mm/backing-dev.c - third_party/linux - Git at Google


 #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;

 	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);

	#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;

	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);