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
, ...);
32 int bdi_register_va(struct backing_dev_info
*bdi
, const char *fmt
,
34 int bdi_register_owner(struct backing_dev_info
*bdi
, struct device
*owner
);
35 void bdi_unregister(struct backing_dev_info
*bdi
);
37 struct backing_dev_info
*bdi_alloc_node(gfp_t gfp_mask
, int node_id
);
38 static inline struct backing_dev_info
*bdi_alloc(gfp_t gfp_mask
)
40 return bdi_alloc_node(gfp_mask
, NUMA_NO_NODE
);
43 void wb_start_background_writeback(struct bdi_writeback
*wb
);
44 void wb_workfn(struct work_struct
*work
);
45 void wb_wakeup_delayed(struct bdi_writeback
*wb
);
47 extern spinlock_t bdi_lock
;
48 extern struct list_head bdi_list
;
50 extern struct workqueue_struct
*bdi_wq
;
52 static inline bool wb_has_dirty_io(struct bdi_writeback
*wb
)
54 return test_bit(WB_has_dirty_io
, &wb
->state
);
57 static inline bool bdi_has_dirty_io(struct backing_dev_info
*bdi
)
60 * @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are
61 * any dirty wbs. See wb_update_write_bandwidth().
63 return atomic_long_read(&bdi
->tot_write_bandwidth
);
66 static inline void __add_wb_stat(struct bdi_writeback
*wb
,
67 enum wb_stat_item item
, s64 amount
)
69 percpu_counter_add_batch(&wb
->stat
[item
], amount
, WB_STAT_BATCH
);
72 static inline void inc_wb_stat(struct bdi_writeback
*wb
, enum wb_stat_item item
)
74 __add_wb_stat(wb
, item
, 1);
77 static inline void dec_wb_stat(struct bdi_writeback
*wb
, enum wb_stat_item item
)
79 __add_wb_stat(wb
, item
, -1);
82 static inline s64
wb_stat(struct bdi_writeback
*wb
, enum wb_stat_item item
)
84 return percpu_counter_read_positive(&wb
->stat
[item
]);
87 static inline s64
wb_stat_sum(struct bdi_writeback
*wb
, enum wb_stat_item item
)
89 return percpu_counter_sum_positive(&wb
->stat
[item
]);
92 extern void wb_writeout_inc(struct bdi_writeback
*wb
);
95 * maximal error of a stat counter.
97 static inline unsigned long wb_stat_error(void)
100 return nr_cpu_ids
* WB_STAT_BATCH
;
106 int bdi_set_min_ratio(struct backing_dev_info
*bdi
, unsigned int min_ratio
);
107 int bdi_set_max_ratio(struct backing_dev_info
*bdi
, unsigned int max_ratio
);
110 * Flags in backing_dev_info::capability
112 * The first three flags control whether dirty pages will contribute to the
113 * VM's accounting and whether writepages() should be called for dirty pages
114 * (something that would not, for example, be appropriate for ramfs)
116 * WARNING: these flags are closely related and should not normally be
117 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
118 * three flags into a single convenience macro.
120 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
121 * BDI_CAP_NO_WRITEBACK: Don't write pages back
122 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
123 * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
125 * BDI_CAP_CGROUP_WRITEBACK: Supports cgroup-aware writeback.
126 * BDI_CAP_SYNCHRONOUS_IO: Device is so fast that asynchronous IO would be
129 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
130 #define BDI_CAP_NO_WRITEBACK 0x00000002
131 #define BDI_CAP_NO_ACCT_WB 0x00000004
132 #define BDI_CAP_STABLE_WRITES 0x00000008
133 #define BDI_CAP_STRICTLIMIT 0x00000010
134 #define BDI_CAP_CGROUP_WRITEBACK 0x00000020
135 #define BDI_CAP_SYNCHRONOUS_IO 0x00000040
137 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
138 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
140 extern struct backing_dev_info noop_backing_dev_info
;
143 * writeback_in_progress - determine whether there is writeback in progress
144 * @wb: bdi_writeback of interest
146 * Determine whether there is writeback waiting to be handled against a
149 static inline bool writeback_in_progress(struct bdi_writeback
*wb
)
151 return test_bit(WB_writeback_running
, &wb
->state
);
154 static inline struct backing_dev_info
*inode_to_bdi(struct inode
*inode
)
156 struct super_block
*sb
;
159 return &noop_backing_dev_info
;
163 if (sb_is_blkdev_sb(sb
))
164 return I_BDEV(inode
)->bd_bdi
;
169 static inline int wb_congested(struct bdi_writeback
*wb
, int cong_bits
)
171 struct backing_dev_info
*bdi
= wb
->bdi
;
173 if (bdi
->congested_fn
)
174 return bdi
->congested_fn(bdi
->congested_data
, cong_bits
);
175 return wb
->congested
->state
& cong_bits
;
178 long congestion_wait(int sync
