230 lines
7.7 KiB
C
230 lines
7.7 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/workqueue.h>
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#include <linux/fs.h>
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#include <linux/flex_proportions.h>
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DECLARE_PER_CPU(int, dirty_throttle_leaks);
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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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* 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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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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* why some writeback work was initiated
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*/
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enum wb_reason {
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WB_REASON_BACKGROUND,
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WB_REASON_TRY_TO_FREE_PAGES,
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WB_REASON_SYNC,
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WB_REASON_PERIODIC,
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WB_REASON_LAPTOP_TIMER,
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WB_REASON_FREE_MORE_MEM,
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WB_REASON_FS_FREE_SPACE,
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/*
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* There is no bdi forker thread any more and works are done
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* by emergency worker, however, this is TPs userland visible
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* and we'll be exposing exactly the same information,
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* so it has a mismatch name.
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*/
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WB_REASON_FORKER_THREAD,
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WB_REASON_MAX,
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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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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(): if 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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enum writeback_sync_modes sync_mode;
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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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unsigned for_sync:1; /* sync(2) WB_SYNC_ALL writeback */
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};
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/*
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* A wb_domain represents a domain that wb's (bdi_writeback's) belong to
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* and are measured against each other in. There always is one global
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* domain, global_wb_domain, that every wb in the system is a member of.
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* This allows measuring the relative bandwidth of each wb to distribute
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* dirtyable memory accordingly.
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*/
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struct wb_domain {
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spinlock_t lock;
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/*
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* Scale the writeback cache size proportional to the relative
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* writeout speed.
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*
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* We do this by keeping a floating proportion between BDIs, based
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* on page writeback completions [end_page_writeback()]. Those
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* devices that write out pages fastest will get the larger share,
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* while the slower will get a smaller share.
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*
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* We use page writeout completions because we are interested in
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* getting rid of dirty pages. Having them written out is the
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* primary goal.
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*
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* We introduce a concept of time, a period over which we measure
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* these events, because demand can/will vary over time. The length
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* of this period itself is measured in page writeback completions.
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*/
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struct fprop_global completions;
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struct timer_list period_timer; /* timer for aging of completions */
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unsigned long period_time;
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/*
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* The dirtyable memory and dirty threshold could be suddenly
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* knocked down by a large amount (eg. on the startup of KVM in a
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* swapless system). This may throw the system into deep dirty
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* exceeded state and throttle heavy/light dirtiers alike. To
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* retain good responsiveness, maintain global_dirty_limit for
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* tracking slowly down to the knocked down dirty threshold.
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*
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* Both fields are protected by ->lock.
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*/
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unsigned long dirty_limit_tstamp;
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unsigned long dirty_limit;
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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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void writeback_inodes_sb(struct super_block *, enum wb_reason reason);
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void writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
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enum wb_reason reason);
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bool try_to_writeback_inodes_sb(struct super_block *, enum wb_reason reason);
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bool try_to_writeback_inodes_sb_nr(struct super_block *, unsigned long nr,
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enum wb_reason reason);
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void sync_inodes_sb(struct super_block *);
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void wakeup_flusher_threads(long nr_pages, enum wb_reason reason);
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void inode_wait_for_writeback(struct inode *inode);
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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, 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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bool zone_dirty_ok(struct zone *zone);
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int wb_domain_init(struct wb_domain *dom, gfp_t gfp);
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extern struct wb_domain global_wb_domain;
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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 unsigned int dirtytime_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 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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int dirtytime_interval_handler(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, 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 wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh);
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void wb_update_bandwidth(struct bdi_writeback *wb, unsigned long start_time);
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void page_writeback_init(void);
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void balance_dirty_pages_ratelimited(struct address_space *mapping);
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bool wb_over_bg_thresh(struct bdi_writeback *wb);
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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 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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void account_page_redirty(struct page *page);
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#endif /* WRITEBACK_H */
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