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- // SPDX-License-Identifier: GPL-2.0
- /*
- * background writeback - scan btree for dirty data and write it to the backing
- * device
- *
- * Copyright 2010, 2011 Kent Overstreet <[email protected]>
- * Copyright 2012 Google, Inc.
- */
- #include "bcache.h"
- #include "btree.h"
- #include "debug.h"
- #include "writeback.h"
- #include <linux/delay.h>
- #include <linux/kthread.h>
- #include <linux/sched/clock.h>
- #include <trace/events/bcache.h>
- static void update_gc_after_writeback(struct cache_set *c)
- {
- if (c->gc_after_writeback != (BCH_ENABLE_AUTO_GC) ||
- c->gc_stats.in_use < BCH_AUTO_GC_DIRTY_THRESHOLD)
- return;
- c->gc_after_writeback |= BCH_DO_AUTO_GC;
- }
- /* Rate limiting */
- static uint64_t __calc_target_rate(struct cached_dev *dc)
- {
- struct cache_set *c = dc->disk.c;
- /*
- * This is the size of the cache, minus the amount used for
- * flash-only devices
- */
- uint64_t cache_sectors = c->nbuckets * c->cache->sb.bucket_size -
- atomic_long_read(&c->flash_dev_dirty_sectors);
- /*
- * Unfortunately there is no control of global dirty data. If the
- * user states that they want 10% dirty data in the cache, and has,
- * e.g., 5 backing volumes of equal size, we try and ensure each
- * backing volume uses about 2% of the cache for dirty data.
- */
- uint32_t bdev_share =
- div64_u64(bdev_nr_sectors(dc->bdev) << WRITEBACK_SHARE_SHIFT,
- c->cached_dev_sectors);
- uint64_t cache_dirty_target =
- div_u64(cache_sectors * dc->writeback_percent, 100);
- /* Ensure each backing dev gets at least one dirty share */
- if (bdev_share < 1)
- bdev_share = 1;
- return (cache_dirty_target * bdev_share) >> WRITEBACK_SHARE_SHIFT;
- }
- static void __update_writeback_rate(struct cached_dev *dc)
- {
- /*
- * PI controller:
- * Figures out the amount that should be written per second.
- *
- * First, the error (number of sectors that are dirty beyond our
- * target) is calculated. The error is accumulated (numerically
- * integrated).
- *
- * Then, the proportional value and integral value are scaled
- * based on configured values. These are stored as inverses to
- * avoid fixed point math and to make configuration easy-- e.g.
- * the default value of 40 for writeback_rate_p_term_inverse
- * attempts to write at a rate that would retire all the dirty
- * blocks in 40 seconds.
- *
- * The writeback_rate_i_inverse value of 10000 means that 1/10000th
- * of the error is accumulated in the integral term per second.
- * This acts as a slow, long-term average that is not subject to
- * variations in usage like the p term.
- */
- int64_t target = __calc_target_rate(dc);
- int64_t dirty = bcache_dev_sectors_dirty(&dc->disk);
- int64_t error = dirty - target;
- int64_t proportional_scaled =
- div_s64(error, dc->writeback_rate_p_term_inverse);
- int64_t integral_scaled;
- uint32_t new_rate;
- /*
- * We need to consider the number of dirty buckets as well
- * when calculating the proportional_scaled, Otherwise we might
- * have an unreasonable small writeback rate at a highly fragmented situation
- * when very few dirty sectors consumed a lot dirty buckets, the
- * worst case is when dirty buckets reached cutoff_writeback_sync and
- * dirty data is still not even reached to writeback percent, so the rate
- * still will be at the minimum value, which will cause the write
- * stuck at a non-writeback mode.
- */
- struct cache_set *c = dc->disk.c;
- int64_t dirty_buckets = c->nbuckets - c->avail_nbuckets;
- if (dc->writeback_consider_fragment &&
- c->gc_stats.in_use > BCH_WRITEBACK_FRAGMENT_THRESHOLD_LOW && dirty > 0) {
- int64_t fragment =
- div_s64((dirty_buckets * c->cache->sb.bucket_size), dirty);
- int64_t fp_term;
- int64_t fps;
- if (c->gc_stats.in_use <= BCH_WRITEBACK_FRAGMENT_THRESHOLD_MID) {
- fp_term = (int64_t)dc->writeback_rate_fp_term_low *
- (c->gc_stats.in_use - BCH_WRITEBACK_FRAGMENT_THRESHOLD_LOW);
- } else if (c->gc_stats.in_use <= BCH_WRITEBACK_FRAGMENT_THRESHOLD_HIGH) {
- fp_term = (int64_t)dc->writeback_rate_fp_term_mid *
- (c->gc_stats.in_use - BCH_WRITEBACK_FRAGMENT_THRESHOLD_MID);
- } else {
- fp_term = (int64_t)dc->writeback_rate_fp_term_high *
- (c->gc_stats.in_use - BCH_WRITEBACK_FRAGMENT_THRESHOLD_HIGH);
- }
- fps = div_s64(dirty, dirty_buckets) * fp_term;
- if (fragment > 3 && fps > proportional_scaled) {
- /* Only overrite the p when fragment > 3 */
- proportional_scaled = fps;
- }
- }
- if ((error < 0 && dc->writeback_rate_integral > 0) ||
- (error > 0 && time_before64(local_clock(),
- dc->writeback_rate.next + NSEC_PER_MSEC))) {
- /*
- * Only decrease the integral term if it's more than
- * zero. Only increase the integral term if the device
- * is keeping up. (Don't wind up the integral
- * ineffectively in either case).
