1 /* SPDX-License-Identifier: GPL-2.0 */
3 * include/linux/backing-dev.h
5 * low-level device information and state which is propagated up through
9 #ifndef _LINUX_BACKING_DEV_H
10 #define _LINUX_BACKING_DEV_H
12 #include <linux/kernel.h>
14 #include <linux/sched.h>
15 #include <linux/blkdev.h>
16 #include <linux/writeback.h>
17 #include <linux/blk-cgroup.h>
18 #include <linux/backing-dev-defs.h>
19 #include <linux/slab.h>
21 static inline struct backing_dev_info
*bdi_get(struct backing_dev_info
*bdi
)
23 kref_get(&bdi
->refcnt
);
27 void bdi_put(struct backing_dev_info
*bdi
);
30 int bdi_register(struct backing_dev_info
*bdi
, const char *fmt
, ...);
31 int bdi_register_va(struct backing_dev_info
*bdi
, const char *fmt
,
33 int bdi_register_owner(struct backing_dev_info
*bdi
, struct device
*owner
);
34 void bdi_unregister(struct backing_dev_info
*bdi
);
36 struct backing_dev_info
*bdi_alloc_node(gfp_t gfp_mask
, int node_id
);
37 static inline struct backing_dev_info
*bdi_alloc(gfp_t gfp_mask
)
39 return bdi_alloc_node(gfp_mask
, NUMA_NO_NODE
);
42 void wb_start_writeback(struct bdi_writeback
*wb
, long nr_pages
,
43 bool range_cyclic
, enum wb_reason reason
);
44 void wb_start_background_writeback(struct bdi_writeback
*wb
);
45 void wb_workfn(struct work_struct
*work
);
46 void wb_wakeup_delayed(struct bdi_writeback
*wb
);
48 extern spinlock_t bdi_lock
;
49 extern struct list_head bdi_list
;
51 extern struct workqueue_struct
*bdi_wq
;
53 static inline bool wb_has_dirty_io(struct bdi_writeback
*wb
)
55 return test_bit(WB_has_dirty_io
, &wb
->state
);
58 static inline bool bdi_has_dirty_io(struct backing_dev_info
*bdi
)
61 * @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are
62 * any dirty wbs. See wb_update_write_bandwidth().
64 return atomic_long_read(&bdi
->tot_write_bandwidth
);
67 static inline void __add_wb_stat(struct bdi_writeback
*wb
,
68 enum wb_stat_item item
, s64 amount
)
70 percpu_counter_add_batch(&wb
->stat
[item
], amount
, WB_STAT_BATCH
);
73 static inline void inc_wb_stat(struct bdi_writeback
*wb
, enum wb_stat_item item
)
75 __add_wb_stat(wb
, item
, 1);
78 static inline void dec_wb_stat(struct bdi_writeback
*wb
, enum wb_stat_item item
)
80 __add_wb_stat(wb
, item
, -1);
83 static inline s64
wb_stat(struct bdi_writeback
*wb
, enum wb_stat_item item
)
85 return percpu_counter_read_positive(&wb
->stat
[item
]);
88 static inline s64
wb_stat_sum(struct bdi_writeback
*wb
, enum wb_stat_item item
)
90 return percpu_counter_sum_positive(&wb
->stat
[item
]);
93 extern void wb_writeout_inc(struct bdi_writeback
*wb
);
96 * maximal error of a stat counter.
98 static inline unsigned long wb_stat_error(struct bdi_writeback
*wb
)
101 return nr_cpu_ids
* WB_STAT_BATCH
;
107 int bdi_set_min_ratio(struct backing_dev_info
*bdi
, unsigned int min_ratio
);
108 int bdi_set_max_ratio(struct backing_dev_info
*bdi
, unsigned int max_ratio
);
111 * Flags in backing_dev_info::capability
113 * The first three flags control whether dirty pages will contribute to the
114 * VM's accounting and whether writepages() should be called for dirty pages
115 * (something that would not, for example, be appropriate for ramfs)
117 * WARNING: these flags are closely related and should not normally be
118 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
119 * three flags into a single convenience macro.
