2 * include/linux/backing-dev.h
4 * low-level device information and state which is propagated up through
8 #ifndef _LINUX_BACKING_DEV_H
9 #define _LINUX_BACKING_DEV_H
11 #include <linux/kernel.h>
13 #include <linux/sched.h>
14 #include <linux/blkdev.h>
15 #include <linux/writeback.h>
16 #include <linux/blk-cgroup.h>
17 #include <linux/backing-dev-defs.h>
18 #include <linux/slab.h>
20 int __must_check
bdi_init(struct backing_dev_info
*bdi
);
21 void bdi_exit(struct backing_dev_info
*bdi
);
24 int bdi_register(struct backing_dev_info
*bdi
, struct device
*parent
,
25 const char *fmt
, ...);
26 int bdi_register_dev(struct backing_dev_info
*bdi
, dev_t dev
);
27 int bdi_register_owner(struct backing_dev_info
*bdi
, struct device
*owner
);
28 void bdi_unregister(struct backing_dev_info
*bdi
);
30 int __must_check
bdi_setup_and_register(struct backing_dev_info
*, char *);
31 void bdi_destroy(struct backing_dev_info
*bdi
);
33 void wb_start_writeback(struct bdi_writeback
*wb
, long nr_pages
,
34 bool range_cyclic
, enum wb_reason reason
);
35 void wb_start_background_writeback(struct bdi_writeback
*wb
);
36 void wb_workfn(struct work_struct
*work
);
37 void wb_wakeup_delayed(struct bdi_writeback
*wb
);
39 extern spinlock_t bdi_lock
;
40 extern struct list_head bdi_list
;
42 extern struct workqueue_struct
*bdi_wq
;
44 static inline bool wb_has_dirty_io(struct bdi_writeback
*wb
)
46 return test_bit(WB_has_dirty_io
, &wb
->state
);
49 static inline bool bdi_has_dirty_io(struct backing_dev_info
*bdi
)
52 * @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are
53 * any dirty wbs. See wb_update_write_bandwidth().
55 return atomic_long_read(&bdi
->tot_write_bandwidth
);
58 static inline void __add_wb_stat(struct bdi_writeback
*wb
,
59 enum wb_stat_item item
, s64 amount
)
61 __percpu_counter_add(&wb
->stat
[item
], amount
, WB_STAT_BATCH
);
64 static inline void __inc_wb_stat(struct bdi_writeback
*wb
,
65 enum wb_stat_item item
)
67 __add_wb_stat(wb
, item
, 1);
70 static inline void inc_wb_stat(struct bdi_writeback
*wb
, enum wb_stat_item item
)
74 local_irq_save(flags
);
75 __inc_wb_stat(wb
, item
);
76 local_irq_restore(flags
);
79 static inline void __dec_wb_stat(struct bdi_writeback
*wb
,
80 enum wb_stat_item item
)
82 __add_wb_stat(wb
, item
, -1);
85 static inline void dec_wb_stat(struct bdi_writeback
*wb
, enum wb_stat_item item
)
89 local_irq_save(flags
);
90 __dec_wb_stat(wb
, item
);
91 local_irq_restore(flags
);
94 static inline s64
wb_stat(struct bdi_writeback
*wb
, enum wb_stat_item item
)
96 return percpu_counter_read_positive(&wb
->stat
[item
]);
99 static inline s64
__wb_stat_sum(struct bdi_writeback
*wb
,
100 enum wb_stat_item item
)
102 return percpu_counter_sum_positive(&wb
->stat
[item
]);
105 static inline s64
wb_stat_sum(struct bdi_writeback
*wb
, enum wb_stat_item item
)
110 local_irq_save(flags
);
111 sum
= __wb_stat_sum(wb
, item
);
112 local_irq_restore(flags
);
117 extern void wb_writeout_inc(struct bdi_writeback
*wb
);
120 * maximal error of a stat counter.
