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 static inline struct backing_dev_info
*bdi_get(struct backing_dev_info
*bdi
)
22 kref_get(&bdi
->refcnt
);
26 void bdi_put(struct backing_dev_info
*bdi
);
29 int bdi_register(struct backing_dev_info
*bdi
, const char *fmt
, ...);
30 int bdi_register_va(struct backing_dev_info
*bdi
, const char *fmt
,
32 int bdi_register_owner(struct backing_dev_info
*bdi
, struct device
*owner
);
33 void bdi_unregister(struct backing_dev_info
*bdi
);
35 struct backing_dev_info
*bdi_alloc_node(gfp_t gfp_mask
, int node_id
);
36 static inline struct backing_dev_info
*bdi_alloc(gfp_t gfp_mask
)
38 return bdi_alloc_node(gfp_mask
, NUMA_NO_NODE
);
41 void wb_start_writeback(struct bdi_writeback
*wb
, long nr_pages
,
42 bool range_cyclic
, enum wb_reason reason
);
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(struct bdi_writeback
*wb
)
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.
127 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
128 #define BDI_CAP_NO_WRITEBACK 0x00000002
129 #define BDI_CAP_NO_ACCT_WB 0x00000004
130 #define BDI_CAP_STABLE_WRITES 0x00000008
131 #define BDI_CAP_STRICTLIMIT 0x00000010
132 #define BDI_CAP_CGROUP_WRITEBACK 0x00000020
134 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
135 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
137 extern struct backing_dev_info noop_backing_dev_info
;
140 * writeback_in_progress - determine whether there is writeback in progress
141 * @wb: bdi_writeback of interest
143 * Determine whether there is writeback waiting to be handled against a
146 static inline bool writeback_in_progress(struct bdi_writeback
*wb
)
148 return test_bit(WB_writeback_running
, &wb
->state
);
151 static inline struct backing_dev_info
*inode_to_bdi(struct inode
*inode
)
153 struct super_block
*sb
;
156 return &noop_backing_dev_info
;
160 if (sb_is_blkdev_sb(sb
))
161 return I_BDEV(inode
)->bd_bdi
;
166 static inline int wb_congested(struct bdi_writeback
*wb
, int cong_bits
)
168 struct backing_dev_info
*bdi
= wb
->bdi
;
170 if (bdi
->congested_fn
)
171 return bdi
->congested_fn(bdi
->congested_data
, cong_bits
);
172 return wb
->congested
->state
& cong_bits
;
175 long congestion_wait(int sync
, long timeout
);
176 long wait_iff_congested(struct pglist_data
*pgdat
, int sync
, long timeout
);
177 int pdflush_proc_obsolete(struct ctl_table
*table
, int write
,
178 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
);
180 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info
*bdi
)
182 return bdi
->capabilities
& BDI_CAP_STABLE_WRITES
;
185 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info
*bdi
)
187 return !(bdi
->capabilities
& BDI_CAP_NO_WRITEBACK
);
190 static inline bool bdi_cap_account_dirty(struct backing_dev_info
*bdi
)
192 return !(bdi
->capabilities
& BDI_CAP_NO_ACCT_DIRTY
);
195 static inline bool bdi_cap_account_writeback(struct backing_dev_info
*bdi
)
197 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
198 return !(bdi
->capabilities
& (BDI_CAP_NO_ACCT_WB
|
199 BDI_CAP_NO_WRITEBACK
));
202 static inline bool mapping_cap_writeback_dirty(struct address_space
*mapping
)
204 return bdi_cap_writeback_dirty(inode_to_bdi(mapping
->host
));
207 static inline bool mapping_cap_account_dirty(struct address_space
*mapping
)
209 return bdi_cap_account_dirty(inode_to_bdi(mapping
->host
));
212 static inline int bdi_sched_wait(void *word
)
218 #ifdef CONFIG_CGROUP_WRITEBACK
220 struct bdi_writeback_congested
*
221 wb_congested_get_create(struct backing_dev_info
*bdi
, int blkcg_id
, gfp_t gfp
);
222 void wb_congested_put(struct bdi_writeback_congested
*congested
);
223 struct bdi_writeback
*wb_get_create(struct backing_dev_info
*bdi
,
224 struct cgroup_subsys_state
*memcg_css
,
226 void wb_memcg_offline(struct mem_cgroup
*memcg
);
227 void wb_blkcg_offline(struct blkcg
*blkcg
);
228 int inode_congested(struct inode
*inode
, int cong_bits
);
231 * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
232 * @inode: inode of interest
234 * cgroup writeback requires support from both the bdi and filesystem.