- *
- * It's necessary to scale this by
- * writeback_rate_update_seconds to keep the integral
- * term dimensioned properly.
- */
- dc->writeback_rate_integral += error *
- dc->writeback_rate_update_seconds;
- }
- integral_scaled = div_s64(dc->writeback_rate_integral,
- dc->writeback_rate_i_term_inverse);
- new_rate = clamp_t(int32_t, (proportional_scaled + integral_scaled),
- dc->writeback_rate_minimum, NSEC_PER_SEC);
- dc->writeback_rate_proportional = proportional_scaled;
- dc->writeback_rate_integral_scaled = integral_scaled;
- dc->writeback_rate_change = new_rate -
- atomic_long_read(&dc->writeback_rate.rate);
- atomic_long_set(&dc->writeback_rate.rate, new_rate);
- dc->writeback_rate_target = target;
- }
- static bool idle_counter_exceeded(struct cache_set *c)
- {
- int counter, dev_nr;
- /*
- * If c->idle_counter is overflow (idel for really long time),
- * reset as 0 and not set maximum rate this time for code
- * simplicity.
- */
- counter = atomic_inc_return(&c->idle_counter);
- if (counter <= 0) {
- atomic_set(&c->idle_counter, 0);
- return false;
- }
- dev_nr = atomic_read(&c->attached_dev_nr);
- if (dev_nr == 0)
- return false;
- /*
- * c->idle_counter is increased by writeback thread of all
- * attached backing devices, in order to represent a rough
- * time period, counter should be divided by dev_nr.
- * Otherwise the idle time cannot be larger with more backing
- * device attached.
- * The following calculation equals to checking
- * (counter / dev_nr) < (dev_nr * 6)
- */
- if (counter < (dev_nr * dev_nr * 6))
- return false;
- return true;
- }
- /*
- * Idle_counter is increased every time when update_writeback_rate() is
- * called. If all backing devices attached to the same cache set have
- * identical dc->writeback_rate_update_seconds values, it is about 6
- * rounds of update_writeback_rate() on each backing device before
- * c->at_max_writeback_rate is set to 1, and then max wrteback rate set
- * to each dc->writeback_rate.rate.
- * In order to avoid extra locking cost for counting exact dirty cached
- * devices number, c->attached_dev_nr is used to calculate the idle
- * throushold. It might be bigger if not all cached device are in write-
- * back mode, but it still works well with limited extra rounds of
- * update_writeback_rate().
- */
- static bool set_at_max_writeback_rate(struct cache_set *c,
- struct cached_dev *dc)
- {
- /* Don't sst max writeback rate if it is disabled */
- if (!c->idle_max_writeback_rate_enabled)
- return false;
- /* Don't set max writeback rate if gc is running */
- if (!c->gc_mark_valid)
- return false;
- if (!idle_counter_exceeded(c))
- return false;
- if (atomic_read(&c->at_max_writeback_rate) != 1)
- atomic_set(&c->at_max_writeback_rate, 1);
- atomic_long_set(&dc->writeback_rate.rate, INT_MAX);
- /* keep writeback_rate_target as existing value */
- dc->writeback_rate_proportional = 0;
- dc->writeback_rate_integral_scaled = 0;
- dc->writeback_rate_change = 0;
- /*
- * In case new I/O arrives during before
- * set_at_max_writeback_rate() returns.
- */
- if (!idle_counter_exceeded(c) ||
- !atomic_read(&c->at_max_writeback_rate))
- return false;
- return true;
- }
- static void update_writeback_rate(struct work_struct *work)
- {
- struct cached_dev *dc = container_of(to_delayed_work(work),
- struct cached_dev,
- writeback_rate_update);
- struct cache_set *c = dc->disk.c;
- /*
- * should check BCACHE_DEV_RATE_DW_RUNNING before calling
- * cancel_delayed_work_sync().
