| 1 |
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| 2 | |
| 3 | * include/linux/backing-dev.h
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| 4 | *
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| 5 | * low-level device information and state which is propagated up through
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| 6 | * to high-level code.
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| 7 |
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| 8 |
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| 9 | #ifndef _LINUX_BACKING_DEV_H
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| 10 | #define _LINUX_BACKING_DEV_H
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| 11 |
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| 12 | #include <linux/kernel.h>
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| 13 | #include <linux/fs.h>
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| 14 | #include <linux/sched.h>
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| 15 | #include <linux/blkdev.h>
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| 16 | #include <linux/device.h>
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| 17 | #include <linux/writeback.h>
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| 18 | #include <linux/blk-cgroup.h>
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| 19 | #include <linux/backing-dev-defs.h>
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| 20 | #include <linux/slab.h>
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| 21 |
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| 22 | static inline struct backing_dev_info *bdi_get(struct backing_dev_info *bdi)
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| 23 | {
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| 24 | kref_get(&bdi->refcnt);
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| 25 | return bdi;
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| 26 | }
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| 27 |
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| 28 | struct backing_dev_info *bdi_get_by_id(u64 id);
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| 29 | void bdi_put(struct backing_dev_info *bdi);
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| 30 |
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| 31 | __printf(2, 3)
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| 32 | int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...);
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| 33 | __printf(2, 0)
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| 34 | int bdi_register_va(struct backing_dev_info *bdi, const char *fmt,
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| 35 | va_list args);
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| 36 | void bdi_set_owner(struct backing_dev_info *bdi, struct device *owner);
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| 37 | void bdi_unregister(struct backing_dev_info *bdi);
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| 38 |
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| 39 | struct backing_dev_info *bdi_alloc(int node_id);
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| 40 |
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| 41 | void wb_start_background_writeback(struct bdi_writeback *wb);
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| 42 | void wb_workfn(struct work_struct *work);
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| 43 | void wb_wakeup_delayed(struct bdi_writeback *wb);
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| 44 |
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| 45 | void wb_wait_for_completion(struct wb_completion *done);
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| 46 |
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| 47 | extern spinlock_t bdi_lock;
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| 48 | extern struct list_head bdi_list;
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| 49 |
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| 50 | extern struct workqueue_struct *bdi_wq;
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| 51 | extern struct workqueue_struct *bdi_async_bio_wq;
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| 52 |
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| 53 | static inline bool wb_has_dirty_io(struct bdi_writeback *wb)
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| 54 | {
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| 55 | return test_bit(WB_has_dirty_io, &wb->state);
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| 56 | }
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| 57 |
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| 58 | static inline bool bdi_has_dirty_io(struct backing_dev_info *bdi)
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| 59 | {
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| 60 | |
| 61 | * @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are
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| 62 | * any dirty wbs. See wb_update_write_bandwidth().
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| 63 |
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| 64 | return atomic_long_read(&bdi->tot_write_bandwidth);
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| 65 | }
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| 66 |
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| 67 | static inline void __add_wb_stat(struct bdi_writeback *wb,
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| 68 | enum wb_stat_item item, s64 amount)
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| 69 | {
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| 70 | percpu_counter_add_batch(&wb->stat[item], amount, WB_STAT_BATCH);
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| 71 | }
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| 72 |
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| 73 | static inline void inc_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
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| 74 | {
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| 75 | __add_wb_stat(wb, item, 1);
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| 76 | }
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| 77 |
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| 78 | static inline void dec_wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
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| 79 | {
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| 80 | __add_wb_stat(wb, item, -1);
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| 81 | }
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| 82 |
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| 83 | static inline s64 wb_stat(struct bdi_writeback *wb, enum wb_stat_item item)
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| 84 | {
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| 85 | return percpu_counter_read_positive(&wb->stat[item]);
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| 86 | }
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| 87 |
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| 88 | static inline s64 wb_stat_sum(struct bdi_writeback *wb, enum wb_stat_item item)
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| 89 | {
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| 90 | return percpu_counter_sum_positive(&wb->stat[item]);
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| 91 | }
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| 92 |
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| 93 | extern void wb_writeout_inc(struct bdi_writeback *wb);
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| 94 |
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| 95 | |
| 96 | * maximal error of a stat counter.