, long timeout
);
179 long wait_iff_congested(int sync
, long timeout
);
181 static inline bool bdi_cap_synchronous_io(struct backing_dev_info
*bdi
)
183 return bdi
->capabilities
& BDI_CAP_SYNCHRONOUS_IO
;
186 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info
*bdi
)
188 return bdi
->capabilities
& BDI_CAP_STABLE_WRITES
;
191 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info
*bdi
)
193 return !(bdi
->capabilities
& BDI_CAP_NO_WRITEBACK
);
196 static inline bool bdi_cap_account_dirty(struct backing_dev_info
*bdi
)
198 return !(bdi
->capabilities
& BDI_CAP_NO_ACCT_DIRTY
);
201 static inline bool bdi_cap_account_writeback(struct backing_dev_info
*bdi
)
203 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
204 return !(bdi
->capabilities
& (BDI_CAP_NO_ACCT_WB
|
205 BDI_CAP_NO_WRITEBACK
));
208 static inline bool mapping_cap_writeback_dirty(struct address_space
*mapping
)
210 return bdi_cap_writeback_dirty(inode_to_bdi(mapping
->host
));
213 static inline bool mapping_cap_account_dirty(struct address_space
*mapping
)
215 return bdi_cap_account_dirty(inode_to_bdi(mapping
->host
));
218 static inline int bdi_sched_wait(void *word
)
224 #ifdef CONFIG_CGROUP_WRITEBACK
226 struct bdi_writeback_congested
*
227 wb_congested_get_create(struct backing_dev_info
*bdi
, int blkcg_id
, gfp_t gfp
);
228 void wb_congested_put(struct bdi_writeback_congested
*congested
);
229 struct bdi_writeback
*wb_get_create(struct backing_dev_info
*bdi
,
230 struct cgroup_subsys_state
*memcg_css
,
232 void wb_memcg_offline(struct mem_cgroup
*memcg
);
233 void wb_blkcg_offline(struct blkcg
*blkcg
);
234 int inode_congested(struct inode
*inode
, int cong_bits
);
237 * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
238 * @inode: inode of interest
240 * cgroup writeback requires support from both the bdi and filesystem.
241 * Also, both memcg and iocg have to be on the default hierarchy. Test
242 * whether all conditions are met.
244 * Note that the test result may change dynamically on the same inode
245 * depending on how memcg and iocg are configured.
247 static inline bool inode_cgwb_enabled(struct inode
*inode
)
249 struct backing_dev_info
*bdi
= inode_to_bdi(inode
);
251 return cgroup_subsys_on_dfl(memory_cgrp_subsys
) &&
252 cgroup_subsys_on_dfl(io_cgrp_subsys
) &&
253 bdi_cap_account_dirty(bdi
) &&
254 (bdi
->capabilities
& BDI_CAP_CGROUP_WRITEBACK
) &&
255 (inode
->i_sb
->s_iflags
& SB_I_CGROUPWB
);
259 * wb_find_current - find wb for %current on a bdi
260 * @bdi: bdi of interest
262 * Find the wb of @bdi which matches both the memcg and blkcg of %current.
263 * Must be called under rcu_read_lock() which protects the returend wb.
266 static inline struct bdi_writeback
*wb_find_current(struct backing_dev_info
*bdi
)
268 struct cgroup_subsys_state
*memcg_css
;
269 struct bdi_writeback
*wb
;
271 memcg_css
= task_css(current
, memory_cgrp_id
);
272 if (!memcg_css
->parent
)
275 wb
= radix_tree_lookup(&bdi
->cgwb_tree
, memcg_css
->id
);
278 * %current's blkcg equals the effective blkcg of its memcg. No
279 * need to use the relatively expensive cgroup_get_e_css().
281 if (likely(wb
&& wb
->blkcg_css
== task_css(current
, io_cgrp_id
)))
287 * wb_get_create_current - get or create wb for %current on a bdi
288 * @bdi: bdi of interest
289 * @gfp: allocation mask
291 * Equivalent to wb_get_create() on %current's memcg. This function is
292 * called from a relatively hot path and optimizes the common cases using
295 static inline struct bdi_writeback
*
296 wb_get_create_current(struct backing_dev_info
*bdi
, gfp_t gfp
)
298 struct bdi_writeback
*wb
;
301 wb
= wb_find_current(bdi
);
302 if (wb
&& unlikely(!wb_tryget(wb
)))
307 struct cgroup_subsys_state
*memcg_css
;
309 memcg_css
= task_get_css(current
, memory_cgrp_id
);
310 wb
= wb_get_create(bdi
, memcg_css
, gfp
);
317 * inode_to_wb_is_valid - test whether an inode has a wb associated
318 * @inode: inode of interest
320 * Returns %true if @inode has a wb associated. May be called without any
323 static inline bool inode_to_wb_is_valid(struct inode
*inode
)
329 * inode_to_wb - determine the wb of an inode
330 * @inode: inode of interest
332 * Returns the wb @inode is currently associated with. The caller must be
333 * holding either @inode->i_lock, the i_pages lock, or the
334 * associated wb's list_lock.
