drivers/md/bcache/writeback.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _BCACHE_WRITEBACK_H
   3 #define _BCACHE_WRITEBACK_H
   4
   5 #define CUTOFF_WRITEBACK        40
   6 #define CUTOFF_WRITEBACK_SYNC   70
   7
   8 #define CUTOFF_WRITEBACK_MAX            70
   9 #define CUTOFF_WRITEBACK_SYNC_MAX       90
  10
  11 #define MAX_WRITEBACKS_IN_PASS  5
  12 #define MAX_WRITESIZE_IN_PASS   5000    /* *512b */
  13
  14 #define WRITEBACK_RATE_UPDATE_SECS_MAX          60
  15 #define WRITEBACK_RATE_UPDATE_SECS_DEFAULT      5
  16
  17 #define BCH_AUTO_GC_DIRTY_THRESHOLD     50
  18
  19 #define BCH_WRITEBACK_FRAGMENT_THRESHOLD_LOW 50
  20 #define BCH_WRITEBACK_FRAGMENT_THRESHOLD_MID 57
  21 #define BCH_WRITEBACK_FRAGMENT_THRESHOLD_HIGH 64
  22
  23 #define BCH_DIRTY_INIT_THRD_MAX 64
  24 /*
  25  * 14 (16384ths) is chosen here as something that each backing device
  26  * should be a reasonable fraction of the share, and not to blow up
  27  * until individual backing devices are a petabyte.
  28  */
  29 #define WRITEBACK_SHARE_SHIFT   14
  30
  31 struct bch_dirty_init_state;
  32 struct dirty_init_thrd_info {
  33         struct bch_dirty_init_state     *state;
  34         struct task_struct              *thread;
  35 };
  36
  37 struct bch_dirty_init_state {
  38         struct cache_set                *c;
  39         struct bcache_device            *d;
  40         int                             total_threads;
  41         int                             key_idx;
  42         spinlock_t                      idx_lock;
  43         atomic_t                        started;
  44         atomic_t                        enough;
  45         wait_queue_head_t               wait;
  46         struct dirty_init_thrd_info     infos[BCH_DIRTY_INIT_THRD_MAX];
  47 };
  48
  49 static inline uint64_t bcache_dev_sectors_dirty(struct bcache_device *d)
  50 {
  51         uint64_t i, ret = 0;
  52
  53         for (i = 0; i < d->nr_stripes; i++)
  54                 ret += atomic_read(d->stripe_sectors_dirty + i);
  55
  56         return ret;
  57 }
  58
  59 static inline int offset_to_stripe(struct bcache_device *d,
  60                                         uint64_t offset)
  61 {
  62         do_div(offset, d->stripe_size);
  63
  64         /* d->nr_stripes is in range [1, INT_MAX] */
  65         if (unlikely(offset >= d->nr_stripes)) {
  66                 pr_err("Invalid stripe %llu (>= nr_stripes %d).\n",
  67                         offset, d->nr_stripes);
  68                 return -EINVAL;
  69         }
  70
  71         /*
  72          * Here offset is definitly smaller than INT_MAX,
  73          * return it as int will never overflow.
  74          */
  75         return offset;
  76 }
  77
  78 static inline bool bcache_dev_stripe_dirty(struct cached_dev *dc,
  79                                            uint64_t offset,
  80                                            unsigned int nr_sectors)
  81 {
  82         int stripe = offset_to_stripe(&dc->disk, offset);
  83
  84         if (stripe < 0)
  85                 return false;
  86
  87         while (1) {
  88                 if (atomic_read(dc->disk.stripe_sectors_dirty + stripe))
  89                         return true;
  90
  91                 if (nr_sectors <= dc->disk.stripe_size)
  92                         return false;
  93
  94                 nr_sectors -= dc->disk.stripe_size;
  95                 stripe++;
  96         }
  97 }
  98
  99 extern unsigned int bch_cutoff_writeback;
 100 extern unsigned int bch_cutoff_writeback_sync;
 101
 102 static inline bool should_writeback(struct cached_dev *dc, struct bio *bio,
 103                                     unsigned int cache_mode, bool would_skip)
 104 {
 105         unsigned int in_use = dc->disk.c->gc_stats.in_use;
 106
 107         if (cache_mode != CACHE_MODE_WRITEBACK ||
 108             test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
 109             in_use > bch_cutoff_writeback_sync)
 110                 return false;
 111
 112         if (bio_op(bio) == REQ_OP_DISCARD)
 113                 return false;
 114
 115         if (dc->partial_stripes_expensive &&
 116             bcache_dev_stripe_dirty(dc, bio->bi_iter.bi_sector,
 117                                     bio_sectors(bio)))
 118                 return true;
 119
 120         if (would_skip)
 121                 return false;
 122
 123         return (op_is_sync(bio->bi_opf) ||
 124                 bio->bi_opf & (REQ_META|REQ_PRIO) ||
 125                 in_use <= bch_cutoff_writeback);
 126 }
 127
 128 static inline void bch_writeback_queue(struct cached_dev *dc)
 129 {
 130         if (!IS_ERR_OR_NULL(dc->writeback_thread))
 131                 wake_up_process(dc->writeback_thread);
 132 }
 133
 134 static inline void bch_writeback_add(struct cached_dev *dc)
 135 {
 136         if (!atomic_read(&dc->has_dirty) &&
 137             !atomic_xchg(&dc->has_dirty, 1)) {
 138                 if (BDEV_STATE(&dc->sb) != BDEV_STATE_DIRTY) {
 139                         SET_BDEV_STATE(&dc->sb, BDEV_STATE_DIRTY);
 140                         /* XXX: should do this synchronously */
 141                         bch_write_bdev_super(dc, NULL);
 142                 }
 143
 144                 bch_writeback_queue(dc);
 145         }
 146 }
 147
 148 void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned int inode,
 149                                   uint64_t offset, int nr_sectors);
 150
 151 void bch_sectors_dirty_init(struct bcache_device *d);
 152 void bch_cached_dev_writeback_init(struct cached_dev *dc);
 153 int bch_cached_dev_writeback_start(struct cached_dev *dc);
 154
 155 #endif