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1/* SPDX-License-Identifier: GPL-2.0 */2/*3 * include/linux/backing-dev.h4 *5 * low-level device information and state which is propagated up through6 * to high-level code.7 */8 9#ifndef _LINUX_BACKING_DEV_H10#define _LINUX_BACKING_DEV_H11 12#include <linux/kernel.h>13#include <linux/fs.h>14#include <linux/sched.h>15#include <linux/device.h>16#include <linux/writeback.h>17#include <linux/backing-dev-defs.h>18#include <linux/slab.h>19 20static inline struct backing_dev_info *bdi_get(struct backing_dev_info *bdi)21{22 kref_get(&bdi->refcnt);23 return bdi;24}25 26struct backing_dev_info *bdi_get_by_id(u64 id);27void bdi_put(struct backing_dev_info *bdi) HWJS_SUSPENDS;28 29__printf(2, 3)30int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...) HWJS_SUSPENDS;31__printf(2, 0)32int bdi_register_va(struct backing_dev_info *bdi, const char *fmt,33 va_list args) HWJS_SUSPENDS;34void bdi_set_owner(struct backing_dev_info *bdi, struct device *owner);35void bdi_unregister(struct backing_dev_info *bdi) HWJS_SUSPENDS;36 37struct backing_dev_info *bdi_alloc(int node_id);38 39void wb_start_background_writeback(struct bdi_writeback *wb) HWJS_SUSPENDS;40void wb_workfn(struct work_struct *work) HWJS_SUSPENDS;41 42void wb_wait_for_completion(struct wb_completion *done) HWJS_SUSPENDS;43 44extern spinlock_t bdi_lock;45extern struct list_head bdi_list;46 47extern struct workqueue_struct *bdi_wq;48 49static inline bool wb_has_dirty_io(struct bdi_writeback *wb)50{51 return test_bit(WB_has_dirty_io, &wb->state);52}53 54static inline bool bdi_has_dirty_io(struct backing_dev_info *bdi)55{56 /*57 * @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are58 * any dirty wbs. See wb_update_write_bandwidth().59 */60 return atomic_long_read(&bdi->tot_write_bandwidth);61}62 63static inline void wb_stat_mod(struct bdi_writeback *wb,64 enum wb_stat_item item, s64 amount)65{66 percpu_counter_add_batch(&wb->stat[item], amount, WB_STAT_BATCH);67}68 69static inline void inc_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)70{71 wb_stat_mod(wb, item, 1);72}73 74static inline void dec_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)75{76 wb_stat_mod(wb, item, -1);77}78 79static inline s64 wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)80{81 return percpu_counter_read_positive(&wb->stat[item]);82}83 84static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item)85{86 return percpu_counter_sum_positive(&wb->stat[item]);87}88 89extern void wb_writeout_inc(struct bdi_writeback *wb);90 91/*92 * maximal error of a stat counter.93 */94static inline unsigned long wb_stat_error(void)95{96#ifdef CONFIG_SMP97 return nr_cpu_ids * WB_STAT_BATCH;98#else99 return 1;100#endif101}102 103/* BDI ratio is expressed as part per 1000000 for finer granularity. */104#define BDI_RATIO_SCALE 10000105 106u64 bdi_get_min_bytes(struct backing_dev_info *bdi);107u64 bdi_get_max_bytes(struct backing_dev_info *bdi);108int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);109int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);110int bdi_set_min_ratio_no_scale(struct backing_dev_info *bdi, unsigned int min_ratio);111int bdi_set_max_ratio_no_scale(struct backing_dev_info *bdi, unsigned int max_ratio);112int bdi_set_min_bytes(struct backing_dev_info *bdi, u64 min_bytes);113int bdi_set_max_bytes(struct backing_dev_info *bdi, u64 max_bytes);114int bdi_set_strict_limit(struct backing_dev_info *bdi, unsigned int strict_limit);115 116/*117 * Flags in backing_dev_info::capability118 *119 * BDI_CAP_WRITEBACK: Supports dirty page writeback, and dirty pages120 * should contribute to accounting121 * BDI_CAP_WRITEBACK_ACCT: Automatically