/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _BCACHE_WRITEBACK_H
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#define _BCACHE_WRITEBACK_H
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#define CUTOFF_WRITEBACK 40
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#define CUTOFF_WRITEBACK_SYNC 70
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#define MAX_WRITEBACKS_IN_PASS 5
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#define MAX_WRITESIZE_IN_PASS 5000 /* *512b */
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#define WRITEBACK_RATE_UPDATE_SECS_MAX 60
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#define WRITEBACK_RATE_UPDATE_SECS_DEFAULT 5
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/*
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* 14 (16384ths) is chosen here as something that each backing device
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* should be a reasonable fraction of the share, and not to blow up
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* until individual backing devices are a petabyte.
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*/
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#define WRITEBACK_SHARE_SHIFT 14
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static inline uint64_t bcache_dev_sectors_dirty(struct bcache_device *d)
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{
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uint64_t i, ret = 0;
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for (i = 0; i < d->nr_stripes; i++)
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ret += atomic_read(d->stripe_sectors_dirty + i);
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return ret;
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}
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static inline int offset_to_stripe(struct bcache_device *d,
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uint64_t offset)
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{
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do_div(offset, d->stripe_size);
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/* d->nr_stripes is in range [1, INT_MAX] */
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if (unlikely(offset >= d->nr_stripes)) {
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pr_err("Invalid stripe %llu (>= nr_stripes %d).\n",
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offset, d->nr_stripes);
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return -EINVAL;
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}
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/*
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* Here offset is definitly smaller than INT_MAX,
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* return it as int will never overflow.
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*/
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return offset;
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}
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static inline bool bcache_dev_stripe_dirty(struct cached_dev *dc,
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uint64_t offset,
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unsigned int nr_sectors)
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{
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int stripe = offset_to_stripe(&dc->disk, offset);
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if (stripe < 0)
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return false;
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while (1) {
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if (atomic_read(dc->disk.stripe_sectors_dirty + stripe))
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return true;
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if (nr_sectors <= dc->disk.stripe_size)
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return false;
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nr_sectors -= dc->disk.stripe_size;
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stripe++;
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}
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}
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static inline bool should_writeback(struct cached_dev *dc, struct bio *bio,
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unsigned int cache_mode, bool would_skip)
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{
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unsigned int in_use = dc->disk.c->gc_stats.in_use;
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if (cache_mode != CACHE_MODE_WRITEBACK ||
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test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
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in_use > CUTOFF_WRITEBACK_SYNC)
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return false;
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if (bio_op(bio) == REQ_OP_DISCARD)
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return false;
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if (dc->partial_stripes_expensive &&
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bcache_dev_stripe_dirty(dc, bio->bi_iter.bi_sector,
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bio_sectors(bio)))
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return true;
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if (would_skip)
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return false;
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return (op_is_sync(bio->bi_opf) ||
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bio->bi_opf & (REQ_META|REQ_PRIO) ||
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in_use <= CUTOFF_WRITEBACK);
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}
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static inline void bch_writeback_queue(struct cached_dev *dc)
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{
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if (!IS_ERR_OR_NULL(dc->writeback_thread))
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wake_up_process(dc->writeback_thread);
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}
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static inline void bch_writeback_add(struct cached_dev *dc)
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{
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if (!atomic_read(&dc->has_dirty) &&
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!atomic_xchg(&dc->has_dirty, 1)) {
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if (BDEV_STATE(&dc->sb) != BDEV_STATE_DIRTY) {
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SET_BDEV_STATE(&dc->sb, BDEV_STATE_DIRTY);
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/* XXX: should do this synchronously */
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bch_write_bdev_super(dc, NULL);
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}
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bch_writeback_queue(dc);
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}
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}
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void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned int inode,
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uint64_t offset, int nr_sectors);
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void bch_sectors_dirty_init(struct bcache_device *d);
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void bch_cached_dev_writeback_init(struct cached_dev *dc);
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int bch_cached_dev_writeback_start(struct cached_dev *dc);
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#endif
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