#include <linux/wait.h> #include <linux/backing-dev.h> #include <linux/fs.h> #include <linux/sched.h> #include <linux/module.h> #include <linux/writeback.h> #include <linux/device.h> static struct class *bdi_class; #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; long background_thresh; long dirty_thresh; long bdi_thresh; get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi); #define K(x) ((x) << (PAGE_SHIFT - 10)) seq_printf(m, "BdiWriteback: %8lu kB\n" "BdiReclaimable: %8lu kB\n" "BdiDirtyThresh: %8lu kB\n" "DirtyThresh: %8lu kB\n" "BackgroundThresh: %8lu kB\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)); #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"); bdi_class->dev_attrs = bdi_dev_attrs; bdi_debug_init(); return 0; } postcore_initcall(bdi_class_init); int bdi_register(struct backing_dev_info *bdi, struct device *parent, const char *fmt, ...) { va_list args; int ret = 0; struct device *dev; if (bdi->dev) /* The driver needs to use separate queues per device */ goto exit; va_start(args, fmt); dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args); va_end(args); if (IS_ERR(dev)) { ret = PTR_ERR(dev); goto exit; } bdi->dev = dev; bdi_debug_register(bdi, dev_name(dev)); exit: return ret; } 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); void bdi_unregister(struct backing_dev_info *bdi) { if (bdi->dev) { bdi_debug_unregister(bdi); device_unregister(bdi->dev); bdi->dev = NULL; } } EXPORT_SYMBOL(bdi_unregister); int bdi_init(struct backing_dev_info *bdi) { int i; int err; bdi->dev = NULL; bdi->min_ratio = 0; bdi->max_ratio = 100; bdi->max_prop_frac = PROP_FRAC_BASE; for (i = 0; i < NR_BDI_STAT_ITEMS; i++) { err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0); if (err) goto err; } bdi->dirty_exceeded = 0; 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; 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); static wait_queue_head_t congestion_wqh[2] = { __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) }; void clear_bdi_congested(struct backing_dev_info *bdi, int rw) { enum bdi_state bit; wait_queue_head_t *wqh = &congestion_wqh[rw]; bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested; clear_bit(bit, &bdi->state); 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 rw) { enum bdi_state bit; bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested; set_bit(bit, &bdi->state); } EXPORT_SYMBOL(set_bdi_congested); /** * congestion_wait - wait for a backing_dev to become uncongested * @rw: READ or WRITE * @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 rw, long timeout) { long ret; DEFINE_WAIT(wait); wait_queue_head_t *wqh = &congestion_wqh[rw]; prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); ret = io_schedule_timeout(timeout); finish_wait(wqh, &wait); return ret; } EXPORT_SYMBOL(congestion_wait);