121 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
122 * BDI_CAP_NO_WRITEBACK: Don't write pages back
123 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
124 * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
126 * BDI_CAP_CGROUP_WRITEBACK: Supports cgroup-aware writeback.
128 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
129 #define BDI_CAP_NO_WRITEBACK 0x00000002
130 #define BDI_CAP_NO_ACCT_WB 0x00000004
131 #define BDI_CAP_STABLE_WRITES 0x00000008
132 #define BDI_CAP_STRICTLIMIT 0x00000010
133 #define BDI_CAP_CGROUP_WRITEBACK 0x00000020
135 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
136 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
138 extern struct backing_dev_info noop_backing_dev_info
;
141 * writeback_in_progress - determine whether there is writeback in progress
142 * @wb: bdi_writeback of interest
144 * Determine whether there is writeback waiting to be handled against a
147 static inline bool writeback_in_progress(struct bdi_writeback
*wb
)
149 return test_bit(WB_writeback_running
, &wb
->state
);
152 static inline struct backing_dev_info
*inode_to_bdi(struct inode
*inode
)
154 struct super_block
*sb
;
157 return &noop_backing_dev_info
;
161 if (sb_is_blkdev_sb(sb
))
162 return I_BDEV(inode
)->bd_bdi
;
167 static inline int wb_congested(struct bdi_writeback
*wb
, int cong_bits
)
169 struct backing_dev_info
*bdi
= wb
->bdi
;
171 if (bdi
->congested_fn
)
172 return bdi
->congested_fn(bdi
->congested_data
, cong_bits
);
173 return wb
->congested
->state
& cong_bits
;
176 long congestion_wait(int sync
, long timeout
);
177 long wait_iff_congested(struct pglist_data
*pgdat
, int sync
, long timeout
);
178 int pdflush_proc_obsolete(struct ctl_table
*table
, int write
,
179 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
);
181 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info
*bdi
)
183 return bdi
->capabilities
& BDI_CAP_STABLE_WRITES
;
186 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info
*bdi
)
188 return !(bdi
->capabilities
& BDI_CAP_NO_WRITEBACK
);
191 static inline bool bdi_cap_account_dirty(struct backing_dev_info
*bdi
)
193 return !(bdi
->capabilities
& BDI_CAP_NO_ACCT_DIRTY
);
196 static inline bool bdi_cap_account_writeback(struct backing_dev_info
*bdi
)
198 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
199 return !(bdi
->capabilities
& (BDI_CAP_NO_ACCT_WB
|
200 BDI_CAP_NO_WRITEBACK
));
203 static inline bool mapping_cap_writeback_dirty(struct address_space
*mapping
)
205 return bdi_cap_writeback_dirty(inode_to_bdi(mapping
->host
));
208 static inline bool mapping_cap_account_dirty(struct address_space
*mapping
)
210 return bdi_cap_account_dirty(inode_to_bdi(mapping
->host
));
213 static inline int bdi_sched_wait(void *word
)
219 #ifdef CONFIG_CGROUP_WRITEBACK
221 struct bdi_writeback_congested
*
222 wb_congested_get_create(struct backing_dev_info
*bdi
, int blkcg_id
, gfp_t gfp
);
223 void wb_congested_put(struct bdi_writeback_congested
*congested
);
224 struct bdi_writeback
*wb_get_create(struct backing_dev_info
*bdi
,
225 struct cgroup_subsys_state
*memcg_css
,
227 void wb_memcg_offline(struct mem_cgroup
*memcg
);
228 void wb_blkcg_offline(struct blkcg
*blkcg
);
229 int inode_congested(struct inode
*inode
, int cong_bits
);
232 * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
233 * @inode: inode of interest
235 * cgroup writeback requires support from both the bdi and filesystem.
