mirror of
https://github.com/FEX-Emu/linux.git
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426e1f5cec
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6: (52 commits) split invalidate_inodes() fs: skip I_FREEING inodes in writeback_sb_inodes fs: fold invalidate_list into invalidate_inodes fs: do not drop inode_lock in dispose_list fs: inode split IO and LRU lists fs: switch bdev inode bdi's correctly fs: fix buffer invalidation in invalidate_list fsnotify: use dget_parent smbfs: use dget_parent exportfs: use dget_parent fs: use RCU read side protection in d_validate fs: clean up dentry lru modification fs: split __shrink_dcache_sb fs: improve DCACHE_REFERENCED usage fs: use percpu counter for nr_dentry and nr_dentry_unused fs: simplify __d_free fs: take dcache_lock inside __d_path fs: do not assign default i_ino in new_inode fs: introduce a per-cpu last_ino allocator new helper: ihold() ...
839 lines
21 KiB
C
839 lines
21 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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void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
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{
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}
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EXPORT_SYMBOL(default_unplug_io_fn);
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struct backing_dev_info default_backing_dev_info = {
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.name = "default",
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.ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE,
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.state = 0,
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.capabilities = BDI_CAP_MAP_COPY,
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.unplug_io_fn = default_unplug_io_fn,
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};
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EXPORT_SYMBOL_GPL(default_backing_dev_info);
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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 and bdi_pending_list, as well as
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* reader side protection for bdi_pending_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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LIST_HEAD(bdi_pending_list);
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static struct task_struct *sync_supers_tsk;
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static struct timer_list sync_supers_timer;
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static int bdi_sync_supers(void *);
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static void sync_supers_timer_fn(unsigned long);
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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 bdi_thresh;
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unsigned long nr_dirty, nr_io, nr_more_io, nr_wb;
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struct inode *inode;
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nr_wb = nr_dirty = nr_io = nr_more_io = 0;
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spin_lock(&inode_lock);
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list_for_each_entry(inode, &wb->b_dirty, i_wb_list)
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nr_dirty++;
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list_for_each_entry(inode, &wb->b_io, i_wb_list)
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nr_io++;
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list_for_each_entry(inode, &wb->b_more_io, i_wb_list)
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nr_more_io++;
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spin_unlock(&inode_lock);
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global_dirty_limits(&background_thresh, &dirty_thresh);
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bdi_thresh = bdi_dirty_limit(bdi, 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: %8lu kB\n"
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"BdiReclaimable: %8lu kB\n"
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"BdiDirtyThresh: %8lu kB\n"
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"DirtyThresh: %8lu kB\n"
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"BackgroundThresh: %8lu kB\n"
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"b_dirty: %8lu\n"
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"b_io: %8lu\n"
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"b_more_io: %8lu\n"
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"bdi_list: %8u\n"
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"state: %8lx\n",
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(unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
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(unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
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K(bdi_thresh), K(dirty_thresh),
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K(background_thresh), nr_dirty, nr_io, nr_more_io,
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!list_empty(&bdi->bdi_list), bdi->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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char *end;
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unsigned long read_ahead_kb;
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ssize_t ret = -EINVAL;
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read_ahead_kb = simple_strtoul(buf, &end, 10);
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if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
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bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
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ret = count;
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}
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return ret;
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}
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#define K(pages) ((pages) << (PAGE_SHIFT - 10))
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#define BDI_SHOW(name, expr) \
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static ssize_t name##_show(struct device *dev, \
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struct device_attribute *attr, char *page) \
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{ \
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struct backing_dev_info *bdi = dev_get_drvdata(dev); \
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\
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return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \
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}
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BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
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static ssize_t min_ratio_store(struct device *dev,
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struct device_attribute *attr, const char *buf, size_t count)
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{
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struct backing_dev_info *bdi = dev_get_drvdata(dev);
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char *end;
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unsigned int ratio;
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ssize_t ret = -EINVAL;
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ratio = simple_strtoul(buf, &end, 10);
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if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
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ret = bdi_set_min_ratio(bdi, ratio);
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if (!ret)
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ret = count;
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}
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return ret;
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}
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BDI_SHOW(min_ratio, bdi->min_ratio)
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static ssize_t max_ratio_store(struct device *dev,
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struct device_attribute *attr, const char *buf, size_t count)
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{
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struct backing_dev_info *bdi = dev_get_drvdata(dev);
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char *end;
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unsigned int ratio;
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ssize_t ret = -EINVAL;
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ratio = simple_strtoul(buf, &end, 10);
