304 lines
6.9 KiB
C
304 lines
6.9 KiB
C
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#include <linux/wait.h>
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#include <linux/backing-dev.h>
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#include <linux/fs.h>
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#include <linux/sched.h>
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#include <linux/module.h>
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#include <linux/writeback.h>
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#include <linux/device.h>
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static struct class *bdi_class;
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#ifdef CONFIG_DEBUG_FS
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#include <linux/debugfs.h>
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#include <linux/seq_file.h>
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static struct dentry *bdi_debug_root;
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static void bdi_debug_init(void)
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{
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bdi_debug_root = debugfs_create_dir("bdi", NULL);
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}
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static int bdi_debug_stats_show(struct seq_file *m, void *v)
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{
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struct backing_dev_info *bdi = m->private;
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long background_thresh;
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long dirty_thresh;
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long bdi_thresh;
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get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi);
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#define K(x) ((x) << (PAGE_SHIFT - 10))
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seq_printf(m,
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"BdiWriteback: %8lu kB\n"
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"BdiReclaimable: %8lu kB\n"
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"BdiDirtyThresh: %8lu kB\n"
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"DirtyThresh: %8lu kB\n"
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"BackgroundThresh: %8lu kB\n",
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(unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
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(unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
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K(bdi_thresh),
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K(dirty_thresh),
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K(background_thresh));
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#undef K
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return 0;
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}
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static int bdi_debug_stats_open(struct inode *inode, struct file *file)
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{
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return single_open(file, bdi_debug_stats_show, inode->i_private);
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}
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static const struct file_operations bdi_debug_stats_fops = {
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.open = bdi_debug_stats_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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};
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static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
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{
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bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
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bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir,
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bdi, &bdi_debug_stats_fops);
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}
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static void bdi_debug_unregister(struct backing_dev_info *bdi)
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{
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debugfs_remove(bdi->debug_stats);
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debugfs_remove(bdi->debug_dir);
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}
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#else
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static inline void bdi_debug_init(void)
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{
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}
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static inline void bdi_debug_register(struct backing_dev_info *bdi,
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const char *name)
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{
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}
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static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
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{
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}
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#endif
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static ssize_t read_ahead_kb_store(struct device *dev,
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struct device_attribute *attr,
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const char *buf, size_t count)
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{
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struct backing_dev_info *bdi = dev_get_drvdata(dev);
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char *end;
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unsigned long read_ahead_kb;
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ssize_t ret = -EINVAL;
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read_ahead_kb = simple_strtoul(buf, &end, 10);
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if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
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bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
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ret = count;
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}
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return ret;
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}
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#define K(pages) ((pages) << (PAGE_SHIFT - 10))
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#define BDI_SHOW(name, expr) \
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static ssize_t name##_show(struct device *dev, \
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struct device_attribute *attr, char *page) \
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{ \
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struct backing_dev_info *bdi = dev_get_drvdata(dev); \
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\
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return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \
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}
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BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
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static ssize_t min_ratio_store(struct device *dev,
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struct device_attribute *attr, const char *buf, size_t count)
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{
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struct backing_dev_info *bdi = dev_get_drvdata(dev);
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char *end;
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unsigned int ratio;
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ssize_t ret = -EINVAL;
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ratio = simple_strtoul(buf, &end, 10);
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if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
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ret = bdi_set_min_ratio(bdi, ratio);
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if (!ret)
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ret = count;
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}
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return ret;
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}
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BDI_SHOW(min_ratio, bdi->min_ratio)
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static ssize_t max_ratio_store(struct device *dev,
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struct device_attribute *attr, const char *buf, size_t count)
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{
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struct backing_dev_info *bdi = dev_get_drvdata(dev);
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char *end;
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unsigned int ratio;
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ssize_t ret = -EINVAL;
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ratio = simple_strtoul(buf, &end, 10);
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if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
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ret = bdi_set_max_ratio(bdi, ratio);
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if (!ret)
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ret = count;
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}
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return ret;
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}
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BDI_SHOW(max_ratio, bdi->max_ratio)
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#define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store)
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static struct device_attribute bdi_dev_attrs[] = {
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__ATTR_RW(read_ahead_kb),
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__ATTR_RW(min_ratio),
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__ATTR_RW(max_ratio),
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__ATTR_NULL,
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};
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static __init int bdi_class_init(void)
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{
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bdi_class = class_create(THIS_MODULE, "bdi");
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bdi_class->dev_attrs = bdi_dev_attrs;
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bdi_debug_init();
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return 0;
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}
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postcore_initcall(bdi_class_init);
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int bdi_register(struct backing_dev_info *bdi, struct device *parent,
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const char *fmt, ...)
