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_background_writeback(struct bdi_writeback
*wb
);
43 void wb_workfn(struct work_struct
*work
);
44 void wb_wakeup_delayed(struct bdi_writeback
*wb
);
46 extern spinlock_t bdi_lock
;
47 extern struct list_head bdi_list
;
49 extern struct workqueue_struct
*bdi_wq
;
51 static inline bool wb_has_dirty_io(struct bdi_writeback
*wb
)
53 return test_bit(WB_has_dirty_io
, &wb
->state
);
56 static inline bool bdi_has_dirty_io(struct backing_dev_info
*bdi
)
59 * @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are
60 * any dirty wbs. See wb_update_write_bandwidth().
62 return atomic_long_read(&bdi
->tot_write_bandwidth
);
65 static inline void __add_wb_stat(struct bdi_writeback
*wb
,
66 enum wb_stat_item item
, s64 amount
)
68 percpu_counter_add_batch(&wb
->stat
[item
], amount
, WB_STAT_BATCH
);
71 static inline void inc_wb_stat(struct bdi_writeback
*wb
, enum wb_stat_item item
)
73 __add_wb_stat(wb
, item
, 1);
76 static inline void dec_wb_stat(struct bdi_writeback
*wb
, enum wb_stat_item item
)
78 __add_wb_stat(wb
, item
, -1);
81 static inline s64
wb_stat(struct bdi_writeback
*wb
, enum wb_stat_item item
)
83 return percpu_counter_read_positive(&wb
->stat
[item
]);
86 static inline s64
wb_stat_sum(struct bdi_writeback
*wb
, enum wb_stat_item item
)
88 return percpu_counter_sum_positive(&wb
->stat
[item
]);
91 extern void wb_writeout_inc(struct bdi_writeback
*wb
);
94 * maximal error of a stat counter.
96 static inline unsigned long wb_stat_error(void)
99 return nr_cpu_ids
* WB_STAT_BATCH
;
105 int bdi_set_min_ratio(struct backing_dev_info
*bdi
, unsigned int min_ratio
);
106 int bdi_set_max_ratio(struct backing_dev_info
*bdi
, unsigned int max_ratio
);
109 * Flags in backing_dev_info::capability
111 * The first three flags control whether dirty pages will contribute to the
112 * VM's accounting and whether writepages() should be called for dirty pages
113 * (something that would not, for example, be appropriate for ramfs)
115 * WARNING: these flags are closely related and should not normally be
116 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
117 * three flags into a single convenience macro.
119 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
120 * BDI_CAP_NO_WRITEBACK: Don't write pages back
121 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
122 * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
124 * BDI_CAP_CGROUP_WRITEBACK: Supports cgroup-aware writeback.
125 * BDI_CAP_SYNCHRONOUS_IO: Device is so fast that asynchronous IO would be
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
134 #define BDI_CAP_SYNCHRONOUS_IO 0x00000040
136 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
137 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
139 extern struct backing_dev_info noop_backing_dev_info
;
142 * writeback_in_progress - determine whether there is writeback in progress
143 * @wb: bdi_writeback of interest
145 * Determine whether there is writeback waiting to be handled against a
148 static inline bool writeback_in_progress(struct bdi_writeback
*wb
)
150 return test_bit(WB_writeback_running
, &wb
->state
);
153 static inline struct backing_dev_info
*inode_to_bdi(struct inode
*inode
)
155 struct super_block
*sb
;
158 return &noop_backing_dev_info
;
162 if (sb_is_blkdev_sb(sb
))
163 return I_BDEV(inode
)->bd_bdi
;
168 static inline int wb_congested(struct bdi_writeback
*wb
, int cong_bits
)
170 struct backing_dev_info
*bdi
= wb
->bdi
;
172 if (bdi
->congested_fn
)
173 return bdi
->congested_fn(bdi
->congested_data
, cong_bits
);
174 return wb
->congested
->state
& cong_bits
;
177 long congestion_wait(int sync
, long timeout
);
178 long wait_iff_congested(struct pglist_data
*pgdat
, int sync
, long timeout
);
180 static inline bool bdi_cap_synchronous_io(struct backing_dev_info
*bdi
)
182 return bdi
->capabilities
& BDI_CAP_SYNCHRONOUS_IO
;
185 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info
*bdi
)
187 return bdi
->capabilities
& BDI_CAP_STABLE_WRITES
