LCOV - code coverage report
Current view: top level - lkbce/include/linux - backing-dev.h (source / functions) Hit Total Coverage
Test: coverage.info Lines: 4 4 100.0 %
Date: 2017-01-25 Functions: 0 0 -

          Line data    Source code
       1             : /*
       2             :  * include/linux/backing-dev.h
       3             :  *
       4             :  * low-level device information and state which is propagated up through
       5             :  * to high-level code.
       6             :  */
       7             : 
       8             : #ifndef _LINUX_BACKING_DEV_H
       9             : #define _LINUX_BACKING_DEV_H
      10             : 
      11             : #include <linux/percpu_counter.h>
      12             : #include <linux/log2.h>
      13             : #include <linux/proportions.h>
      14             : #include <linux/kernel.h>
      15             : #include <linux/fs.h>
      16             : #include <linux/sched.h>
      17             : #include <linux/writeback.h>
      18             : #include <asm/atomic.h>
      19             : 
      20             : struct page;
      21             : struct device;
      22             : struct dentry;
      23             : 
      24             : /*
      25             :  * Bits in backing_dev_info.state
      26             :  */
      27             : enum bdi_state {
      28             :         BDI_pending,            /* On its way to being activated */
      29             :         BDI_wb_alloc,           /* Default embedded wb allocated */
      30             :         BDI_async_congested,    /* The async (write) queue is getting full */
      31             :         BDI_sync_congested,     /* The sync queue is getting full */
      32             :         BDI_registered,         /* bdi_register() was done */
      33             :         BDI_unused,             /* Available bits start here */
      34             : };
      35             : 
      36           1 : typedef int (congested_fn)(void *, int);
      37             : 
      38             : enum bdi_stat_item {
      39             :         BDI_RECLAIMABLE,
      40             :         BDI_WRITEBACK,
      41             :         NR_BDI_STAT_ITEMS
      42             : };
      43           1 : 
      44             : #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
      45             : 
      46             : struct bdi_writeback {
      47             :         struct list_head list;                  /* hangs off the bdi */
      48             : 
      49             :         struct backing_dev_info *bdi;           /* our parent bdi */
      50             :         unsigned int nr;
      51             : 
      52             :         unsigned long last_old_flush;           /* last old data flush */
      53             : 
      54             :         struct task_struct      *task;          /* writeback task */
      55             :         struct list_head        b_dirty;        /* dirty inodes */
      56             :         struct list_head        b_io;           /* parked for writeback */
      57             :         struct list_head        b_more_io;      /* parked for more writeback */
      58             : };
      59           1 : 
      60             : struct backing_dev_info {
      61             :         struct list_head bdi_list;
      62             :         struct rcu_head rcu_head;
      63             :         unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
      64             :         unsigned long state;    /* Always use atomic bitops on this */
      65             :         unsigned int capabilities; /* Device capabilities */
      66             :         congested_fn *congested_fn; /* Function pointer if device is md/dm */
      67             :         void *congested_data;   /* Pointer to aux data for congested func */
      68             :         void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
      69             :         void *unplug_io_data;
      70             : 
      71             :         char *name;
      72             : 
      73             :         struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
      74             : 
      75             :         struct prop_local_percpu completions;
      76             :         int dirty_exceeded;
      77             : 
      78             :         unsigned int min_ratio;
      79             :         unsigned int max_ratio, max_prop_frac;
      80             : 
      81             :         struct bdi_writeback wb;  /* default writeback info for this bdi */
      82             :         spinlock_t wb_lock;       /* protects update side of wb_list */
      83             :         struct list_head wb_list; /* the flusher threads hanging off this bdi */
      84             :         unsigned long wb_mask;    /* bitmask of registered tasks */
      85             :         unsigned int wb_cnt;      /* number of registered tasks */
      86             : 
      87             :         struct list_head work_list;
      88             : 
      89             :         struct device *dev;
      90             : 
      91             : #ifdef CONFIG_DEBUG_FS
      92             :         struct dentry *debug_dir;
      93             :         struct dentry *debug_stats;
      94             : #endif
      95             : };
      96             : 
      97             : int bdi_init(struct backing_dev_info *bdi);
      98             : void bdi_destroy(struct backing_dev_info *bdi);
      99             : 
     100             : int bdi_register(struct backing_dev_info *bdi, struct device *parent,
     101             :                 const char *fmt, ...);
     102             : int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
     103             : void bdi_unregister(struct backing_dev_info *bdi);
     104             : void bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb,
     105             :                                 long nr_pages);
     106             : int bdi_writeback_task(struct bdi_writeback *wb);
