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         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  */
  79 void writeback_inodes(struct writeback_control *wbc);
  80 int inode_wait(void *);
  81 void sync_inodes_sb(struct super_block *, int wait);
  82 void sync_inodes(int wait);
  83
  84 /* writeback.h requires fs.h; it, too, is not included from here. */
  85 static inline void wait_on_inode(struct inode *inode)
  86 {
  87         might_sleep();
  88         wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,
  89                                                         TASK_UNINTERRUPTIBLE);
  90 }
  91 static inline void inode_sync_wait(struct inode *inode)
  92 {
  93         might_sleep();
  94         wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
  95                                                         TASK_UNINTERRUPTIBLE);
  96 }
  97
  98
  99 /*
 100  * mm/page-writeback.c
 101  */
 102 int wakeup_pdflush(long nr_pages);
 103 void laptop_io_completion(void);
 104 void laptop_sync_completion(void);
 105 void throttle_vm_writeout(gfp_t gfp_mask);
 106
 107 /* These are exported to sysctl. */
 108 extern int dirty_background_ratio;
 109 extern unsigned long dirty_background_bytes;
 110 extern int vm_dirty_ratio;
 111 extern unsigned long vm_dirty_bytes;
 112 extern unsigned int dirty_writeback_interval;
 113 extern unsigned int dirty_expire_interval;
 114 extern int vm_highmem_is_dirtyable;
 115 extern int block_dump;
 116 extern int laptop_mode;
 117
 118 extern unsigned long determine_dirtyable_memory(void);
 119
 120 extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
 121                 struct file *filp, void __user *buffer, size_t *lenp,
 122                 loff_t *ppos);
 123 extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
 124                 struct file *filp, void __user *buffer, size_t *lenp,
 125                 loff_t *ppos);
 126 extern int dirty_ratio_handler(struct ctl_table *table, int write,
 127                 struct file *filp, void __user *buffer, size_t *lenp,
 128                 loff_t *ppos);
 129 extern int dirty_bytes_handler(struct ctl_table *table, int write,
 130                 struct file *filp, void __user *buffer, size_t *lenp,
 131                 loff_t *ppos);
 132
 133 struct ctl_table;
 134 struct file;
 135 int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
 136                                       void __user *, size_t *, loff_t *);
 137
 138 void get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
 139                       unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
 140
 141 void page_writeback_init(void);
 142 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
 143                                         unsigned long nr_pages_dirtied);
 144
 145 static inline void
 146 balance_dirty_pages_ratelimited(struct address_space *mapping)
 147 {
 148         balance_dirty_pages_ratelimited_nr(mapping, 1);
 149 }
 150
 151 typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
 152                                 void *data);
 153
 154 int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
 155 int generic_writepages(struct address_space *mapping,
 156                        struct writeback_control *wbc);
 157 int write_cache_pages(struct address_space *mapping,
 158                       struct writeback_control *wbc, writepage_t writepage,
 159                       void *data);
 160 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 161 int sync_page_range(struct inode *inode, struct address_space *mapping,
 162                         loff_t pos, loff_t count);
 163 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
 164                            loff_t pos, loff_t count);
 165 void set_page_dirty_balance(struct page *page, int page_mkwrite);
 166 void writeback_set_ratelimit(void);
 167
 168 /* pdflush.c */
 169 extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
 170                                    read-only. */
 171
 172
 173 #endif          /* WRITEBACK_H */