06d6cf6959
Filesystems like ext4 needs to start a new transaction in the writepages for block allocation. This happens with delayed allocation and there is limit to how many credits we can request from the journal layer. So we call write_cache_pages multiple times with wbc->nr_to_write set to the maximum possible value limitted by the max journal credits available. Add a new mode to writeback that enables us to handle this behaviour. In the new mode we update the wbc->range_start to point to the new offset to be written. Next call to call to write_cache_pages will start writeout from specified range_start offset. In the new mode we also limit writing to the specified wbc->range_end. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Mingming Cao <cmm@us.ibm.com> Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
154 lines
4.6 KiB
C
154 lines
4.6 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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* Yes, writeback.h requires sched.h
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* No, sched.h is not included from here.
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*/
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static inline int task_is_pdflush(struct task_struct *task)
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{
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return task->flags & PF_FLUSHER;
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}
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#define current_is_pdflush() task_is_pdflush(current)
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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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WB_SYNC_HOLD, /* Hold the inode on sb_dirty for sys_sync() */
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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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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_reclaim:1; /* Invoked from the page allocator */
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unsigned for_writepages:1; /* This is a writepages() call */
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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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unsigned range_cont: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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void writeback_inodes(struct writeback_control *wbc);
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int inode_wait(void *);
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void sync_inodes_sb(struct super_block *, int wait);
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void sync_inodes(int wait);
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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_LOCK, inode_wait,
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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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int wakeup_pdflush(long nr_pages);
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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 int vm_dirty_ratio;
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extern int dirty_writeback_interval;
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extern 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 int dirty_ratio_handler(struct ctl_table *table, int write,
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struct file *filp, void __user *buffer, size_t *lenp,
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loff_t *ppos);
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struct ctl_table;
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struct file;
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int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
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void __user *, size_t *, loff_t *);
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void get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty,
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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 pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
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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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int sync_page_range(struct inode *inode, struct address_space *mapping,
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loff_t pos, loff_t count);
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int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
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loff_t pos, loff_t count);
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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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