;
190 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info
*bdi
)
192 return !(bdi
->capabilities
& BDI_CAP_NO_WRITEBACK
);
195 static inline bool bdi_cap_account_dirty(struct backing_dev_info
*bdi
)
197 return !(bdi
->capabilities
& BDI_CAP_NO_ACCT_DIRTY
);
200 static inline bool bdi_cap_account_writeback(struct backing_dev_info
*bdi
)
202 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
203 return !(bdi
->capabilities
& (BDI_CAP_NO_ACCT_WB
|
204 BDI_CAP_NO_WRITEBACK
));
207 static inline bool mapping_cap_writeback_dirty(struct address_space
*mapping
)
209 return bdi_cap_writeback_dirty(inode_to_bdi(mapping
->host
));
212 static inline bool mapping_cap_account_dirty(struct address_space
*mapping
)
214 return bdi_cap_account_dirty(inode_to_bdi(mapping
->host
));
217 static inline int bdi_sched_wait(void *word
)
223 #ifdef CONFIG_CGROUP_WRITEBACK
225 struct bdi_writeback_congested
*
226 wb_congested_get_create(struct backing_dev_info
*bdi
, int blkcg_id
, gfp_t gfp
);
227 void wb_congested_put(struct bdi_writeback_congested
*congested
);
228 struct bdi_writeback
*wb_get_create(struct backing_dev_info
*bdi
,
229 struct cgroup_subsys_state
*memcg_css
,
231 void wb_memcg_offline(struct mem_cgroup
*memcg
);
232 void wb_blkcg_offline(struct blkcg
*blkcg
);
233 int inode_congested(struct inode
*inode
, int cong_bits
);
236 * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
237 * @inode: inode of interest
239 * cgroup writeback requires support from both the bdi and filesystem.
240 * Also, both memcg and iocg have to be on the default hierarchy. Test
241 * whether all conditions are met.
243 * Note that the test result may change dynamically on the same inode
244 * depending on how memcg and iocg are configured.
246 static inline bool inode_cgwb_enabled(struct inode
*inode
)
248 struct backing_dev_info
*bdi
= inode_to_bdi(inode
);
250 return cgroup_subsys_on_dfl(memory_cgrp_subsys
) &&
251 cgroup_subsys_on_dfl(io_cgrp_subsys
) &&
252 bdi_cap_account_dirty(bdi
) &&
253 (bdi
->capabilities
& BDI_CAP_CGROUP_WRITEBACK
) &&
254 (inode
->i_sb
->s_iflags
& SB_I_CGROUPWB
);
258 * wb_find_current - find wb for %current on a bdi
259 * @bdi: bdi of interest
261 * Find the wb of @bdi which matches both the memcg and blkcg of %current.
262 * Must be called under rcu_read_lock() which protects the returend wb.
265 static inline struct bdi_writeback
*wb_find_current(struct backing_dev_info
*bdi
)
267 struct cgroup_subsys_state
*memcg_css
;
268 struct bdi_writeback
*wb
;
270 memcg_css
= task_css(current
, memory_cgrp_id
);
271 if (!memcg_css
->parent
)
274 wb
= radix_tree_lookup(&bdi
->cgwb_tree
, memcg_css
->id
);
277 * %current's blkcg equals the effective blkcg of its memcg. No
278 * need to use the relatively expensive cgroup_get_e_css().
280 if (likely(wb
&& wb
->blkcg_css
== task_css(current
, io_cgrp_id
)))
286 * wb_get_create_current - get or create wb for %current on a bdi
287 * @bdi: bdi of interest
288 * @gfp: allocation mask
290 * Equivalent to wb_get_create() on %current's memcg. This function is
291 * called from a relatively hot path and optimizes the common cases using
294 static inline struct bdi_writeback
*
295 wb_get_create_current(struct backing_dev_info
*bdi
, gfp_t gfp
)
297 struct bdi_writeback
*wb
;
300 wb
= wb_find_current(bdi
);
301 if (wb
&& unlikely(!wb_tryget(wb
)))
306 struct cgroup_subsys_state
*memcg_css
;
308 memcg_css
= task_get_css(current
, memory_cgrp_id
);
309 wb
= wb_get_create(bdi
, memcg_css
, gfp
);
316 * inode_to_wb_is_valid - test whether an inode has a wb associated
317 * @inode: inode of interest
319 * Returns %true if @inode has a wb associated. May be called without any
322 static inline bool inode_to_wb_is_valid(struct inode
*inode
)
328 * inode_to_wb - determine the wb of an inode
329 * @inode: inode of interest
331 * Returns the wb @inode is currently associated with. The caller must be
332 * holding either @inode->i_lock, @inode->i_mapping->tree_lock, or the
333 * associated wb's list_lock.