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if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
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ret = bdi_set_max_ratio(bdi, ratio);
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if (!ret)
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ret = count;
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}
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return ret;
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}
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BDI_SHOW(max_ratio, bdi->max_ratio)
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#define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store)
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static struct device_attribute bdi_dev_attrs[] = {
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__ATTR_RW(read_ahead_kb),
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__ATTR_RW(min_ratio),
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__ATTR_RW(max_ratio),
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__ATTR_NULL,
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};
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static __init int bdi_class_init(void)
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{
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bdi_class = class_create(THIS_MODULE, "bdi");
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if (IS_ERR(bdi_class))
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return PTR_ERR(bdi_class);
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bdi_class->dev_attrs = bdi_dev_attrs;
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bdi_debug_init();
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return 0;
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}
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postcore_initcall(bdi_class_init);
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static int __init default_bdi_init(void)
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{
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int err;
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sync_supers_tsk = kthread_run(bdi_sync_supers, NULL, "sync_supers");
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BUG_ON(IS_ERR(sync_supers_tsk));
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setup_timer(&sync_supers_timer, sync_supers_timer_fn, 0);
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bdi_arm_supers_timer();
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err = bdi_init(&default_backing_dev_info);
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if (!err)
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bdi_register(&default_backing_dev_info, NULL, "default");
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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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int bdi_has_dirty_io(struct backing_dev_info *bdi)
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{
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return wb_has_dirty_io(&bdi->wb);
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}
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static void bdi_flush_io(struct backing_dev_info *bdi)
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{
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struct writeback_control wbc = {
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.sync_mode = WB_SYNC_NONE,
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.older_than_this = NULL,
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.range_cyclic = 1,
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.nr_to_write = 1024,
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};
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writeback_inodes_wb(&bdi->wb, &wbc);
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}
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/*
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* kupdated() used to do this. We cannot do it from the bdi_forker_thread()
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* or we risk deadlocking on ->s_umount. The longer term solution would be
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* to implement sync_supers_bdi() or similar and simply do it from the
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* bdi writeback thread individually.
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*/
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static int bdi_sync_supers(void *unused)
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{
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set_user_nice(current, 0);
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while (!kthread_should_stop()) {
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set_current_state(TASK_INTERRUPTIBLE);
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schedule();
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/*
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* Do this periodically, like kupdated() did before.
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*/
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sync_supers();
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}
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return 0;
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}
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void bdi_arm_supers_timer(void)
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{
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unsigned long next;
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if (!dirty_writeback_interval)
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return;
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next = msecs_to_jiffies(dirty_writeback_interval * 10) + jiffies;
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mod_timer(&sync_supers_timer, round_jiffies_up(next));
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}
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static void sync_supers_timer_fn(unsigned long unused)
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{
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wake_up_process(sync_supers_tsk);
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bdi_arm_supers_timer();
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}
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static void wakeup_timer_fn(unsigned long data)
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{
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struct backing_dev_info *bdi = (struct backing_dev_info *)data;
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spin_lock_bh(&bdi->wb_lock);
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if (bdi->wb.task) {
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trace_writeback_wake_thread(bdi);
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wake_up_process(bdi->wb.task);
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} else {
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/*
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* When bdi tasks are inactive for long time, they are killed.
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* In this case we have to wake-up the forker thread which
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* should create and run the bdi thread.
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*/
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trace_writeback_wake_forker_thread(bdi);
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wake_up_process(default_backing_dev_info.wb.task);
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}
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spin_unlock_bh(&bdi->wb_lock);
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}
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/*
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* This function is used when the first inode for this bdi 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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void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi)
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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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mod_timer(&bdi->wb.wakeup_timer, jiffies + timeout);
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}
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/*
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* Calculate the longest interval (jiffies) bdi threads are allowed to be
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* inactive.
