down, &wb->state); |
| } |
| |
| static void wb_exit(struct bdi_writeback *wb) |
| { |
| int i; |
| |
| WARN_ON(delayed_work_pending(&wb->dwork)); |
| |
| for (i = 0; i < NR_WB_STAT_ITEMS; i++) |
| percpu_counter_destroy(&wb->stat[i]); |
| |
| fprop_local_destroy_percpu(&wb->completions); |
| wb_congested_put(wb->congested); |
| if (wb != &wb->bdi->wb) |
| bdi_put(wb->bdi); |
| } |
| |
| #ifdef CONFIG_CGROUP_WRITEBACK |
| |
| #include <linux/memcontrol.h> |
| |
| /* |
| * cgwb_lock protects bdi->cgwb_tree, bdi->cgwb_congested_tree, |
| * blkcg->cgwb_list, and memcg->cgwb_list. bdi->cgwb_tree is also RCU |
| * protected. |
| */ |
| static DEFINE_SPINLOCK(cgwb_lock); |
| |
| /** |
| * wb_congested_get_create - get or create a wb_congested |
| * @bdi: associated bdi |
| * @blkcg_id: ID of the associated blkcg |
| * @gfp: allocation mask |
| * |
| * Look up the wb_congested for @blkcg_id on @bdi. If missing, create one. |
| * The returned wb_congested has its reference count incremented. Returns |
| * NULL on failure. |
| */ |
| struct bdi_writeback_congested * |
| wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp) |
| { |
| struct bdi_writeback_congested *new_congested = NULL, *congested; |
| struct rb_node **node, *parent; |
| unsigned long flags; |
| retry: |
| spin_lock_irqsave(&cgwb_lock, flags); |
| |
| node = &bdi->cgwb_congested_tree.rb_node; |
| parent = NULL; |
| |
| while (*node != NULL) { |
| parent = *node; |
| congested = rb_entry(parent, struct bdi_writeback_congested, |
| rb_node); |
| if (congested->blkcg_id < blkcg_id) |
| node = &parent->rb_left; |
| else if (congested->blkcg_id > blkcg_id) |
| node = &parent->rb_right; |
| else |
| goto found; |
| } |
| |
| if (new_congested) { |
| /* !found and storage for new one already allocated, insert */ |
| congested = new_congested; |
| new_congested = NULL; |
| rb_link_node(&congested->rb_node, parent, node); |
| rb_insert_color(&congested->rb_node, &bdi->cgwb_congested_tree); |
| goto found; |
| } |
| |
| spin_unlock_irqrestore(&cgwb_lock, flags); |
| |
| /* allocate storage for new one and retry */ |
| new_congested = kzalloc(sizeof(*new_congested), gfp); |
| if (!new_congested) |
| return NULL; |
| |
| atomic_set(&new_congested->refcnt, 0); |
| new_congested->__bdi = bdi; |
| new_congested->blkcg_id = blkcg_id; |
| goto retry; |
| |
| found: |
| atomic_inc(&congested->refcnt); |
| spin_unlock_irqrestore(&cgwb_lock, flags); |
| kfree(new_congested); |
| return congested; |
| } |
| |
| /** |
| * wb_congested_put - put a wb_congested |
| * @congested: wb_congested to put |
| * |
| * Put @congested and destroy it if the refcnt reaches zero. |
| */ |
| void wb_congested_put(struct bdi_writeback_congested *congested) |
| { |
| unsigned long flags; |
| |
| local_irq_save(flags); |
| if (!atomic_dec_and_lock(&congested->refcnt, &cgwb_lock)) { |
| local_irq_restore(flags); |
| return; |
| } |
| |
| /* bdi might already have been destroyed leaving @congested unlinked */ |
| if (congested->__bdi) { |
| rb_erase(&congested->rb_node, |
| &congested->__bdi->cgwb_congested_tree); |
| congested->__bdi = NULL; |
| } |
| |
| spin_unlock_irqrestore(&cgwb_lock, flags); |
| kfree(congested); |
| } |
| |
| static void cgwb_release_workfn(struct work_struct *work) |
| { |
| struct bdi_writeback *wb = container_of(work, struct bdi_writeback, |
| release_work); |
| |
