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![Christoph Hellwig](/assets/img/avatar_default.png)
We never set any congested bits in the group writeback instances of it. And for the simpler bdi-wide case a simple scalar field is all that that is needed. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
1016 lines
25 KiB
C
1016 lines
25 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/wait.h>
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#include <linux/rbtree.h>
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#include <linux/backing-dev.h>
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#include <linux/kthread.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.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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struct backing_dev_info noop_backing_dev_info = {
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.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
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};
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EXPORT_SYMBOL_GPL(noop_backing_dev_info);
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static struct class *bdi_class;
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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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#define K(x) ((x) << (PAGE_SHIFT - 10))
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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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#undef K
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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 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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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)
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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)
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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 *page)
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{
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struct backing_dev_info *bdi = dev_get_drvdata(dev);
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return snprintf(page, PAGE_SIZE-1, "%d\n",
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bdi_cap_stable_pages_required(bdi) ? 1 : 0);
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}
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static DEVICE_ATTR_RO(stable_pages_required);
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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_max_ratio.attr,
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&dev_attr_stable_pages_required.attr,
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NULL,
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};
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ATTRIBUTE_GROUPS(bdi_dev);
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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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if (IS_ERR(bdi_class))
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return PTR_ERR(bdi_class);
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bdi_class->dev_groups = bdi_dev_groups;
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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 bdi_init(struct backing_dev_info *bdi);
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static int __init default_bdi_init(void)
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{
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int err;
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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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err = bdi_init(&noop_backing_dev_info);
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return err;
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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_bh(&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_bh(&wb->work_lock);
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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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if (wb != &bdi->wb)
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bdi_get(bdi);
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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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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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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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goto out_put_bdi;
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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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out_put_bdi:
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if (wb != &bdi->wb)
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bdi_put(bdi);
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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_bh(&wb->work_lock);
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if (!test_and_clear_bit(WB_registered, &wb->state)) {
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spin_unlock_bh(&wb->work_lock);
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return;
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}
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spin_unlock_bh(&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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}
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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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if (wb != &wb->bdi->wb)
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bdi_put(wb->bdi);
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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, and memcg->cgwb_list.
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* 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 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 blkcg *blkcg = css_to_blkcg(wb->blkcg_css);
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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(blkcg);
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fprop_local_destroy_percpu(&wb->memcg_completions);
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percpu_ref_exit(&wb->refcnt);
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wb_exit(wb);
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kfree_rcu(wb, 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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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 blkcg *blkcg;
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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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blkcg = css_to_blkcg(blkcg_css);
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memcg_cgwb_list = &memcg->cgwb_list;
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blkcg_cgwb_list = &blkcg->cgwb_list;
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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_WORK(&wb->release_work, cgwb_release_workfn);
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set_bit(WB_registered, &wb->state);
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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
|
|
* whether they're still online. Don't link @wb if any is dead.
|
|
* See wb_memcg_offline() and wb_blkcg_offline().
|
|
*/
|
|
ret = -ENODEV;
|
|
spin_lock_irqsave(&cgwb_lock, flags);
|
|
if (test_bit(WB_registered, &bdi->wb.state) &&
|
|
blkcg_cgwb_list->next && memcg_cgwb_list->next) {
|
|
/* we might have raced another instance of this function */
|
|
ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb);
|
|
if (!ret) {
|
|
list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list);
|
|
list_add(&wb->memcg_node, memcg_cgwb_list);
|
|
list_add(&wb->blkcg_node, blkcg_cgwb_list);
|
|
blkcg_pin_online(blkcg);
|
|
css_get(memcg_css);
|
|
css_get(blkcg_css);
|
|
}
|
|
}
|
|
spin_unlock_irqrestore(&cgwb_lock, flags);
|
|
if (ret) {
|
|
if (ret == -EEXIST)
|
|
ret = 0;
|
|
goto err_fprop_exit;
|
|
}
|
|
goto out_put;
|
|
|
|
err_fprop_exit:
|
|
fprop_local_destroy_percpu(&wb->memcg_completions);
|
|
err_ref_exit:
|
|
percpu_ref_exit(&wb->refcnt);
|
|
err_wb_exit:
|
|
wb_exit(wb);
|
|
err_free:
|
|
kfree(wb);
|
|
out_put:
|
|
css_put(blkcg_css);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* wb_get_lookup - get wb for a given memcg
|
|
* @bdi: target bdi
|
|
* @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
|
|
*
|
|
* Try to get the wb for @memcg_css on @bdi. The returned wb has its
|
|
* refcount incremented.
