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9af7c7426c
The check for root memcg will be done in wb_get_lookup(), so remove the redundant one to simplify the code. Link: https://lkml.kernel.org/r/20230808084431.1632934-1-alexjlzheng@tencent.com Signed-off-by: Jinliang Zheng <alexjlzheng@tencent.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
1132 lines
28 KiB
C
1132 lines
28 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/blkdev.h>
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#include <linux/wait.h>
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#include <linux/rbtree.h>
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#include <linux/kthread.h>
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#include <linux/backing-dev.h>
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#include <linux/blk-cgroup.h>
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#include <linux/freezer.h>
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#include <linux/fs.h>
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#include <linux/pagemap.h>
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#include <linux/mm.h>
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#include <linux/sched/mm.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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#include <trace/events/writeback.h>
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#include "internal.h"
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struct backing_dev_info noop_backing_dev_info;
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EXPORT_SYMBOL_GPL(noop_backing_dev_info);
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static const char *bdi_unknown_name = "(unknown)";
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/*
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* bdi_lock protects bdi_tree and updates to bdi_list. bdi_list has RCU
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* reader side locking.
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*/
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DEFINE_SPINLOCK(bdi_lock);
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static u64 bdi_id_cursor;
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static struct rb_root bdi_tree = RB_ROOT;
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LIST_HEAD(bdi_list);
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/* bdi_wq serves all asynchronous writeback tasks */
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struct workqueue_struct *bdi_wq;
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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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struct bdi_writeback *wb = &bdi->wb;
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unsigned long background_thresh;
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unsigned long dirty_thresh;
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unsigned long wb_thresh;
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unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time;
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struct inode *inode;
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nr_dirty = nr_io = nr_more_io = nr_dirty_time = 0;
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spin_lock(&wb->list_lock);
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list_for_each_entry(inode, &wb->b_dirty, i_io_list)
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nr_dirty++;
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list_for_each_entry(inode, &wb->b_io, i_io_list)
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nr_io++;
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list_for_each_entry(inode, &wb->b_more_io, i_io_list)
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nr_more_io++;
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list_for_each_entry(inode, &wb->b_dirty_time, i_io_list)
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if (inode->i_state & I_DIRTY_TIME)
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nr_dirty_time++;
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spin_unlock(&wb->list_lock);
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global_dirty_limits(&background_thresh, &dirty_thresh);
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wb_thresh = wb_calc_thresh(wb, dirty_thresh);
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seq_printf(m,
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"BdiWriteback: %10lu kB\n"
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"BdiReclaimable: %10lu kB\n"
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"BdiDirtyThresh: %10lu kB\n"
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"DirtyThresh: %10lu kB\n"
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"BackgroundThresh: %10lu kB\n"
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"BdiDirtied: %10lu kB\n"
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"BdiWritten: %10lu kB\n"
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"BdiWriteBandwidth: %10lu kBps\n"
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"b_dirty: %10lu\n"
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"b_io: %10lu\n"
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"b_more_io: %10lu\n"
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"b_dirty_time: %10lu\n"
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"bdi_list: %10u\n"
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"state: %10lx\n",
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(unsigned long) K(wb_stat(wb, WB_WRITEBACK)),
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(unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)),
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K(wb_thresh),
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K(dirty_thresh),
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K(background_thresh),
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(unsigned long) K(wb_stat(wb, WB_DIRTIED)),
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(unsigned long) K(wb_stat(wb, WB_WRITTEN)),
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(unsigned long) K(wb->write_bandwidth),
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nr_dirty,
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nr_io,
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nr_more_io,
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nr_dirty_time,
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!list_empty(&bdi->bdi_list), bdi->wb.state);
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return 0;
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}
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DEFINE_SHOW_ATTRIBUTE(bdi_debug_stats);
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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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debugfs_create_file("stats", 0444, bdi->debug_dir, bdi,
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&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_recursive(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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unsigned long read_ahead_kb;
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ssize_t ret;
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ret = kstrtoul(buf, 10, &read_ahead_kb);
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if (ret < 0)
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return ret;
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bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
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return count;
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}
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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 *buf) \
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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 sysfs_emit(buf, "%lld\n", (long long)expr); \
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} \
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static DEVICE_ATTR_RW(name);
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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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unsigned int ratio;
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ssize_t ret;
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ret = kstrtouint(buf, 10, &ratio);
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if (ret < 0)
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return ret;
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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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return ret;
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}
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BDI_SHOW(min_ratio, bdi->min_ratio / BDI_RATIO_SCALE)
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static ssize_t min_ratio_fine_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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unsigned int ratio;
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ssize_t ret;
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ret = kstrtouint(buf, 10, &ratio);
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if (ret < 0)
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return ret;
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ret = bdi_set_min_ratio_no_scale(bdi, ratio);
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if (!ret)