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| 97 |
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| 98 | static inline unsigned long wb_stat_error(void)
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| 99 | {
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| 100 | #ifdef CONFIG_SMP
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| 101 | return nr_cpu_ids * WB_STAT_BATCH;
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| 102 | #else
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| 103 | return 1;
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| 104 | #endif
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| 105 | }
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| 106 |
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| 107 | int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
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| 108 | int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
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| 109 |
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| 110 | |
| 111 | * Flags in backing_dev_info::capability
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| 112 | *
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| 113 | * BDI_CAP_WRITEBACK: Supports dirty page writeback, and dirty pages
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| 114 | * should contribute to accounting
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| 115 | * BDI_CAP_WRITEBACK_ACCT: Automatically account writeback pages
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| 116 | * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold
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| 117 |
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| 118 | #define BDI_CAP_WRITEBACK (1 << 0)
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| 119 | #define BDI_CAP_WRITEBACK_ACCT (1 << 1)
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| 120 | #define BDI_CAP_STRICTLIMIT (1 << 2)
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| 121 |
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| 122 | extern struct backing_dev_info noop_backing_dev_info;
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| 123 |
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| 124 | |
| 125 | * writeback_in_progress - determine whether there is writeback in progress
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| 126 | * @wb: bdi_writeback of interest
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| 127 | *
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| 128 | * Determine whether there is writeback waiting to be handled against a
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| 129 | * bdi_writeback.
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| 130 |
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| 131 | static inline bool writeback_in_progress(struct bdi_writeback *wb)
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| 132 | {
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| 133 | return test_bit(WB_writeback_running, &wb->state);
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| 134 | }
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| 135 |
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| 136 | static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
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| 137 | {
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| 138 | struct super_block *sb;
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| 139 |
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| 140 | if (!inode)
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| 141 | return &noop_backing_dev_info;
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| 142 |
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| 143 | sb = inode->i_sb;
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| 144 | #ifdef CONFIG_BLOCK
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| 145 | if (sb_is_blkdev_sb(sb))
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| 146 | return I_BDEV(inode)->bd_bdi;
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| 147 | #endif
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| 148 | return sb->s_bdi;
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| 149 | }
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| 150 |
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| 151 | static inline int wb_congested(struct bdi_writeback *wb, int cong_bits)
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| 152 | {
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| 153 | return wb->congested & cong_bits;
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| 154 | }
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| 155 |
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| 156 | long congestion_wait(int sync, long timeout);
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| 157 | long wait_iff_congested(int sync, long timeout);
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| 158 |
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| 159 | static inline bool mapping_can_writeback(struct address_space *mapping)
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| 160 | {
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| 161 | return inode_to_bdi(mapping->host)->capabilities & BDI_CAP_WRITEBACK;
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| 162 | }
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| 163 |
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| 164 | static inline int bdi_sched_wait(void *word)
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| 165 | {
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| 166 | schedule();
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| 167 | return 0;
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| 168 | }
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| 169 |
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| 170 | #ifdef CONFIG_CGROUP_WRITEBACK
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| 171 |
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| 172 | struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,
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| 173 | struct cgroup_subsys_state *memcg_css);
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| 174 | struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
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| 175 | struct cgroup_subsys_state *memcg_css,
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| 176 | gfp_t gfp);
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| 177 | void wb_memcg_offline(struct mem_cgroup *memcg);
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| 178 | void wb_blkcg_offline(struct blkcg *blkcg);
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| 179 | int inode_congested(struct inode *inode, int cong_bits);
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| 180 |
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| 181 | |
| 182 | * inode_cgwb_enabled - test whether cgroup writeback is enabled on an inode
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| 183 | * @inode: inode of interest
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| 184 | *
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| 185 | * Cgroup writeback requires support from the filesystem. Also, both memcg and
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| 186 | * iocg have to be on the default hierarchy. Test whether all conditions are
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| 187 | * met.
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| 188 | *
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| 189 | * Note that the test result may change dynamically on the same inode
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| 190 | * depending on how memcg and iocg are configured.
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| 191 |
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| 192 | static inline bool inode_cgwb_enabled(struct inode *inode)
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| 193 | {
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| 194 | struct backing_dev_info *bdi = inode_to_bdi(inode);
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| 195 |
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| 196 | return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&
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| 197 | cgroup_subsys_on_dfl(io_cgrp_subsys) &&
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| 198 | (bdi->capabilities & BDI_CAP_WRITEBACK) &&
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| 199 | (inode->i_sb->s_iflags & SB_I_CGROUPWB);
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| 200 | }
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| 201 |
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| 202 | |
| 203 | * wb_find_current - find wb for %current on a bdi
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| 204 | * @bdi: bdi of interest
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| 205 | *
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| 206 | * Find the wb of @bdi which matches both the memcg and blkcg of %current.
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| 207 | * Must be called under rcu_read_lock() which protects the returend wb.
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| 208 | * NULL if not found.
