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 unsigned offset_to_stripe(struct bcache_device *d,
  32                                         uint64_t offset)
  33 {
  34         do_div(offset, d->stripe_size);
  35         return offset;
  36 }
  37
  38 static inline bool bcache_dev_stripe_dirty(struct cached_dev *dc,
  39                                            uint64_t offset,
  40                                            unsigned nr_sectors)
  41 {
  42         unsigned stripe = offset_to_stripe(&dc->disk, offset);
  43
  44         while (1) {
  45                 if (atomic_read(dc->disk.stripe_sectors_dirty + stripe))
  46                         return true;
  47
  48                 if (nr_sectors <= dc->disk.stripe_size)
  49                         return false;
  50
  51                 nr_sectors -= dc->disk.stripe_size;
  52                 stripe++;
  53         }
  54 }
  55
  56 static inline bool should_writeback(struct cached_dev *dc, struct bio *bio,
  57                                     unsigned cache_mode, bool would_skip)
  58 {
  59         unsigned in_use = dc->disk.c->gc_stats.in_use;
  60
  61         if (cache_mode != CACHE_MODE_WRITEBACK ||
  62             test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
  63             in_use > CUTOFF_WRITEBACK_SYNC)
  64                 return false;
  65
  66         if (dc->partial_stripes_expensive &&
  67             bcache_dev_stripe_dirty(dc, bio->bi_iter.bi_sector,
  68                                     bio_sectors(bio)))
  69                 return true;
  70
  71         if (would_skip)
  72                 return false;
  73
  74         return (op_is_sync(bio->bi_opf) ||
  75                 bio->bi_opf & (REQ_META|REQ_PRIO) ||
  76                 in_use <= CUTOFF_WRITEBACK);
  77 }
  78
  79 static inline void bch_writeback_queue(struct cached_dev *dc)
  80 {
  81         if (!IS_ERR_OR_NULL(dc->writeback_thread))
  82                 wake_up_process(dc->writeback_thread);
  83 }
  84
  85 static inline void bch_writeback_add(struct cached_dev *dc)
  86 {
  87         if (!atomic_read(&dc->has_dirty) &&
  88             !atomic_xchg(&dc->has_dirty, 1)) {
  89                 if (BDEV_STATE(&dc->sb) != BDEV_STATE_DIRTY) {
  90                         SET_BDEV_STATE(&dc->sb, BDEV_STATE_DIRTY);
  91                         /* XXX: should do this synchronously */
  92                         bch_write_bdev_super(dc, NULL);
  93                 }
  94
  95                 bch_writeback_queue(dc);
  96         }
  97 }
  98
  99 void bcache_dev_sectors_dirty_add(struct cache_set *, unsigned, uint64_t, int);
 100
 101 void bch_sectors_dirty_init(struct bcache_device *);
 102 void bch_cached_dev_writeback_init(struct cached_dev *);
 103 int bch_cached_dev_writeback_start(struct cached_dev *);
 104
 105 #endif