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ret = count;
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return ret;
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}
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BDI_SHOW(min_ratio_fine, 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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unsigned int ratio;
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ssize_t ret;
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ret = kstrtouint(buf, 10, &ratio);
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if (ret < 0)
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return ret;
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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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return ret;
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}
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BDI_SHOW(max_ratio, bdi->max_ratio / BDI_RATIO_SCALE)
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static ssize_t max_ratio_fine_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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unsigned int ratio;
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ssize_t ret;
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ret = kstrtouint(buf, 10, &ratio);
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if (ret < 0)
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return ret;
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ret = bdi_set_max_ratio_no_scale(bdi, ratio);
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if (!ret)
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ret = count;
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return ret;
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}
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BDI_SHOW(max_ratio_fine, bdi->max_ratio)
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static ssize_t min_bytes_show(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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struct backing_dev_info *bdi = dev_get_drvdata(dev);
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return sysfs_emit(buf, "%llu\n", bdi_get_min_bytes(bdi));
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}
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static ssize_t min_bytes_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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u64 bytes;
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ssize_t ret;
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ret = kstrtoull(buf, 10, &bytes);
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if (ret < 0)
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return ret;
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ret = bdi_set_min_bytes(bdi, bytes);
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if (!ret)
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ret = count;
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return ret;
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}
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static DEVICE_ATTR_RW(min_bytes);
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static ssize_t max_bytes_show(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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struct backing_dev_info *bdi = dev_get_drvdata(dev);
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return sysfs_emit(buf, "%llu\n", bdi_get_max_bytes(bdi));
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}
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static ssize_t max_bytes_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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u64 bytes;
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ssize_t ret;
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ret = kstrtoull(buf, 10, &bytes);
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if (ret < 0)
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return ret;
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ret = bdi_set_max_bytes(bdi, bytes);
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if (!ret)
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ret = count;
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return ret;
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}
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static DEVICE_ATTR_RW(max_bytes);
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static ssize_t stable_pages_required_show(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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dev_warn_once(dev,
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"the stable_pages_required attribute has been removed. Use the stable_writes queue attribute instead.\n");
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return sysfs_emit(buf, "%d\n", 0);
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}
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static DEVICE_ATTR_RO(stable_pages_required);
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static ssize_t strict_limit_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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unsigned int strict_limit;
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ssize_t ret;
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ret = kstrtouint(buf, 10, &strict_limit);
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if (ret < 0)
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return ret;
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ret = bdi_set_strict_limit(bdi, strict_limit);
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if (!ret)
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ret = count;
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return ret;
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}
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static ssize_t strict_limit_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct backing_dev_info *bdi = dev_get_drvdata(dev);
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return sysfs_emit(buf, "%d\n",
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!!(bdi->capabilities & BDI_CAP_STRICTLIMIT));
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}
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static DEVICE_ATTR_RW(strict_limit);
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static struct attribute *bdi_dev_attrs[] = {
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&dev_attr_read_ahead_kb.attr,
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&dev_attr_min_ratio.attr,
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&dev_attr_min_ratio_fine.attr,
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&dev_attr_max_ratio.attr,
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&dev_attr_max_ratio_fine.attr,
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&dev_attr_min_bytes.attr,
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&dev_attr_max_bytes.attr,
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&dev_attr_stable_pages_required.attr,
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&dev_attr_strict_limit.attr,
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NULL,
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};
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ATTRIBUTE_GROUPS(bdi_dev);
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static const struct class bdi_class = {
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.name = "bdi",
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.dev_groups = bdi_dev_groups,
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};
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static __init int bdi_class_init(void)
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{
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int ret;
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ret = class_register(&bdi_class);
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if (ret)
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return ret;
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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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static int __init default_bdi_init(void)
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{
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bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_UNBOUND |
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WQ_SYSFS, 0);
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if (!bdi_wq)
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return -ENOMEM;
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return 0;
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}
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subsys_initcall(default_bdi_init);
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/*
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* This function is used when the first inode for this wb is marked dirty. It
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* wakes-up the corresponding bdi thread which should then take care of the
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* periodic background write-out of dirty inodes. Since the write-out would
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* starts only 'dirty_writeback_interval' centisecs from now anyway, we just
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* set up a timer which wakes the bdi thread up later.