|
|
*
|
|
* This function uses css_get() on @memcg_css and thus expects its refcnt
|
|
* to be positive on invocation. IOW, rcu_read_lock() protection on
|
|
* @memcg_css isn't enough. try_get it before calling this function.
|
|
*
|
|
* A wb is keyed by its associated memcg. As blkcg implicitly enables
|
|
* memcg on the default hierarchy, memcg association is guaranteed to be
|
|
* more specific (equal or descendant to the associated blkcg) and thus can
|
|
* identify both the memcg and blkcg associations.
|
|
*
|
|
* Because the blkcg associated with a memcg may change as blkcg is enabled
|
|
* and disabled closer to root in the hierarchy, each wb keeps track of
|
|
* both the memcg and blkcg associated with it and verifies the blkcg on
|
|
* each lookup. On mismatch, the existing wb is discarded and a new one is
|
|
* created.
|
|
*/
|
|
struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,
|
|
struct cgroup_subsys_state *memcg_css)
|
|
{
|
|
struct bdi_writeback *wb;
|
|
|
|
if (!memcg_css->parent)
|
|
return &bdi->wb;
|
|
|
|
rcu_read_lock();
|
|
wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
|
|
if (wb) {
|
|
struct cgroup_subsys_state *blkcg_css;
|
|
|
|
/* see whether the blkcg association has changed */
|
|
blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
|
|
if (unlikely(wb->blkcg_css != blkcg_css || !wb_tryget(wb)))
|
|
wb = NULL;
|
|
css_put(blkcg_css);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
return wb;
|
|
}
|
|
|
|
/**
|
|
* wb_get_create - get wb for a given memcg, create if necessary
|
|
* @bdi: target bdi
|
|
* @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
|
|
* @gfp: allocation mask to use
|
|
*
|
|
* Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to
|
|
* create one. See wb_get_lookup() for more details.
|
|
*/
|
|
struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
|
|
struct cgroup_subsys_state *memcg_css,
|
|
gfp_t gfp)
|
|
{
|
|
struct bdi_writeback *wb;
|
|
|
|
might_sleep_if(gfpflags_allow_blocking(gfp));
|
|
|
|
if (!memcg_css->parent)
|
|
return &bdi->wb;
|
|
|
|
do {
|
|
wb = wb_get_lookup(bdi, memcg_css);
|
|
} while (!wb && !cgwb_create(bdi, memcg_css, gfp));
|
|
|
|
return wb;
|
|
}
|
|
|
|
static int cgwb_bdi_init(struct backing_dev_info *bdi)
|
|
{
|
|
int ret;
|
|
|
|
INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC);
|
|
mutex_init(&bdi->cgwb_release_mutex);
|
|
init_rwsem(&bdi->wb_switch_rwsem);
|
|
|
|
ret = wb_init(&bdi->wb, bdi, GFP_KERNEL);
|
|
if (!ret) {
|
|
bdi->wb.memcg_css = &root_mem_cgroup->css;
|
|
bdi->wb.blkcg_css = blkcg_root_css;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static void cgwb_bdi_unregister(struct backing_dev_info *bdi)
|
|
{
|
|
struct radix_tree_iter iter;
|
|
void **slot;
|
|
struct bdi_writeback *wb;
|
|
|
|
WARN_ON(test_bit(WB_registered, &bdi->wb.state));
|
|
|
|
spin_lock_irq(&cgwb_lock);
|
|
radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0)
|
|
cgwb_kill(*slot);
|
|
spin_unlock_irq(&cgwb_lock);
|
|
|
|
mutex_lock(&bdi->cgwb_release_mutex);
|
|
spin_lock_irq(&cgwb_lock);
|
|
while (!list_empty(&bdi->wb_list)) {
|
|
wb = list_first_entry(&bdi->wb_list, struct bdi_writeback,
|
|
bdi_node);
|
|
spin_unlock_irq(&cgwb_lock);
|
|
wb_shutdown(wb);
|
|
spin_lock_irq(&cgwb_lock);
|
|
}
|
|
spin_unlock_irq(&cgwb_lock);
|
|
mutex_unlock(&bdi->cgwb_release_mutex);
|
|
}
|
|
|
|
/**
|
|
* wb_memcg_offline - kill all wb's associated with a memcg being offlined
|
|
* @memcg: memcg being offlined
|
|
*
|
|
* Also prevents creation of any new wb's associated with @memcg.
