405 lines
13 KiB
C
405 lines
13 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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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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#include <linux/backing-dev-defs.h>
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#include <linux/blk_types.h>
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struct bio;
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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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* 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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* When writeback IOs are bounced through async layers, only the
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* initial synchronous phase should be accounted towards inode
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* cgroup ownership arbitration to avoid confusion. Later stages
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* can set the following flag to disable the accounting.
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*/
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unsigned no_cgroup_owner:1;
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unsigned punt_to_cgroup:1; /* cgrp punting, see __REQ_CGROUP_PUNT */
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#ifdef CONFIG_CGROUP_WRITEBACK
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struct bdi_writeback *wb; /* wb this writeback is issued under */
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struct inode *inode; /* inode being written out */
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/* foreign inode detection, see wbc_detach_inode() */
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int wb_id; /* current wb id */
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int wb_lcand_id; /* last foreign candidate wb id */
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int wb_tcand_id; /* this foreign candidate wb id */
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size_t wb_bytes; /* bytes written by current wb */
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size_t wb_lcand_bytes; /* bytes written by last candidate */
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size_t wb_tcand_bytes; /* bytes written by this candidate */
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#endif
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};
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static inline int wbc_to_write_flags(struct writeback_control *wbc)
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{
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int flags = 0;
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if (wbc->punt_to_cgroup)
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flags = REQ_CGROUP_PUNT;
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if (wbc->sync_mode == WB_SYNC_ALL)
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flags |= REQ_SYNC;
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else if (wbc->for_kupdate || wbc->for_background)
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flags |= REQ_BACKGROUND;
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return flags;
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}
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#ifdef CONFIG_CGROUP_WRITEBACK
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#define wbc_blkcg_css(wbc) \
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((wbc)->wb ? (wbc)->wb->blkcg_css : blkcg_root_css)
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#else
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#define wbc_blkcg_css(wbc) (blkcg_root_css)
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#endif /* CONFIG_CGROUP_WRITEBACK */
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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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* wb_domain_size_changed - memory available to a wb_domain has changed
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* @dom: wb_domain of interest
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*
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* This function should be called when the amount of memory available to
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* @dom has changed. It resets @dom's dirty limit parameters to prevent
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* the past values which don't match the current configuration from skewing
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* dirty throttling. Without this, when memory size of a wb_domain is
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* greatly reduced, the dirty throttling logic may allow too many pages to
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* be dirtied leading to consecutive unnecessary OOMs and may get stuck in
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* that situation.
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*/
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static inline void wb_domain_size_changed(struct wb_domain *dom)
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{
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spin_lock(&dom->lock);
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dom->dirty_limit_tstamp = jiffies;
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dom->dirty_limit = 0;
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spin_unlock(&dom->lock);
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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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void try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason);
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void sync_inodes_sb(struct super_block *);
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void wakeup_flusher_threads(enum wb_reason reason);
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void wakeup_flusher_threads_bdi(struct backing_dev_info *bdi,
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enum wb_reason reason);
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void inode_wait_for_writeback(struct inode *inode);
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void inode_io_list_del(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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#ifdef CONFIG_CGROUP_WRITEBACK
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#include <linux/cgroup.h>
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#include <linux/bio.h>
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void __inode_attach_wb(struct inode *inode, struct page *page);
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void wbc_attach_and_unlock_inode(struct writeback_control *wbc,
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struct inode *inode)
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__releases(&inode->i_lock);
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void wbc_detach_inode(struct writeback_control *wbc);
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void wbc_account_cgroup_owner(struct writeback_control *wbc, struct page *page,
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size_t bytes);
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int cgroup_writeback_by_id(u64 bdi_id, int memcg_id,
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enum wb_reason reason, struct wb_completion *done);
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void cgroup_writeback_umount(void);
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bool cleanup_offline_cgwb(struct bdi_writeback *wb);
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/**
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* inode_attach_wb - associate an inode with its wb
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* @inode: inode of interest
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* @page: page being dirtied (may be NULL)
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*
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* If @inode doesn't have its wb, associate it with the wb matching the
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* memcg of @page or, if @page is NULL, %current. May be called w/ or w/o
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* @inode->i_lock.
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*/
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static inline void inode_attach_wb(struct inode *inode, struct page *page)
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{
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if (!inode->i_wb)
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__inode_attach_wb(inode, page);
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}
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/**
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* inode_detach_wb - disassociate an inode from its wb
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* @inode: inode of interest
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*
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* @inode is being freed. Detach from its wb.