account writeback pages122 * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold123 */124#define BDI_CAP_WRITEBACK (1 << 0)125#define BDI_CAP_WRITEBACK_ACCT (1 << 1)126#define BDI_CAP_STRICTLIMIT (1 << 2)127 128extern struct backing_dev_info noop_backing_dev_info;129 130int bdi_init(struct backing_dev_info *bdi);131 132/**133 * writeback_in_progress - determine whether there is writeback in progress134 * @wb: bdi_writeback of interest135 *136 * Determine whether there is writeback waiting to be handled against a137 * bdi_writeback.138 */139static inline bool writeback_in_progress(struct bdi_writeback *wb)140{141 return test_bit(WB_writeback_running, &wb->state);142}143 144struct backing_dev_info *inode_to_bdi(struct inode *inode);145 146static inline bool mapping_can_writeback(struct address_space *mapping)147{148 return inode_to_bdi(mapping->host)->capabilities & BDI_CAP_WRITEBACK;149}150 151#ifdef CONFIG_CGROUP_WRITEBACK152 153struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,154 struct cgroup_subsys_state *memcg_css);155struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,156 struct cgroup_subsys_state *memcg_css,157 gfp_t gfp);158void wb_memcg_offline(struct mem_cgroup *memcg);159void wb_blkcg_offline(struct cgroup_subsys_state *css);160 161/**162 * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode163 * @inode: inode of interest164 *165 * Cgroup writeback requires support from the filesystem. Also, both memcg and166 * iocg have to be on the default hierarchy. Test whether all conditions are167 * met.168 *169 * Note that the test result may change dynamically on the same inode170 * depending on how memcg and iocg are configured.171 */172static inline bool inode_cgwb_enabled(struct inode *inode)173{174 struct backing_dev_info *bdi = inode_to_bdi(inode);175 176 return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&177 cgroup_subsys_on_dfl(io_cgrp_subsys) &&178 (bdi->capabilities & BDI_CAP_WRITEBACK) &&179 (inode->i_sb->s_iflags & SB_I_CGROUPWB);180}181 182/**183 * wb_find_current - find wb for %current on a bdi184 * @bdi: bdi of interest185 *186 * Find the wb of @bdi which matches both the memcg and blkcg of %current.187 * Must be called under rcu_read_lock() which protects the returend wb.188 * NULL if not found.189 */190static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)191{192 struct cgroup_subsys_state *memcg_css;193 struct bdi_writeback *wb;194 195 memcg_css = task_css(current, memory_cgrp_id);196 if (!memcg_css->parent)197 return &bdi->wb;198 199 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);200 201 /*202 * %current's blkcg equals the effective blkcg of its memcg. No203 * need to use the relatively expensive cgroup_get_e_css().204 */205 if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id)))206 return wb;207 return NULL;208}209 210/**211 * wb_get_create_current - get or create wb for %current on a bdi212 * @bdi: bdi of interest213 * @gfp: allocation mask214 *215 * Equivalent to wb_get_create() on %current's memcg. This function is216 * called from a relatively hot path and optimizes the common cases using217 * wb_find_current().218 */219static inline struct bdi_writeback *220wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)221{222 struct bdi_writeback *wb;223 224 rcu_read_lock();225 wb = wb_find_current(bdi);226 if (wb && unlikely(!wb_tryget(wb)))227 wb = NULL;228 rcu_read_unlock();229 230 if (unlikely(!wb)) {231 struct cgroup_subsys_state *memcg_css;232 233 memcg_css = task_get_css(current, memory_cgrp_id);234 wb = wb_get_create(bdi, memcg_css, gfp);235 css_put(memcg_css);236 }237 return wb;238}239 240/**241 * inode_to_wb - determine the wb of an inode242 * @inode: inode of