Subversion Repositories test_project

/*

 * include/linux/backing-dev.h

 *

 * low-level device information and state which is propagated up through

 * to high-level code.

 */

#ifndef _LINUX_BACKING_DEV_H

#define _LINUX_BACKING_DEV_H

#include <linux/percpu_counter.h>

#include <linux/log2.h>

#include <linux/proportions.h>

#include <asm/atomic.h>

struct page;

/*

 * Bits in backing_dev_info.state

 */

enum bdi_state {

        BDI_pdflush,            /* A pdflush thread is working this device */

        BDI_write_congested,    /* The write queue is getting full */

        BDI_read_congested,     /* The read queue is getting full */

        BDI_unused,             /* Available bits start here */

};

typedef int (congested_fn)(void *, int);

enum bdi_stat_item {

        BDI_RECLAIMABLE,

        BDI_WRITEBACK,

        NR_BDI_STAT_ITEMS

};

#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))

struct backing_dev_info {

        unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */

        unsigned long state;    /* Always use atomic bitops on this */

        unsigned int capabilities; /* Device capabilities */

        congested_fn *congested_fn; /* Function pointer if device is md/dm */

        void *congested_data;   /* Pointer to aux data for congested func */

        void (*unplug_io_fn)(struct backing_dev_info *, struct page *);

        void *unplug_io_data;

        struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];

        struct prop_local_percpu completions;

        int dirty_exceeded;

};

int bdi_init(struct backing_dev_info *bdi);

void bdi_destroy(struct backing_dev_info *bdi);

static inline void __add_bdi_stat(struct backing_dev_info *bdi,

                enum bdi_stat_item item, s64 amount)

{

        __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);

}

static inline void __inc_bdi_stat(struct backing_dev_info *bdi,

                enum bdi_stat_item item)

{

        __add_bdi_stat(bdi, item, 1);

}

static inline void inc_bdi_stat(struct backing_dev_info *bdi,

                enum bdi_stat_item item)

{

        unsigned long flags;

        local_irq_save(flags);

        __inc_bdi_stat(bdi, item);

        local_irq_restore(flags);

}

static inline void __dec_bdi_stat(struct backing_dev_info *bdi,

                enum bdi_stat_item item)

{

        __add_bdi_stat(bdi, item, -1);

}

static inline void dec_bdi_stat(struct backing_dev_info *bdi,

                enum bdi_stat_item item)

{

        unsigned long flags;

        local_irq_save(flags);

        __dec_bdi_stat(bdi, item);

        local_irq_restore(flags);

}

static inline s64 bdi_stat(struct backing_dev_info *bdi,

                enum bdi_stat_item item)

{

        return percpu_counter_read_positive(&bdi->bdi_stat[item]);

}

static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,

                enum bdi_stat_item item)

{

        return percpu_counter_sum_positive(&bdi->bdi_stat[item]);

}

static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,

                enum bdi_stat_item item)

{

        s64 sum;

        unsigned long flags;

        local_irq_save(flags);

        sum = __bdi_stat_sum(bdi, item);

        local_irq_restore(flags);

        return sum;

}

/*

 * maximal error of a stat counter.

 */

static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)

{

#ifdef CONFIG_SMP

        return nr_cpu_ids * BDI_STAT_BATCH;

#else

        return 1;

#endif

}

/*

 * Flags in backing_dev_info::capability

 * - The first two flags control whether dirty pages will contribute to the

 *   VM's accounting and whether writepages() should be called for dirty pages

 *   (something that would not, for example, be appropriate for ramfs)

 * - These flags let !MMU mmap() govern direct device mapping vs immediate

 *   copying more easily for MAP_PRIVATE, especially for ROM filesystems

 */

#define BDI_CAP_NO_ACCT_DIRTY   0x00000001      /* Dirty pages shouldn't contribute to accounting */

#define BDI_CAP_NO_WRITEBACK    0x00000002      /* Don't write pages back */

#define BDI_CAP_MAP_COPY        0x00000004      /* Copy can be mapped (MAP_PRIVATE) */

#define BDI_CAP_MAP_DIRECT      0x00000008      /* Can be mapped directly (MAP_SHARED) */

#define BDI_CAP_READ_MAP        0x00000010      /* Can be mapped for reading */

#define BDI_CAP_WRITE_MAP       0x00000020      /* Can be mapped for writing */

#define BDI_CAP_EXEC_MAP        0x00000040      /* Can be mapped for execution */

#define BDI_CAP_VMFLAGS \

        (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)

#if defined(VM_MAYREAD) && \

        (BDI_CAP_READ_MAP != VM_MAYREAD || \

         BDI_CAP_WRITE_MAP != VM_MAYWRITE || \

         BDI_CAP_EXEC_MAP != VM_MAYEXEC)

#error please change backing_dev_info::capabilities flags

#endif

extern struct backing_dev_info default_backing_dev_info;

void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);

int writeback_acquire(struct backing_dev_info *bdi);

int writeback_in_progress(struct backing_dev_info *bdi);

void writeback_release(struct backing_dev_info *bdi);

static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)

{

        if (bdi->congested_fn)

                return bdi->congested_fn(bdi->congested_data, bdi_bits);

        return (bdi->state & bdi_bits);

}

static inline int bdi_read_congested(struct backing_dev_info *bdi)

{

        return bdi_congested(bdi, 1 << BDI_read_congested);

}

static inline int bdi_write_congested(struct backing_dev_info *bdi)

{

        return bdi_congested(bdi, 1 << BDI_write_congested);

}

static inline int bdi_rw_congested(struct backing_dev_info *bdi)

{

        return bdi_congested(bdi, (1 << BDI_read_congested)|

                                  (1 << BDI_write_congested));

}

void clear_bdi_congested(struct backing_dev_info *bdi, int rw);

void set_bdi_congested(struct backing_dev_info *bdi, int rw);

long congestion_wait(int rw, long timeout);

#define bdi_cap_writeback_dirty(bdi) \

        (!((bdi)->capabilities & BDI_CAP_NO_WRITEBACK))

#define bdi_cap_account_dirty(bdi) \

        (!((bdi)->capabilities & BDI_CAP_NO_ACCT_DIRTY))

#define mapping_cap_writeback_dirty(mapping) \

        bdi_cap_writeback_dirty((mapping)->backing_dev_info)

#define mapping_cap_account_dirty(mapping) \

        bdi_cap_account_dirty((mapping)->backing_dev_info)

#endif          /* _LINUX_BACKING_DEV_H */