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*
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* Note, we wouldn't bother setting up the timer, but this function is on the
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* fast-path (used by '__mark_inode_dirty()'), so we save few context switches
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* by delaying the wake-up.
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*
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* We have to be careful not to postpone flush work if it is scheduled for
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* earlier. Thus we use queue_delayed_work().
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*/
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void wb_wakeup_delayed(struct bdi_writeback *wb)
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{
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unsigned long timeout;
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timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
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spin_lock_irq(&wb->work_lock);
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if (test_bit(WB_registered, &wb->state))
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queue_delayed_work(bdi_wq, &wb->dwork, timeout);
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spin_unlock_irq(&wb->work_lock);
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}
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static void wb_update_bandwidth_workfn(struct work_struct *work)
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{
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struct bdi_writeback *wb = container_of(to_delayed_work(work),
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struct bdi_writeback, bw_dwork);
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wb_update_bandwidth(wb);
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}
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/*
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* Initial write bandwidth: 100 MB/s
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*/
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#define INIT_BW (100 << (20 - PAGE_SHIFT))
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static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
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gfp_t gfp)
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{
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int i, err;
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memset(wb, 0, sizeof(*wb));
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wb->bdi = bdi;
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wb->last_old_flush = jiffies;
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INIT_LIST_HEAD(&wb->b_dirty);
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INIT_LIST_HEAD(&wb->b_io);
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INIT_LIST_HEAD(&wb->b_more_io);
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INIT_LIST_HEAD(&wb->b_dirty_time);
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spin_lock_init(&wb->list_lock);
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atomic_set(&wb->writeback_inodes, 0);
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wb->bw_time_stamp = jiffies;
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wb->balanced_dirty_ratelimit = INIT_BW;
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wb->dirty_ratelimit = INIT_BW;
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wb->write_bandwidth = INIT_BW;
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wb->avg_write_bandwidth = INIT_BW;
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spin_lock_init(&wb->work_lock);
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INIT_LIST_HEAD(&wb->work_list);
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INIT_DELAYED_WORK(&wb->dwork, wb_workfn);
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INIT_DELAYED_WORK(&wb->bw_dwork, wb_update_bandwidth_workfn);
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wb->dirty_sleep = jiffies;
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err = fprop_local_init_percpu(&wb->completions, gfp);
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if (err)
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return err;
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for (i = 0; i < NR_WB_STAT_ITEMS; i++) {
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err = percpu_counter_init(&wb->stat[i], 0, gfp);
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if (err)
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goto out_destroy_stat;
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}
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return 0;
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out_destroy_stat:
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while (i--)
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percpu_counter_destroy(&wb->stat[i]);
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fprop_local_destroy_percpu(&wb->completions);
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return err;
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}
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static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb);
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/*
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* Remove bdi from the global list and shutdown any threads we have running
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*/
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static void wb_shutdown(struct bdi_writeback *wb)
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{
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/* Make sure nobody queues further work */
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spin_lock_irq(&wb->work_lock);
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if (!test_and_clear_bit(WB_registered, &wb->state)) {
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spin_unlock_irq(&wb->work_lock);
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return;
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}
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spin_unlock_irq(&wb->work_lock);
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cgwb_remove_from_bdi_list(wb);
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/*
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* Drain work list and shutdown the delayed_work. !WB_registered
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* tells wb_workfn() that @wb is dying and its work_list needs to
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* be drained no matter what.