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*/
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static inline void inode_detach_wb(struct inode *inode)
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{
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if (inode->i_wb) {
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WARN_ON_ONCE(!(inode->i_state & I_CLEAR));
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wb_put(inode->i_wb);
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inode->i_wb = NULL;
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}
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}
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/**
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* wbc_attach_fdatawrite_inode - associate wbc and inode for fdatawrite
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* @wbc: writeback_control of interest
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* @inode: target inode
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*
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* This function is to be used by __filemap_fdatawrite_range(), which is an
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* alternative entry point into writeback code, and first ensures @inode is
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* associated with a bdi_writeback and attaches it to @wbc.
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*/
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static inline void wbc_attach_fdatawrite_inode(struct writeback_control *wbc,
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struct inode *inode)
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{
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spin_lock(&inode->i_lock);
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inode_attach_wb(inode, NULL);
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wbc_attach_and_unlock_inode(wbc, inode);
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}
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/**
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* wbc_init_bio - writeback specific initializtion of bio
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* @wbc: writeback_control for the writeback in progress
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* @bio: bio to be initialized
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*
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* @bio is a part of the writeback in progress controlled by @wbc. Perform
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* writeback specific initialization. This is used to apply the cgroup
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* writeback context. Must be called after the bio has been associated with
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* a device.
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*/
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static inline void wbc_init_bio(struct writeback_control *wbc, struct bio *bio)
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{
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/*
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* pageout() path doesn't attach @wbc to the inode being written
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* out. This is intentional as we don't want the function to block
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* behind a slow cgroup. Ultimately, we want pageout() to kick off
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* regular writeback instead of writing things out itself.
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*/
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if (wbc->wb)
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bio_associate_blkg_from_css(bio, wbc->wb->blkcg_css);
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}
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#else /* CONFIG_CGROUP_WRITEBACK */
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static inline void inode_attach_wb(struct inode *inode, struct page *page)
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{
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}
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static inline void inode_detach_wb(struct inode *inode)
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{
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}
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static inline void wbc_attach_and_unlock_inode(struct writeback_control *wbc,
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struct inode *inode)
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__releases(&inode->i_lock)
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{
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spin_unlock(&inode->i_lock);
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}
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static inline void wbc_attach_fdatawrite_inode(struct writeback_control *wbc,
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struct inode *inode)
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{
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}
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static inline void wbc_detach_inode(struct writeback_control *wbc)
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{
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}
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static inline void wbc_init_bio(struct writeback_control *wbc, struct bio *bio)
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{
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}
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static inline void wbc_account_cgroup_owner(struct writeback_control *wbc,
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struct page *page, size_t bytes)
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{
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}
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static inline void cgroup_writeback_umount(void)
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{
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}
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#endif /* CONFIG_CGROUP_WRITEBACK */
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/*
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* mm/page-writeback.c
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*/
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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_timer_fn(struct timer_list *t);
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bool node_dirty_ok(struct pglist_data *pgdat);
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int wb_domain_init(struct wb_domain *dom, gfp_t gfp);
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#ifdef CONFIG_CGROUP_WRITEBACK
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void wb_domain_exit(struct wb_domain *dom);
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#endif
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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 laptop_mode;
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int dirty_background_ratio_handler(struct ctl_table *table, int write,
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void *buffer, size_t *lenp, loff_t *ppos);
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int dirty_background_bytes_handler(struct ctl_table *table, int write,
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void *buffer, size_t *lenp, loff_t *ppos);
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int dirty_ratio_handler(struct ctl_table *table, int write,
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void *buffer, size_t *lenp, loff_t *ppos);
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int dirty_bytes_handler(struct ctl_table *table, int write,
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void *buffer, size_t *lenp, loff_t *ppos);
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int dirtytime_interval_handler(struct ctl_table *table, int write,
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void *buffer, size_t *lenp, loff_t *ppos);
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int dirty_writeback_centisecs_handler(struct ctl_table *table, int write,
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void *buffer, size_t *lenp, loff_t *ppos);
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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);
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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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bool filemap_dirty_folio(struct address_space *mapping, struct folio *folio);
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void folio_account_redirty(struct folio *folio);
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static inline void account_page_redirty(struct page *page)
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{
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folio_account_redirty(page_folio(page));
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}
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bool folio_redirty_for_writepage(struct writeback_control *, struct folio *);
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bool redirty_page_for_writepage(struct writeback_control *, struct page *);
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void sb_mark_inode_writeback(struct inode *inode);
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void sb_clear_inode_writeback(struct inode *inode);
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#endif /* WRITEBACK_H */
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