Release 4.12 include/linux/backing-dev-defs.h
#ifndef __LINUX_BACKING_DEV_DEFS_H
#define __LINUX_BACKING_DEV_DEFS_H
#include <linux/list.h>
#include <linux/radix-tree.h>
#include <linux/rbtree.h>
#include <linux/spinlock.h>
#include <linux/percpu_counter.h>
#include <linux/percpu-refcount.h>
#include <linux/flex_proportions.h>
#include <linux/timer.h>
#include <linux/workqueue.h>
#include <linux/kref.h>
struct page;
struct device;
struct dentry;
/*
* Bits in bdi_writeback.state
*/
enum wb_state {
WB_registered, /* bdi_register() was done */
WB_shutting_down, /* wb_shutdown() in progress */
WB_writeback_running, /* Writeback is in progress */
WB_has_dirty_io, /* Dirty inodes on ->b_{dirty|io|more_io} */
};
enum wb_congested_state {
WB_async_congested, /* The async (write) queue is getting full */
WB_sync_congested, /* The sync queue is getting full */
};
typedef int (congested_fn)(void *, int);
enum wb_stat_item {
WB_RECLAIMABLE,
WB_WRITEBACK,
WB_DIRTIED,
WB_WRITTEN,
NR_WB_STAT_ITEMS
};
#define WB_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
/*
* For cgroup writeback, multiple wb's may map to the same blkcg. Those
* wb's can operate mostly independently but should share the congested
* state. To facilitate such sharing, the congested state is tracked using
* the following struct which is created on demand, indexed by blkcg ID on
* its bdi, and refcounted.
*/
struct bdi_writeback_congested {
unsigned long state; /* WB_[a]sync_congested flags */
atomic_t refcnt; /* nr of attached wb's and blkg */
#ifdef CONFIG_CGROUP_WRITEBACK
struct backing_dev_info *__bdi; /* the associated bdi, set to NULL
* on bdi unregistration. For memcg-wb
* internal use only! */
int blkcg_id; /* ID of the associated blkcg */
struct rb_node rb_node; /* on bdi->cgwb_congestion_tree */
#endif
};
/*
* Each wb (bdi_writeback) can perform writeback operations, is measured
* and throttled, independently. Without cgroup writeback, each bdi
* (bdi_writeback) is served by its embedded bdi->wb.
*
* On the default hierarchy, blkcg implicitly enables memcg. This allows
* using memcg's page ownership for attributing writeback IOs, and every
* memcg - blkcg combination can be served by its own wb by assigning a
* dedicated wb to each memcg, which enables isolation across different
* cgroups and propagation of IO back pressure down from the IO layer upto
* the tasks which are generating the dirty pages to be written back.
*
* A cgroup wb is indexed on its bdi by the ID of the associated memcg,
* refcounted with the number of inodes attached to it, and pins the memcg
* and the corresponding blkcg. As the corresponding blkcg for a memcg may
* change as blkcg is disabled and enabled higher up in the hierarchy, a wb
* is tested for blkcg after lookup and removed from index on mismatch so
* that a new wb for the combination can be created.
*/
struct bdi_writeback {
struct backing_dev_info *bdi; /* our parent bdi */
unsigned long state; /* Always use atomic bitops on this */
unsigned long last_old_flush; /* last old data flush */
struct list_head b_dirty; /* dirty inodes */
struct list_head b_io; /* parked for writeback */
struct list_head b_more_io; /* parked for more writeback */
struct list_head b_dirty_time; /* time stamps are dirty */
spinlock_t list_lock; /* protects the b_* lists */
struct percpu_counter stat[NR_WB_STAT_ITEMS];
struct bdi_writeback_congested *congested;
unsigned long bw_time_stamp; /* last time write bw is updated */
unsigned long dirtied_stamp;
unsigned long written_stamp; /* pages written at bw_time_stamp */
unsigned long write_bandwidth; /* the estimated write bandwidth */
unsigned long avg_write_bandwidth; /* further smoothed write bw, > 0 */
/*
* The base dirty throttle rate, re-calculated on every 200ms.
* All the bdi tasks' dirty rate will be curbed under it.
* @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit
* in small steps and is much more smooth/stable than the latter.