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*/
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static unsigned long bdi_longest_inactive(void)
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{
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unsigned long interval;
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interval = msecs_to_jiffies(dirty_writeback_interval * 10);
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return max(5UL * 60 * HZ, interval);
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}
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static int bdi_forker_thread(void *ptr)
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{
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struct bdi_writeback *me = ptr;
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current->flags |= PF_SWAPWRITE;
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set_freezable();
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/*
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* Our parent may run at a different priority, just set us to normal
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*/
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set_user_nice(current, 0);
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for (;;) {
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struct task_struct *task = NULL;
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struct backing_dev_info *bdi;
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enum {
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NO_ACTION, /* Nothing to do */
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FORK_THREAD, /* Fork bdi thread */
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KILL_THREAD, /* Kill inactive bdi thread */
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} action = NO_ACTION;
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/*
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* Temporary measure, we want to make sure we don't see
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* dirty data on the default backing_dev_info
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*/
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if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list)) {
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del_timer(&me->wakeup_timer);
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wb_do_writeback(me, 0);
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}
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spin_lock_bh(&bdi_lock);
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set_current_state(TASK_INTERRUPTIBLE);
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list_for_each_entry(bdi, &bdi_list, bdi_list) {
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bool have_dirty_io;
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if (!bdi_cap_writeback_dirty(bdi) ||
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bdi_cap_flush_forker(bdi))
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continue;
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WARN(!test_bit(BDI_registered, &bdi->state),
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"bdi %p/%s is not registered!\n", bdi, bdi->name);
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have_dirty_io = !list_empty(&bdi->work_list) ||
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wb_has_dirty_io(&bdi->wb);
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/*
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* If the bdi has work to do, but the thread does not
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* exist - create it.
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*/
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if (!bdi->wb.task && have_dirty_io) {
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/*
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* Set the pending bit - if someone will try to
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* unregister this bdi - it'll wait on this bit.
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*/
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set_bit(BDI_pending, &bdi->state);
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action = FORK_THREAD;
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break;
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}
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spin_lock(&bdi->wb_lock);
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/*
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* If there is no work to do and the bdi thread was
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* inactive long enough - kill it. The wb_lock is taken
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* to make sure no-one adds more work to this bdi and
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* wakes the bdi thread up.
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*/
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if (bdi->wb.task && !have_dirty_io &&
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time_after(jiffies, bdi->wb.last_active +
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bdi_longest_inactive())) {
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task = bdi->wb.task;
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bdi->wb.task = NULL;
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spin_unlock(&bdi->wb_lock);
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set_bit(BDI_pending, &bdi->state);
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action = KILL_THREAD;
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break;
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}
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spin_unlock(&bdi->wb_lock);
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}
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spin_unlock_bh(&bdi_lock);
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/* Keep working if default bdi still has things to do */
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if (!list_empty(&me->bdi->work_list))
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__set_current_state(TASK_RUNNING);
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switch (action) {
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case FORK_THREAD:
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__set_current_state(TASK_RUNNING);
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task = kthread_create(bdi_writeback_thread, &bdi->wb,
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"flush-%s", dev_name(bdi->dev));
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if (IS_ERR(task)) {
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/*
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* If thread creation fails, force writeout of
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* the bdi from the thread.
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*/
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bdi_flush_io(bdi);
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} else {
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/*
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* The spinlock makes sure we do not lose
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* wake-ups when racing with 'bdi_queue_work()'.
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* And as soon as the bdi thread is visible, we
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* can start it.
