mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 19:29:37 +00:00
![Tetsuo Handa](/assets/img/avatar_default.png)
Jan Stancek has reported that system occasionally hanging after "oom01" testcase from LTP triggers OOM. Guessing from a result that there is a kworker thread doing memory allocation and the values between "Node 0 Normal free:" and "Node 0 Normal:" differs when hanging, vmstat is not up-to-date for some reason. According to commit373ccbe592
("mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress"), it meant to force the kworker thread to take a short sleep, but it by error used schedule_timeout(1). We missed that schedule_timeout() in state TASK_RUNNING doesn't do anything. Fix it by using schedule_timeout_uninterruptible(1) which forces the kworker thread to take a short sleep in order to make sure that vmstat is up-to-date. Fixes:373ccbe592
("mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress") Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: Jan Stancek <jstancek@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Tejun Heo <tj@kernel.org> Cc: Cristopher Lameter <clameter@sgi.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Arkadiusz Miskiewicz <arekm@maven.pl> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1035 lines
26 KiB
C
1035 lines
26 KiB
C
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#include <linux/wait.h>
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#include <linux/backing-dev.h>
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#include <linux/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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static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0);
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struct backing_dev_info noop_backing_dev_info = {
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.name = "noop",
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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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/*
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* bdi_lock protects updates to bdi_list. bdi_list has RCU reader side
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* locking.
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*/
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DEFINE_SPINLOCK(bdi_lock);
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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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static int bdi_debug_stats_open(struct inode *inode, struct file *file)
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{
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return single_open(file, bdi_debug_stats_show, inode->i_private);
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}
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static const struct file_operations bdi_debug_stats_fops = {
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.open = bdi_debug_stats_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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};
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static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
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{
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bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
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bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir,
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bdi, &bdi_debug_stats_fops);
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}
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static void bdi_debug_unregister(struct backing_dev_info *bdi)
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{
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debugfs_remove(bdi->debug_stats);
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debugfs_remove(bdi->debug_dir);
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}
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#else
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static inline void bdi_debug_init(void)
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{
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}
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static inline void bdi_debug_register(struct backing_dev_info *bdi,
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const char *name)
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{
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}
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static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
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{
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}
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#endif
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static ssize_t read_ahead_kb_store(struct device *dev,
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struct device_attribute *attr,
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const char *buf, size_t count)
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{
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struct backing_dev_info *bdi = dev_get_drvdata(dev);
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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 __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_FREEZABLE |
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WQ_UNBOUND | 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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int blkcg_id, 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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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->congested = wb_congested_get_create(bdi, blkcg_id, gfp);
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if (!wb->congested)
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return -ENOMEM;
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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_cong;
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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_cong:
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wb_congested_put(wb->congested);
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return err;
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}
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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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/*
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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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wb_congested_put(wb->congested);
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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, bdi->cgwb_congested_tree,
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* blkcg->cgwb_list, and memcg->cgwb_list. bdi->cgwb_tree is also RCU
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* protected. cgwb_release_wait is used to wait for the completion of cgwb
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* releases from bdi destruction path.
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*/
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static DEFINE_SPINLOCK(cgwb_lock);
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static DECLARE_WAIT_QUEUE_HEAD(cgwb_release_wait);
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/**
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* wb_congested_get_create - get or create a wb_congested
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* @bdi: associated bdi
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* @blkcg_id: ID of the associated blkcg
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* @gfp: allocation mask
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*
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* Look up the wb_congested for @blkcg_id on @bdi. If missing, create one.
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* The returned wb_congested has its reference count incremented. Returns
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* NULL on failure.
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*/
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struct bdi_writeback_congested *
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wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
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{
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struct bdi_writeback_congested *new_congested = NULL, *congested;
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struct rb_node **node, *parent;
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unsigned long flags;
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retry:
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spin_lock_irqsave(&cgwb_lock, flags);
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node = &bdi->cgwb_congested_tree.rb_node;
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parent = NULL;
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|
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while (*node != NULL) {
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parent = *node;
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congested = container_of(parent, struct bdi_writeback_congested,
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rb_node);
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if (congested->blkcg_id < blkcg_id)
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node = &parent->rb_left;
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else if (congested->blkcg_id > blkcg_id)
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node = &parent->rb_right;
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else
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goto found;
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}
|
|
|
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if (new_congested) {
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/* !found and storage for new one already allocated, insert */
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congested = new_congested;
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new_congested = NULL;
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rb_link_node(&congested->rb_node, parent, node);
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rb_insert_color(&congested->rb_node, &bdi->cgwb_congested_tree);
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goto found;
|
|
}
|
|
|
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spin_unlock_irqrestore(&cgwb_lock, flags);
|
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|
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/* allocate storage for new one and retry */
|
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new_congested = kzalloc(sizeof(*new_congested), gfp);
|
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if (!new_congested)
|
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return NULL;
|
|
|
|
atomic_set(&new_congested->refcnt, 0);
|
|
new_congested->bdi = bdi;
|
|
new_congested->blkcg_id = blkcg_id;
|
|
goto retry;
|
|
|
|
found:
|
|
atomic_inc(&congested->refcnt);
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|
spin_unlock_irqrestore(&cgwb_lock, flags);
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kfree(new_congested);
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return congested;
|
|
}
|
|
|
|
/**
|
|
* wb_congested_put - put a wb_congested
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|
* @congested: wb_congested to put
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|
*
|
|
* Put @congested and destroy it if the refcnt reaches zero.
