LXR linux/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
  31struct bch_dirty_init_state;
  32struct dirty_init_thrd_info {
  33        struct bch_dirty_init_state     *state;
  34        struct task_struct              *thread;
  35};
  36
  37struct 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
  49static 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
  59static 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
  78static 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
  99extern unsigned int bch_cutoff_writeback;
 100extern unsigned int bch_cutoff_writeback_sync;
 101
 102static 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
 128static 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
 134static 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
 148void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned int inode,
 149                                  uint64_t offset, int nr_sectors);
 150
 151void bch_sectors_dirty_init(struct bcache_device *d);
 152void bch_cached_dev_writeback_init(struct cached_dev *dc);
 153int bch_cached_dev_writeback_start(struct cached_dev *dc);
 154
 155#endif
 156