236 * Also, both memcg and iocg have to be on the default hierarchy. Test
237 * whether all conditions are met.
239 * Note that the test result may change dynamically on the same inode
240 * depending on how memcg and iocg are configured.
242 static inline bool inode_cgwb_enabled(struct inode
*inode
)
244 struct backing_dev_info
*bdi
= inode_to_bdi(inode
);
246 return cgroup_subsys_on_dfl(memory_cgrp_subsys
) &&
247 cgroup_subsys_on_dfl(io_cgrp_subsys
) &&
248 bdi_cap_account_dirty(bdi
) &&
249 (bdi
->capabilities
& BDI_CAP_CGROUP_WRITEBACK
) &&
250 (inode
->i_sb
->s_iflags
& SB_I_CGROUPWB
);
254 * wb_find_current - find wb for %current on a bdi
255 * @bdi: bdi of interest
257 * Find the wb of @bdi which matches both the memcg and blkcg of %current.
258 * Must be called under rcu_read_lock() which protects the returend wb.
261 static inline struct bdi_writeback
*wb_find_current(struct backing_dev_info
*bdi
)
263 struct cgroup_subsys_state
*memcg_css
;
264 struct bdi_writeback
*wb
;
266 memcg_css
= task_css(current
, memory_cgrp_id
);
267 if (!memcg_css
->parent
)
270 wb
= radix_tree_lookup(&bdi
->cgwb_tree
, memcg_css
->id
);
273 * %current's blkcg equals the effective blkcg of its memcg. No
274 * need to use the relatively expensive cgroup_get_e_css().
276 if (likely(wb
&& wb
->blkcg_css
== task_css(current
, io_cgrp_id
)))
282 * wb_get_create_current - get or create wb for %current on a bdi
283 * @bdi: bdi of interest
284 * @gfp: allocation mask
286 * Equivalent to wb_get_create() on %current's memcg. This function is
287 * called from a relatively hot path and optimizes the common cases using
290 static inline struct bdi_writeback
*
291 wb_get_create_current(struct backing_dev_info
*bdi
, gfp_t gfp
)
293 struct bdi_writeback
*wb
;
296 wb
= wb_find_current(bdi
);
297 if (wb
&& unlikely(!wb_tryget(wb
)))
302 struct cgroup_subsys_state
*memcg_css
;
304 memcg_css
= task_get_css(current
, memory_cgrp_id
);
305 wb
= wb_get_create(bdi
, memcg_css
, gfp
);
312 * inode_to_wb_is_valid - test whether an inode has a wb associated
313 * @inode: inode of interest
315 * Returns %true if @inode has a wb associated. May be called without any
318 static inline bool inode_to_wb_is_valid(struct inode
*inode
)
324 * inode_to_wb - determine the wb of an inode
325 * @inode: inode of interest
327 * Returns the wb @inode is currently associated with. The caller must be
328 * holding either @inode->i_lock, @inode->i_mapping->tree_lock, or the
329 * associated wb's list_lock.
331 static inline struct bdi_writeback
*inode_to_wb(struct inode
*inode
)
333 #ifdef CONFIG_LOCKDEP
334 WARN_ON_ONCE(debug_locks
&&
335 (!lockdep_is_held(&inode
->i_lock
) &&
336 !lockdep_is_held(&inode
->i_mapping
->tree_lock
) &&
337 !lockdep_is_held(&inode
->i_wb
->list_lock
)));
343 * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
344 * @inode: target inode
345 * @lockedp: temp bool output param, to be passed to the end function
347 * The caller wants to access the wb associated with @inode but isn't
348 * holding inode->i_lock, mapping->tree_lock or wb->list_lock. This
349 * function determines the wb associated with @inode and ensures that the
350 * association doesn't change until the transaction is finished with
351 * unlocked_inode_to_wb_end().
353 * The caller must call unlocked_inode_to_wb_end() with *@lockdep
354 * afterwards and can't sleep during transaction. IRQ may or may not be
355 * disabled on return.