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*/
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mod_delayed_work(bdi_wq, &wb->dwork, 0);
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flush_delayed_work(&wb->dwork);
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WARN_ON(!list_empty(&wb->work_list));
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flush_delayed_work(&wb->bw_dwork);
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}
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static void wb_exit(struct bdi_writeback *wb)
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{
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int i;
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WARN_ON(delayed_work_pending(&wb->dwork));
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for (i = 0; i < NR_WB_STAT_ITEMS; i++)
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percpu_counter_destroy(&wb->stat[i]);
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fprop_local_destroy_percpu(&wb->completions);
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}
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#ifdef CONFIG_CGROUP_WRITEBACK
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#include <linux/memcontrol.h>
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/*
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* cgwb_lock protects bdi->cgwb_tree, blkcg->cgwb_list, offline_cgwbs and
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* memcg->cgwb_list. bdi->cgwb_tree is also RCU protected.
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*/
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static DEFINE_SPINLOCK(cgwb_lock);
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static struct workqueue_struct *cgwb_release_wq;
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static LIST_HEAD(offline_cgwbs);
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static void cleanup_offline_cgwbs_workfn(struct work_struct *work);
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static DECLARE_WORK(cleanup_offline_cgwbs_work, cleanup_offline_cgwbs_workfn);
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static void cgwb_free_rcu(struct rcu_head *rcu_head)
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{
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struct bdi_writeback *wb = container_of(rcu_head,
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struct bdi_writeback, rcu);
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percpu_ref_exit(&wb->refcnt);
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kfree(wb);
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}
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static void cgwb_release_workfn(struct work_struct *work)
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{
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struct bdi_writeback *wb = container_of(work, struct bdi_writeback,
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release_work);
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struct backing_dev_info *bdi = wb->bdi;
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mutex_lock(&wb->bdi->cgwb_release_mutex);
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wb_shutdown(wb);
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css_put(wb->memcg_css);
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css_put(wb->blkcg_css);
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mutex_unlock(&wb->bdi->cgwb_release_mutex);
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/* triggers blkg destruction if no online users left */
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blkcg_unpin_online(wb->blkcg_css);
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fprop_local_destroy_percpu(&wb->memcg_completions);
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spin_lock_irq(&cgwb_lock);
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list_del(&wb->offline_node);
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spin_unlock_irq(&cgwb_lock);
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wb_exit(wb);
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bdi_put(bdi);
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WARN_ON_ONCE(!list_empty(&wb->b_attached));
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call_rcu(&wb->rcu, cgwb_free_rcu);
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}
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static void cgwb_release(struct percpu_ref *refcnt)
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{
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struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback,
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refcnt);
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queue_work(cgwb_release_wq, &wb->release_work);
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}
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static void cgwb_kill(struct bdi_writeback *wb)
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{
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lockdep_assert_held(&cgwb_lock);
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WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id));
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list_del(&wb->memcg_node);
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list_del(&wb->blkcg_node);
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list_add(&wb->offline_node, &offline_cgwbs);
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percpu_ref_kill(&wb->refcnt);
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}
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static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
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{
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spin_lock_irq(&cgwb_lock);
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list_del_rcu(&wb->bdi_node);
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spin_unlock_irq(&cgwb_lock);
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}
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static int cgwb_create(struct backing_dev_info *bdi,
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struct cgroup_subsys_state *memcg_css, gfp_t gfp)
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{
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struct mem_cgroup *memcg;
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struct cgroup_subsys_state *blkcg_css;
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struct list_head *memcg_cgwb_list, *blkcg_cgwb_list;
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struct bdi_writeback *wb;
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unsigned long flags;
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int ret = 0;
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memcg = mem_cgroup_from_css(memcg_css);
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blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
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memcg_cgwb_list = &memcg->cgwb_list;
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blkcg_cgwb_list = blkcg_get_cgwb_list(blkcg_css);
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/* look up again under lock and discard on blkcg mismatch */
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spin_lock_irqsave(&cgwb_lock, flags);
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wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
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if (wb && wb->blkcg_css != blkcg_css) {
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cgwb_kill(wb);
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wb = NULL;
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}
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spin_unlock_irqrestore(&cgwb_lock, flags);
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if (wb)
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goto out_put;
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/* need to create a new one */
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wb = kmalloc(sizeof(*wb), gfp);
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if (!wb) {
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ret = -ENOMEM;
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goto out_put;
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}
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ret = wb_init(wb, bdi, gfp);
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if (ret)
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goto err_free;
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ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp);
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if (ret)
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goto err_wb_exit;
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ret = fprop_local_init_percpu(&wb->memcg_completions, gfp);
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if (ret)
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goto err_ref_exit;
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wb->memcg_css = memcg_css;
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wb->blkcg_css = blkcg_css;
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INIT_LIST_HEAD(&wb->b_attached);
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INIT_WORK(&wb->release_work, cgwb_release_workfn);
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set_bit(WB_registered, &wb->state);
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bdi_get(bdi);
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/*
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* The root wb determines the registered state of the whole bdi and
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* memcg_cgwb_list and blkcg_cgwb_list's next pointers indicate
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* whether they're still online. Don't link @wb if any is dead.