122 static inline unsigned long wb_stat_error(struct bdi_writeback
*wb
)
125 return nr_cpu_ids
* WB_STAT_BATCH
;
131 int bdi_set_min_ratio(struct backing_dev_info
*bdi
, unsigned int min_ratio
);
132 int bdi_set_max_ratio(struct backing_dev_info
*bdi
, unsigned int max_ratio
);
135 * Flags in backing_dev_info::capability
137 * The first three flags control whether dirty pages will contribute to the
138 * VM's accounting and whether writepages() should be called for dirty pages
139 * (something that would not, for example, be appropriate for ramfs)
141 * WARNING: these flags are closely related and should not normally be
142 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
143 * three flags into a single convenience macro.
145 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
146 * BDI_CAP_NO_WRITEBACK: Don't write pages back
147 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
148 * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
150 * BDI_CAP_CGROUP_WRITEBACK: Supports cgroup-aware writeback.
152 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
153 #define BDI_CAP_NO_WRITEBACK 0x00000002
154 #define BDI_CAP_NO_ACCT_WB 0x00000004
155 #define BDI_CAP_STABLE_WRITES 0x00000008
156 #define BDI_CAP_STRICTLIMIT 0x00000010
157 #define BDI_CAP_CGROUP_WRITEBACK 0x00000020
159 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
160 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
162 extern struct backing_dev_info noop_backing_dev_info
;
165 * writeback_in_progress - determine whether there is writeback in progress
166 * @wb: bdi_writeback of interest
168 * Determine whether there is writeback waiting to be handled against a
171 static inline bool writeback_in_progress(struct bdi_writeback
*wb
)
173 return test_bit(WB_writeback_running
, &wb
->state
);
176 static inline struct backing_dev_info
*inode_to_bdi(struct inode
*inode
)
178 struct super_block
*sb
;
181 return &noop_backing_dev_info
;
185 if (sb_is_blkdev_sb(sb
))
186 return blk_get_backing_dev_info(I_BDEV(inode
));
191 static inline int wb_congested(struct bdi_writeback
*wb
, int cong_bits
)
193 struct backing_dev_info
*bdi
= wb
->bdi
;
195 if (bdi
->congested_fn
)
196 return bdi
->congested_fn(bdi
->congested_data
, cong_bits
);
197 return wb
->congested
->state
& cong_bits
;
200 long congestion_wait(int sync
, long timeout
);
201 long wait_iff_congested(struct pglist_data
*pgdat
, int sync
, long timeout
);
202 int pdflush_proc_obsolete(struct ctl_table
*table
, int write
,
203 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
);
205 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info
*bdi
)
207 return bdi
->capabilities
& BDI_CAP_STABLE_WRITES
;
210 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info
*bdi
)
212 return !(bdi
->capabilities
& BDI_CAP_NO_WRITEBACK
);
215 static inline bool bdi_cap_account_dirty(struct backing_dev_info
*bdi
)
217 return !(bdi
->capabilities
& BDI_CAP_NO_ACCT_DIRTY
);
220 static inline bool bdi_cap_account_writeback(struct backing_dev_info
*bdi
)
222 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
223 return !(bdi
->capabilities
& (BDI_CAP_NO_ACCT_WB
|
224 BDI_CAP_NO_WRITEBACK
));
227 static inline bool mapping_cap_writeback_dirty(struct address_space
*mapping
)
229 return bdi_cap_writeback_dirty(inode_to_bdi(mapping
->host
));
232 static inline bool mapping_cap_account_dirty(struct address_space
*mapping
)
234 return bdi_cap_account_dirty(inode_to_bdi(mapping
->host
));
237 static inline int bdi_sched_wait(void *word
)
243 #ifdef CONFIG_CGROUP_WRITEBACK
245 struct bdi_writeback_congested
*
246 wb_congested_get_create(struct backing_dev_info
*bdi
, int blkcg_id
, gfp_t gfp
);
247 void wb_congested_put(struct bdi_writeback_congested
*congested
);
248 struct bdi_writeback
*wb_get_create(struct backing_dev_info
*bdi
,
249 struct cgroup_subsys_state
*memcg_css
,
251 void wb_memcg_offline(struct mem_cgroup
*memcg
);
252 void wb_blkcg_offline(struct blkcg
*blkcg
);
253 int inode_congested(struct inode
*inode
, int cong_bits
);
256 * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
257 * @inode: inode of interest
259 * cgroup writeback requires support from both the bdi and filesystem.