| wb_shutdown(wb); |
| |
| css_put(wb->memcg_css); |
| css_put(wb->blkcg_css); |
| |
| fprop_local_destroy_percpu(&wb->memcg_completions); |
| percpu_ref_exit(&wb->refcnt); |
| wb_exit(wb); |
| kfree_rcu(wb, rcu); |
| } |
| |
| static void cgwb_release(struct percpu_ref *refcnt) |
| { |
| struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback, |
| refcnt); |
| schedule_work(&wb->release_work); |
| } |
| |
| static void cgwb_kill(struct bdi_writeback *wb) |
| { |
| lockdep_assert_held(&cgwb_lock); |
| |
| WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id)); |
| list_del(&wb->memcg_node); |
| list_del(&wb->blkcg_node); |
| percpu_ref_kill(&wb->refcnt); |
| } |
| |
| static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb) |
| { |
| spin_lock_irq(&cgwb_lock); |
| list_del_rcu(&wb->bdi_node); |
| spin_unlock_irq(&cgwb_lock); |
| } |
| |
| static int cgwb_create(struct backing_dev_info *bdi, |
| struct cgroup_subsys_state *memcg_css, gfp_t gfp) |
| { |
| struct mem_cgroup *memcg; |
| struct cgroup_subsys_state *blkcg_css; |
| struct blkcg *blkcg; |
| struct list_head *memcg_cgwb_list, *blkcg_cgwb_list; |
| struct bdi_writeback *wb; |
| unsigned long flags; |
| int ret = 0; |
| |
| memcg = mem_cgroup_from_css(memcg_css); |
| blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys); |
| blkcg = css_to_blkcg(blkcg_css); |
| memcg_cgwb_list = mem_cgroup_cgwb_list(memcg); |
| blkcg_cgwb_list = &blkcg->cgwb_list; |
| |
| /* look up again under lock and discard on blkcg mismatch */ |
| spin_lock_irqsave(&cgwb_lock, flags); |
| wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); |
| if (wb && wb->blkcg_css != blkcg_css) { |
| cgwb_kill(wb); |
| wb = NULL; |
| } |
| spin_unlock_irqrestore(&cgwb_lock, flags); |
| if (wb) |
| goto out_put; |
| |
| /* need to create a new one */ |
| wb = kmalloc(sizeof(*wb), gfp); |
| if (!wb) { |
| ret = -ENOMEM; |
| goto out_put; |
| } |
| |
| ret = wb_init(wb, bdi, blkcg_css->id, gfp); |
| if (ret) |
| goto err_free; |
| |
| ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp); |
| if (ret) |
| goto err_wb_exit; |
| |
| ret = fprop_local_init_percpu(&wb->memcg_completions, gfp); |
| if (ret) |
| goto err_ref_exit; |
| |
| wb->memcg_css = memcg_css; |
| wb->blkcg_css = blkcg_css; |
| INIT_WORK(&wb->release_work, cgwb_release_workfn); |
| set_bit(WB_registered, &wb->state); |
| |
| /* |
| * The root wb determines the registered state of the whole bdi and |
| * memcg_cgwb_list and blkcg_cgwb_list's next pointers indicate |
| * whether they're still online. Don't link @wb if any is dead. |
| * See wb_memcg_offline() and wb_blkcg_offline(). |
| */ |
| ret = -ENODEV; |
| spin_lock_irqsave(&cgwb_lock, flags); |
| if (test_bit(WB_registered, &bdi->wb.state) && |
| blkcg_cgwb_list->next && memcg_cgwb_list->next) { |
| /* we might have raced another instance of this function */ |
| ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb); |
| if (!ret) { |
| list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list); |
| list_add(&wb->memcg_node, memcg_cgwb_list); |
| list_add(&wb->blkcg_node, blkcg_cgwb_list); |
| css_get(memcg_css); |
| css_get(blkcg_css); |
| } |
| } |
| spin_unlock_irqrestore(&cgwb_lock, flags); |
| if (ret) { |
| if (ret == -EEXIST) |
| ret = 0; |
| goto err_fprop_exit; |
| } |
| goto out_put; |
| |
| err_fprop_exit: |
| fprop_local_destroy_percpu(&wb->memcg_completions); |
