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mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-22 20:23:57 +08:00
linux-next/mm/backing-dev.c
Linus Torvalds b0a1ea51bd Merge branch 'for-4.3/blkcg' of git://git.kernel.dk/linux-block
Pull blk-cg updates from Jens Axboe:
 "A bit later in the cycle, but this has been in the block tree for a a
  while.  This is basically four patchsets from Tejun, that improve our
  buffered cgroup writeback.  It was dependent on the other cgroup
  changes, but they went in earlier in this cycle.

  Series 1 is set of 5 patches that has cgroup writeback updates:

   - bdi_writeback iteration fix which could lead to some wb's being
     skipped or repeated during e.g. sync under memory pressure.

   - Simplification of wb work wait mechanism.

   - Writeback tracepoints updated to report cgroup.

  Series 2 is is a set of updates for the CFQ cgroup writeback handling:

     cfq has always charged all async IOs to the root cgroup.  It didn't
     have much choice as writeback didn't know about cgroups and there
     was no way to tell who to blame for a given writeback IO.
     writeback finally grew support for cgroups and now tags each
     writeback IO with the appropriate cgroup to charge it against.

     This patchset updates cfq so that it follows the blkcg each bio is
     tagged with.  Async cfq_queues are now shared across cfq_group,
     which is per-cgroup, instead of per-request_queue cfq_data.  This
     makes all IOs follow the weight based IO resource distribution
     implemented by cfq.

     - Switched from GFP_ATOMIC to GFP_NOWAIT as suggested by Jeff.

     - Other misc review points addressed, acks added and rebased.

  Series 3 is the blkcg policy cleanup patches:

     This patchset contains assorted cleanups for blkcg_policy methods
     and blk[c]g_policy_data handling.

     - alloc/free added for blkg_policy_data.  exit dropped.

     - alloc/free added for blkcg_policy_data.

     - blk-throttle's async percpu allocation is replaced with direct
       allocation.

     - all methods now take blk[c]g_policy_data instead of blkcg_gq or
       blkcg.

  And finally, series 4 is a set of patches cleaning up the blkcg stats
  handling:

    blkcg's stats have always been somwhat of a mess.  This patchset
    tries to improve the situation a bit.

     - The following patches added to consolidate blkcg entry point and
       blkg creation.  This is in itself is an improvement and helps
       colllecting common stats on bio issue.

     - per-blkg stats now accounted on bio issue rather than request
       completion so that bio based and request based drivers can behave
       the same way.  The issue was spotted by Vivek.

     - cfq-iosched implements custom recursive stats and blk-throttle
       implements custom per-cpu stats.  This patchset make blkcg core
       support both by default.

     - cfq-iosched and blk-throttle keep track of the same stats
       multiple times.  Unify them"

* 'for-4.3/blkcg' of git://git.kernel.dk/linux-block: (45 commits)
  blkcg: use CGROUP_WEIGHT_* scale for io.weight on the unified hierarchy
  blkcg: s/CFQ_WEIGHT_*/CFQ_WEIGHT_LEGACY_*/
  blkcg: implement interface for the unified hierarchy
  blkcg: misc preparations for unified hierarchy interface
  blkcg: separate out tg_conf_updated() from tg_set_conf()
  blkcg: move body parsing from blkg_conf_prep() to its callers
  blkcg: mark existing cftypes as legacy
  blkcg: rename subsystem name from blkio to io
  blkcg: refine error codes returned during blkcg configuration
  blkcg: remove unnecessary NULL checks from __cfqg_set_weight_device()
  blkcg: reduce stack usage of blkg_rwstat_recursive_sum()
  blkcg: remove cfqg_stats->sectors
  blkcg: move io_service_bytes and io_serviced stats into blkcg_gq
  blkcg: make blkg_[rw]stat_recursive_sum() to be able to index into blkcg_gq
  blkcg: make blkcg_[rw]stat per-cpu
  blkcg: add blkg_[rw]stat->aux_cnt and replace cfq_group->dead_stats with it
  blkcg: consolidate blkg creation in blkcg_bio_issue_check()
  blk-throttle: improve queue bypass handling
  blkcg: move root blkg lookup optimization from throtl_lookup_tg() to __blkg_lookup()
  blkcg: inline [__]blkg_lookup()
  ...
2015-09-10 18:56:14 -07:00

