Line data    Source code

       1             : /* SPDX-License-Identifier: GPL-2.0 */
       2             : #ifndef __LINUX_BACKING_DEV_DEFS_H
       3             : #define __LINUX_BACKING_DEV_DEFS_H
       4             : 
       5             : #include <linux/list.h>
       6             : #include <linux/radix-tree.h>
       7             : #include <linux/rbtree.h>
       8             : #include <linux/spinlock.h>
       9             : #include <linux/percpu_counter.h>
      10             : #include <linux/percpu-refcount.h>
      11             : #include <linux/flex_proportions.h>
      12             : #include <linux/timer.h>
      13             : #include <linux/workqueue.h>
      14             : #include <linux/kref.h>
      15             : #include <linux/refcount.h>
      16             : 
      17             : struct page;
      18             : struct device;
      19             : struct dentry;
      20             : 
      21             : /*
      22             :  * Bits in bdi_writeback.state
      23             :  */
      24             : enum wb_state {
      25             :         WB_registered,          /* bdi_register() was done */
      26             :         WB_writeback_running,   /* Writeback is in progress */
      27             :         WB_has_dirty_io,        /* Dirty inodes on ->b_{dirty|io|more_io} */
      28             :         WB_start_all,           /* nr_pages == 0 (all) work pending */
      29             : };
      30             : 
      31             : enum wb_stat_item {
      32             :         WB_RECLAIMABLE,
      33             :         WB_WRITEBACK,
      34             :         WB_DIRTIED,
      35             :         WB_WRITTEN,
      36             :         NR_WB_STAT_ITEMS
      37             : };
      38             : 
      39             : #define WB_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
      40             : 
      41             : /*
      42             :  * why some writeback work was initiated
      43             :  */
      44             : enum wb_reason {
      45             :         WB_REASON_BACKGROUND,
      46             :         WB_REASON_VMSCAN,
      47             :         WB_REASON_SYNC,
      48             :         WB_REASON_PERIODIC,
      49             :         WB_REASON_LAPTOP_TIMER,
      50             :         WB_REASON_FS_FREE_SPACE,
      51             :         /*
      52             :          * There is no bdi forker thread any more and works are done
      53             :          * by emergency worker, however, this is TPs userland visible
      54             :          * and we'll be exposing exactly the same information,
      55             :          * so it has a mismatch name.
      56             :          */
      57             :         WB_REASON_FORKER_THREAD,
      58             :         WB_REASON_FOREIGN_FLUSH,
      59             : 
      60             :         WB_REASON_MAX,
      61             : };
      62             : 
      63             : struct wb_completion {
      64             :         atomic_t                cnt;
      65             :         wait_queue_head_t       *waitq;
      66             : };
      67             : 
      68             : #define __WB_COMPLETION_INIT(_waitq)    \
      69             :         (struct wb_completion){ .cnt = ATOMIC_INIT(1), .waitq = (_waitq) }
      70             : 
      71             : /*
      72             :  * If one wants to wait for one or more wb_writeback_works, each work's
      73             :  * ->done should be set to a wb_completion defined using the following
      74             :  * macro.  Once all work items are issued with wb_queue_work(), the caller
      75             :  * can wait for the completion of all using wb_wait_for_completion().  Work
      76             :  * items which are waited upon aren't freed automatically on completion.
      77             :  */
      78             : #define WB_COMPLETION_INIT(bdi)         __WB_COMPLETION_INIT(&(bdi)->wb_waitq)
      79             : 
      80             : #define DEFINE_WB_COMPLETION(cmpl, bdi) \
      81             :         struct wb_completion cmpl = WB_COMPLETION_INIT(bdi)
      82             : 
      83             : /*
      84             :  * Each wb (bdi_writeback) can perform writeback operations, is measured
      85             :  * and throttled, independently.  Without cgroup writeback, each bdi
      86             :  * (bdi_writeback) is served by its embedded bdi->wb.
      87             :  *
      88             :  * On the default hierarchy, blkcg implicitly enables memcg.  This allows
      89             :  * using memcg's page ownership for attributing writeback IOs, and every
      90             :  * memcg - blkcg combination can be served by its own wb by assigning a
      91             :  * dedicated wb to each memcg, which enables isolation across different
      92             :  * cgroups and propagation of IO back pressure down from the IO layer upto
      93             :  * the tasks which are generating the dirty pages to be written back.
