LXR linux/include/linux/writeback.h

   1/*
   2 * include/linux/writeback.h
   3 */
   4#ifndef WRITEBACK_H
   5#define WRITEBACK_H
   6
   7#include <linux/sched.h>
   8#include <linux/fs.h>
   9
  10struct backing_dev_info;
  11
  12extern spinlock_t inode_lock;
  13extern struct list_head inode_in_use;
  14extern struct list_head inode_unused;
  15
  16/*
  17 * Yes, writeback.h requires sched.h
  18 * No, sched.h is not included from here.
  19 */
  20static inline int task_is_pdflush(struct task_struct *task)
  21{
  22        return task->flags & PF_FLUSHER;
  23}
  24
  25#define current_is_pdflush()    task_is_pdflush(current)
  26
  27/*
  28 * fs/fs-writeback.c
  29 */
  30enum writeback_sync_modes {
  31        WB_SYNC_NONE,   /* Don't wait on anything */
  32        WB_SYNC_ALL,    /* Wait on every mapping */
  33};
  34
  35/*
  36 * A control structure which tells the writeback code what to do.  These are
  37 * always on the stack, and hence need no locking.  They are always initialised
  38 * in a manner such that unspecified fields are set to zero.
  39 */
  40struct writeback_control {
  41        struct backing_dev_info *bdi;   /* If !NULL, only write back this
  42                                           queue */
  43        enum writeback_sync_modes sync_mode;
  44        unsigned long *older_than_this; /* If !NULL, only write back inodes
  45                                           older than this */
  46        long nr_to_write;               /* Write this many pages, and decrement
  47                                           this for each page written */
  48        long pages_skipped;             /* Pages which were not written */
  49
  50        /*
  51         * For a_ops->writepages(): is start or end are non-zero then this is
  52         * a hint that the filesystem need only write out the pages inside that
  53         * byterange.  The byte at `end' is included in the writeout request.
  54         */
  55        loff_t range_start;
  56        loff_t range_end;
  57
  58        unsigned nonblocking:1;         /* Don't get stuck on request queues */
  59        unsigned encountered_congestion:1; /* An output: a queue is full */
  60        unsigned for_kupdate:1;         /* A kupdate writeback */
  61        unsigned for_reclaim:1;         /* Invoked from the page allocator */
  62        unsigned for_writepages:1;      /* This is a writepages() call */
  63        unsigned range_cyclic:1;        /* range_start is cyclic */
  64        unsigned more_io:1;             /* more io to be dispatched */
  65        /*
  66         * write_cache_pages() won't update wbc->nr_to_write and
  67         * mapping->writeback_index if no_nrwrite_index_update
  68         * is set.  write_cache_pages() may write more than we
  69         * requested and we want to make sure nr_to_write and
  70         * writeback_index are updated in a consistent manner
  71         * so we use a single control to update them
  72         */
  73        unsigned no_nrwrite_index_update:1;
  74};
  75
  76/*
  77 * fs/fs-writeback.c
  78 */     
  79void writeback_inodes(struct writeback_control *wbc);
  80int inode_wait(void *);
  81void sync_inodes_sb(struct super_block *, int wait);
  82
  83/* writeback.h requires fs.h; it, too, is not included from here. */
  84static inline void wait_on_inode(struct inode *inode)
  85{
  86        might_sleep();
  87        wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,
  88                                                        TASK_UNINTERRUPTIBLE);
  89}
  90static inline void inode_sync_wait(struct inode *inode)
  91{
  92        might_sleep();
  93        wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
  94                                                        TASK_UNINTERRUPTIBLE);
  95}
  96
  97
  98/*
  99 * mm/page-writeback.c
 100 */
 101int wakeup_pdflush(long nr_pages);
 102void laptop_io_completion(void);
 103void laptop_sync_completion(void);
 104void throttle_vm_writeout(gfp_t gfp_mask);
 105
 106/* These are exported to sysctl. */
 107extern int dirty_background_ratio;
 108extern unsigned long dirty_background_bytes;
 109extern int vm_dirty_ratio;
 110extern unsigned long vm_dirty_bytes;
 111extern unsigned int dirty_writeback_interval;
 112extern unsigned int dirty_expire_interval;
 113extern int vm_highmem_is_dirtyable;
 114extern int block_dump;
 115extern int laptop_mode;
 116
 117extern unsigned long determine_dirtyable_memory(void);
 118
 119extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
 120                struct file *filp, void __user *buffer, size_t *lenp,
 121                loff_t *ppos);
 122extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
 123                struct file *filp, void __user *buffer, size_t *lenp,
 124                loff_t *ppos);
 125extern int dirty_ratio_handler(struct ctl_table *table, int write,
 126                struct file *filp, void __user *buffer, size_t *lenp,
 127                loff_t *ppos);
 128extern int dirty_bytes_handler(struct ctl_table *table, int write,
 129                struct file *filp, void __user *buffer, size_t *lenp,
 130                loff_t *ppos);
 131
 132struct ctl_table;
 133struct file;
 134int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
 135                                      void __user *, size_t *, loff_t *);
 136
 137void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
 138                      unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
 139
 140void page_writeback_init(void);
 141void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 142                                        unsigned long nr_pages_dirtied);
 143
 144static inline void
 145balance_dirty_pages_ratelimited(struct address_space *mapping)
 146{
 147        balance_dirty_pages_ratelimited_nr(mapping, 1);
 148}
 149
 150typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
 151                                void *data);
 152
 153int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
 154int generic_writepages(struct address_space *mapping,
 155                       struct writeback_control *wbc);
 156int write_cache_pages(struct address_space *mapping,
 157                      struct writeback_control *wbc, writepage_t writepage,
 158                      void *data);
 159int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 160int sync_page_range(struct inode *inode, struct address_space *mapping,
 161                        loff_t pos, loff_t count);
 162int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
 163                           loff_t pos, loff_t count);
 164void set_page_dirty_balance(struct page *page, int page_mkwrite);
 165void writeback_set_ratelimit(void);
 166
 167/* pdflush.c */
 168extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
 169                                   read-only. */
 170
 171
 172#endif          /* WRITEBACK_H */
 173