| err_ref_exit: |
| percpu_ref_exit(&wb->refcnt); |
| err_wb_exit: |
| wb_exit(wb); |
| err_free: |
| kfree(wb); |
| out_put: |
| css_put(blkcg_css); |
| return ret; |
| } |
| |
| /** |
| * wb_get_create - get wb for a given memcg, create if necessary |
| * @bdi: target bdi |
| * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref) |
| * @gfp: allocation mask to use |
| * |
| * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to |
| * create one. The returned wb has its refcount incremented. |
| * |
| * This function uses css_get() on @memcg_css and thus expects its refcnt |
| * to be positive on invocation. IOW, rcu_read_lock() protection on |
| * @memcg_css isn't enough. try_get it before calling this function. |
| * |
| * A wb is keyed by its associated memcg. As blkcg implicitly enables |
| * memcg on the default hierarchy, memcg association is guaranteed to be |
| * more specific (equal or descendant to the associated blkcg) and thus can |
| * identify both the memcg and blkcg associations. |
| * |
| * Because the blkcg associated with a memcg may change as blkcg is enabled |
| * and disabled closer to root in the hierarchy, each wb keeps track of |
| * both the memcg and blkcg associated with it and verifies the blkcg on |
| * each lookup. On mismatch, the existing wb is discarded and a new one is |
| * created. |
| */ |
| struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi, |
| struct cgroup_subsys_state *memcg_css, |
| gfp_t gfp) |
| { |
| struct bdi_writeback *wb; |
| |
| might_sleep_if(gfpflags_allow_blocking(gfp)); |
| |
| if (!memcg_css->parent) |
| return &bdi->wb; |
| |
| do { |
| rcu_read_lock(); |
| wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); |
| if (wb) { |
| struct cgroup_subsys_state *blkcg_css; |
| |
| /* see whether the blkcg association has changed */ |
| blkcg_css = cgroup_get_e_css(memcg_css->cgroup, |
| &io_cgrp_subsys); |
| if (unlikely(wb->blkcg_css != blkcg_css || |
| !wb_tryget(wb))) |
| wb = NULL; |
| css_put(blkcg_css); |
| } |
| rcu_read_unlock(); |
| } while (!wb && !cgwb_create(bdi, memcg_css, gfp)); |
| |
| return wb; |
| } |
| |
| static int cgwb_bdi_init(struct backing_dev_info *bdi) |
| { |
| int ret; |
| |
| INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC); |
| bdi->cgwb_congested_tree = RB_ROOT; |
| |
| ret = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL); |
| if (!ret) { |
| bdi->wb.memcg_css = &root_mem_cgroup->css; |
| bdi->wb.blkcg_css = blkcg_root_css; |
| } |
| return ret; |
| } |
| |
| static void cgwb_bdi_unregister(struct backing_dev_info *bdi) |
| { |
| struct radix_tree_iter iter; |
| void **slot; |
| struct bdi_writeback *wb; |
| |
| WARN_ON(test_bit(WB_registered, &bdi->wb.state)); |
| |
| spin_lock_irq(&cgwb_lock); |
| radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0) |
| cgwb_kill(*slot); |
| |
| while (!list_empty(&bdi->wb_list)) { |
| wb = list_first_entry(&bdi->wb_list, struct bdi_writeback, |
| bdi_node); |
| spin_unlock_irq(&cgwb_lock); |
| wb_shutdown(wb); |
| spin_lock_irq(&cgwb_lock); |
| } |
| spin_unlock_irq(&cgwb_lock); |
| } |
| |
| /** |
| * wb_memcg_offline - kill all wb's associated with a memcg being offlined |
| * @memcg: memcg being offlined |
| * |
| * Also prevents creation of any new wb's associated with @memcg. |
| */ |
| void wb_memcg_offline(struct mem_cgroup *memcg) |