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* See wb_memcg_offline() and wb_blkcg_offline().
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*/
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ret = -ENODEV;
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spin_lock_irqsave(&cgwb_lock, flags);
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if (test_bit(WB_registered, &bdi->wb.state) &&
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blkcg_cgwb_list->next && memcg_cgwb_list->next) {
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/* we might have raced another instance of this function */
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ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb);
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if (!ret) {
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list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list);
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list_add(&wb->memcg_node, memcg_cgwb_list);
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list_add(&wb->blkcg_node, blkcg_cgwb_list);
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blkcg_pin_online(blkcg_css);
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css_get(memcg_css);
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css_get(blkcg_css);
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}
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}
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spin_unlock_irqrestore(&cgwb_lock, flags);
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if (ret) {
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if (ret == -EEXIST)
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ret = 0;
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goto err_fprop_exit;
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}
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goto out_put;
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err_fprop_exit:
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bdi_put(bdi);
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fprop_local_destroy_percpu(&wb->memcg_completions);
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err_ref_exit:
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percpu_ref_exit(&wb->refcnt);
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err_wb_exit:
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wb_exit(wb);
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err_free:
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kfree(wb);
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out_put:
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css_put(blkcg_css);
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return ret;
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}
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/**
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* wb_get_lookup - get wb for a given memcg
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* @bdi: target bdi
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* @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
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*
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* Try to get the wb for @memcg_css on @bdi. The returned wb has its
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* refcount incremented.
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*
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* This function uses css_get() on @memcg_css and thus expects its refcnt
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* to be positive on invocation. IOW, rcu_read_lock() protection on
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* @memcg_css isn't enough. try_get it before calling this function.
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*
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* A wb is keyed by its associated memcg. As blkcg implicitly enables
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* memcg on the default hierarchy, memcg association is guaranteed to be
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* more specific (equal or descendant to the associated blkcg) and thus can
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* identify both the memcg and blkcg associations.
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*
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* Because the blkcg associated with a memcg may change as blkcg is enabled
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* and disabled closer to root in the hierarchy, each wb keeps track of
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* both the memcg and blkcg associated with it and verifies the blkcg on
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* each lookup. On mismatch, the existing wb is discarded and a new one is
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* created.
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*/
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struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,
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struct cgroup_subsys_state *memcg_css)
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{
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struct bdi_writeback *wb;
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if (!memcg_css->parent)
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return &bdi->wb;
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rcu_read_lock();
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wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
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if (wb) {
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struct cgroup_subsys_state *blkcg_css;
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/* see whether the blkcg association has changed */
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blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
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if (unlikely(wb->blkcg_css != blkcg_css || !wb_tryget(wb)))
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wb = NULL;
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css_put(blkcg_css);
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}
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rcu_read_unlock();
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return wb;
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}
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/**
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* wb_get_create - get wb for a given memcg, create if necessary
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* @bdi: target bdi
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* @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
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* @gfp: allocation mask to use
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*
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* Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to
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* create one. See wb_get_lookup() for more details.
