diff options
Diffstat (limited to 'include/linux/backing-dev.h')
-rw-r--r-- | include/linux/backing-dev.h | 366 |
1 files changed, 366 insertions, 0 deletions
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h new file mode 100644 index 000000000..439815cc1 --- /dev/null +++ b/include/linux/backing-dev.h @@ -0,0 +1,366 @@ +/* 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/device.h> +#include <linux/writeback.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); +void bdi_set_owner(struct backing_dev_info *bdi, struct device *owner); +void bdi_unregister(struct backing_dev_info *bdi); + +struct backing_dev_info *bdi_alloc(int node_id); + +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 wb_stat_mod(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) +{ + wb_stat_mod(wb, item, 1); +} + +static inline void dec_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item) +{ + wb_stat_mod(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 + * + * BDI_CAP_WRITEBACK: Supports dirty page writeback, and dirty pages + * should contribute to accounting + * BDI_CAP_WRITEBACK_ACCT: Automatically account writeback pages + * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold + */ +#define BDI_CAP_WRITEBACK (1 << 0) +#define BDI_CAP_WRITEBACK_ACCT (1 << 1) +#define BDI_CAP_STRICTLIMIT (1 << 2) + +extern struct backing_dev_info noop_backing_dev_info; + +int bdi_init(struct backing_dev_info *bdi); + +/** + * 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); +} + +struct backing_dev_info *inode_to_bdi(struct inode *inode); + +static inline bool mapping_can_writeback(struct address_space *mapping) +{ + return inode_to_bdi(mapping->host)->capabilities & BDI_CAP_WRITEBACK; +} + +#ifdef CONFIG_CGROUP_WRITEBACK + +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 cgroup_subsys_state *css); + +/** + * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode + * @inode: inode of interest + * + * Cgroup writeback requires support from the 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->capabilities & BDI_CAP_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 - 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; +} + +static inline struct bdi_writeback *inode_to_wb_wbc( + struct inode *inode, + struct writeback_control *wbc) +{ + /* + * If wbc does not have inode attached, it means cgroup writeback was + * disabled when wbc started. Just use the default wb in that case. + */ + return wbc->wb ? wbc->wb : &inode_to_bdi(inode)->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 *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 struct bdi_writeback *inode_to_wb(struct inode *inode) +{ + return &inode_to_bdi(inode)->wb; +} + +static inline struct bdi_writeback *inode_to_wb_wbc( + struct inode *inode, + struct writeback_control *wbc) +{ + return inode_to_wb(inode); +} + + +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 cgroup_subsys_state *css) +{ +} + +#endif /* CONFIG_CGROUP_WRITEBACK */ + +const char *bdi_dev_name(struct backing_dev_info *bdi); + +#endif /* _LINUX_BACKING_DEV_H */ |