| { |
| struct list_head *memcg_cgwb_list = mem_cgroup_cgwb_list(memcg); |
| struct bdi_writeback *wb, *next; |
| |
| spin_lock_irq(&cgwb_lock); |
| list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node) |
| cgwb_kill(wb); |
| memcg_cgwb_list->next = NULL; /* prevent new wb's */ |
| spin_unlock_irq(&cgwb_lock); |
| } |
| |
| /** |
| * wb_blkcg_offline - kill all wb's associated with a blkcg being offlined |
| * @blkcg: blkcg being offlined |
| * |
| * Also prevents creation of any new wb's associated with @blkcg. |
| */ |
| void wb_blkcg_offline(struct blkcg *blkcg) |
| { |
| struct bdi_writeback *wb, *next; |
| |
| spin_lock_irq(&cgwb_lock); |
| list_for_each_entry_safe(wb, next, &blkcg->cgwb_list, blkcg_node) |
| cgwb_kill(wb); |
| blkcg->cgwb_list.next = NULL; /* prevent new wb's */ |
| spin_unlock_irq(&cgwb_lock); |
| } |
| |
| static void cgwb_bdi_exit(struct backing_dev_info *bdi) |
| { |
| struct rb_node *rbn; |
| |
| spin_lock_irq(&cgwb_lock); |
| while ((rbn = rb_first(&bdi->cgwb_congested_tree))) { |
| struct bdi_writeback_congested *congested = |
| rb_entry(rbn, struct bdi_writeback_congested, rb_node); |
| |
| rb_erase(rbn, &bdi->cgwb_congested_tree); |
| congested->__bdi = NULL; /* mark @congested unlinked */ |
| } |
| spin_unlock_irq(&cgwb_lock); |
| } |
| |
| static void cgwb_bdi_register(struct backing_dev_info *bdi) |
| { |
| spin_lock_irq(&cgwb_lock); |
| list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list); |
| spin_unlock_irq(&cgwb_lock); |
| } |
| |
| #else /* CONFIG_CGROUP_WRITEBACK */ |
| |
| static int cgwb_bdi_init(struct backing_dev_info *bdi) |
| { |
| int err; |
| |
| bdi->wb_congested = kzalloc(sizeof(*bdi->wb_congested), GFP_KERNEL); |
| if (!bdi->wb_congested) |
| return -ENOMEM; |
| |
| atomic_set(&bdi->wb_congested->refcnt, 1); |
| |
| err = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL); |
| if (err) { |
| wb_congested_put(bdi->wb_congested); |
| return err; |
| } |
| return 0; |
| } |
| |
| static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { } |
| |
| static void cgwb_bdi_exit(struct backing_dev_info *bdi) |
| { |
| wb_congested_put(bdi->wb_congested); |
| } |
| |
| static void cgwb_bdi_register(struct backing_dev_info *bdi) |
| { |
| list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list); |
| } |
| |
| static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb) |
| { |
| list_del_rcu(&wb->bdi_node); |
| } |
| |
| #endif /* CONFIG_CGROUP_WRITEBACK */ |
| |
| static int bdi_init(struct backing_dev_info *bdi) |
| { |
| int ret; |
| |
| bdi->dev = NULL; |
| |
| kref_init(&bdi->refcnt); |
| bdi->min_ratio = 0; |
| bdi->max_ratio = 100; |
| bdi->max_prop_frac = FPROP_FRAC_BASE; |
| INIT_LIST_HEAD(&bdi->bdi_list); |
| INIT_LIST_HEAD(&bdi->wb_list); |
| init_waitqueue_head(&bdi->wb_waitq); |
| |
| ret = cgwb_bdi_init(bdi); |
| |
| return ret; |
| } |
| |
| struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id) |
| { |
| struct backing_dev_info *bdi; |
| |
| bdi = kmalloc_node(sizeof(struct backing_dev_info), |
| gfp_mask | __GFP_ZERO, node_id); |
| if (!bdi) |
| return NULL; |
| |
| if (bdi_init(bdi)) { |
| kfree(bdi); |
| return NULL; |
| } |
| return bdi; |
| } |
| EXPORT_SYMBOL(bdi_alloc_node); |
| |
| int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args) |
| { |
| struct device *dev; |
| |