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*/
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struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
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struct cgroup_subsys_state *memcg_css,
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gfp_t gfp)
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{
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struct bdi_writeback *wb;
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might_alloc(gfp);
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do {
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wb = wb_get_lookup(bdi, memcg_css);
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} while (!wb && !cgwb_create(bdi, memcg_css, gfp));
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return wb;
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}
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static int cgwb_bdi_init(struct backing_dev_info *bdi)
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{
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int ret;
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INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC);
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mutex_init(&bdi->cgwb_release_mutex);
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init_rwsem(&bdi->wb_switch_rwsem);
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ret = wb_init(&bdi->wb, bdi, GFP_KERNEL);
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if (!ret) {
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bdi->wb.memcg_css = &root_mem_cgroup->css;
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bdi->wb.blkcg_css = blkcg_root_css;
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}
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return ret;
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}
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static void cgwb_bdi_unregister(struct backing_dev_info *bdi)
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{
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struct radix_tree_iter iter;
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void **slot;
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struct bdi_writeback *wb;
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WARN_ON(test_bit(WB_registered, &bdi->wb.state));
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spin_lock_irq(&cgwb_lock);
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radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0)
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cgwb_kill(*slot);
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spin_unlock_irq(&cgwb_lock);
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mutex_lock(&bdi->cgwb_release_mutex);
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spin_lock_irq(&cgwb_lock);
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while (!list_empty(&bdi->wb_list)) {
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wb = list_first_entry(&bdi->wb_list, struct bdi_writeback,
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bdi_node);
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spin_unlock_irq(&cgwb_lock);
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wb_shutdown(wb);
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spin_lock_irq(&cgwb_lock);
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}
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spin_unlock_irq(&cgwb_lock);
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mutex_unlock(&bdi->cgwb_release_mutex);
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}
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/*
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* cleanup_offline_cgwbs_workfn - try to release dying cgwbs
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*
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* Try to release dying cgwbs by switching attached inodes to the nearest
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* living ancestor's writeback. Processed wbs are placed at the end
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* of the list to guarantee the forward progress.
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*/
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static void cleanup_offline_cgwbs_workfn(struct work_struct *work)
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{
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struct bdi_writeback *wb;
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LIST_HEAD(processed);
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spin_lock_irq(&cgwb_lock);
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while (!list_empty(&offline_cgwbs)) {
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wb = list_first_entry(&offline_cgwbs, struct bdi_writeback,
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offline_node);
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list_move(&wb->offline_node, &processed);
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/*
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* If wb is dirty, cleaning up the writeback by switching
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* attached inodes will result in an effective removal of any
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* bandwidth restrictions, which isn't the goal. Instead,
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* it can be postponed until the next time, when all io
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* will be likely completed. If in the meantime some inodes
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* will get re-dirtied, they should be eventually switched to
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* a new cgwb.
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*/
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if (wb_has_dirty_io(wb))
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continue;
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if (!wb_tryget(wb))
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continue;
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spin_unlock_irq(&cgwb_lock);
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while (cleanup_offline_cgwb(wb))
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cond_resched();
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spin_lock_irq(&cgwb_lock);
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wb_put(wb);
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}
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if (!list_empty(&processed))
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list_splice_tail(&processed, &offline_cgwbs);
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spin_unlock_irq(&cgwb_lock);
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}
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/**
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* wb_memcg_offline - kill all wb's associated with a memcg being offlined
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* @memcg: memcg being offlined
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*
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* Also prevents creation of any new wb's associated with @memcg.
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*/
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void wb_memcg_offline(struct mem_cgroup *memcg)
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{
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struct list_head *memcg_cgwb_list = &memcg->cgwb_list;
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struct bdi_writeback *wb, *next;
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spin_lock_irq(&cgwb_lock);
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list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node)
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cgwb_kill(wb);
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memcg_cgwb_list->next = NULL; /* prevent new wb's */
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spin_unlock_irq(&cgwb_lock);
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queue_work(system_unbound_wq, &cleanup_offline_cgwbs_work);
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}
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/**
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* wb_blkcg_offline - kill all wb's associated with a blkcg being offlined
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* @css: blkcg being offlined
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*
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* Also prevents creation of any new wb's associated with @blkcg.