      94             :  *
      95             :  * A cgroup wb is indexed on its bdi by the ID of the associated memcg,
      96             :  * refcounted with the number of inodes attached to it, and pins the memcg
      97             :  * and the corresponding blkcg.  As the corresponding blkcg for a memcg may
      98             :  * change as blkcg is disabled and enabled higher up in the hierarchy, a wb
      99             :  * is tested for blkcg after lookup and removed from index on mismatch so
     100             :  * that a new wb for the combination can be created.
     101             :  *
     102             :  * Each bdi_writeback that is not embedded into the backing_dev_info must hold
     103             :  * a reference to the parent backing_dev_info.  See cgwb_create() for details.
     104             :  */
     105             : struct bdi_writeback {
     106             :         struct backing_dev_info *bdi;   /* our parent bdi */
     107             : 
     108             :         unsigned long state;            /* Always use atomic bitops on this */
     109             :         unsigned long last_old_flush;   /* last old data flush */
     110             : 
     111             :         struct list_head b_dirty;       /* dirty inodes */
     112             :         struct list_head b_io;          /* parked for writeback */
     113             :         struct list_head b_more_io;     /* parked for more writeback */
     114             :         struct list_head b_dirty_time;  /* time stamps are dirty */
     115             :         spinlock_t list_lock;           /* protects the b_* lists */
     116             : 
     117             :         atomic_t writeback_inodes;      /* number of inodes under writeback */
     118             :         struct percpu_counter stat[NR_WB_STAT_ITEMS];
     119             : 
     120             :         unsigned long bw_time_stamp;    /* last time write bw is updated */
     121             :         unsigned long dirtied_stamp;
     122             :         unsigned long written_stamp;    /* pages written at bw_time_stamp */
     123             :         unsigned long write_bandwidth;  /* the estimated write bandwidth */
     124             :         unsigned long avg_write_bandwidth; /* further smoothed write bw, > 0 */
     125             : 
     126             :         /*
     127             :          * The base dirty throttle rate, re-calculated on every 200ms.
     128             :          * All the bdi tasks' dirty rate will be curbed under it.
     129             :          * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit
     130             :          * in small steps and is much more smooth/stable than the latter.
     131             :          */
     132             :         unsigned long dirty_ratelimit;
     133             :         unsigned long balanced_dirty_ratelimit;
     134             : 
     135             :         struct fprop_local_percpu completions;
     136             :         int dirty_exceeded;
     137             :         enum wb_reason start_all_reason;
     138             : 
     139             :         spinlock_t work_lock;           /* protects work_list & dwork scheduling */
     140             :         struct list_head work_list;
     141             :         struct delayed_work dwork;      /* work item used for writeback */
     142             :         struct delayed_work bw_dwork;   /* work item used for bandwidth estimate */
     143             : 
     144             :         unsigned long dirty_sleep;      /* last wait */
     145             : 
     146             :         struct list_head bdi_node;      /* anchored at bdi->wb_list */
     147             : 
     148             : #ifdef CONFIG_CGROUP_WRITEBACK
     149             :         struct percpu_ref refcnt;       /* used only for !root wb's */
     150             :         struct fprop_local_percpu memcg_completions;
     151             :         struct cgroup_subsys_state *memcg_css; /* the associated memcg */
     152             :         struct cgroup_subsys_state *blkcg_css; /* and blkcg */
     153             :         struct list_head memcg_node;    /* anchored at memcg->cgwb_list */
     154             :         struct list_head blkcg_node;    /* anchored at blkcg->cgwb_list */
     155             :         struct list_head b_attached;    /* attached inodes, protected by list_lock */
     156             :         struct list_head offline_node;  /* anchored at offline_cgwbs */
     157             : 
     158             :         union {
     159             :                 struct work_struct release_work;
     160             :                 struct rcu_head rcu;
     161             :         };
     162             : #endif
     163             : };
     164             : 
     165             : struct backing_dev_info {
     166             :         u64 id;
     167             :         struct rb_node rb_node; /* keyed by ->id */
     168             :         struct list_head bdi_list;
     169             :         unsigned long ra_pages; /* max readahead in PAGE_SIZE units */
     170             :         unsigned long io_pages; /* max allowed IO size */
     171             : 
     172             :         struct kref refcnt;     /* Reference counter for the structure */
     173             :         unsigned int capabilities; /* Device capabilities */
     174             :         unsigned int min_ratio;
     175             :         unsigned int max_ratio, max_prop_frac;
     176             : 
     177             :         /*
     178             :          * Sum of avg_write_bw of wbs with dirty inodes.  > 0 if there are
     179             :          * any dirty wbs, which is depended upon by bdi_has_dirty().