335 static inline struct bdi_writeback
*inode_to_wb(const struct inode
*inode
)
337 #ifdef CONFIG_LOCKDEP
338 WARN_ON_ONCE(debug_locks
&&
339 (!lockdep_is_held(&inode
->i_lock
) &&
340 !lockdep_is_held(&inode
->i_mapping
->tree_lock
) &&
341 !lockdep_is_held(&inode
->i_wb
->list_lock
)));
347 * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
348 * @inode: target inode
349 * @lockedp: temp bool output param, to be passed to the end function
351 * The caller wants to access the wb associated with @inode but isn't
352 * holding inode->i_lock, mapping->tree_lock or wb->list_lock. This
353 * function determines the wb associated with @inode and ensures that the
354 * association doesn't change until the transaction is finished with
355 * unlocked_inode_to_wb_end().
357 * The caller must call unlocked_inode_to_wb_end() with *@lockdep
358 * afterwards and can't sleep during transaction. IRQ may or may not be
359 * disabled on return.
361 static inline struct bdi_writeback
*
362 unlocked_inode_to_wb_begin(struct inode
*inode
, bool *lockedp
)
367 * Paired with store_release in inode_switch_wb_work_fn() and
368 * ensures that we see the new wb if we see cleared I_WB_SWITCH.
370 *lockedp
= smp_load_acquire(&inode
->i_state
) & I_WB_SWITCH
;
372 if (unlikely(*lockedp
))
373 spin_lock_irq(&inode
->i_mapping
->tree_lock
);
376 * Protected by either !I_WB_SWITCH + rcu_read_lock() or tree_lock.
377 * inode_to_wb() will bark. Deref directly.
383 * unlocked_inode_to_wb_end - end inode wb access transaction
384 * @inode: target inode
385 * @locked: *@lockedp from unlocked_inode_to_wb_begin()
387 static inline void unlocked_inode_to_wb_end(struct inode
*inode
, bool locked
)
389 if (unlikely(locked
))
390 spin_unlock_irq(&inode
->i_mapping
->tree_lock
);
395 #else /* CONFIG_CGROUP_WRITEBACK */
397 static inline bool inode_cgwb_enabled(struct inode
*inode
)
402 static inline struct bdi_writeback_congested
*
403 wb_congested_get_create(struct backing_dev_info
*bdi
, int blkcg_id
, gfp_t gfp
)
405 atomic_inc(&bdi
->wb_congested
->refcnt
);
406 return bdi
->wb_congested
;
409 static inline void wb_congested_put(struct bdi_writeback_congested
*congested
)
411 if (atomic_dec_and_test(&congested
->refcnt
))
415 static inline struct bdi_writeback
*wb_find_current(struct backing_dev_info
*bdi
)
420 static inline struct bdi_writeback
*
421 wb_get_create_current(struct backing_dev_info
*bdi
, gfp_t gfp
)
426 static inline bool inode_to_wb_is_valid(struct inode
*inode
)
431 static inline struct bdi_writeback
*inode_to_wb(struct inode
*inode
)
433 return &inode_to_bdi(inode
)->wb
;
436 static inline struct bdi_writeback
*
437 unlocked_inode_to_wb_begin(struct inode
*inode
, bool *lockedp
)
439 return inode_to_wb(inode
);
442 static inline void unlocked_inode_to_wb_end(struct inode
*inode
, bool locked
)
446 static inline void wb_memcg_offline(struct mem_cgroup
*memcg
)
450 static inline void wb_blkcg_offline(struct blkcg
*blkcg
)
454 static inline int inode_congested(struct inode
*inode
, int cong_bits
)
456 return wb_congested(&inode_to_bdi(inode
)->wb
, cong_bits
);
459 #endif /* CONFIG_CGROUP_WRITEBACK */
461 static inline int inode_read_congested(struct inode
*inode
)
463 return inode_congested(inode
, 1 << WB_sync_congested
);
466 static inline int inode_write_congested(struct inode
*inode
)
468 return inode_congested(inode
, 1 << WB_async_congested
);
471 static inline int inode_rw_congested(struct inode
*inode
)
473 return inode_congested(inode
, (1 << WB_sync_congested
) |
474 (1 << WB_async_congested
));
477 static inline int bdi_congested(struct backing_dev_info
*bdi
, int cong_bits
)
479 return wb_congested(&bdi
->wb
, cong_bits
);
482 static inline int bdi_read_congested(struct backing_dev_info
*bdi
)
484 return bdi_congested(bdi
, 1 << WB_sync_congested
);
487 static inline int bdi_write_congested(struct backing_dev_info
*bdi
)
489 return bdi_congested(bdi
, 1 << WB_async_congested
);
492 static inline int bdi_rw_congested(struct backing_dev_info
*bdi
)
494 return bdi_congested(bdi
, (1 << WB_sync_congested
) |
495 (1 << WB_async_congested
));
498 #endif /* _LINUX_BACKING_DEV_H */