interest243 *244 * Returns the wb @inode is currently associated with. The caller must be245 * holding either @inode->i_lock, the i_pages lock, or the246 * associated wb's list_lock.247 */248static inline struct bdi_writeback *inode_to_wb(const struct inode *inode)249{250#ifdef CONFIG_LOCKDEP251 WARN_ON_ONCE(debug_locks &&252 (!lockdep_is_held(&inode->i_lock) &&253 !lockdep_is_held(&inode->i_mapping->i_pages.xa_lock) &&254 !lockdep_is_held(&inode->i_wb->list_lock)));255#endif256 return inode->i_wb;257}258 259static inline struct bdi_writeback *inode_to_wb_wbc(260 struct inode *inode,261 struct writeback_control *wbc)262{263 /*264 * If wbc does not have inode attached, it means cgroup writeback was265 * disabled when wbc started. Just use the default wb in that case.266 */267 return wbc->wb ? wbc->wb : &inode_to_bdi(inode)->wb;268}269 270/**271 * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction272 * @inode: target inode273 * @cookie: output param, to be passed to the end function274 *275 * The caller wants to access the wb associated with @inode but isn't276 * holding inode->i_lock, the i_pages lock or wb->list_lock. This277 * function determines the wb associated with @inode and ensures that the278 * association doesn't change until the transaction is finished with279 * unlocked_inode_to_wb_end().280 *281 * The caller must call unlocked_inode_to_wb_end() with *@cookie afterwards and282 * can't sleep during the transaction. IRQs may or may not be disabled on283 * return.284 */285static inline struct bdi_writeback *286unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie)287{288 rcu_read_lock();289 290 /*291 * Paired with store_release in inode_switch_wbs_work_fn() and292 * ensures that we see the new wb if we see cleared I_WB_SWITCH.293 */294 cookie->locked = smp_load_acquire(&inode->i_state) & I_WB_SWITCH;295 296 if (unlikely(cookie->locked))297 xa_lock_irqsave(&inode->i_mapping->i_pages, cookie->flags);298 299 /*300 * Protected by either !I_WB_SWITCH + rcu_read_lock() or the i_pages301 * lock. inode_to_wb() will bark. Deref directly.302 */303 return inode->i_wb;304}305 306/**307 * unlocked_inode_to_wb_end - end inode wb access transaction308 * @inode: target inode309 * @cookie: @cookie from unlocked_inode_to_wb_begin()310 */311static inline void unlocked_inode_to_wb_end(struct inode *inode,312 struct wb_lock_cookie *cookie)313{314 if (unlikely(cookie->locked))315 xa_unlock_irqrestore(&inode->i_mapping->i_pages, cookie->flags);316 317 rcu_read_unlock();318}319 320#else /* CONFIG_CGROUP_WRITEBACK */321 322static inline bool inode_cgwb_enabled(struct inode *inode)323{324 return false;325}326 327static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)328{329 return &bdi->wb;330}331 332static inline struct bdi_writeback *333wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)334{335 return &bdi->wb;336}337 338static inline struct bdi_writeback *inode_to_wb(struct inode *inode)339{340 return &inode_to_bdi(inode)->wb;341}342 343static inline struct bdi_writeback *inode_to_wb_wbc(344 struct inode *inode,345 struct writeback_control *wbc)346{347 return inode_to_wb(inode);348}349 350 351static inline struct bdi_writeback *352unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie)353{354 return inode_to_wb(inode);355}356 357static inline void unlocked_inode_to_wb_end(struct inode *inode,358 struct wb_lock_cookie *cookie)359{360}361 362static inline void wb_memcg_offline(struct mem_cgroup *memcg)363{364}365 366static inline void wb_blkcg_offline(struct cgroup_subsys_state *css)367{368}369 370#endif /* CONFIG_CGROUP_WRITEBACK */371 372const char *bdi_dev_name(struct backing_dev_info *bdi);373 374#endif /* _LINUX_BACKING_DEV_H */375