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