     107             : int bdi_has_dirty_io(struct backing_dev_info *bdi);
     108             : 
     109             : extern spinlock_t bdi_lock;
     110             : extern struct list_head bdi_list;
     111             : 
     112             : static inline int wb_has_dirty_io(struct bdi_writeback *wb)
     113             : {
     114             :         return !list_empty(&wb->b_dirty) ||
     115             :                !list_empty(&wb->b_io) ||
     116             :                !list_empty(&wb->b_more_io);
     117             : }
     118             : 
     119             : static inline void __add_bdi_stat(struct backing_dev_info *bdi,
     120             :                 enum bdi_stat_item item, s64 amount)
     121             : {
     122             :         __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
     123             : }
     124             : 
     125             : static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
     126             :                 enum bdi_stat_item item)
     127             : {
     128             :         __add_bdi_stat(bdi, item, 1);
     129             : }
     130             : 
     131             : static inline void inc_bdi_stat(struct backing_dev_info *bdi,
     132             :                 enum bdi_stat_item item)
     133             : {
     134             :         unsigned long flags;
     135             : 
     136             :         local_irq_save(flags);
     137             :         __inc_bdi_stat(bdi, item);
     138             :         local_irq_restore(flags);
     139             : }
     140             : 
     141             : static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
     142             :                 enum bdi_stat_item item)
     143             : {
     144             :         __add_bdi_stat(bdi, item, -1);
     145             : }
     146             : 
     147             : static inline void dec_bdi_stat(struct backing_dev_info *bdi,
     148             :                 enum bdi_stat_item item)
     149             : {
     150             :         unsigned long flags;
     151             : 
     152             :         local_irq_save(flags);
     153             :         __dec_bdi_stat(bdi, item);
     154             :         local_irq_restore(flags);
     155             : }
     156             : 
     157             : static inline s64 bdi_stat(struct backing_dev_info *bdi,
     158             :                 enum bdi_stat_item item)
     159             : {
     160             :         return percpu_counter_read_positive(&bdi->bdi_stat[item]);
     161             : }
     162             : 
     163             : static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
     164             :                 enum bdi_stat_item item)
     165             : {
     166             :         return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
     167             : }
     168             : 
     169             : static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
     170             :                 enum bdi_stat_item item)
     171             : {
     172             :         s64 sum;
     173             :         unsigned long flags;
     174             : 
     175             :         local_irq_save(flags);
     176             :         sum = __bdi_stat_sum(bdi, item);
     177             :         local_irq_restore(flags);
     178             : 
     179             :         return sum;
     180             : }
     181             : 
     182             : extern void bdi_writeout_inc(struct backing_dev_info *bdi);
     183             : 
     184             : /*
     185             :  * maximal error of a stat counter.
     186             :  */
     187             : static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
     188             : {
     189             : #ifdef CONFIG_SMP
     190             :         return nr_cpu_ids * BDI_STAT_BATCH;
     191             : #else
     192             :         return 1;
     193             : #endif
     194             : }
     195             : 
     196             : int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
     197             : int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
     198             : 
     199             : /*
     200             :  * Flags in backing_dev_info::capability
     201             :  *
     202             :  * The first three flags control whether dirty pages will contribute to the
     203             :  * VM's accounting and whether writepages() should be called for dirty pages
     204             :  * (something that would not, for example, be appropriate for ramfs)
     205             :  *
     206             :  * WARNING: these flags are closely related and should not normally be
     207             :  * used separately.  The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
     208             :  * three flags into a single convenience macro.
     209             :  *
     210             :  * BDI_CAP_NO_ACCT_DIRTY:  Dirty pages shouldn't contribute to accounting
     211             :  * BDI_CAP_NO_WRITEBACK:   Don't write pages back
     212             :  * BDI_CAP_NO_ACCT_WB:     Don't automatically account writeback pages
     213             :  *
     214             :  * These flags let !MMU mmap() govern direct device mapping vs immediate
     215             :  * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
     216             :  *
     217             :  * BDI_CAP_MAP_COPY:       Copy can be mapped (MAP_PRIVATE)
     218             :  * BDI_CAP_MAP_DIRECT:     Can be mapped directly (MAP_SHARED)
     219             :  * BDI_CAP_READ_MAP:       Can be mapped for reading
     220             :  * BDI_CAP_WRITE_MAP:      Can be mapped for writing
     221             :  * BDI_CAP_EXEC_MAP:       Can be mapped for execution
     222             :  *
     223             :  * BDI_CAP_SWAP_BACKED:    Count shmem/tmpfs objects as swap-backed.
