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 MAX_WRITEBACKS_IN_PASS  5
   9 #define MAX_WRITESIZE_IN_PASS   5000    /* *512b */
  10
  11 #define WRITEBACK_RATE_UPDATE_SECS_MAX          60
  12 #define WRITEBACK_RATE_UPDATE_SECS_DEFAULT      5
  13
  14 /*
  15  * 14 (16384ths) is chosen here as something that each backing device
  16  * should be a reasonable fraction of the share, and not to blow up
  17  * until individual backing devices are a petabyte.
  18  */
  19 #define WRITEBACK_SHARE_SHIFT   14
  20
  21 static inline uint64_t bcache_dev_sectors_dirty(struct bcache_device *d)
  22 {
  23         uint64_t i, ret = 0;
  24
  25         for (i = 0; i < d->nr_stripes; i++)
  26                 ret += atomic_read(d->stripe_sectors_dirty + i);
  27
  28         return ret;
  29 }
  30
  31 static inline uint64_t  bcache_flash_devs_sectors_dirty(struct cache_set *c)
  32 {
  33         uint64_t i, ret = 0;
  34
  35         mutex_lock(&bch_register_lock);
  36
  37         for (i = 0; i < c->devices_max_used; i++) {
  38                 struct bcache_device *d = c->devices[i];
  39
  40                 if (!d || !UUID_FLASH_ONLY(&c->uuids[i]))
  41                         continue;
  42            ret += bcache_dev_sectors_dirty(d);
  43         }
  44
  45         mutex_unlock(&bch_register_lock);
  46
  47         return ret;
  48 }
  49
  50 static inline unsigned offset_to_stripe(struct bcache_device *d,
  51                                         uint64_t offset)
  52 {
  53         do_div(offset, d->stripe_size);
  54         return offset;
  55 }
  56
  57 static inline bool bcache_dev_stripe_dirty(struct cached_dev *dc,
  58                                            uint64_t offset,
  59                                            unsigned nr_sectors)
  60 {
  61         unsigned stripe = offset_to_stripe(&dc->disk, offset);
  62
  63         while (1) {
  64                 if (atomic_read(dc->disk.stripe_sectors_dirty + stripe))
  65                         return true;
  66
  67                 if (nr_sectors <= dc->disk.stripe_size)
  68                         return false;
  69
  70                 nr_sectors -= dc->disk.stripe_size;
  71                 stripe++;
  72         }
  73 }
  74
  75 static inline bool should_writeback(struct cached_dev *dc, struct bio *bio,
  76                                     unsigned cache_mode, bool would_skip)
  77 {
  78         unsigned in_use = dc->disk.c->gc_stats.in_use;
  79
  80         if (cache_mode != CACHE_MODE_WRITEBACK ||
  81             test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
  82             in_use > CUTOFF_WRITEBACK_SYNC)
  83                 return false;
  84
  85         if (dc->partial_stripes_expensive &&
  86             bcache_dev_stripe_dirty(dc, bio->bi_iter.bi_sector,
  87                                     bio_sectors(bio)))
  88                 return true;
  89
  90         if (would_skip)
  91                 return false;
  92
  93         return (op_is_sync(bio->bi_opf) ||
  94                 bio->bi_opf & (REQ_META|REQ_PRIO) ||
  95                 in_use <= CUTOFF_WRITEBACK);
  96 }
  97
  98 static inline void bch_writeback_queue(struct cached_dev *dc)
  99 {
 100         if (!IS_ERR_OR_NULL(dc->writeback_thread))
 101                 wake_up_process(dc->writeback_thread);
 102 }
 103
 104 static inline void bch_writeback_add(struct cached_dev *dc)
 105 {
 106         if (!atomic_read(&dc->has_dirty) &&
 107             !atomic_xchg(&dc->has_dirty, 1)) {
 108                 refcount_inc(&dc->count);
 109
 110                 if (BDEV_STATE(&dc->sb) != BDEV_STATE_DIRTY) {
 111                         SET_BDEV_STATE(&dc->sb, BDEV_STATE_DIRTY);
 112                         /* XXX: should do this synchronously */
 113                         bch_write_bdev_super(dc, NULL);
 114                 }
 115
 116                 bch_writeback_queue(dc);
 117         }
 118 }
 119
 120 void bcache_dev_sectors_dirty_add(struct cache_set *, unsigned, uint64_t, int);
 121
 122 void bch_sectors_dirty_init(struct bcache_device *);
 123 void bch_cached_dev_writeback_init(struct cached_dev *);
 124 int bch_cached_dev_writeback_start(struct cached_dev *);
 125
 126 #endif