260 * Also, both memcg and iocg have to be on the default hierarchy. Test
261 * whether all conditions are met.
263 * Note that the test result may change dynamically on the same inode
264 * depending on how memcg and iocg are configured.
266 static inline bool inode_cgwb_enabled(struct inode
*inode
)
268 struct backing_dev_info
*bdi
= inode_to_bdi(inode
);
270 return cgroup_subsys_on_dfl(memory_cgrp_subsys
) &&
271 cgroup_subsys_on_dfl(io_cgrp_subsys
) &&
272 bdi_cap_account_dirty(bdi
) &&
273 (bdi
->capabilities
& BDI_CAP_CGROUP_WRITEBACK
) &&
274 (inode
->i_sb
->s_iflags
& SB_I_CGROUPWB
);
278 * wb_find_current - find wb for %current on a bdi
279 * @bdi: bdi of interest
281 * Find the wb of @bdi which matches both the memcg and blkcg of %current.
282 * Must be called under rcu_read_lock() which protects the returend wb.
285 static inline struct bdi_writeback
*wb_find_current(struct backing_dev_info
*bdi
)
287 struct cgroup_subsys_state
*memcg_css
;
288 struct bdi_writeback
*wb
;
290 memcg_css
= task_css(current
, memory_cgrp_id
);
291 if (!memcg_css
->parent
)
294 wb
= radix_tree_lookup(&bdi
->cgwb_tree
, memcg_css
->id
);
297 * %current's blkcg equals the effective blkcg of its memcg. No
298 * need to use the relatively expensive cgroup_get_e_css().
300 if (likely(wb
&& wb
->blkcg_css
== task_css(current
, io_cgrp_id
)))
306 * wb_get_create_current - get or create wb for %current on a bdi
307 * @bdi: bdi of interest
308 * @gfp: allocation mask
310 * Equivalent to wb_get_create() on %current's memcg. This function is
311 * called from a relatively hot path and optimizes the common cases using
314 static inline struct bdi_writeback
*
315 wb_get_create_current(struct backing_dev_info
*bdi
, gfp_t gfp
)
317 struct bdi_writeback
*wb
;
320 wb
= wb_find_current(bdi
);
321 if (wb
&& unlikely(!wb_tryget(wb
)))
326 struct cgroup_subsys_state
*memcg_css
;
328 memcg_css
= task_get_css(current
, memory_cgrp_id
);
329 wb
= wb_get_create(bdi
, memcg_css
, gfp
);
336 * inode_to_wb_is_valid - test whether an inode has a wb associated
337 * @inode: inode of interest
339 * Returns %true if @inode has a wb associated. May be called without any
342 static inline bool inode_to_wb_is_valid(struct inode
*inode
)
348 * inode_to_wb - determine the wb of an inode
349 * @inode: inode of interest
351 * Returns the wb @inode is currently associated with. The caller must be
352 * holding either @inode->i_lock, @inode->i_mapping->tree_lock, or the
353 * associated wb's list_lock.
355 static inline struct bdi_writeback
*inode_to_wb(struct inode
*inode
)
357 #ifdef CONFIG_LOCKDEP
358 WARN_ON_ONCE(debug_locks
&&
359 (!lockdep_is_held(&inode
->i_lock
) &&
360 !lockdep_is_held(&inode
->i_mapping
->tree_lock
) &&
361 !lockdep_is_held(&inode
->i_wb
->list_lock
)));
367 * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
368 * @inode: target inode
369 * @lockedp: temp bool output param, to be passed to the end function
371 * The caller wants to access the wb associated with @inode but isn't
372 * holding inode->i_lock, mapping->tree_lock or wb->list_lock. This
373 * function determines the wb associated with @inode and ensures that the
374 * association doesn't change until the transaction is finished with
375 * unlocked_inode_to_wb_end().