357 static inline struct bdi_writeback
*
358 unlocked_inode_to_wb_begin(struct inode
*inode
, bool *lockedp
)
363 * Paired with store_release in inode_switch_wb_work_fn() and
364 * ensures that we see the new wb if we see cleared I_WB_SWITCH.
366 *lockedp
= smp_load_acquire(&inode
->i_state
) & I_WB_SWITCH
;
368 if (unlikely(*lockedp
))
369 spin_lock_irq(&inode
->i_mapping
->tree_lock
);
372 * Protected by either !I_WB_SWITCH + rcu_read_lock() or tree_lock.
373 * inode_to_wb() will bark. Deref directly.
379 * unlocked_inode_to_wb_end - end inode wb access transaction
380 * @inode: target inode
381 * @locked: *@lockedp from unlocked_inode_to_wb_begin()
383 static inline void unlocked_inode_to_wb_end(struct inode
*inode
, bool locked
)
385 if (unlikely(locked
))
386 spin_unlock_irq(&inode
->i_mapping
->tree_lock
);
391 #else /* CONFIG_CGROUP_WRITEBACK */
393 static inline bool inode_cgwb_enabled(struct inode
*inode
)
398 static inline struct bdi_writeback_congested
*
399 wb_congested_get_create(struct backing_dev_info
*bdi
, int blkcg_id
, gfp_t gfp
)
401 atomic_inc(&bdi
->wb_congested
->refcnt
);
402 return bdi
->wb_congested
;
405 static inline void wb_congested_put(struct bdi_writeback_congested
*congested
)
407 if (atomic_dec_and_test(&congested
->refcnt
))
411 static inline struct bdi_writeback
*wb_find_current(struct backing_dev_info
*bdi
)
416 static inline struct bdi_writeback
*
417 wb_get_create_current(struct backing_dev_info
*bdi
, gfp_t gfp
)
422 static inline bool inode_to_wb_is_valid(struct inode
*inode
)
427 static inline struct bdi_writeback
*inode_to_wb(struct inode
*inode
)
429 return &inode_to_bdi(inode
)->wb
;
432 static inline struct bdi_writeback
*
433 unlocked_inode_to_wb_begin(struct inode
*inode
, bool *lockedp
)
435 return inode_to_wb(inode
);
438 static inline void unlocked_inode_to_wb_end(struct inode
*inode
, bool locked
)
442 static inline void wb_memcg_offline(struct mem_cgroup
*memcg
)
446 static inline void wb_blkcg_offline(struct blkcg
*blkcg
)
450 static inline int inode_congested(struct inode
*inode
, int cong_bits
)
452 return wb_congested(&inode_to_bdi(inode
)->wb
, cong_bits
);
455 #endif /* CONFIG_CGROUP_WRITEBACK */
457 static inline int inode_read_congested(struct inode
*inode
)
459 return inode_congested(inode
, 1 << WB_sync_congested
);
462 static inline int inode_write_congested(struct inode
*inode
)
464 return inode_congested(inode
, 1 << WB_async_congested
);
467 static inline int inode_rw_congested(struct inode
*inode
)
469 return inode_congested(inode
, (1 << WB_sync_congested
) |
470 (1 << WB_async_congested
));
473 static inline int bdi_congested(struct backing_dev_info
*bdi
, int cong_bits
)
475 return wb_congested(&bdi
->wb
, cong_bits
);
478 static inline int bdi_read_congested(struct backing_dev_info
*bdi
)
480 return bdi_congested(bdi
, 1 << WB_sync_congested
);
483 static inline int bdi_write_congested(struct backing_dev_info
*bdi
)
485 return bdi_congested(bdi
, 1 << WB_async_congested
);
488 static inline int bdi_rw_congested(struct backing_dev_info
*bdi
)
490 return bdi_congested(bdi
, (1 << WB_sync_congested
) |
491 (1 << WB_async_congested
));
494 #endif /* _LINUX_BACKING_DEV_H */