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| 209 |
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| 210 | static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
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| 211 | {
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| 212 | struct cgroup_subsys_state *memcg_css;
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| 213 | struct bdi_writeback *wb;
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| 214 |
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| 215 | memcg_css = task_css(current, memory_cgrp_id);
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| 216 | if (!memcg_css->parent)
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| 217 | return &bdi->wb;
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| 218 |
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| 219 | wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
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| 220 |
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| 221 | |
| 222 | * %current's blkcg equals the effective blkcg of its memcg. No
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| 223 | * need to use the relatively expensive cgroup_get_e_css().
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| 224 |
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| 225 | if (likely(wb && wb->blkcg_css == task_css(current, io_cgrp_id)))
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| 226 | return wb;
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| 227 | return NULL;
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| 228 | }
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| 229 |
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| 230 | |
| 231 | * wb_get_create_current - get or create wb for %current on a bdi
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| 232 | * @bdi: bdi of interest
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| 233 | * @gfp: allocation mask
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| 234 | *
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| 235 | * Equivalent to wb_get_create() on %current's memcg. This function is
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| 236 | * called from a relatively hot path and optimizes the common cases using
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| 237 | * wb_find_current().
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| 238 |
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| 239 | static inline struct bdi_writeback *
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| 240 | wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
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| 241 | {
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| 242 | struct bdi_writeback *wb;
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| 243 |
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| 244 | rcu_read_lock();
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| 245 | wb = wb_find_current(bdi);
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| 246 | if (wb && unlikely(!wb_tryget(wb)))
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| 247 | wb = NULL;
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| 248 | rcu_read_unlock();
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| 249 |
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| 250 | if (unlikely(!wb)) {
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| 251 | struct cgroup_subsys_state *memcg_css;
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| 252 |
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| 253 | memcg_css = task_get_css(current, memory_cgrp_id);
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| 254 | wb = wb_get_create(bdi, memcg_css, gfp);
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| 255 | css_put(memcg_css);
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| 256 | }
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| 257 | return wb;
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| 258 | }
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| 259 |
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| 260 | |
| 261 | * inode_to_wb_is_valid - test whether an inode has a wb associated
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| 262 | * @inode: inode of interest
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| 263 | *
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| 264 | * Returns %true if @inode has a wb associated. May be called without any
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| 265 | * locking.
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| 266 |
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| 267 | static inline bool inode_to_wb_is_valid(struct inode *inode)
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| 268 | {
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| 269 | return inode->i_wb;
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| 270 | }
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| 271 |
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| 272 | |
| 273 | * inode_to_wb - determine the wb of an inode
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| 274 | * @inode: inode of interest
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| 275 | *
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| 276 | * Returns the wb @inode is currently associated with. The caller must be
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| 277 | * holding either @inode->i_lock, the i_pages lock, or the
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| 278 | * associated wb's list_lock.
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| 279 |
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| 280 | static inline struct bdi_writeback *inode_to_wb(const struct inode *inode)
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| 281 | {
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| 282 | #ifdef CONFIG_LOCKDEP
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| 283 | WARN_ON_ONCE(debug_locks &&
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| 284 | (!lockdep_is_held(&inode->i_lock) &&
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| 285 | !lockdep_is_held(&inode->i_mapping->i_pages.xa_lock) &&
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| 286 | !lockdep_is_held(&inode->i_wb->list_lock)));
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| 287 | #endif
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| 288 | return inode->i_wb;
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| 289 | }
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| 290 |
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| 291 | |
| 292 | * unlocked_inode_to_wb_begin - begin unlocked inode wb access transaction
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| 293 | * @inode: target inode
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| 294 | * @cookie: output param, to be passed to the end function
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| 295 | *
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| 296 | * The caller wants to access the wb associated with @inode but isn't
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| 297 | * holding inode->i_lock, the i_pages lock or wb->list_lock. This
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| 298 | * function determines the wb associated with @inode and ensures that the
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| 299 | * association doesn't change until the transaction is finished with
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| 300 | * unlocked_inode_to_wb_end().
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| 301 | *
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| 302 | * The caller must call unlocked_inode_to_wb_end() with *@cookie afterwards and
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| 303 | * can't sleep during the transaction. IRQs may or may not be disabled on
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| 304 | * return.
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| 305 |
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| 306 | static inline struct bdi_writeback *
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| 307 | unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie)
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| 308 | {
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| 309 | rcu_read_lock();
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| 310 |
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| 311 | |
| 312 | * Paired with store_release in inode_switch_wbs_work_fn() and
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| 313 | * ensures that we see the new wb if we see cleared I_WB_SWITCH.
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| 314 |
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| 315 | cookie->locked = smp_load_acquire(&inode->i_state) & I_WB_SWITCH;
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| 316 |
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| 317 | if (unlikely(cookie->locked))
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| 318 | xa_lock_irqsave(&inode->i_mapping->i_pages, cookie->flags);
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| 319 |
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| 320 | |
| 321 | * Protected by either !I_WB_SWITCH + rcu_read_lock() or the i_pages
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| 322 | * lock. inode_to_wb() will bark. Deref directly.