| if (bdi->dev) /* The driver needs to use separate queues per device */ |
| return 0; |
| |
| dev = device_create_vargs(bdi_class, NULL, MKDEV(0, 0), bdi, fmt, args); |
| if (IS_ERR(dev)) |
| return PTR_ERR(dev); |
| |
| cgwb_bdi_register(bdi); |
| bdi->dev = dev; |
| |
| bdi_debug_register(bdi, dev_name(dev)); |
| set_bit(WB_registered, &bdi->wb.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_va); |
| |
| int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...) |
| { |
| va_list args; |
| int ret; |
| |
| va_start(args, fmt); |
| ret = bdi_register_va(bdi, fmt, args); |
| va_end(args); |
| return ret; |
| } |
| EXPORT_SYMBOL(bdi_register); |
| |
| int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner) |
| { |
| int rc; |
| |
| rc = bdi_register(bdi, "%u:%u", MAJOR(owner->devt), MINOR(owner->devt)); |
| if (rc) |
| return rc; |
| /* Leaking owner reference... */ |
| WARN_ON(bdi->owner); |
| bdi->owner = owner; |
| get_device(owner); |
| return 0; |
| } |
| EXPORT_SYMBOL(bdi_register_owner); |
| |
| /* |
| * 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(); |
| } |
| |
| void bdi_unregister(struct backing_dev_info *bdi) |
| { |
| /* make sure nobody finds us on the bdi_list anymore */ |
| bdi_remove_from_list(bdi); |
| wb_shutdown(&bdi->wb); |
| cgwb_bdi_unregister(bdi); |
| |
| if (bdi->dev) { |
| bdi_debug_unregister(bdi); |
| device_unregister(bdi->dev); |
| bdi->dev = NULL; |
| } |
| |
| if (bdi->owner) { |
| put_device(bdi->owner); |
| bdi->owner = NULL; |
| } |
| } |
| |
| static void release_bdi(struct kref *ref) |
| { |
| struct backing_dev_info *bdi = |
| container_of(ref, struct backing_dev_info, refcnt); |
| |
| if (test_bit(WB_registered, &bdi->wb.state)) |
| bdi_unregister(bdi); |
| WARN_ON_ONCE(bdi->dev); |
| wb_exit(&bdi->wb); |
| cgwb_bdi_exit(bdi); |
| kfree(bdi); |
| } |
| |
| void bdi_put(struct backing_dev_info *bdi) |
| { |
| kref_put(&bdi->refcnt, release_bdi); |
| } |
| EXPORT_SYMBOL(bdi_put); |
| |
| 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_wb_congested[2]; |
| |
| void clear_wb_congested(struct bdi_writeback_congested *congested, int sync) |
| { |
| wait_queue_head_t *wqh = &congestion_wqh[sync]; |
| enum wb_congested_state bit; |
| |
| bit = sync ? WB_sync_congested : WB_async_congested; |
| if (test_and_clear_bit(bit, &congested->state)) |
| atomic_dec(&nr_wb_congested[sync]); |
| smp_mb__after_atomic(); |
| if (waitqueue_active(wqh)) |
| wake_up(wqh); |
| } |
| EXPORT_SYMBOL(clear_wb_congested); |
| |
| void set_wb_congested(struct bdi_writeback_congested *congested, int sync) |
| { |
| enum wb_congested_state bit; |
| |
| bit = sync ? WB_sync_congested : WB_async_congested; |
| if (!test_and_set_bit(bit, &congested->state)) |
| atomic_inc(&nr_wb_congested[sync]); |
| } |
| EXPORT_SYMBOL(set_wb_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 pgdat to complete writes |
| * @pgdat: A pgdat 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 |
| * @pgdat 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 pgdat 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 pglist_data *pgdat, 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 pgdat, yield if necessary instead |
| * of sleeping on the congestion queue |
| */ |
| if (atomic_read(&nr_wb_congested[sync]) == 0 || |
| !test_bit(PGDAT_CONGESTED, &pgdat->flags)) { |
| 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); |