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*/
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spin_lock_bh(&bdi->wb_lock);
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bdi->wb.task = task;
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spin_unlock_bh(&bdi->wb_lock);
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wake_up_process(task);
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}
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break;
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case KILL_THREAD:
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__set_current_state(TASK_RUNNING);
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kthread_stop(task);
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break;
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case NO_ACTION:
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if (!wb_has_dirty_io(me) || !dirty_writeback_interval)
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/*
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* There are no dirty data. The only thing we
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* should now care about is checking for
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* inactive bdi threads and killing them. Thus,
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|
* let's sleep for longer time, save energy and
|
|
* be friendly for battery-driven devices.
|
|
*/
|
|
schedule_timeout(bdi_longest_inactive());
|
|
else
|
|
schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10));
|
|
try_to_freeze();
|
|
/* Back to the main loop */
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Clear pending bit and wakeup anybody waiting to tear us down.
|
|
*/
|
|
clear_bit(BDI_pending, &bdi->state);
|
|
smp_mb__after_clear_bit();
|
|
wake_up_bit(&bdi->state, BDI_pending);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* 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();
|
|
}
|
|
|
|
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;
|
|
|
|
/*
|
|
* Just start the forker thread for our default backing_dev_info,
|
|
* and add other bdi's to the list. They will get a thread created
|
|
* on-demand when they need it.
|
|
*/
|
|
if (bdi_cap_flush_forker(bdi)) {
|
|
struct bdi_writeback *wb = &bdi->wb;
|
|
|
|
wb->task = kthread_run(bdi_forker_thread, wb, "bdi-%s",
|
|
dev_name(dev));
|
|
if (IS_ERR(wb->task))
|
|
return PTR_ERR(wb->task);
|
|
}
|
|
|
|
bdi_debug_register(bdi, dev_name(dev));
|
|
set_bit(BDI_registered, &bdi->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 the global list and shutdown any threads we have running
|
|
*/
|
|
static void bdi_wb_shutdown(struct backing_dev_info *bdi)
|
|
{
|
|
if (!bdi_cap_writeback_dirty(bdi))
|
|
return;
|
|
|
|
/*
|
|
* Make sure nobody finds us on the bdi_list anymore
|
|
*/
|
|
bdi_remove_from_list(bdi);
|
|
|
|
/*
|
|
* If setup is pending, wait for that to complete first
|
|
*/
|
|
wait_on_bit(&bdi->state, BDI_pending, bdi_sched_wait,
|
|
TASK_UNINTERRUPTIBLE);
|
|
|
|
/*
|
|
* Finally, kill the kernel thread. We don't need to be RCU
|
|
* safe anymore, since the bdi is gone from visibility. Force
|
|
* unfreeze of the thread before calling kthread_stop(), otherwise
|
|
* it would never exet if it is currently stuck in the refrigerator.
|
|
*/
|
|
if (bdi->wb.task) {
|
|
thaw_process(bdi->wb.task);
|
|
kthread_stop(bdi->wb.task);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This bdi is going away now, make sure that no super_blocks point to it
|
|
*/
|
|
static void bdi_prune_sb(struct backing_dev_info *bdi)
|
|
{
|
|
struct super_block *sb;
|
|
|
|
spin_lock(&sb_lock);
|
|
list_for_each_entry(sb, &super_blocks, s_list) {
|
|
if (sb->s_bdi == bdi)