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| 323 |
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| 324 | return inode->i_wb;
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| 325 | }
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| 326 |
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| 327 | |
| 328 | * unlocked_inode_to_wb_end - end inode wb access transaction
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| 329 | * @inode: target inode
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| 330 | * @cookie: @cookie from unlocked_inode_to_wb_begin()
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| 331 |
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| 332 | static inline void unlocked_inode_to_wb_end(struct inode *inode,
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| 333 | struct wb_lock_cookie *cookie)
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| 334 | {
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| 335 | if (unlikely(cookie->locked))
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| 336 | xa_unlock_irqrestore(&inode->i_mapping->i_pages, cookie->flags);
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| 337 |
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| 338 | rcu_read_unlock();
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| 339 | }
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| 340 |
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| 341 | #else
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| 342 |
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| 343 | static inline bool inode_cgwb_enabled(struct inode *inode)
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| 344 | {
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| 345 | return false;
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| 346 | }
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| 347 |
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| 348 | static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi)
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| 349 | {
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| 350 | return &bdi->wb;
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| 351 | }
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| 352 |
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| 353 | static inline struct bdi_writeback *
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| 354 | wb_get_create_current(struct backing_dev_info *bdi, gfp_t gfp)
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| 355 | {
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| 356 | return &bdi->wb;
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| 357 | }
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| 358 |
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| 359 | static inline bool inode_to_wb_is_valid(struct inode *inode)
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| 360 | {
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| 361 | return true;
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| 362 | }
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| 363 |
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| 364 | static inline struct bdi_writeback *inode_to_wb(struct inode *inode)
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| 365 | {
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| 366 | return &inode_to_bdi(inode)->wb;
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| 367 | }
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| 368 |
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| 369 | static inline struct bdi_writeback *
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| 370 | unlocked_inode_to_wb_begin(struct inode *inode, struct wb_lock_cookie *cookie)
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| 371 | {
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| 372 | return inode_to_wb(inode);
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| 373 | }
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| 374 |
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| 375 | static inline void unlocked_inode_to_wb_end(struct inode *inode,
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| 376 | struct wb_lock_cookie *cookie)
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| 377 | {
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| 378 | }
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| 379 |
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| 380 | static inline void wb_memcg_offline(struct mem_cgroup *memcg)
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| 381 | {
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| 382 | }
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| 383 |
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| 384 | static inline void wb_blkcg_offline(struct blkcg *blkcg)
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| 385 | {
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| 386 | }
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| 387 |
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| 388 | static inline int inode_congested(struct inode *inode, int cong_bits)
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| 389 | {
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| 390 | return wb_congested(&inode_to_bdi(inode)->wb, cong_bits);
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| 391 | }
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| 392 |
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| 393 | #endif
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| 394 |
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| 395 | static inline int inode_read_congested(struct inode *inode)
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| 396 | {
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| 397 | return inode_congested(inode, 1 << WB_sync_congested);
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| 398 | }
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| 399 |
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| 400 | static inline int inode_write_congested(struct inode *inode)
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| 401 | {
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| 402 | return inode_congested(inode, 1 << WB_async_congested);
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| 403 | }
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| 404 |
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| 405 | static inline int inode_rw_congested(struct inode *inode)
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| 406 | {
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| 407 | return inode_congested(inode, (1 << WB_sync_congested) |
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| 408 | (1 << WB_async_congested));
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| 409 | }
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| 410 |
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| 411 | static inline int bdi_congested(struct backing_dev_info *bdi, int cong_bits)
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| 412 | {
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| 413 | return wb_congested(&bdi->wb, cong_bits);
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| 414 | }
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| 415 |
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| 416 | static inline int bdi_read_congested(struct backing_dev_info *bdi)
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| 417 | {
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| 418 | return bdi_congested(bdi, 1 << WB_sync_congested);
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| 419 | }
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| 420 |
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| 421 | static inline int bdi_write_congested(struct backing_dev_info *bdi)
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| 422 | {
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| 423 | return bdi_congested(bdi, 1 << WB_async_congested);
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| 424 | }
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| 425 |
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| 426 | static inline int bdi_rw_congested(struct backing_dev_info *bdi)
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| 427 | {
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| 428 | return bdi_congested(bdi, (1 << WB_sync_congested) |
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| 429 | (1 << WB_async_congested));
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| 430 | }
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| 431 |
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| 432 | const char *bdi_dev_name(struct backing_dev_info *bdi);
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| 433 |
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| 434 | #endif
|