- */
- set_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags);
- /* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */
- smp_mb__after_atomic();
- /*
- * CACHE_SET_IO_DISABLE might be set via sysfs interface,
- * check it here too.
- */
- if (!test_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags) ||
- test_bit(CACHE_SET_IO_DISABLE, &c->flags)) {
- clear_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags);
- /* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */
- smp_mb__after_atomic();
- return;
- }
- /*
- * If the whole cache set is idle, set_at_max_writeback_rate()
- * will set writeback rate to a max number. Then it is
- * unncessary to update writeback rate for an idle cache set
- * in maximum writeback rate number(s).
- */
- if (atomic_read(&dc->has_dirty) && dc->writeback_percent &&
- !set_at_max_writeback_rate(c, dc)) {
- do {
- if (!down_read_trylock((&dc->writeback_lock))) {
- dc->rate_update_retry++;
- if (dc->rate_update_retry <=
- BCH_WBRATE_UPDATE_MAX_SKIPS)
- break;
- down_read(&dc->writeback_lock);
- dc->rate_update_retry = 0;
- }
- __update_writeback_rate(dc);
- update_gc_after_writeback(c);
- up_read(&dc->writeback_lock);
- } while (0);
- }
- /*
- * CACHE_SET_IO_DISABLE might be set via sysfs interface,
- * check it here too.
- */
- if (test_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags) &&
- !test_bit(CACHE_SET_IO_DISABLE, &c->flags)) {
- schedule_delayed_work(&dc->writeback_rate_update,
- dc->writeback_rate_update_seconds * HZ);
- }
- /*
- * should check BCACHE_DEV_RATE_DW_RUNNING before calling
- * cancel_delayed_work_sync().
- */
- clear_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags);
- /* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */
- smp_mb__after_atomic();
- }
- static unsigned int writeback_delay(struct cached_dev *dc,
- unsigned int sectors)
- {
- if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
- !dc->writeback_percent)
- return 0;
- return bch_next_delay(&dc->writeback_rate, sectors);
- }
- struct dirty_io {
- struct closure cl;
- struct cached_dev *dc;
- uint16_t sequence;
- struct bio bio;
- };
- static void dirty_init(struct keybuf_key *w)
- {
- struct dirty_io *io = w->private;
- struct bio *bio = &io->bio;
- bio_init(bio, NULL, bio->bi_inline_vecs,
- DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS), 0);
- if (!io->dc->writeback_percent)
- bio_set_prio(bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
- bio->bi_iter.bi_size = KEY_SIZE(&w->key) << 9;
- bio->bi_private = w;
- bch_bio_map(bio, NULL);
- }
- static void dirty_io_destructor(struct closure *cl)
- {
- struct dirty_io *io = container_of(cl, struct dirty_io, cl);
- kfree(io);
- }
- static void write_dirty_finish(struct closure *cl)
- {
- struct dirty_io *io = container_of(cl, struct dirty_io, cl);
- struct keybuf_key *w = io->bio.bi_private;
- struct cached_dev *dc = io->dc;
- bio_free_pages(&io->bio);
- /* This is kind of a dumb way of signalling errors. */
- if (KEY_DIRTY(&w->key)) {
- int ret;
- unsigned int i;
- struct keylist keys;
- bch_keylist_init(&keys);
- bkey_copy(keys.top, &w->key);
- SET_KEY_DIRTY(keys.top, false);
- bch_keylist_push(&keys);
- for (i = 0; i < KEY_PTRS(&w->key); i++)
- atomic_inc(&PTR_BUCKET(dc->disk.c, &w->key, i)->pin);
- ret = bch_btree_insert(dc->disk.c, &keys, NULL, &w->key);
- if (ret)
- trace_bcache_writeback_collision(&w->key);
- atomic_long_inc(ret
- ? &dc->disk.c->writeback_keys_failed
- : &dc->disk.c->writeback_keys_done);
- }
- bch_keybuf_del(&dc->writeback_keys, w);
- up(&dc->in_flight);
- closure_return_with_destructor(cl, dirty_io_destructor);
- }
- static void dirty_endio(struct bio *bio)
- {
- struct keybuf_key *w = bio->bi_private;
- struct dirty_io *io = w->private;
- if (bio->bi_status) {
- SET_KEY_DIRTY(&w->key, false);
- bch_count_backing_io_errors(io->dc, bio);
- }
- closure_put(&io->cl);
- }
- static void write_dirty(struct closure *cl)
- {
- struct dirty_io *io = container_of(cl, struct dirty_io, cl);
- struct keybuf_key *w = io->bio.bi_private;
- struct cached_dev *dc = io->dc;
- uint16_t next_sequence;
- if (atomic_read(&dc->writeback_sequence_next) != io->sequence) {
- /* Not our turn to write; wait for a write to complete */
- closure_wait(&dc->writeback_ordering_wait, cl);
- if (atomic_read(&dc->writeback_sequence_next) == io->sequence) {
- /*
- * Edge case-- it happened in indeterminate order
- * relative to when we were added to wait list..