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*/
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void wb_blkcg_offline(struct cgroup_subsys_state *css)
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{
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struct bdi_writeback *wb, *next;
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struct list_head *list = blkcg_get_cgwb_list(css);
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spin_lock_irq(&cgwb_lock);
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list_for_each_entry_safe(wb, next, list, blkcg_node)
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cgwb_kill(wb);
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list->next = NULL; /* prevent new wb's */
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spin_unlock_irq(&cgwb_lock);
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}
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static void cgwb_bdi_register(struct backing_dev_info *bdi)
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{
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spin_lock_irq(&cgwb_lock);
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list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
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spin_unlock_irq(&cgwb_lock);
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}
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static int __init cgwb_init(void)
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{
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/*
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* There can be many concurrent release work items overwhelming
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* system_wq. Put them in a separate wq and limit concurrency.
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* There's no point in executing many of these in parallel.
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*/
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cgwb_release_wq = alloc_workqueue("cgwb_release", 0, 1);
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if (!cgwb_release_wq)
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return -ENOMEM;
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return 0;
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}
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subsys_initcall(cgwb_init);
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#else /* CONFIG_CGROUP_WRITEBACK */
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static int cgwb_bdi_init(struct backing_dev_info *bdi)
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{
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return wb_init(&bdi->wb, bdi, GFP_KERNEL);
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}
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static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { }
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static void cgwb_bdi_register(struct backing_dev_info *bdi)
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{
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list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
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}
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static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
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{
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list_del_rcu(&wb->bdi_node);
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}
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#endif /* CONFIG_CGROUP_WRITEBACK */
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int bdi_init(struct backing_dev_info *bdi)
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{
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bdi->dev = NULL;
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kref_init(&bdi->refcnt);
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bdi->min_ratio = 0;
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bdi->max_ratio = 100 * BDI_RATIO_SCALE;
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bdi->max_prop_frac = FPROP_FRAC_BASE;
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INIT_LIST_HEAD(&bdi->bdi_list);
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INIT_LIST_HEAD(&bdi->wb_list);
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init_waitqueue_head(&bdi->wb_waitq);
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return cgwb_bdi_init(bdi);
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}
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struct backing_dev_info *bdi_alloc(int node_id)
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{
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struct backing_dev_info *bdi;
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bdi = kzalloc_node(sizeof(*bdi), GFP_KERNEL, node_id);
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if (!bdi)
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return NULL;
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|
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if (bdi_init(bdi)) {
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kfree(bdi);
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return NULL;
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}
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bdi->capabilities = BDI_CAP_WRITEBACK | BDI_CAP_WRITEBACK_ACCT;
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bdi->ra_pages = VM_READAHEAD_PAGES;
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bdi->io_pages = VM_READAHEAD_PAGES;
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timer_setup(&bdi->laptop_mode_wb_timer, laptop_mode_timer_fn, 0);
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return bdi;
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}
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EXPORT_SYMBOL(bdi_alloc);
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|
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static struct rb_node **bdi_lookup_rb_node(u64 id, struct rb_node **parentp)
|
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{
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struct rb_node **p = &bdi_tree.rb_node;
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struct rb_node *parent = NULL;
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struct backing_dev_info *bdi;
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lockdep_assert_held(&bdi_lock);
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while (*p) {
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parent = *p;
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bdi = rb_entry(parent, struct backing_dev_info, rb_node);
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|
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if (bdi->id > id)
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p = &(*p)->rb_left;
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else if (bdi->id < id)
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p = &(*p)->rb_right;
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else
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break;
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}
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|
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if (parentp)
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*parentp = parent;
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return p;
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}
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|
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/**
|
|
* bdi_get_by_id - lookup and get bdi from its id
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* @id: bdi id to lookup
|
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*
|
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* Find bdi matching @id and get it. Returns NULL if the matching bdi
|
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* doesn't exist or is already unregistered.