377 * The caller must call unlocked_inode_to_wb_end() with *@lockdep
378 * afterwards and can't sleep during transaction. IRQ may or may not be
379 * disabled on return.
381 static inline struct bdi_writeback
*
382 unlocked_inode_to_wb_begin(struct inode
*inode
, bool *lockedp
)
387 * Paired with store_release in inode_switch_wb_work_fn() and
388 * ensures that we see the new wb if we see cleared I_WB_SWITCH.
390 *lockedp
= smp_load_acquire(&inode
->i_state
) & I_WB_SWITCH
;
392 if (unlikely(*lockedp
))
393 spin_lock_irq(&inode
->i_mapping
->tree_lock
);
396 * Protected by either !I_WB_SWITCH + rcu_read_lock() or tree_lock.
397 * inode_to_wb() will bark. Deref directly.
403 * unlocked_inode_to_wb_end - end inode wb access transaction
404 * @inode: target inode
405 * @locked: *@lockedp from unlocked_inode_to_wb_begin()
407 static inline void unlocked_inode_to_wb_end(struct inode
*inode
, bool locked
)
409 if (unlikely(locked
))
410 spin_unlock_irq(&inode
->i_mapping
->tree_lock
);
415 #else /* CONFIG_CGROUP_WRITEBACK */
417 static inline bool inode_cgwb_enabled(struct inode
*inode
)
422 static inline struct bdi_writeback_congested
*
423 wb_congested_get_create(struct backing_dev_info
*bdi
, int blkcg_id
, gfp_t gfp
)
425 atomic_inc(&bdi
->wb_congested
->refcnt
);
426 return bdi
->wb_congested
;
429 static inline void wb_congested_put(struct bdi_writeback_congested
*congested
)
431 if (atomic_dec_and_test(&congested
->refcnt
))
435 static inline struct bdi_writeback
*wb_find_current(struct backing_dev_info
*bdi
)
440 static inline struct bdi_writeback
*
441 wb_get_create_current(struct backing_dev_info
*bdi
, gfp_t gfp
)
446 static inline bool inode_to_wb_is_valid(struct inode
*inode
)
451 static inline struct bdi_writeback
*inode_to_wb(struct inode
*inode
)
453 return &inode_to_bdi(inode
)->wb
;
456 static inline struct bdi_writeback
*
457 unlocked_inode_to_wb_begin(struct inode
*inode
, bool *lockedp
)
459 return inode_to_wb(inode
);
462 static inline void unlocked_inode_to_wb_end(struct inode
*inode
, bool locked
)
466 static inline void wb_memcg_offline(struct mem_cgroup
*memcg
)
470 static inline void wb_blkcg_offline(struct blkcg
*blkcg
)
474 static inline int inode_congested(struct inode
*inode
, int cong_bits
)
476 return wb_congested(&inode_to_bdi(inode
)->wb
, cong_bits
);
479 #endif /* CONFIG_CGROUP_WRITEBACK */
481 static inline int inode_read_congested(struct inode
*inode
)
483 return inode_congested(inode
, 1 << WB_sync_congested
);
486 static inline int inode_write_congested(struct inode
*inode
)
488 return inode_congested(inode
, 1 << WB_async_congested
);
491 static inline int inode_rw_congested(struct inode
*inode
)
493 return inode_congested(inode
, (1 << WB_sync_congested
) |
494 (1 << WB_async_congested
));
497 static inline int bdi_congested(struct backing_dev_info
*bdi
, int cong_bits
)
499 return wb_congested(&bdi
->wb
, cong_bits
);
502 static inline int bdi_read_congested(struct backing_dev_info
*bdi
)
504 return bdi_congested(bdi
, 1 << WB_sync_congested
);
507 static inline int bdi_write_congested(struct backing_dev_info
*bdi
)
509 return bdi_congested(bdi
, 1 << WB_async_congested
);
512 static inline int bdi_rw_congested(struct backing_dev_info
*bdi
)
514 return bdi_congested(bdi
, (1 << WB_sync_congested
) |
515 (1 << WB_async_congested
));
518 #endif /* _LINUX_BACKING_DEV_H */