999 lines
26 KiB
C

#include <linux/wait.h>
#include <linux/backing-dev.h>
#include <linux/kthread.h>
#include <linux/freezer.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/writeback.h>
#include <linux/device.h>
#include <trace/events/writeback.h>
static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0);
struct backing_dev_info noop_backing_dev_info = {
.name = "noop",
.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
};
EXPORT_SYMBOL_GPL(noop_backing_dev_info);
static struct class *bdi_class;
/*
* bdi_lock protects updates to bdi_list. bdi_list has RCU reader side
* locking.
*/
DEFINE_SPINLOCK(bdi_lock);
LIST_HEAD(bdi_list);
/* bdi_wq serves all asynchronous writeback tasks */
struct workqueue_struct *bdi_wq;
#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>
#include <linux/seq_file.h>
static struct dentry *bdi_debug_root;
static void bdi_debug_init(void)
{
bdi_debug_root = debugfs_create_dir("bdi", NULL);
}
static int bdi_debug_stats_show(struct seq_file *m, void *v)
{
struct backing_dev_info *bdi = m->private;
struct bdi_writeback *wb = &bdi->wb;
unsigned long background_thresh;
unsigned long dirty_thresh;
unsigned long wb_thresh;
unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time;
struct inode *inode;
nr_dirty = nr_io = nr_more_io = nr_dirty_time = 0;
spin_lock(&wb->list_lock);
list_for_each_entry(inode, &wb->b_dirty, i_io_list)
nr_dirty++;
list_for_each_entry(inode, &wb->b_io, i_io_list)
nr_io++;
list_for_each_entry(inode, &wb->b_more_io, i_io_list)
nr_more_io++;
list_for_each_entry(inode, &wb->b_dirty_time, i_io_list)
if (inode->i_state & I_DIRTY_TIME)
nr_dirty_time++;
spin_unlock(&wb->list_lock);
global_dirty_limits(&background_thresh, &dirty_thresh);
wb_thresh = wb_calc_thresh(wb, dirty_thresh);
#define K(x) ((x) << (PAGE_SHIFT - 10))
seq_printf(m,
"BdiWriteback: %10lu kB\n"
"BdiReclaimable: %10lu kB\n"
"BdiDirtyThresh: %10lu kB\n"
"DirtyThresh: %10lu kB\n"
"BackgroundThresh: %10lu kB\n"
"BdiDirtied: %10lu kB\n"
"BdiWritten: %10lu kB\n"
"BdiWriteBandwidth: %10lu kBps\n"
"b_dirty: %10lu\n"
"b_io: %10lu\n"
"b_more_io: %10lu\n"
"b_dirty_time: %10lu\n"
"bdi_list: %10u\n"
"state: %10lx\n",
(unsigned long) K(wb_stat(wb, WB_WRITEBACK)),
(unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)),
K(wb_thresh),
K(dirty_thresh),
K(background_thresh),
(unsigned long) K(wb_stat(wb, WB_DIRTIED)),
(unsigned long) K(wb_stat(wb, WB_WRITTEN)),
(unsigned long) K(wb->write_bandwidth),
nr_dirty,
nr_io,
nr_more_io,
nr_dirty_time,
!list_empty(&bdi->bdi_list), bdi->wb.state);
#undef K
return 0;
}
static int bdi_debug_stats_open(struct inode *inode, struct file *file)
{
return single_open(file, bdi_debug_stats_show, inode->i_private);
}
static const struct file_operations bdi_debug_stats_fops = {
.open = bdi_debug_stats_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
{
bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir,
bdi, &bdi_debug_stats_fops);
}
static void bdi_debug_unregister(struct backing_dev_info *bdi)
{
debugfs_remove(bdi->debug_stats);
debugfs_remove(bdi->debug_dir);
}
#else
static inline void bdi_debug_init(void)
{
}
static inline void bdi_debug_register(struct backing_dev_info *bdi,
const char *name)
{
}
static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
{
}
#endif
static ssize_t read_ahead_kb_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct backing_dev_info *bdi = dev_get_drvdata(dev);
unsigned long read_ahead_kb;
ssize_t ret;
ret = kstrtoul(buf, 10, &read_ahead_kb);
if (ret < 0)
return ret;
bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
return count;
}
#define K(pages) ((pages) << (PAGE_SHIFT - 10))
#define BDI_SHOW(name, expr) \
static ssize_t name##_show(struct device *dev, \
struct device_attribute *attr, char *page) \
{ \
struct backing_dev_info *bdi = dev_get_drvdata(dev); \
\
return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \
} \
static DEVICE_ATTR_RW(name);
BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
static ssize_t min_ratio_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
struct backing_dev_info *bdi = dev_get_drvdata(dev);
unsigned int ratio;
ssize_t ret;
ret = kstrtouint(buf, 10, &ratio);
if (ret < 0)
return ret;
ret = bdi_set_min_ratio(bdi, ratio);
if (!ret)
ret = count;
return ret;
}
BDI_SHOW(min_ratio, bdi->min_ratio)
static ssize_t max_ratio_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
struct backing_dev_info *bdi = dev_get_drvdata(dev);
unsigned int ratio;
ssize_t ret;
ret = kstrtouint(buf, 10, &ratio);
if (ret < 0)
return ret;
ret = bdi_set_max_ratio(bdi, ratio);
if (!ret)
ret = count;
return ret;
}
BDI_SHOW(max_ratio, bdi->max_ratio)
static ssize_t stable_pages_required_show(struct device *dev,
struct device_attribute *attr,
char *page)
{
struct backing_dev_info *bdi = dev_get_drvdata(dev);
return snprintf(page, PAGE_SIZE-1, "%d\n",
bdi_cap_stable_pages_required(bdi) ? 1 : 0);
}
static DEVICE_ATTR_RO(stable_pages_required);
static struct attribute *bdi_dev_attrs[] = {
&dev_attr_read_ahead_kb.attr,
&dev_attr_min_ratio.attr,
&dev_attr_max_ratio.attr,
&dev_attr_stable_pages_required.attr,
NULL,
};
ATTRIBUTE_GROUPS(bdi_dev);
static __init int bdi_class_init(void)
{
bdi_class = class_create(THIS_MODULE, "bdi");
if (IS_ERR(bdi_class))
return PTR_ERR(bdi_class);
bdi_class->dev_groups = bdi_dev_groups;
bdi_debug_init();
return 0;
}
postcore_initcall(bdi_class_init);
static int __init default_bdi_init(void)
{
int err;
bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_FREEZABLE |
WQ_UNBOUND | WQ_SYSFS, 0);
if (!bdi_wq)
return -ENOMEM;
err = bdi_init(&noop_backing_dev_info);
return err;
}
subsys_initcall(default_bdi_init);
/*
* This function is used when the first inode for this wb is marked dirty. It
* wakes-up the corresponding bdi thread which should then take care of the
* periodic background write-out of dirty inodes. Since the write-out would
* starts only 'dirty_writeback_interval' centisecs from now anyway, we just
* set up a timer which wakes the bdi thread up later.
*
* Note, we wouldn't bother setting up the timer, but this function is on the
* fast-path (used by '__mark_inode_dirty()'), so we save few context switches
* by delaying the wake-up.
*
* We have to be careful not to postpone flush work if it is scheduled for
* earlier. Thus we use queue_delayed_work().
*/
void wb_wakeup_delayed(struct bdi_writeback *wb)
{
unsigned long timeout;
timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
spin_lock_bh(&wb->work_lock);
if (test_bit(WB_registered, &wb->state))
queue_delayed_work(bdi_wq, &wb->dwork, timeout);
spin_unlock_bh(&wb->work_lock);
}
/*
* Initial write bandwidth: 100 MB/s
*/
#define INIT_BW (100 << (20 - PAGE_SHIFT))
static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
int blkcg_id, gfp_t gfp)
{
int i, err;
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);
INIT_LIST_HEAD(&wb->b_dirty_time);
spin_lock_init(&wb->list_lock);
wb->bw_time_stamp = jiffies;
wb->balanced_dirty_ratelimit = INIT_BW;
wb->dirty_ratelimit = INIT_BW;
wb->write_bandwidth = INIT_BW;
wb->avg_write_bandwidth = INIT_BW;
spin_lock_init(&wb->work_lock);
INIT_LIST_HEAD(&wb->work_list);
INIT_DELAYED_WORK(&wb->dwork, wb_workfn);
wb->congested = wb_congested_get_create(bdi, blkcg_id, gfp);
if (!wb->congested)
return -ENOMEM;
err = fprop_local_init_percpu(&wb->completions, gfp);
if (err)
goto out_put_cong;
for (i = 0; i < NR_WB_STAT_ITEMS; i++) {
err = percpu_counter_init(&wb->stat[i], 0, gfp);
if (err)
goto out_destroy_stat;
}
return 0;
out_destroy_stat:
while (--i)
percpu_counter_destroy(&wb->stat[i]);
fprop_local_destroy_percpu(&wb->completions);
out_put_cong:
wb_congested_put(wb->congested);
return err;
}
/*
* Remove bdi from the global list and shutdown any threads we have running
*/
static void wb_shutdown(struct bdi_writeback *wb)
{
