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
  10 struct backing_dev_info;
  11
  12 extern spinlock_t inode_lock;
  13 extern struct list_head inode_in_use;
  14 extern struct list_head inode_unused;
  15
  16 /*
  17  * Yes, writeback.h requires sched.h
  18  * No, sched.h is not included from here.
  19  */
  20 static 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  */
  30 enum 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  */
  40 struct writeback_control {
  41         struct backing_dev_info *bdi;   /* If !NULL, only write back this
  42                                            queue */
  43         struct super_block *sb;         /* if !NULL, only write inodes from
  44                                            this super_block */
  45         enum writeback_sync_modes sync_mode;
  46         unsigned long *older_than_this; /* If !NULL, only write back inodes
  47                                            older than this */
  48         long nr_to_write;               /* Write this many pages, and decrement
  49                                            this for each page written */
  50         long pages_skipped;             /* Pages which were not written */
  51
  52         /*
  53          * For a_ops->writepages(): is start or end are non-zero then this is
  54          * a hint that the filesystem need only write out the pages inside that
  55          * byterange.  The byte at `end' is included in the writeout request.
  56          */
  57         loff_t range_start;
  58         loff_t range_end;
  59
  60         unsigned nonblocking:1;         /* Don't get stuck on request queues */
  61         unsigned encountered_congestion:1; /* An output: a queue is full */
  62         unsigned for_kupdate:1;         /* A kupdate writeback */
  63         unsigned for_reclaim:1;         /* Invoked from the page allocator */
  64         unsigned for_writepages:1;      /* This is a writepages() call */
  65         unsigned range_cyclic:1;        /* range_start is cyclic */
  66         unsigned more_io:1;             /* more io to be dispatched */
  67         /*
  68          * write_cache_pages() won't update wbc->nr_to_write and
  69          * mapping->writeback_index if no_nrwrite_index_update
  70          * is set.  write_cache_pages() may write more than we
  71          * requested and we want to make sure nr_to_write and
  72          * writeback_index are updated in a consistent manner
  73          * so we use a single control to update them
  74          */
  75         unsigned no_nrwrite_index_update:1;
  76 };
  77
  78 /*
  79  * fs/fs-writeback.c
  80  */
  81 struct bdi_writeback;
  82 int inode_wait(void *);
  83 long writeback_inodes_sb(struct super_block *);
  84 long sync_inodes_sb(struct super_block *);
  85 void writeback_inodes_wbc(struct writeback_control *wbc);
  86 long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
  87 void wakeup_flusher_threads(long nr_pages);
  88
  89 /* writeback.h requires fs.h; it, too, is not included from here. */
  90 static inline void wait_on_inode(struct inode *inode)
  91 {
  92         might_sleep();
  93         wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,
  94                                                         TASK_UNINTERRUPTIBLE);
  95 }
  96 static inline void inode_sync_wait(struct inode *inode)
  97 {
  98         might_sleep();
  99         wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
 100                                                         TASK_UNINTERRUPTIBLE);
 101 }
 102
 103
 104 /*
 105  * mm/page-writeback.c
 106  */
 107 void laptop_io_completion(void);
 108 void laptop_sync_completion(void);
 109 void throttle_vm_writeout(gfp_t gfp_mask);
 110
 111 /* These are exported to sysctl. */
 112 extern int dirty_background_ratio;
 113 extern unsigned long dirty_background_bytes;
 114 extern int vm_dirty_ratio;
 115 extern unsigned long vm_dirty_bytes;
 116 extern unsigned int dirty_writeback_interval;
 117 extern unsigned int dirty_expire_interval;
 118 extern int vm_highmem_is_dirtyable;
 119 extern int block_dump;
 120 extern int laptop_mode;
 121
 122 extern unsigned long determine_dirtyable_memory(void);
 123
 124 extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
 125                 struct file *filp, void __user *buffer, size_t *lenp,
 126                 loff_t *ppos);
 127 extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
 128                 struct file *filp, void __user *buffer, size_t *lenp,
 129                 loff_t *ppos);
 130 extern int dirty_ratio_handler(struct ctl_table *table, int write,
 131                 struct file *filp, void __user *buffer, size_t *lenp,
 132                 loff_t *ppos);
 133 extern int dirty_bytes_handler(struct ctl_table *table, int write,
 134                 struct file *filp, void __user *buffer, size_t *lenp,
 135                 loff_t *ppos);
 136
 137 struct ctl_table;
 138 struct file;
 139 int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
 140                                       void __user *, size_t *, loff_t *);
 141
 142 void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
 143                       unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
 144
 145 void page_writeback_init(void);
 146 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 147                                         unsigned long nr_pages_dirtied);
 148
 149 static inline void
 150 balance_dirty_pages_ratelimited(struct address_space *mapping)
 151 {
 152         balance_dirty_pages_ratelimited_nr(mapping, 1);
 153 }
 154
 155 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
 156                                 void *data);
 157
 158 int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
 159 int generic_writepages(struct address_space *mapping,
 160                        struct writeback_control *wbc);
 161 int write_cache_pages(struct address_space *mapping,
 162                       struct writeback_control *wbc, writepage_t writepage,
 163                       void *data);
 164 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 165 int sync_page_range(struct inode *inode, struct address_space *mapping,
 166                         loff_t pos, loff_t count);
 167 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
 168                            loff_t pos, loff_t count);
 169 void set_page_dirty_balance(struct page *page, int page_mkwrite);
 170 void writeback_set_ratelimit(void);
 171
 172 /* pdflush.c */
 173 extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
 174                                    read-only. */
 175
 176
 177 #endif          /* WRITEBACK_H */