     224             :  */
     225             : #define BDI_CAP_NO_ACCT_DIRTY   0x00000001
     226             : #define BDI_CAP_NO_WRITEBACK    0x00000002
     227             : #define BDI_CAP_MAP_COPY        0x00000004
     228             : #define BDI_CAP_MAP_DIRECT      0x00000008
     229             : #define BDI_CAP_READ_MAP        0x00000010
     230             : #define BDI_CAP_WRITE_MAP       0x00000020
     231             : #define BDI_CAP_EXEC_MAP        0x00000040
     232             : #define BDI_CAP_NO_ACCT_WB      0x00000080
     233             : #define BDI_CAP_SWAP_BACKED     0x00000100
     234             : 
     235             : #define BDI_CAP_VMFLAGS \
     236             :         (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
     237             : 
     238             : #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
     239             :         (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
     240             : 
     241             : #if defined(VM_MAYREAD) && \
     242             :         (BDI_CAP_READ_MAP != VM_MAYREAD || \
     243             :          BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
     244             :          BDI_CAP_EXEC_MAP != VM_MAYEXEC)
     245             : #error please change backing_dev_info::capabilities flags
     246             : #endif
     247             : 
     248             : extern struct backing_dev_info default_backing_dev_info;
     249             : void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);
     250             : 
     251             : int writeback_in_progress(struct backing_dev_info *bdi);
     252             : 
     253             : static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
     254             : {
     255             :         if (bdi->congested_fn)
     256             :                 return bdi->congested_fn(bdi->congested_data, bdi_bits);
     257             :         return (bdi->state & bdi_bits);
     258             : }
     259             : 
     260             : static inline int bdi_read_congested(struct backing_dev_info *bdi)
     261             : {
     262             :         return bdi_congested(bdi, 1 << BDI_sync_congested);
     263             : }
     264             : 
     265             : static inline int bdi_write_congested(struct backing_dev_info *bdi)
     266             : {
     267             :         return bdi_congested(bdi, 1 << BDI_async_congested);
     268             : }
     269             : 
     270             : static inline int bdi_rw_congested(struct backing_dev_info *bdi)
     271             : {
     272             :         return bdi_congested(bdi, (1 << BDI_sync_congested) |
     273             :                                   (1 << BDI_async_congested));
     274             : }
     275             : 
     276             : enum {
     277             :         BLK_RW_ASYNC    = 0,
     278             :         BLK_RW_SYNC     = 1,
     279             : };
     280             : 
     281             : void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
     282             : void set_bdi_congested(struct backing_dev_info *bdi, int sync);
     283             : long congestion_wait(int sync, long timeout);
     284             : 
     285             : 
     286             : static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
     287             : {
     288             :         return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
     289             : }
     290             : 
     291             : static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
     292             : {
     293             :         return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
     294             : }
     295             : 
     296             : static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
     297             : {
     298             :         /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
     299             :         return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
     300             :                                       BDI_CAP_NO_WRITEBACK));
     301             : }
     302             : 
     303             : static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
     304             : {
     305             :         return bdi->capabilities & BDI_CAP_SWAP_BACKED;
     306             : }
     307             : 
     308             : static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi)
     309             : {
     310             :         return bdi == &default_backing_dev_info;
     311             : }
     312             : 
     313             : static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
     314             : {
     315             :         return bdi_cap_writeback_dirty(mapping->backing_dev_info);
     316             : }
     317             : 
     318             : static inline bool mapping_cap_account_dirty(struct address_space *mapping)
     319             : {
     320             :         return bdi_cap_account_dirty(mapping->backing_dev_info);
     321             : }
     322             : 
     323             : static inline bool mapping_cap_swap_backed(struct address_space *mapping)
     324             : {
     325             :         return bdi_cap_swap_backed(mapping->backing_dev_info);
     326             : }
     327             : 
     328             : static inline int bdi_sched_wait(void *word)
     329             : {
     330             :         schedule();
     331             :         return 0;
     332             : }
     333             : 
     334             : static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
     335             :                                        struct page *page)
     336             : {
     337             :         if (bdi && bdi->unplug_io_fn)
     338             :                 bdi->unplug_io_fn(bdi, page);
     339             : }
     340             : 
     341             : static inline void blk_run_address_space(struct address_space *mapping)
     342             : {
     343             :         if (mapping)
     344             :                 blk_run_backing_dev(mapping->backing_dev_info, NULL);
     345             : }
     346             : 
     347             : #endif          /* _LINUX_BACKING_DEV_H */

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