194 lines
6.2 KiB
C
194 lines
6.2 KiB
C
/*
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* include/linux/writeback.h
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*/
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#ifndef WRITEBACK_H
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#define WRITEBACK_H
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#include <linux/sched.h>
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#include <linux/fs.h>
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/*
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* The 1/4 region under the global dirty thresh is for smooth dirty throttling:
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*
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* (thresh - thresh/DIRTY_FULL_SCOPE, thresh)
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*
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* The 1/16 region above the global dirty limit will be put to maximum pauses:
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*
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* (limit, limit + limit/DIRTY_MAXPAUSE_AREA)
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*
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* The 1/16 region above the max-pause region, dirty exceeded bdi's will be put
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* to loops:
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*
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* (limit + limit/DIRTY_MAXPAUSE_AREA, limit + limit/DIRTY_PASSGOOD_AREA)
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*
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* Further beyond, all dirtier tasks will enter a loop waiting (possibly long
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* time) for the dirty pages to drop, unless written enough pages.
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*
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* The global dirty threshold is normally equal to the global dirty limit,
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* except when the system suddenly allocates a lot of anonymous memory and
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* knocks down the global dirty threshold quickly, in which case the global
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* dirty limit will follow down slowly to prevent livelocking all dirtier tasks.
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*/
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#define DIRTY_SCOPE 8
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#define DIRTY_FULL_SCOPE (DIRTY_SCOPE / 2)
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#define DIRTY_MAXPAUSE_AREA 16
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#define DIRTY_PASSGOOD_AREA 8
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/*
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* 4MB minimal write chunk size
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*/
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#define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_CACHE_SHIFT - 10))
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struct backing_dev_info;
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/*
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* fs/fs-writeback.c
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*/
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enum writeback_sync_modes {
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WB_SYNC_NONE, /* Don't wait on anything */
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WB_SYNC_ALL, /* Wait on every mapping */
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};
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/*
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* A control structure which tells the writeback code what to do. These are
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* always on the stack, and hence need no locking. They are always initialised
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* in a manner such that unspecified fields are set to zero.
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*/
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struct writeback_control {
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enum writeback_sync_modes sync_mode;
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long nr_to_write; /* Write this many pages, and decrement
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this for each page written */
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long pages_skipped; /* Pages which were not written */
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/*
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* For a_ops->writepages(): is start or end are non-zero then this is
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* a hint that the filesystem need only write out the pages inside that
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* byterange. The byte at `end' is included in the writeout request.
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*/
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loff_t range_start;
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loff_t range_end;
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unsigned for_kupdate:1; /* A kupdate writeback */
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unsigned for_background:1; /* A background writeback */
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unsigned tagged_writepages:1; /* tag-and-write to avoid livelock */
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unsigned for_reclaim:1; /* Invoked from the page allocator */
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unsigned range_cyclic:1; /* range_start is cyclic */
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};
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/*
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* fs/fs-writeback.c
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*/
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struct bdi_writeback;
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int inode_wait(void *);
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void writeback_inodes_sb(struct super_block *);
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void writeback_inodes_sb_nr(struct super_block *, unsigned long nr);
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int writeback_inodes_sb_if_idle(struct super_block *);
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int writeback_inodes_sb_nr_if_idle(struct super_block *, unsigned long nr);
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void sync_inodes_sb(struct super_block *);
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long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages);
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long wb_do_writeback(struct bdi_writeback *wb, int force_wait);
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void wakeup_flusher_threads(long nr_pages);
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/* writeback.h requires fs.h; it, too, is not included from here. */
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static inline void wait_on_inode(struct inode *inode)
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{
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might_sleep();
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wait_on_bit(&inode->i_state, __I_NEW, inode_wait, TASK_UNINTERRUPTIBLE);
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}
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static inline void inode_sync_wait(struct inode *inode)
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{
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might_sleep();
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wait_on_bit(&inode->i_state, __I_SYNC, inode_wait,
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TASK_UNINTERRUPTIBLE);
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}
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/*
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* mm/page-writeback.c
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*/
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#ifdef CONFIG_BLOCK
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void laptop_io_completion(struct backing_dev_info *info);
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void laptop_sync_completion(void);
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void laptop_mode_sync(struct work_struct *work);
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void laptop_mode_timer_fn(unsigned long data);
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#else
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static inline void laptop_sync_completion(void) { }
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#endif
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void throttle_vm_writeout(gfp_t gfp_mask);
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extern unsigned long global_dirty_limit;
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/* These are exported to sysctl. */
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extern int dirty_background_ratio;
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extern unsigned long dirty_background_bytes;
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extern int vm_dirty_ratio;
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extern unsigned long vm_dirty_bytes;
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extern unsigned int dirty_writeback_interval;
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extern unsigned int dirty_expire_interval;
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extern int vm_highmem_is_dirtyable;
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extern int block_dump;
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extern int laptop_mode;
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extern unsigned long determine_dirtyable_memory(void);
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extern int dirty_background_ratio_handler(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp,
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loff_t *ppos);
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extern int dirty_background_bytes_handler(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp,
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loff_t *ppos);
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extern int dirty_ratio_handler(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp,
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loff_t *ppos);
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extern int dirty_bytes_handler(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp,
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loff_t *ppos);
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struct ctl_table;
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int dirty_writeback_centisecs_handler(struct ctl_table *, int,
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void __user *, size_t *, loff_t *);
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void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty);
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unsigned long bdi_dirty_limit(struct backing_dev_info *bdi,
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unsigned long dirty);
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void __bdi_update_bandwidth(struct backing_dev_info *bdi,
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unsigned long thresh,
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unsigned long dirty,
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unsigned long bdi_thresh,
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unsigned long bdi_dirty,
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unsigned long start_time);
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void page_writeback_init(void);
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void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
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unsigned long nr_pages_dirtied);
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static inline void
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balance_dirty_pages_ratelimited(struct address_space *mapping)
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{
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balance_dirty_pages_ratelimited_nr(mapping, 1);
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}
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typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
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void *data);
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int generic_writepages(struct address_space *mapping,
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struct writeback_control *wbc);
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void tag_pages_for_writeback(struct address_space *mapping,
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pgoff_t start, pgoff_t end);
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int write_cache_pages(struct address_space *mapping,
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struct writeback_control *wbc, writepage_t writepage,
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void *data);
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int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
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void set_page_dirty_balance(struct page *page, int page_mkwrite);
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void writeback_set_ratelimit(void);
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void tag_pages_for_writeback(struct address_space *mapping,
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pgoff_t start, pgoff_t end);
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/* pdflush.c */
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extern int nr_pdflush_threads; /* Global so it can be exported to sysctl
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read-only. */
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#endif /* WRITEBACK_H */
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