|
|
*/
|
|
void wb_memcg_offline(struct mem_cgroup *memcg)
|
|
{
|
|
struct list_head *memcg_cgwb_list = &memcg->cgwb_list;
|
|
struct bdi_writeback *wb, *next;
|
|
|
|
spin_lock_irq(&cgwb_lock);
|
|
list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node)
|
|
cgwb_kill(wb);
|
|
memcg_cgwb_list->next = NULL; /* prevent new wb's */
|
|
spin_unlock_irq(&cgwb_lock);
|
|
}
|
|
|
|
/**
|
|
* wb_blkcg_offline - kill all wb's associated with a blkcg being offlined
|
|
* @blkcg: blkcg being offlined
|
|
*
|
|
* Also prevents creation of any new wb's associated with @blkcg.
|
|
*/
|
|
void wb_blkcg_offline(struct blkcg *blkcg)
|
|
{
|
|
struct bdi_writeback *wb, *next;
|
|
|
|
spin_lock_irq(&cgwb_lock);
|
|
list_for_each_entry_safe(wb, next, &blkcg->cgwb_list, blkcg_node)
|
|
cgwb_kill(wb);
|
|
blkcg->cgwb_list.next = NULL; /* prevent new wb's */
|
|
spin_unlock_irq(&cgwb_lock);
|
|
}
|
|
|
|
static void cgwb_bdi_register(struct backing_dev_info *bdi)
|
|
{
|
|
spin_lock_irq(&cgwb_lock);
|
|
list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
|
|
spin_unlock_irq(&cgwb_lock);
|
|
}
|
|
|
|
static int __init cgwb_init(void)
|
|
{
|
|
/*
|
|
* There can be many concurrent release work items overwhelming
|
|
* system_wq. Put them in a separate wq and limit concurrency.
|
|
* There's no point in executing many of these in parallel.