|
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*/
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struct backing_dev_info *bdi_get_by_id(u64 id)
|
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{
|
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struct backing_dev_info *bdi = NULL;
|
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struct rb_node **p;
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|
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spin_lock_bh(&bdi_lock);
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p = bdi_lookup_rb_node(id, NULL);
|
|
if (*p) {
|
|
bdi = rb_entry(*p, struct backing_dev_info, rb_node);
|
|
bdi_get(bdi);
|
|
}
|
|
spin_unlock_bh(&bdi_lock);
|
|
|
|
return bdi;
|
|
}
|
|
|
|
int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args)
|
|
{
|
|
struct device *dev;
|
|
struct rb_node *parent, **p;
|
|
|
|
if (bdi->dev) /* The driver needs to use separate queues per device */
|
|
return 0;
|
|
|
|
vsnprintf(bdi->dev_name, sizeof(bdi->dev_name), fmt, args);
|
|
dev = device_create(&bdi_class, NULL, MKDEV(0, 0), bdi, bdi->dev_name);
|
|
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);
|
|
|
|
bdi->id = ++bdi_id_cursor;
|
|
|
|
p = bdi_lookup_rb_node(bdi->id, &parent);
|
|
rb_link_node(&bdi->rb_node, parent, p);
|
|
rb_insert_color(&bdi->rb_node, &bdi_tree);
|
|
|
|
list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
|
|
|
|
spin_unlock_bh(&bdi_lock);
|
|
|
|
trace_writeback_bdi_register(bdi);
|
|
return 0;
|
|
}
|
|
|
|
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);
|
|
|
|
void bdi_set_owner(struct backing_dev_info *bdi, struct device *owner)
|
|
{
|
|
WARN_ON_ONCE(bdi->owner);
|
|
bdi->owner = owner;
|
|
get_device(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);
|
|
rb_erase(&bdi->rb_node, &bdi_tree);
|
|
list_del_rcu(&bdi->bdi_list);
|
|
spin_unlock_bh(&bdi_lock);
|
|
|
|
synchronize_rcu_expedited();
|
|
}
|
|
|
|
void bdi_unregister(struct backing_dev_info *bdi)
|
|
{
|
|
del_timer_sync(&bdi->laptop_mode_wb_timer);
|
|
|
|
/* make sure nobody finds us on the bdi_list anymore */
|
|
bdi_remove_from_list(bdi);
|
|
wb_shutdown(&bdi->wb);
|
|
cgwb_bdi_unregister(bdi);
|
|
|
|
/*
|
|
* If this BDI's min ratio has been set, use bdi_set_min_ratio() to
|
|
* update the global bdi_min_ratio.
|
|
*/
|
|
if (bdi->min_ratio)
|
|
bdi_set_min_ratio(bdi, 0);
|
|
|
|
if (bdi->dev) {
|
|
bdi_debug_unregister(bdi);
|
|
device_unregister(bdi->dev);
|
|
bdi->dev = NULL;
|
|
}
|
|
|
|
if (bdi->owner) {
|
|
put_device(bdi->owner);
|
|
bdi->owner = NULL;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(bdi_unregister);
|
|
|
|
static void release_bdi(struct kref *ref)
|
|
{
|
|
struct backing_dev_info *bdi =
|
|
container_of(ref, struct backing_dev_info, refcnt);
|
|
|
|
WARN_ON_ONCE(test_bit(WB_registered, &bdi->wb.state));
|
|
WARN_ON_ONCE(bdi->dev);
|
|
wb_exit(&bdi->wb);
|
|
kfree(bdi);
|
|
}
|
|
|
|
void bdi_put(struct backing_dev_info *bdi)
|
|
{
|
|
kref_put(&bdi->refcnt, release_bdi);
|
|
}
|
|
EXPORT_SYMBOL(bdi_put);
|
|
|
|
struct backing_dev_info *inode_to_bdi(struct inode *inode)
|
|
{
|
|
struct super_block *sb;
|
|
|
|
if (!inode)
|
|
return &noop_backing_dev_info;
|
|
|
|
sb = inode->i_sb;
|
|
#ifdef CONFIG_BLOCK
|
|
if (sb_is_blkdev_sb(sb))
|
|
return I_BDEV(inode)->bd_disk->bdi;
|
|
#endif
|
|
return sb->s_bdi;
|
|
}
|
|
EXPORT_SYMBOL(inode_to_bdi);
|
|
|
|
const char *bdi_dev_name(struct backing_dev_info *bdi)
|
|
{
|
|
if (!bdi || !bdi->dev)
|
|
return bdi_unknown_name;
|
|
return bdi->dev_name;
|
|
}
|
|
EXPORT_SYMBOL_GPL(bdi_dev_name);
|