235 * Also, both memcg and iocg have to be on the default hierarchy. Test
236 * whether all conditions are met.
238 * Note that the test result may change dynamically on the same inode
239 * depending on how memcg and iocg are configured.
241 static inline bool inode_cgwb_enabled(struct inode
*inode
)
243 struct backing_dev_info
*bdi
= inode_to_bdi(inode
);
245 return cgroup_subsys_on_dfl(memory_cgrp_subsys
) &&
246 cgroup_subsys_on_dfl(io_cgrp_subsys
) &&
247 bdi_cap_account_dirty(bdi
) &&
248 (bdi
->capabilities
& BDI_CAP_CGROUP_WRITEBACK
) &&
249 (inode
->i_sb
->s_iflags
& SB_I_CGROUPWB
);
253 * wb_find_current - find wb for %current on a bdi
254 * @bdi: bdi of interest
256 * Find the wb of @bdi which matches both the memcg and blkcg of %current.
257 * Must be called under rcu_read_lock() which protects the returend wb.
260 static inline struct bdi_writeback
*wb_find_current(struct backing_dev_info
*bdi
)
262 struct cgroup_subsys_state
*memcg_css
;
263 struct bdi_writeback
*wb
;
265 memcg_css
= task_css(current
, memory_cgrp_id
);
266 if (!memcg_css
->parent
)
269 wb
= radix_tree_lookup(&bdi
->cgwb_tree
, memcg_css
->id
);
272 * %current's blkcg equals the effective blkcg of its memcg. No
273 * need to use the relatively expensive cgroup_get_e_css().
275 if (likely(wb
&& wb
->blkcg_css
== task_css(current
, io_cgrp_id
)))
281 * wb_get_create_current - get or create wb for %current on a bdi
282 * @bdi: bdi of interest
283 * @gfp: allocation mask
285 * Equivalent to wb_get_create() on %current's memcg. This function is
286 * called from a relatively hot path and optimizes the common cases using
289 static inline struct bdi_writeback
*
290 wb_get_create_current(struct backing_dev_info
*bdi
, gfp_t gfp
)
292 struct bdi_writeback
*wb
;
295 wb
= wb_find_current(bdi
);
296 if (wb
&& unlikely(!wb_tryget(wb
)))
301 struct cgroup_subsys_state
*memcg_css
;
303 memcg_css
= task_get_css(current
, memory_cgrp_id
);
304 wb
= wb_get_create(bdi
, memcg_css
, gfp
);
311 * inode_to_wb_is_valid - test whether an inode has a wb associated
312 * @inode: inode of interest
314 * Returns %true if @inode has a wb associated. May be called without any
317 static inline bool inode_to_wb_is_valid(struct inode
*inode
)
323 * inode_to_wb - determine the wb of an inode
324 * @inode: inode of interest
326 * Returns the wb @inode is currently associated with. The caller must be
327 * holding either @inode->i_lock, @inode->i_mapping->tree_lock, or the
328 * associated wb's list_lock.
330 static inline struct bdi_writeback
*inode_to_wb(struct inode
*inode
)
332 #ifdef CONFIG_LOCKDEP
333 WARN_ON_ONCE(debug_locks
&&
334 (!lockdep_is_held(&inode
->i_lock
) &&
335 !lockdep_is_held(&inode
->i_mapping
->tree_lock
) &&
336 !lockdep_is_held(&inode
->i_wb
->list_lock
)));
342 * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
343 * @inode: target inode
344 * @lockedp: temp bool output param, to be passed to the end function
346 * The caller wants to access the wb associated with @inode but isn't
347 * holding inode->i_lock, mapping->tree_lock or wb->list_lock. This
348 * function determines the wb associated with @inode and ensures that the
349 * association doesn't change until the transaction is finished with
350 * unlocked_inode_to_wb_end().