|
|
*/
|
|
void wb_congested_put(struct bdi_writeback_congested *congested)
|
|
{
|
|
unsigned long flags;
|
|
|
|
local_irq_save(flags);
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if (!atomic_dec_and_lock(&congested->refcnt, &cgwb_lock)) {
|
|
local_irq_restore(flags);
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return;
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}
|
|
|
|
/* bdi might already have been destroyed leaving @congested unlinked */
|
|
if (congested->bdi) {
|
|
rb_erase(&congested->rb_node,
|
|
&congested->bdi->cgwb_congested_tree);
|
|
congested->bdi = NULL;
|
|
}
|
|
|
|
spin_unlock_irqrestore(&cgwb_lock, flags);
|
|
kfree(congested);
|
|
}
|
|
|
|
static void cgwb_release_workfn(struct work_struct *work)
|
|
{
|
|
struct bdi_writeback *wb = container_of(work, struct bdi_writeback,
|
|
release_work);
|
|
struct backing_dev_info *bdi = wb->bdi;
|
|
|
|
spin_lock_irq(&cgwb_lock);
|
|
list_del_rcu(&wb->bdi_node);
|
|
spin_unlock_irq(&cgwb_lock);
|
|
|
|
wb_shutdown(wb);
|
|
|
|
css_put(wb->memcg_css);
|
|
css_put(wb->blkcg_css);
|
|
|
|
fprop_local_destroy_percpu(&wb->memcg_completions);
|
|
percpu_ref_exit(&wb->refcnt);
|
|
wb_exit(wb);
|
|
kfree_rcu(wb, rcu);
|
|
|
|
if (atomic_dec_and_test(&bdi->usage_cnt))
|
|
wake_up_all(&cgwb_release_wait);
|
|
}
|
|
|
|
static void cgwb_release(struct percpu_ref *refcnt)
|
|
{
|
|
struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback,
|
|
refcnt);
|
|
schedule_work(&wb->release_work);
|
|
}
|
|
|
|
static void cgwb_kill(struct bdi_writeback *wb)
|
|
{
|
|
lockdep_assert_held(&cgwb_lock);
|
|
|
|
WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id));
|
|
list_del(&wb->memcg_node);
|
|
list_del(&wb->blkcg_node);
|
|
percpu_ref_kill(&wb->refcnt);
|
|
}
|
|
|
|
static int cgwb_create(struct backing_dev_info *bdi,
|
|
struct cgroup_subsys_state *memcg_css, gfp_t gfp)
|
|
{
|
|
struct mem_cgroup *memcg;
|
|
struct cgroup_subsys_state *blkcg_css;
|
|
struct blkcg *blkcg;
|
|
struct list_head *memcg_cgwb_list, *blkcg_cgwb_list;
|
|
struct bdi_writeback *wb;
|
|
unsigned long flags;
|
|
int ret = 0;
|
|
|
|
memcg = mem_cgroup_from_css(memcg_css);
|
|
blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
|
|
blkcg = css_to_blkcg(blkcg_css);
|
|
memcg_cgwb_list = mem_cgroup_cgwb_list(memcg);
|
|
blkcg_cgwb_list = &blkcg->cgwb_list;
|
|
|
|
/* look up again under lock and discard on blkcg mismatch */
|
|
spin_lock_irqsave(&cgwb_lock, flags);
|
|
wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
|
|
if (wb && wb->blkcg_css != blkcg_css) {
|
|
cgwb_kill(wb);
|
|
wb = NULL;
|
|
}
|
|
spin_unlock_irqrestore(&cgwb_lock, flags);
|
|
if (wb)
|
|
goto out_put;
|
|
|
|
/* need to create a new one */
|
|
wb = kmalloc(sizeof(*wb), gfp);
|
|
if (!wb)
|
|
return -ENOMEM;
|
|
|
|
ret = wb_init(wb, bdi, blkcg_css->id, gfp);
|
|
if (ret)
|
|
goto err_free;
|
|
|
|
ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp);
|
|
if (ret)
|
|
goto err_wb_exit;
|
|
|
|