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{
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va_list args;
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int ret = 0;
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struct device *dev;
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va_start(args, fmt);
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dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args);
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va_end(args);
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if (IS_ERR(dev)) {
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ret = PTR_ERR(dev);
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goto exit;
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}
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bdi->dev = dev;
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bdi_debug_register(bdi, dev_name(dev));
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exit:
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return ret;
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}
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EXPORT_SYMBOL(bdi_register);
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int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
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{
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return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev));
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}
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EXPORT_SYMBOL(bdi_register_dev);
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void bdi_unregister(struct backing_dev_info *bdi)
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{
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if (bdi->dev) {
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bdi_debug_unregister(bdi);
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device_unregister(bdi->dev);
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bdi->dev = NULL;
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}
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}
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EXPORT_SYMBOL(bdi_unregister);
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int bdi_init(struct backing_dev_info *bdi)
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{
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int i;
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int err;
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bdi->dev = NULL;
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bdi->min_ratio = 0;
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bdi->max_ratio = 100;
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bdi->max_prop_frac = PROP_FRAC_BASE;
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for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
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err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0);
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if (err)
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goto err;
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}
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bdi->dirty_exceeded = 0;
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err = prop_local_init_percpu(&bdi->completions);
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if (err) {
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err:
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while (i--)
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percpu_counter_destroy(&bdi->bdi_stat[i]);
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}
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return err;
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}
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EXPORT_SYMBOL(bdi_init);
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void bdi_destroy(struct backing_dev_info *bdi)
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{
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int i;
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bdi_unregister(bdi);
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for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
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percpu_counter_destroy(&bdi->bdi_stat[i]);
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prop_local_destroy_percpu(&bdi->completions);
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}
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EXPORT_SYMBOL(bdi_destroy);
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static wait_queue_head_t congestion_wqh[2] = {
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__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
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__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
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};
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void clear_bdi_congested(struct backing_dev_info *bdi, int rw)
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{
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enum bdi_state bit;
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wait_queue_head_t *wqh = &congestion_wqh[rw];
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bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
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clear_bit(bit, &bdi->state);
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smp_mb__after_clear_bit();
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if (waitqueue_active(wqh))
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wake_up(wqh);
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}
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EXPORT_SYMBOL(clear_bdi_congested);
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void set_bdi_congested(struct backing_dev_info *bdi, int rw)
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{
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enum bdi_state bit;
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bit = (rw == WRITE) ? BDI_write_congested : BDI_read_congested;
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set_bit(bit, &bdi->state);
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}
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EXPORT_SYMBOL(set_bdi_congested);
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/**
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* congestion_wait - wait for a backing_dev to become uncongested
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* @rw: READ or WRITE
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* @timeout: timeout in jiffies
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*
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* Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
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* write congestion. If no backing_devs are congested then just wait for the
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* next write to be completed.
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*/
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long congestion_wait(int rw, long timeout)
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{
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long ret;
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DEFINE_WAIT(wait);
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wait_queue_head_t *wqh = &congestion_wqh[rw];
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prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
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ret = io_schedule_timeout(timeout);
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finish_wait(wqh, &wait);
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return ret;
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}
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EXPORT_SYMBOL(congestion_wait);
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