     180             :          */
     181             :         atomic_long_t tot_write_bandwidth;
     182             : 
     183             :         struct bdi_writeback wb;  /* the root writeback info for this bdi */
     184             :         struct list_head wb_list; /* list of all wbs */
     185             : #ifdef CONFIG_CGROUP_WRITEBACK
     186             :         struct radix_tree_root cgwb_tree; /* radix tree of active cgroup wbs */
     187             :         struct mutex cgwb_release_mutex;  /* protect shutdown of wb structs */
     188             :         struct rw_semaphore wb_switch_rwsem; /* no cgwb switch while syncing */
     189             : #endif
     190             :         wait_queue_head_t wb_waitq;
     191             : 
     192             :         struct device *dev;
     193             :         char dev_name[64];
     194             :         struct device *owner;
     195             : 
     196             :         struct timer_list laptop_mode_wb_timer;
     197             : 
     198             : #ifdef CONFIG_DEBUG_FS
     199             :         struct dentry *debug_dir;
     200             : #endif
     201             : };
     202             : 
     203             : struct wb_lock_cookie {
     204             :         bool locked;
     205             :         unsigned long flags;
     206             : };
     207             : 
     208             : #ifdef CONFIG_CGROUP_WRITEBACK
     209             : 
     210             : /**
     211             :  * wb_tryget - try to increment a wb's refcount
     212             :  * @wb: bdi_writeback to get
     213             :  */
     214   170973555 : static inline bool wb_tryget(struct bdi_writeback *wb)
     215             : {
     216   170973555 :         if (wb != &wb->bdi->wb)
     217   170923929 :                 return percpu_ref_tryget(&wb->refcnt);
     218             :         return true;
     219             : }
     220             : 
     221             : /**
     222             :  * wb_get - increment a wb's refcount
     223             :  * @wb: bdi_writeback to get
     224             :  */
     225   107316283 : static inline void wb_get(struct bdi_writeback *wb)
     226             : {
     227   107316283 :         if (wb != &wb->bdi->wb)
     228   106556477 :                 percpu_ref_get(&wb->refcnt);
     229   107315067 : }
     230             : 
     231             : /**
     232             :  * wb_put - decrement a wb's refcount
     233             :  * @wb: bdi_writeback to put
     234             :  * @nr: number of references to put
     235             :  */
     236   287987314 : static inline void wb_put_many(struct bdi_writeback *wb, unsigned long nr)
     237             : {
     238   287987314 :         if (WARN_ON_ONCE(!wb->bdi)) {
     239             :                 /*
     240             :                  * A driver bug might cause a file to be removed before bdi was
     241             :                  * initialized.
     242             :                  */
     243             :                 return;
     244             :         }
     245             : 
     246   287987314 :         if (wb != &wb->bdi->wb)
     247   285510391 :                 percpu_ref_put_many(&wb->refcnt, nr);
     248             : }
     249             : 
     250             : /**
     251             :  * wb_put - decrement a wb's refcount
     252             :  * @wb: bdi_writeback to put
     253             :  */
     254             : static inline void wb_put(struct bdi_writeback *wb)
     255             : {
     256   288003293 :         wb_put_many(wb, 1);
     257           0 : }
     258             : 
     259             : /**
     260             :  * wb_dying - is a wb dying?
     261             :  * @wb: bdi_writeback of interest
     262             :  *
     263             :  * Returns whether @wb is unlinked and being drained.
     264             :  */
     265             : static inline bool wb_dying(struct bdi_writeback *wb)
     266             : {
     267    44409833 :         return percpu_ref_is_dying(&wb->refcnt);
     268             : }
     269             : 
     270             : #else   /* CONFIG_CGROUP_WRITEBACK */
     271             : 
     272             : static inline bool wb_tryget(struct bdi_writeback *wb)
     273             : {
     274             :         return true;
     275             : }
     276             : 
     277             : static inline void wb_get(struct bdi_writeback *wb)
     278             : {
     279             : }
     280             : 
     281             : static inline void wb_put(struct bdi_writeback *wb)
     282             : {
     283             : }
     284             : 
     285             : static inline void wb_put_many(struct bdi_writeback *wb, unsigned long nr)
     286             : {
     287             : }
     288             : 
     289             : static inline bool wb_dying(struct bdi_writeback *wb)
     290             : {
     291             :         return false;
     292             : }
     293             : 
     294             : #endif  /* CONFIG_CGROUP_WRITEBACK */
     295             : 
     296             : #endif  /* __LINUX_BACKING_DEV_DEFS_H */