336 static inline struct bdi_writeback
*inode_to_wb(const struct inode
*inode
)
338 #ifdef CONFIG_LOCKDEP
339 WARN_ON_ONCE(debug_locks
&&
340 (!lockdep_is_held(&inode
->i_lock
) &&
341 !lockdep_is_held(&inode
->i_mapping
->i_pages
.xa_lock
) &&
342 !lockdep_is_held(&inode
->i_wb
->list_lock
)));
348 * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
349 * @inode: target inode
350 * @cookie: output param, to be passed to the end function
352 * The caller wants to access the wb associated with @inode but isn't
353 * holding inode->i_lock, the i_pages lock or wb->list_lock. This
354 * function determines the wb associated with @inode and ensures that the
355 * association doesn't change until the transaction is finished with
356 * unlocked_inode_to_wb_end().
358 * The caller must call unlocked_inode_to_wb_end() with *@cookie afterwards and
359 * can't sleep during the transaction. IRQs may or may not be disabled on
362 static inline struct bdi_writeback
*
363 unlocked_inode_to_wb_begin(struct inode
*inode
, struct wb_lock_cookie
*cookie
)
368 * Paired with store_release in inode_switch_wb_work_fn() and
369 * ensures that we see the new wb if we see cleared I_WB_SWITCH.
371 cookie
->locked
= smp_load_acquire(&inode
->i_state
) & I_WB_SWITCH
;
373 if (unlikely(cookie
->locked
))
374 xa_lock_irqsave(&inode
->i_mapping
->i_pages
, cookie
->flags
);
377 * Protected by either !I_WB_SWITCH + rcu_read_lock() or the i_pages
378 * lock. inode_to_wb() will bark. Deref directly.
384 * unlocked_inode_to_wb_end - end inode wb access transaction
385 * @inode: target inode
386 * @cookie: @cookie from unlocked_inode_to_wb_begin()
388 static inline void unlocked_inode_to_wb_end(struct inode
*inode
,
389 struct wb_lock_cookie
*cookie
)
391 if (unlikely(cookie
->locked
))
392 xa_unlock_irqrestore(&inode
->i_mapping
->i_pages
, cookie
->flags
);
397 #else /* CONFIG_CGROUP_WRITEBACK */
399 static inline bool inode_cgwb_enabled(struct inode
*inode
)
404 static inline struct bdi_writeback_congested
*
405 wb_congested_get_create(struct backing_dev_info
*bdi
, int blkcg_id
, gfp_t gfp
)
407 refcount_inc(&bdi
->wb_congested
->refcnt
);
408 return bdi
->wb_congested
;
411 static inline void wb_congested_put(struct bdi_writeback_congested
*congested
)
413 if (refcount_dec_and_test(&congested
->refcnt
))
417 static inline struct bdi_writeback
*wb_find_current(struct backing_dev_info
*bdi
)
422 static inline struct bdi_writeback
*
423 wb_get_create_current(struct backing_dev_info
*bdi
, gfp_t gfp
)
428 static inline bool inode_to_wb_is_valid(struct inode
*inode
)
433 static inline struct bdi_writeback
*inode_to_wb(struct inode
*inode
)
435 return &inode_to_bdi(inode
)->wb
;
438 static inline struct bdi_writeback
*
439 unlocked_inode_to_wb_begin(struct inode
*inode
, struct wb_lock_cookie
*cookie
)
441 return inode_to_wb(inode
);
444 static inline void unlocked_inode_to_wb_end(struct inode
*inode
,
445 struct wb_lock_cookie
*cookie
)
449 static inline void wb_memcg_offline(struct mem_cgroup
*memcg
)
453 static inline void wb_blkcg_offline(struct blkcg
*blkcg
)
457 static inline int inode_congested(struct inode
*inode
, int cong_bits
)
459 return wb_congested(&inode_to_bdi(inode
)->wb
, cong_bits
);
462 #endif /* CONFIG_CGROUP_WRITEBACK */
464 static inline int inode_read_congested(struct inode
*inode
)
466 return inode_congested(inode
, 1 << WB_sync_congested
);
469 static inline int inode_write_congested(struct inode
*inode
)
471 return inode_congested(inode
, 1 << WB_async_congested
);
474 static inline int inode_rw_congested(struct inode
*inode
)
476 return inode_congested(inode
, (1 << WB_sync_congested
) |
477 (1 << WB_async_congested
));
480 static inline int bdi_congested(struct backing_dev_info
*bdi
, int cong_bits
)
482 return wb_congested(&bdi
->wb
, cong_bits
);
485 static inline int bdi_read_congested(struct backing_dev_info
*bdi
)
487 return bdi_congested(bdi
, 1 << WB_sync_congested
);
490 static inline int bdi_write_congested(struct backing_dev_info
*bdi
)
492 return bdi_congested(bdi
, 1 << WB_async_congested
);
495 static inline int bdi_rw_congested(struct backing_dev_info
*bdi
)
497 return bdi_congested(bdi
, (1 << WB_sync_congested
) |
498 (1 << WB_async_congested
));
501 #endif /* _LINUX_BACKING_DEV_H */