ret = fprop_local_init_percpu(&wb->memcg_completions, gfp);
|
|
if (ret)
|
|
goto err_ref_exit;
|
|
|
|
wb->memcg_css = memcg_css;
|
|
wb->blkcg_css = blkcg_css;
|
|
INIT_WORK(&wb->release_work, cgwb_release_workfn);
|
|
set_bit(WB_registered, &wb->state);
|
|
|
|
/*
|
|
* The root wb determines the registered state of the whole bdi and
|
|
* 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) {
|
|
atomic_inc(&bdi->usage_cnt);
|
|
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);
|
|
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_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. 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_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 {
|
|
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();
|
|
} 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);
|
|
bdi->cgwb_congested_tree = RB_ROOT;
|
|
atomic_set(&bdi->usage_cnt, 1);
|
|
|
|
ret = wb_init(&bdi->wb, bdi, 1, 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_destroy(struct backing_dev_info *bdi)
|
|
{
|
|
struct radix_tree_iter iter;
|
|
struct rb_node *rbn;
|
|
void **slot;
|
|
|
|
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);
|
|
|
|
while ((rbn = rb_first(&bdi->cgwb_congested_tree))) {
|
|
struct bdi_writeback_congested *congested =
|
|
rb_entry(rbn, struct bdi_writeback_congested, rb_node);
|
|
|
|
rb_erase(rbn, &bdi->cgwb_congested_tree);
|
|
congested->bdi = NULL; /* mark @congested unlinked */
|
|
}
|
|
|
|
spin_unlock_irq(&cgwb_lock);
|
|
|
|
/*
|
|
* All cgwb's and their congested states must be shutdown and
|
|
* released before returning. Drain the usage counter to wait for
|
|
* all cgwb's and cgwb_congested's ever created on @bdi.
|
|
*/
|
|
atomic_dec(&bdi->usage_cnt);
|
|
wait_event(cgwb_release_wait, !atomic_read(&bdi->usage_cnt));
|
|
}
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
LIST_HEAD(to_destroy);
|
|
struct list_head *memcg_cgwb_list = mem_cgroup_cgwb_list(memcg);
|
|
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)
|
|
{
|
|
LIST_HEAD(to_destroy);
|
|
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);
|
|
}
|
|
|
|
#else /* CONFIG_CGROUP_WRITEBACK */
|
|
|
|
static int cgwb_bdi_init(struct backing_dev_info *bdi)
|
|
{
|
|
int err;
|
|
|
|
bdi->wb_congested = kzalloc(sizeof(*bdi->wb_congested), GFP_KERNEL);
|
|
if (!bdi->wb_congested)
|
|
return -ENOMEM;
|
|
|
|
err = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL);
|
|
if (err) {
|
|
kfree(bdi->wb_congested);
|
|
return err;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static void cgwb_bdi_destroy(struct backing_dev_info *bdi) { }
|
|
|
|
#endif /* CONFIG_CGROUP_WRITEBACK */
|
|
|
|
int bdi_init(struct backing_dev_info *bdi)
|
|
{
|
|
int ret;
|
|
|
|
bdi->dev = NULL;
|
|
|
|
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);
|
|
|
|
list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(bdi_init);
|
|
|
|
int bdi_register(struct backing_dev_info *bdi, struct device *parent,
|
|
const char *fmt, ...)
