/* SPDX-License-Identifier: GPL-2.0 *//* * include/linux/backing-dev.h * * low-level device information and state which is propagated up through * to high-level code. */ #ifndef _LINUX_BACKING_DEV_H#define _LINUX_BACKING_DEV_H #include <linux/kernel.h>#include <linux/fs.h>#include <linux/sched.h>#include <linux/blkdev.h>#include <linux/writeback.h>#include <linux/blk-cgroup.h>#include <linux/backing-dev-defs.h>#include <linux/slab.h> static inline struct backing_dev_info *bdi_get(struct backing_dev_info *bdi){	kref_get(&bdi->refcnt);	return bdi;} struct backing_dev_info *bdi_get_by_id(u64 id);void bdi_put(struct backing_dev_info *bdi); __printf(2, 3)int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...);__printf(2, 0)int bdi_register_va(struct backing_dev_info *bdi, const char *fmt,		    va_list args);int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner);void bdi_unregister(struct backing_dev_info *bdi); struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id);static inline struct backing_dev_info *bdi_alloc(gfp_t gfp_mask){	return bdi_alloc_node(gfp_mask, NUMA_NO_NODE);} void wb_start_background_writeback(struct bdi_writeback *wb);void wb_workfn(struct work_struct *work);void wb_wakeup_delayed(struct bdi_writeback *wb); void wb_wait_for_completion(struct wb_completion *done); extern spinlock_t bdi_lock;extern struct list_head bdi_list; extern struct workqueue_struct *bdi_wq;extern struct workqueue_struct *bdi_async_bio_wq; static inline bool wb_has_dirty_io(struct bdi_writeback *wb){	return test_bit(WB_has_dirty_io, &wb->state);} static inline bool bdi_has_dirty_io(struct backing_dev_info *bdi){	/*	 * @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are	 * any dirty wbs.  See wb_update_write_bandwidth().	 */	return atomic_long_read(&bdi->tot_write_bandwidth);} static inline void __add_wb_stat(struct bdi_writeback *wb,				 enum wb_stat_item item, s64 amount){	percpu_counter_add_batch(&wb->stat[item], amount, WB_STAT_BATCH);} static inline void inc_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item){	__add_wb_stat(wb, item, 1);} static inline void dec_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item){	__add_wb_stat(wb, item, -1);} static inline s64 wb_stat(struct bdi_writeback *wb, enum wb_stat_item item){	return percpu_counter_read_positive(&wb->stat[item]);} static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item){	return percpu_counter_sum_positive(&wb->stat[item]);} extern void wb_writeout_inc(struct bdi_writeback *wb); /* * maximal error of a stat counter. */static inline unsigned long wb_stat_error(void){#ifdef CONFIG_SMP	return nr_cpu_ids * WB_STAT_BATCH;#else	return 1;#endif} int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio); /* * Flags in backing_dev_info::capability * * The first three flags control whether dirty pages will contribute to the * VM's accounting and whether writepages() should be called for dirty pages * (something that would not, for example, be appropriate for ramfs) * * WARNING: these flags are closely related and should not normally be * used separately.  The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these * three flags into a single convenience macro. * * BDI_CAP_NO_ACCT_DIRTY:  Dirty pages shouldn't contribute to accounting * BDI_CAP_NO_WRITEBACK:   Don't write pages back * BDI_CAP_NO_ACCT_WB:     Don't automatically account writeback pages * BDI_CAP_STRICTLIMIT:    Keep number of dirty pages below bdi threshold. * * BDI_CAP_CGROUP_WRITEBACK: Supports cgroup-aware writeback. * BDI_CAP_SYNCHRONOUS_IO: Device is so fast that asynchronous IO would be *			   inefficient. */#define BDI_CAP_NO_ACCT_DIRTY	0x00000001#define BDI_CAP_NO_WRITEBACK	0x00000002#define BDI_CAP_NO_ACCT_WB	0x00000004#define BDI_CAP_STABLE_WRITES	0x00000008#define BDI_CAP_STRICTLIMIT	0x00000010#define BDI_CAP_CGROUP_WRITEBACK 0x00000020#define BDI_CAP_SYNCHRONOUS_IO	0x00000040 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \	(BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB) extern struct backing_dev_info noop_backing_dev_info; /** * writeback_in_progress - determine whether there is writeback in progress * @wb: bdi_writeback of interest * * Determine whether there is writeback waiting to be handled against a * bdi_writeback. */static inline bool writeback_in_progress(struct bdi_writeback *wb){	return test_bit(WB_writeback_running, &wb->state);} static inline struct backing_dev_info *inode_to_bdi(struct inode *inode){	struct super_block *sb; 	if (!inode)		return &noop_backing_dev_info; 	sb = inode->i_sb;#ifdef CONFIG_BLOCK	if (sb_is_blkdev_sb(sb))		return I_BDEV(inode)->bd_bdi;#endif	return sb->s_bdi;} static inline int wb_congested(struct bdi_writeback *wb, int cong_bits){	struct backing_dev_info *bdi = wb->bdi; 	if (bdi->congested_fn)		return bdi->congested_fn(bdi->congested_data, cong_bits);	return wb->congested->state & cong_bits;} long congestion_wait(int sync, long timeout);long wait_iff_congested(int sync, long timeout); static inline bool bdi_cap_synchronous_io(struct backing_dev_info *bdi){	return bdi->capabilities & BDI_CAP_SYNCHRONOUS_IO;} static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi){	return bdi->capabilities & BDI_CAP_STABLE_WRITES;} static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi){	return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);} static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi){	return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);} static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi){	/* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */	return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |				      BDI_CAP_NO_WRITEBACK));} static inline bool mapping_cap_writeback_dirty(struct address_space *mapping){	return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host));} static inline bool mapping_cap_account_dirty(struct address_space *mapping){	return bdi_cap_account_dirty(inode_to_bdi(mapping->host));} static inline int bdi_sched_wait(void *word){	schedule();	return 0;} #ifdef CONFIG_CGROUP_WRITEBACK struct bdi_writeback_congested *wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp);void wb_congested_put(struct bdi_writeback_congested *congested);struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,				    struct cgroup_subsys_state *memcg_css);struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,				    struct cgroup_subsys_state *memcg_css,				    gfp_t gfp);void wb_memcg_offline(struct mem_cgroup *memcg);void wb_blkcg_offline(struct blkcg *blkcg);int inode_congested(struct inode *inode, int cong_bits); /** * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode * @inode: inode of interest * * cgroup writeback requires support from both the bdi and filesystem. * Also, both memcg and iocg have to be on the default hierarchy.  Test * whether all conditions are met. * * Note that the test result may change dynamically on the same inode * depending on how memcg and iocg are configured. */static inline bool inode_cgwb_enabled(struct inode *inode){	struct backing_dev_info *bdi = inode_to_bdi(inode); 	return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&		cgroup_subsys_on_dfl(io_cgrp_subsys) &&		bdi_cap_account_dirty(bdi) &&		(bdi->capabilities & BDI_CAP_CGROUP_WRITEBACK) &&		(inode->i_sb->s_iflags & SB_I_CGROUPWB);} /** * wb_find_current - find wb for %current on a bdi * @bdi: bdi of interest * * Find the wb of @bdi which matches both the memcg and blkcg of %current. * Must be called under rcu_read_lock() which protects the returend wb. * NULL if not found. */static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi){	struct cgroup_subsys_state *memcg_css;	struct bdi_writeback *wb; 	memcg_css = task_css(current, memory_cgrp_id);	if (!memcg_css->parent)		return &bdi->wb; 	wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); 	/*	 * %current's blkcg equals the effective blkcg of its memcg.  No	 * need to use the relatively expensive cgroup_get_e_css().	 */	if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id)))		return wb;	return NULL;} /** * wb_get_create_current - get or create wb for %current on a bdi * @bdi: bdi of interest * @gfp: allocation mask * * Equivalent to wb_get_create() on %current's memcg.  This function is * called from a relatively hot path and optimizes the common cases using * wb_find_current(). */static inline struct bdi_writeback *wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp){	struct bdi_writeback *wb; 	rcu_read_lock();	wb = wb_find_current(bdi);	if (wb && unlikely(!wb_tryget(wb)))		wb = NULL;	rcu_read_unlock(); 	if (unlikely(!wb)) {		struct cgroup_subsys_state *memcg_css; 		memcg_css = task_get_css(current, memory_cgrp_id);		wb = wb_get_create(bdi, memcg_css, gfp);		css_put(memcg_css);	}	return wb;} /** * inode_to_wb_is_valid - test whether an inode has a wb associated * @inode: inode of interest * * Returns %true if @inode has a wb associated.  