|
|
*/
|
|
cgwb_release_wq = alloc_workqueue("cgwb_release", 0, 1);
|
|
if (!cgwb_release_wq)
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
subsys_initcall(cgwb_init);
|
|
|
|
#else /* CONFIG_CGROUP_WRITEBACK */
|
|
|
|
static int cgwb_bdi_init(struct backing_dev_info *bdi)
|
|
{
|
|
return wb_init(&bdi->wb, bdi, GFP_KERNEL);
|
|
}
|
|
|
|
static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { }
|
|
|
|
static void cgwb_bdi_register(struct backing_dev_info *bdi)
|
|
{
|
|
list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
|
|
}
|
|
|
|
static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
|
|
{
|
|
list_del_rcu(&wb->bdi_node);
|
|
}
|
|
|
|
#endif /* CONFIG_CGROUP_WRITEBACK */
|
|
|
|
static int bdi_init(struct backing_dev_info *bdi)
|
|
{
|
|
int ret;
|
|
|
|
bdi->dev = NULL;
|
|
|
|
kref_init(&bdi->refcnt);
|
|
bdi->min_ratio = 0;
|
|
bdi->max_ratio = 100;
|
|
bdi->max_prop_frac = FPROP_FRAC_BASE;
|
|
INIT_LIST_HEAD(&bdi->bdi_list);
|
|
INIT_LIST_HEAD(&bdi->wb_list);
|
|
init_waitqueue_head(&bdi->wb_waitq);
|
|
|
|
ret = cgwb_bdi_init(bdi);
|
|
|
|
return ret;
|
|
}
|
|
|
|
struct backing_dev_info *bdi_alloc(int node_id)
|
|
{
|
|
struct backing_dev_info *bdi;
|
|
|
|
bdi = kzalloc_node(sizeof(*bdi), GFP_KERNEL, node_id);
|
|
if (!bdi)
|
|
return NULL;
|
|
|
|
if (bdi_init(bdi)) {
|
|
kfree(bdi);
|
|
return NULL;
|
|
}
|
|
return bdi;
|
|
}
|
|
EXPORT_SYMBOL(bdi_alloc);
|
|
|
|
static struct rb_node **bdi_lookup_rb_node(u64 id, struct rb_node **parentp)
|
|
{
|
|
struct rb_node **p = &bdi_tree.rb_node;
|
|
struct rb_node *parent = NULL;
|
|
struct backing_dev_info *bdi;
|
|
|
|
lockdep_assert_held(&bdi_lock);
|
|
|
|
while (*p) {
|
|
parent = *p;
|
|
bdi = rb_entry(parent, struct backing_dev_info, rb_node);
|
|
|
|
if (bdi->id > id)
|
|
p = &(*p)->rb_left;
|
|
else if (bdi->id < id)
|
|
p = &(*p)->rb_right;
|
|
else
|
|
break;
|
|
}
|
|
|
|
if (parentp)
|
|
*parentp = parent;
|
|
return p;
|
|
}
|
|
|
|
/**
|
|
* bdi_get_by_id - lookup and get bdi from its id
|
|
* @id: bdi id to lookup
|
|
*
|
|
* Find bdi matching @id and get it. Returns NULL if the matching bdi
|
|
* doesn't exist or is already unregistered.
|
|
*/
|
|
struct backing_dev_info *bdi_get_by_id(u64 id)
|
|
{
|
|
struct backing_dev_info *bdi = NULL;
|
|
struct rb_node **p;
|
|
|
|
spin_lock_bh(&bdi_lock);
|
|
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)
|
|
{
|
|
/* make sure nobody finds us on the bdi_list anymore */
|
|
bdi_remove_from_list(bdi);
|
|
wb_shutdown(&bdi->wb);
|
|
cgwb_bdi_unregister(bdi);
|
|
|
|
if (bdi->dev) {
|
|
bdi_debug_unregister(bdi);
|
|
device_unregister(bdi->dev);
|
|
bdi->dev = NULL;
|
|
}
|
|
|
|
if (bdi->owner) {
|
|
put_device(bdi->owner);
|
|
bdi->owner = NULL;
|
|
}
|
|
}
|
|
|
|
static void release_bdi(struct kref *ref)
|
|
{
|
|
struct backing_dev_info *bdi =
|
|
container_of(ref, struct backing_dev_info, refcnt);
|
|
|
|
if (test_bit(WB_registered, &bdi->wb.state))
|
|
bdi_unregister(bdi);
|
|
WARN_ON_ONCE(bdi->dev);
|
|
wb_exit(&bdi->wb);
|
|
kfree(bdi);
|
|
}
|
|
|
|
void bdi_put(struct backing_dev_info *bdi)
|
|
{
|
|
kref_put(&bdi->refcnt, release_bdi);
|
|
}
|
|
EXPORT_SYMBOL(bdi_put);
|
|
|
|
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);
|
|
|
|