/* Make sure nobody queues further work */
spin_lock_bh(&wb->work_lock);
if (!test_and_clear_bit(WB_registered, &wb->state)) {
spin_unlock_bh(&wb->work_lock);
return;
}
spin_unlock_bh(&wb->work_lock);
/*
* Drain work list and shutdown the delayed_work. !WB_registered
* tells wb_workfn() that @wb is dying and its work_list needs to
* be drained no matter what.
*/
mod_delayed_work(bdi_wq, &wb->dwork, 0);
flush_delayed_work(&wb->dwork);
WARN_ON(!list_empty(&wb->work_list));
}
static void wb_exit(struct bdi_writeback *wb)
{
int i;
WARN_ON(delayed_work_pending(&wb->dwork));
for (i = 0; i < NR_WB_STAT_ITEMS; i++)
percpu_counter_destroy(&wb->stat[i]);
fprop_local_destroy_percpu(&wb->completions);
wb_congested_put(wb->congested);
}
#ifdef CONFIG_CGROUP_WRITEBACK
#include <linux/memcontrol.h>
/*
* cgwb_lock protects bdi->cgwb_tree, bdi->cgwb_congested_tree,
* blkcg->cgwb_list, and memcg->cgwb_list. bdi->cgwb_tree is also RCU
* protected. cgwb_release_wait is used to wait for the completion of cgwb
* releases from bdi destruction path.
*/
static DEFINE_SPINLOCK(cgwb_lock);
static DECLARE_WAIT_QUEUE_HEAD(cgwb_release_wait);
/**
* wb_congested_get_create - get or create a wb_congested
* @bdi: associated bdi
* @blkcg_id: ID of the associated blkcg
* @gfp: allocation mask
*
* Look up the wb_congested for @blkcg_id on @bdi. If missing, create one.
* The returned wb_congested has its reference count incremented. Returns
* NULL on failure.
*/
struct bdi_writeback_congested *
wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
{
struct bdi_writeback_congested *new_congested = NULL, *congested;
struct rb_node **node, *parent;
unsigned long flags;
retry:
spin_lock_irqsave(&cgwb_lock, flags);
node = &bdi->cgwb_congested_tree.rb_node;
parent = NULL;
while (*node != NULL) {
parent = *node;
congested = container_of(parent, struct bdi_writeback_congested,
rb_node);
if (congested->blkcg_id < blkcg_id)
node = &parent->rb_left;
else if (congested->blkcg_id > blkcg_id)
node = &parent->rb_right;
else
goto found;
}
if (new_congested) {
/* !found and storage for new one already allocated, insert */
congested = new_congested;
new_congested = NULL;
rb_link_node(&congested->rb_node, parent, node);
rb_insert_color(&congested->rb_node, &bdi->cgwb_congested_tree);
goto found;
}
spin_unlock_irqrestore(&cgwb_lock, flags);
/* allocate storage for new one and retry */
new_congested = kzalloc(sizeof(*new_congested), gfp);
if (!new_congested)
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);
spin_unlock_irqrestore(&cgwb_lock, flags);
kfree(new_congested);
return congested;
}
/**
* wb_congested_put - put a wb_congested
* @congested: wb_congested to put
*
* 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);
if (!atomic_dec_and_lock(&congested->refcnt, &cgwb_lock)) {
local_irq_restore(flags);
return;
}
/* 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;
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(&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(gfp & __GFP_WAIT);
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 = mem_cgroup_root_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 bdi_writeback_congested *congested, *congested_n;
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);
rbtree_postorder_for_each_entry_safe(congested, congested_n,
&bdi->cgwb_congested_tree, rb_node) {
rb_erase(&congested->rb_node, &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)
{
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_waitqueue_head(&bdi->wb_waitq);
return cgwb_bdi_init(bdi);
}
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_destroy(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;
}
wb_exit(&bdi->wb);
}
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, 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_wb_congested[sync]) == 0 ||
!test_bit(ZONE_CONGESTED, &zone->flags)) {
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;
}