May be called without any * locking. */static inline bool inode_to_wb_is_valid(struct inode *inode){	return inode->i_wb;} /** * inode_to_wb - determine the wb of an inode * @inode: inode of interest * * Returns the wb @inode is currently associated with.  The caller must be * holding either @inode->i_lock, the i_pages lock, or the * associated wb's list_lock. */static inline struct bdi_writeback *inode_to_wb(const struct inode *inode){#ifdef CONFIG_LOCKDEP	WARN_ON_ONCE(debug_locks &&		     (!lockdep_is_held(&inode->i_lock) &&		      !lockdep_is_held(&inode->i_mapping->i_pages.xa_lock) &&		      !lockdep_is_held(&inode->i_wb->list_lock)));#endif	return inode->i_wb;} /** * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction * @inode: target inode * @cookie: output param, to be passed to the end function * * The caller wants to access the wb associated with @inode but isn't * holding inode->i_lock, the i_pages lock or wb->list_lock.  This * function determines the wb associated with @inode and ensures that the * association doesn't change until the transaction is finished with * unlocked_inode_to_wb_end(). * * The caller must call unlocked_inode_to_wb_end() with *@cookie afterwards and * can't sleep during the transaction.  IRQs may or may not be disabled on * return. */static inline struct bdi_writeback *unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie){	rcu_read_lock(); 	/*	 * Paired with store_release in inode_switch_wbs_work_fn() and	 * ensures that we see the new wb if we see cleared I_WB_SWITCH.	 */	cookie->locked = smp_load_acquire(&inode->i_state) & I_WB_SWITCH; 	if (unlikely(cookie->locked))		xa_lock_irqsave(&inode->i_mapping->i_pages, cookie->flags); 	/*	 * Protected by either !I_WB_SWITCH + rcu_read_lock() or the i_pages	 * lock.  inode_to_wb() will bark.  Deref directly.	 */	return inode->i_wb;} /** * unlocked_inode_to_wb_end - end inode wb access transaction * @inode: target inode * @cookie: @cookie from unlocked_inode_to_wb_begin() */static inline void unlocked_inode_to_wb_end(struct inode *inode,					    struct wb_lock_cookie *cookie){	if (unlikely(cookie->locked))		xa_unlock_irqrestore(&inode->i_mapping->i_pages, cookie->flags); 	rcu_read_unlock();} #else	/* CONFIG_CGROUP_WRITEBACK */ static inline bool inode_cgwb_enabled(struct inode *inode){	return false;} static inline struct bdi_writeback_congested *wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp){	refcount_inc(&bdi->wb_congested->refcnt);	return bdi->wb_congested;} static inline void wb_congested_put(struct bdi_writeback_congested *congested){	if (refcount_dec_and_test(&congested->refcnt))		kfree(congested);} static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi){	return &bdi->wb;} static inline struct bdi_writeback *wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp){	return &bdi->wb;} static inline bool inode_to_wb_is_valid(struct inode *inode){	return true;} static inline struct bdi_writeback *inode_to_wb(struct inode *inode){	return &inode_to_bdi(inode)->wb;} static inline struct bdi_writeback *unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie){	return inode_to_wb(inode);} static inline void unlocked_inode_to_wb_end(struct inode *inode,					    struct wb_lock_cookie *cookie){} static inline void wb_memcg_offline(struct mem_cgroup *memcg){} static inline void wb_blkcg_offline(struct blkcg *blkcg){} static inline int inode_congested(struct inode *inode, int cong_bits){	return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);} #endif	/* CONFIG_CGROUP_WRITEBACK */ static inline int inode_read_congested(struct inode *inode){	return inode_congested(inode, 1 << WB_sync_congested);} static inline int inode_write_congested(struct inode *inode){	return inode_congested(inode, 1 << WB_async_congested);} static inline int inode_rw_congested(struct inode *inode){	return inode_congested(inode, (1 << WB_sync_congested) |				      (1 << WB_async_congested));} static inline int bdi_congested(struct backing_dev_info *bdi, int cong_bits){	return wb_congested(&bdi->wb, cong_bits);} static inline int bdi_read_congested(struct backing_dev_info *bdi){	return bdi_congested(bdi, 1 << WB_sync_congested);} static inline int bdi_write_congested(struct backing_dev_info *bdi){	return bdi_congested(bdi, 1 << WB_async_congested);} 

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