|
|
{
|
|
va_list args;
|
|
struct device *dev;
|
|
|
|
if (bdi->dev) /* The driver needs to use separate queues per device */
|
|
return 0;
|
|
|
|
va_start(args, fmt);
|
|
dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args);
|
|
va_end(args);
|
|
if (IS_ERR(dev))
|
|
return PTR_ERR(dev);
|
|
|
|
bdi->dev = dev;
|
|
|
|
bdi_debug_register(bdi, dev_name(dev));
|
|
set_bit(WB_registered, &bdi->wb.state);
|
|
|
|
spin_lock_bh(&bdi_lock);
|
|
list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
|
|
spin_unlock_bh(&bdi_lock);
|
|
|
|
trace_writeback_bdi_register(bdi);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(bdi_register);
|
|
|
|
int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
|
|
{
|
|
return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev));
|
|
}
|
|
EXPORT_SYMBOL(bdi_register_dev);
|
|
|
|
/*
|
|
* 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);
|
|
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_destroy(bdi);
|
|
|
|
if (bdi->dev) {
|
|
bdi_debug_unregister(bdi);
|
|
device_unregister(bdi->dev);
|
|
bdi->dev = NULL;
|
|
}
|
|
}
|
|
|
|
void bdi_exit(struct backing_dev_info *bdi)
|
|
{
|
|
WARN_ON_ONCE(bdi->dev);
|
|
wb_exit(&bdi->wb);
|
|
}
|
|
|
|
void bdi_destroy(struct backing_dev_info *bdi)
|
|
{
|
|
bdi_unregister(bdi);
|
|
bdi_exit(bdi);
|
|
}
|
|
EXPORT_SYMBOL(bdi_destroy);
|
|
|
|
/*
|
|
* For use from filesystems to quickly init and register a bdi associated
|
|
* with dirty writeback
|
|
*/
|
|
int bdi_setup_and_register(struct backing_dev_info *bdi, char *name)
|
|
{
|
|
int err;
|
|
|
|
bdi->name = name;
|
|
bdi->capabilities = 0;
|
|
err = bdi_init(bdi);
|
|
if (err)
|
|
return err;
|
|
|
|
err = bdi_register(bdi, NULL, "%.28s-%ld", name,
|
|
atomic_long_inc_return(&bdi_seq));
|
|
if (err) {
|
|
bdi_destroy(bdi);
|
|
return err;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(bdi_setup_and_register);
|
|
|
|
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_wb_congested(struct bdi_writeback_congested *congested, int sync)
|
|
{
|
|
wait_queue_head_t *wqh = &congestion_wqh[sync];
|
|
enum wb_state bit;
|
|
|
|
bit = sync ? WB_sync_congested : WB_async_congested;
|
|
if (test_and_clear_bit(bit, &congested->state))
|
|
atomic_dec(&nr_wb_congested[sync]);
|
|
smp_mb__after_atomic();
|
|
if (waitqueue_active(wqh))
|
|
wake_up(wqh);
|
|
}
|
|
EXPORT_SYMBOL(clear_wb_congested);
|
|
|
|
void set_wb_congested(struct bdi_writeback_congested *congested, int sync)
|
|
{
|
|
enum wb_state bit;
|
|
|
|
bit = sync ? WB_sync_congested : WB_async_congested;
|
|
if (!test_and_set_bit(bit, &congested->state))
|
|
atomic_inc(&nr_wb_congested[sync]);
|
|
}
|
|
EXPORT_SYMBOL(set_wb_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 zone to complete writes
|
|
* @zone: A zone to check if it is heavily congested
|
|
* @sync: SYNC or ASYNC IO
|
|
* @timeout: timeout in jiffies
|
|
*
|
|
* In the event of a congested backing_dev (any backing_dev) and the given
|
|
* @zone has experienced recent congestion, this waits for up to @timeout
|
|
* jiffies for either a BDI to exit congestion of the given @sync queue
|
|
* or a write to complete.
|
|
*
|
|
* In the absence of zone congestion, a short sleep or a cond_resched is
|
|
* performed to yield the processor and to allow other subsystems to make
|
|
* a forward progress.
|
|
*
|
|
* 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(struct zone *zone, 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, or heavy congestion is not being
|
|
* encountered in the current zone, yield if necessary instead
|
|
* of sleeping on the congestion queue
|
|
*/
|
|
if (atomic_read(&nr_wb_congested[sync]) == 0 ||
|
|
!test_bit(ZONE_CONGESTED, &zone->flags)) {
|
|
|
|
/*
|
|
* Memory allocation/reclaim might be called from a WQ
|
|
* context and the current implementation of the WQ
|
|
* concurrency control doesn't recognize that a particular
|
|
* WQ is congested if the worker thread is looping without
|
|
* ever sleeping. Therefore we have to do a short sleep
|
|
* here rather than calling cond_resched().
|
|
*/
|
|
if (current->flags & PF_WQ_WORKER)
|
|
schedule_timeout_uninterruptible(1);
|
|
else
|
|
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);
|
|
|
|
int pdflush_proc_obsolete(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
char kbuf[] = "0\n";
|
|
|
|
if (*ppos || *lenp < sizeof(kbuf)) {
|
|
*lenp = 0;
|
|
return 0;
|
|
}
|
|
|
|
if (copy_to_user(buffer, kbuf, sizeof(kbuf)))
|
|
return -EFAULT;
|
|
printk_once(KERN_WARNING "%s exported in /proc is scheduled for removal\n",
|
|
table->procname);
|
|
|
|
*lenp = 2;
|
|
*ppos += *lenp;
|
|
return 2;
|
|
}
|