352 * The caller must call unlocked_inode_to_wb_end() with *@lockdep
353 * afterwards and can't sleep during transaction. IRQ may or may not be
354 * disabled on return.
356 static inline struct bdi_writeback
*
357 unlocked_inode_to_wb_begin(struct inode
*inode
, bool *lockedp
)
362 * Paired with store_release in inode_switch_wb_work_fn() and
363 * ensures that we see the new wb if we see cleared I_WB_SWITCH.
365 *lockedp
= smp_load_acquire(&inode
->i_state
) & I_WB_SWITCH
;
367 if (unlikely(*lockedp
))
368 spin_lock_irq(&inode
->i_mapping
->tree_lock
);
371 * Protected by either !I_WB_SWITCH + rcu_read_lock() or tree_lock.
372 * inode_to_wb() will bark. Deref directly.
378 * unlocked_inode_to_wb_end - end inode wb access transaction
379 * @inode: target inode
380 * @locked: *@lockedp from unlocked_inode_to_wb_begin()
382 static inline void unlocked_inode_to_wb_end(struct inode
*inode
, bool locked
)
384 if (unlikely(locked
))
385 spin_unlock_irq(&inode
->i_mapping
->tree_lock
);
390 #else /* CONFIG_CGROUP_WRITEBACK */
392 static inline bool inode_cgwb_enabled(struct inode
*inode
)
397 static inline struct bdi_writeback_congested
*
398 wb_congested_get_create(struct backing_dev_info
*bdi
, int blkcg_id
, gfp_t gfp
)
400 atomic_inc(&bdi
->wb_congested
->refcnt
);
401 return bdi
->wb_congested
;
404 static inline void wb_congested_put(struct bdi_writeback_congested
*congested
)
406 if (atomic_dec_and_test(&congested
->refcnt
))
410 static inline struct bdi_writeback
*wb_find_current(struct backing_dev_info
*bdi
)
415 static inline struct bdi_writeback
*
416 wb_get_create_current(struct backing_dev_info
*bdi
, gfp_t gfp
)
421 static inline bool inode_to_wb_is_valid(struct inode
*inode
)
426 static inline struct bdi_writeback
*inode_to_wb(struct inode
*inode
)
428 return &inode_to_bdi(inode
)->wb
;
431 static inline struct bdi_writeback
*
432 unlocked_inode_to_wb_begin(struct inode
*inode
, bool *lockedp
)
434 return inode_to_wb(inode
);
437 static inline void unlocked_inode_to_wb_end(struct inode
*inode
, bool locked
)
441 static inline void wb_memcg_offline(struct mem_cgroup
*memcg
)
445 static inline void wb_blkcg_offline(struct blkcg
*blkcg
)
449 static inline int inode_congested(struct inode
*inode
, int cong_bits
)
451 return wb_congested(&inode_to_bdi(inode
)->wb
, cong_bits
);
454 #endif /* CONFIG_CGROUP_WRITEBACK */
456 static inline int inode_read_congested(struct inode
*inode
)
458 return inode_congested(inode
, 1 << WB_sync_congested
);
461 static inline int inode_write_congested(struct inode
*inode
)
463 return inode_congested(inode
, 1 << WB_async_congested
);
466 static inline int inode_rw_congested(struct inode
*inode
)
468 return inode_congested(inode
, (1 << WB_sync_congested
) |
469 (1 << WB_async_congested
));
472 static inline int bdi_congested(struct backing_dev_info
*bdi
, int cong_bits
)
474 return wb_congested(&bdi
->wb
, cong_bits
);
477 static inline int bdi_read_congested(struct backing_dev_info
*bdi
)
479 return bdi_congested(bdi
, 1 << WB_sync_congested
);
482 static inline int bdi_write_congested(struct backing_dev_info
*bdi
)
484 return bdi_congested(bdi
, 1 << WB_async_congested
);
487 static inline int bdi_rw_congested(struct backing_dev_info
*bdi
)
489 return bdi_congested(bdi
, (1 << WB_sync_congested
) |
490 (1 << WB_async_congested
));
493 #endif /* _LINUX_BACKING_DEV_H */