|
|
sb->s_bdi = NULL;
|
|
}
|
|
spin_unlock(&sb_lock);
|
|
}
|
|
|
|
void bdi_unregister(struct backing_dev_info *bdi)
|
|
{
|
|
if (bdi->dev) {
|
|
trace_writeback_bdi_unregister(bdi);
|
|
bdi_prune_sb(bdi);
|
|
del_timer_sync(&bdi->wb.wakeup_timer);
|
|
|
|
if (!bdi_cap_flush_forker(bdi))
|
|
bdi_wb_shutdown(bdi);
|
|
bdi_debug_unregister(bdi);
|
|
device_unregister(bdi->dev);
|
|
bdi->dev = NULL;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(bdi_unregister);
|
|
|
|
static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
|
|
{
|
|
memset(wb, 0, sizeof(*wb));
|
|
|
|
wb->bdi = bdi;
|
|
wb->last_old_flush = jiffies;
|
|
INIT_LIST_HEAD(&wb->b_dirty);
|
|
INIT_LIST_HEAD(&wb->b_io);
|
|
INIT_LIST_HEAD(&wb->b_more_io);
|
|
setup_timer(&wb->wakeup_timer, wakeup_timer_fn, (unsigned long)bdi);
|
|
}
|
|
|
|
int bdi_init(struct backing_dev_info *bdi)
|
|
{
|
|
int i, err;
|
|
|
|
bdi->dev = NULL;
|
|
|
|
bdi->min_ratio = 0;
|
|
bdi->max_ratio = 100;
|
|
bdi->max_prop_frac = PROP_FRAC_BASE;
|
|
spin_lock_init(&bdi->wb_lock);
|
|
INIT_LIST_HEAD(&bdi->bdi_list);
|
|
INIT_LIST_HEAD(&bdi->work_list);
|
|
|
|
bdi_wb_init(&bdi->wb, bdi);
|
|
|
|
for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
|
|
err = percpu_counter_init(&bdi->bdi_stat[i], 0);
|
|
if (err)
|
|
goto err;
|
|
}
|
|
|
|
bdi->dirty_exceeded = 0;
|
|
err = prop_local_init_percpu(&bdi->completions);
|
|
|
|
if (err) {
|
|
err:
|
|
while (i--)
|
|
percpu_counter_destroy(&bdi->bdi_stat[i]);
|
|
}
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL(bdi_init);
|
|
|
|
void bdi_destroy(struct backing_dev_info *bdi)
|
|
{
|
|
int i;
|
|
|
|
/*
|
|
* Splice our entries to the default_backing_dev_info, if this
|
|
* bdi disappears
|
|
*/
|
|
if (bdi_has_dirty_io(bdi)) {
|
|
struct bdi_writeback *dst = &default_backing_dev_info.wb;
|
|
|
|
spin_lock(&inode_lock);
|
|
list_splice(&bdi->wb.b_dirty, &dst->b_dirty);
|
|
list_splice(&bdi->wb.b_io, &dst->b_io);
|
|
list_splice(&bdi->wb.b_more_io, &dst->b_more_io);
|
|
spin_unlock(&inode_lock);
|
|
}
|
|
|
|
bdi_unregister(bdi);
|
|
|
|
for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
|
|
percpu_counter_destroy(&bdi->bdi_stat[i]);
|
|
|
|
prop_local_destroy_percpu(&bdi->completions);
|
|
}
|
|
EXPORT_SYMBOL(bdi_destroy);
|
|
|
|
/*
|
|
* 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,
|
|
unsigned int cap)
|
|
{
|
|
char tmp[32];
|
|
int err;
|
|
|
|
bdi->name = name;
|
|
bdi->capabilities = cap;
|
|
err = bdi_init(bdi);
|
|
if (err)
|
|
return err;
|
|
|
|
sprintf(tmp, "%.28s%s", name, "-%d");
|
|
err = bdi_register(bdi, NULL, tmp, 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_bdi_congested[2];
|
|
|
|
void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
|
|
{
|
|
enum bdi_state bit;
|
|
wait_queue_head_t *wqh = &congestion_wqh[sync];
|
|
|
|
bit = sync ? BDI_sync_congested : BDI_async_congested;
|
|
if (test_and_clear_bit(bit, &bdi->state))
|
|
atomic_dec(&nr_bdi_congested[sync]);
|
|
smp_mb__after_clear_bit();
|
|
if (waitqueue_active(wqh))
|
|
wake_up(wqh);
|
|
}
|
|
EXPORT_SYMBOL(clear_bdi_congested);
|
|
|
|
void set_bdi_congested(struct backing_dev_info *bdi, int sync)
|
|
{
|
|
enum bdi_state bit;
|
|
|
|
bit = sync ? BDI_sync_congested : BDI_async_congested;
|
|
if (!test_and_set_bit(bit, &bdi->state))
|
|
atomic_inc(&nr_bdi_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 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 absense of zone congestion, cond_resched() is called to yield
|
|
* the processor if necessary but otherwise does not sleep.
|
|
*
|
|
* 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_bdi_congested[sync]) == 0 ||
|
|
!zone_is_reclaim_congested(zone)) {
|
|
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);
|