*/
unsigned long dirty_ratelimit;
unsigned long balanced_dirty_ratelimit;
struct fprop_local_percpu completions;
int dirty_exceeded;
spinlock_t work_lock; /* protects work_list & dwork scheduling */
struct list_head work_list;
struct delayed_work dwork; /* work item used for writeback */
unsigned long dirty_sleep; /* last wait */
struct list_head bdi_node; /* anchored at bdi->wb_list */
#ifdef CONFIG_CGROUP_WRITEBACK
struct percpu_ref refcnt; /* used only for !root wb's */
struct fprop_local_percpu memcg_completions;
struct cgroup_subsys_state *memcg_css; /* the associated memcg */
struct cgroup_subsys_state *blkcg_css; /* and blkcg */
struct list_head memcg_node; /* anchored at memcg->cgwb_list */
struct list_head blkcg_node; /* anchored at blkcg->cgwb_list */
union {
struct work_struct release_work;
struct rcu_head rcu;
};
#endif
};
struct backing_dev_info {
struct list_head bdi_list;
unsigned long ra_pages; /* max readahead in PAGE_SIZE units */
unsigned long io_pages; /* max allowed IO size */
congested_fn *congested_fn; /* Function pointer if device is md/dm */
void *congested_data; /* Pointer to aux data for congested func */
const char *name;
struct kref refcnt; /* Reference counter for the structure */
unsigned int capabilities; /* Device capabilities */
unsigned int min_ratio;
unsigned int max_ratio, max_prop_frac;
/*
* Sum of avg_write_bw of wbs with dirty inodes. > 0 if there are
* any dirty wbs, which is depended upon by bdi_has_dirty().
*/
atomic_long_t tot_write_bandwidth;
struct bdi_writeback wb; /* the root writeback info for this bdi */
struct list_head wb_list; /* list of all wbs */
#ifdef CONFIG_CGROUP_WRITEBACK
struct radix_tree_root cgwb_tree; /* radix tree of active cgroup wbs */
struct rb_root cgwb_congested_tree; /* their congested states */
#else
struct bdi_writeback_congested *wb_congested;
#endif
wait_queue_head_t wb_waitq;
struct device *dev;
struct device *owner;
struct timer_list laptop_mode_wb_timer;
#ifdef CONFIG_DEBUG_FS
struct dentry *debug_dir;
struct dentry *debug_stats;
#endif
};
enum {
BLK_RW_ASYNC = 0,
BLK_RW_SYNC = 1,
};
void clear_wb_congested(struct bdi_writeback_congested *congested, int sync);
void set_wb_congested(struct bdi_writeback_congested *congested, int sync);
static inline void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
{
clear_wb_congested(bdi->wb.congested, sync);
}
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static inline void set_bdi_congested(struct backing_dev_info *bdi, int sync)
{
set_wb_congested(bdi->wb.congested, sync);
}
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#ifdef CONFIG_CGROUP_WRITEBACK
/**
* wb_tryget - try to increment a wb's refcount
* @wb: bdi_writeback to get
*/
static inline bool wb_tryget(struct bdi_writeback *wb)
{
if (wb != &wb->bdi->wb)
return percpu_ref_tryget(&wb->refcnt);
return true;
}
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/**
* wb_get - increment a wb's refcount
* @wb: bdi_writeback to get
*/
static inline void wb_get(struct bdi_writeback *wb)
{
if (wb != &wb->bdi->wb)
percpu_ref_get(&wb->refcnt);
}
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/**
* wb_put - decrement a wb's refcount
* @wb: bdi_writeback to put
*/
static inline void wb_put(struct bdi_writeback *wb)
{
if (wb != &wb->bdi->wb)
percpu_ref_put(&wb->refcnt);
}
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/**
* wb_dying - is a wb dying?
* @wb: bdi_writeback of interest
*
* Returns whether @wb is unlinked and being drained.
*/
static inline bool wb_dying(struct bdi_writeback *wb)
{
return percpu_ref_is_dying(&wb->refcnt);
}
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#else /* CONFIG_CGROUP_WRITEBACK */
static inline bool wb_tryget(struct bdi_writeback *wb)
{
return true;
}
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static inline void wb_get(struct bdi_writeback *wb)
{
}
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static inline void wb_put(struct bdi_writeback *wb)
{
}
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static inline bool wb_dying(struct bdi_writeback *wb)
{
return false;
}
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#endif /* CONFIG_CGROUP_WRITEBACK */
#endif /* __LINUX_BACKING_DEV_DEFS_H */
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