static wait_queue_head_t congestion_wqh[2] = {
|
|
__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
|
|
__WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
|
|
};
|
|
static atomic_t nr_wb_congested[2];
|
|
|
|
void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
|
|
{
|
|
wait_queue_head_t *wqh = &congestion_wqh[sync];
|
|
enum wb_congested_state bit;
|
|
|
|
bit = sync ? WB_sync_congested : WB_async_congested;
|
|
if (test_and_clear_bit(bit, &bdi->wb.congested))
|
|
atomic_dec(&nr_wb_congested[sync]);
|
|
smp_mb__after_atomic();
|
|
if (waitqueue_active(wqh))
|
|
wake_up(wqh);
|
|
}
|
|
EXPORT_SYMBOL(clear_bdi_congested);
|
|
|
|
void set_bdi_congested(struct backing_dev_info *bdi, int sync)
|
|
{
|
|
enum wb_congested_state bit;
|
|
|
|
bit = sync ? WB_sync_congested : WB_async_congested;
|
|
if (!test_and_set_bit(bit, &bdi->wb.congested))
|
|
atomic_inc(&nr_wb_congested[sync]);
|
|
}
|
|
EXPORT_SYMBOL(set_bdi_congested);
|
|
|
|
/**
|
|
* congestion_wait - wait for a backing_dev to become uncongested
|
|
* @sync: SYNC or ASYNC IO
|
|
* @timeout: timeout in jiffies
|
|
*
|
|
* Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
|
|
* write congestion. If no backing_devs are congested then just wait for the
|
|
* next write to be completed.
|
|
*/
|
|
long congestion_wait(int sync, long timeout)
|
|
{
|
|
long ret;
|
|
unsigned long start = jiffies;
|
|
DEFINE_WAIT(wait);
|
|
wait_queue_head_t *wqh = &congestion_wqh[sync];
|
|
|
|
prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
|
|
ret = io_schedule_timeout(timeout);
|
|
finish_wait(wqh, &wait);
|
|
|
|
trace_writeback_congestion_wait(jiffies_to_usecs(timeout),
|
|
jiffies_to_usecs(jiffies - start));
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(congestion_wait);
|
|
|
|
/**
|
|
* wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a pgdat to complete writes
|
|
* @sync: SYNC or ASYNC IO
|
|
* @timeout: timeout in jiffies
|
|
*
|
|
* In the event of a congested backing_dev (any backing_dev) this waits
|
|
* for up to @timeout jiffies for either a BDI to exit congestion of the
|
|
* given @sync queue or a write to complete.
|
|
*
|
|
* The return value is 0 if the sleep is for the full timeout. Otherwise,
|
|
* it is the number of jiffies that were still remaining when the function
|
|
* returned. return_value == timeout implies the function did not sleep.
|
|
*/
|
|
long wait_iff_congested(int sync, long timeout)
|
|
{
|
|
long ret;
|
|
unsigned long start = jiffies;
|
|
DEFINE_WAIT(wait);
|
|
wait_queue_head_t *wqh = &congestion_wqh[sync];
|
|
|
|
/*
|
|
* If there is no congestion, yield if necessary instead
|
|
* of sleeping on the congestion queue
|
|
*/
|
|
if (atomic_read(&nr_wb_congested[sync]) == 0) {
|
|
cond_resched();
|
|
|
|
/* In case we scheduled, work out time remaining */
|
|
ret = timeout - (jiffies - start);
|
|
if (ret < 0)
|
|
ret = 0;
|
|
|
|
goto out;
|
|
}
|
|
|
|
/* Sleep until uncongested or a write happens */
|
|
prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
|
|
ret = io_schedule_timeout(timeout);
|
|
finish_wait(wqh, &wait);
|
|
|
|
out:
|
|
trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout),
|
|
jiffies_to_usecs(jiffies - start));
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(wait_iff_congested);
|