17bd55d037
ext4, at least, would like to start pushing on writeback if it starts to get close to ENOSPC when reserving worst-case blocks for delalloc writes. Writing out delalloc data will convert those worst-case predictions into usually smaller actual usage, freeing up space before we hit ENOSPC based on this speculation. Thanks to Jens for the suggestion for the helper function, & the naming help. I've made the helper return status on whether writeback was started even though I don't plan to use it in the ext4 patch; it seems like it would be potentially useful to test this in some cases. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Acked-by: Jan Kara <jack@suse.cz>
161 lines
5.1 KiB
C
161 lines
5.1 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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struct backing_dev_info;
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extern spinlock_t inode_lock;
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extern struct list_head inode_in_use;
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extern struct list_head inode_unused;
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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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struct backing_dev_info *bdi; /* If !NULL, only write back this
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queue */
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struct super_block *sb; /* if !NULL, only write inodes from
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this super_block */
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enum writeback_sync_modes sync_mode;
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unsigned long *older_than_this; /* If !NULL, only write back inodes
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older than this */
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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 nonblocking:1; /* Don't get stuck on request queues */
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unsigned encountered_congestion:1; /* An output: a queue is full */
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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 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 more_io:1; /* more io to be dispatched */
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/*
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* write_cache_pages() won't update wbc->nr_to_write and
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* mapping->writeback_index if no_nrwrite_index_update
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* is set. write_cache_pages() may write more than we
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* requested and we want to make sure nr_to_write and
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* writeback_index are updated in a consistent manner
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* so we use a single control to update them
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*/
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unsigned no_nrwrite_index_update:1;
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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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int writeback_inodes_sb_if_idle(struct super_block *);
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void sync_inodes_sb(struct super_block *);
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void writeback_inodes_wbc(struct writeback_control *wbc);
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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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void laptop_io_completion(void);
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void laptop_sync_completion(void);
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void throttle_vm_writeout(gfp_t gfp_mask);
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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 get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
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unsigned long *pbdi_dirty, struct backing_dev_info *bdi);
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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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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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/* 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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