- */
- closure_wake_up(&dc->writeback_ordering_wait);
- }
- continue_at(cl, write_dirty, io->dc->writeback_write_wq);
- return;
- }
- next_sequence = io->sequence + 1;
- /*
- * IO errors are signalled using the dirty bit on the key.
- * If we failed to read, we should not attempt to write to the
- * backing device. Instead, immediately go to write_dirty_finish
- * to clean up.
- */
- if (KEY_DIRTY(&w->key)) {
- dirty_init(w);
- bio_set_op_attrs(&io->bio, REQ_OP_WRITE, 0);
- io->bio.bi_iter.bi_sector = KEY_START(&w->key);
- bio_set_dev(&io->bio, io->dc->bdev);
- io->bio.bi_end_io = dirty_endio;
- /* I/O request sent to backing device */
- closure_bio_submit(io->dc->disk.c, &io->bio, cl);
- }
- atomic_set(&dc->writeback_sequence_next, next_sequence);
- closure_wake_up(&dc->writeback_ordering_wait);
- continue_at(cl, write_dirty_finish, io->dc->writeback_write_wq);
- }
- static void read_dirty_endio(struct bio *bio)
- {
- struct keybuf_key *w = bio->bi_private;
- struct dirty_io *io = w->private;
- /* is_read = 1 */
- bch_count_io_errors(io->dc->disk.c->cache,
- bio->bi_status, 1,
- "reading dirty data from cache");
- dirty_endio(bio);
- }
- static void read_dirty_submit(struct closure *cl)
- {
- struct dirty_io *io = container_of(cl, struct dirty_io, cl);
- closure_bio_submit(io->dc->disk.c, &io->bio, cl);
- continue_at(cl, write_dirty, io->dc->writeback_write_wq);
- }
- static void read_dirty(struct cached_dev *dc)
- {
- unsigned int delay = 0;
- struct keybuf_key *next, *keys[MAX_WRITEBACKS_IN_PASS], *w;
- size_t size;
- int nk, i;
- struct dirty_io *io;
- struct closure cl;
- uint16_t sequence = 0;
- BUG_ON(!llist_empty(&dc->writeback_ordering_wait.list));
- atomic_set(&dc->writeback_sequence_next, sequence);
- closure_init_stack(&cl);
- /*
- * XXX: if we error, background writeback just spins. Should use some
- * mempools.
- */
- next = bch_keybuf_next(&dc->writeback_keys);
- while (!kthread_should_stop() &&
- !test_bit(CACHE_SET_IO_DISABLE, &dc->disk.c->flags) &&
- next) {
- size = 0;
- nk = 0;
- do {
- BUG_ON(ptr_stale(dc->disk.c, &next->key, 0));
- /*
- * Don't combine too many operations, even if they
- * are all small.
- */
- if (nk >= MAX_WRITEBACKS_IN_PASS)
- break;
- /*
- * If the current operation is very large, don't
- * further combine operations.
- */
- if (size >= MAX_WRITESIZE_IN_PASS)
- break;
- /*
- * Operations are only eligible to be combined
- * if they are contiguous.
- *
- * TODO: add a heuristic willing to fire a
- * certain amount of non-contiguous IO per pass,
- * so that we can benefit from backing device
- * command queueing.
- */
- if ((nk != 0) && bkey_cmp(&keys[nk-1]->key,
- &START_KEY(&next->key)))
- break;
- size += KEY_SIZE(&next->key);
- keys[nk++] = next;
- } while ((next = bch_keybuf_next(&dc->writeback_keys)));
- /* Now we have gathered a set of 1..5 keys to write back. */
- for (i = 0; i < nk; i++) {
- w = keys[i];
- io = kzalloc(struct_size(io, bio.bi_inline_vecs,
- DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS)),
- GFP_KERNEL);
- if (!io)
- goto err;
- w->private = io;
- io->dc = dc;
- io->sequence = sequence++;
- dirty_init(w);
- bio_set_op_attrs(&io->bio, REQ_OP_READ, 0);
- io->bio.bi_iter.bi_sector = PTR_OFFSET(&w->key, 0);
- bio_set_dev(&io->bio, dc->disk.c->cache->bdev);
- io->bio.bi_end_io = read_dirty_endio;
- if (bch_bio_alloc_pages(&io->bio, GFP_KERNEL))
- goto err_free;
- trace_bcache_writeback(&w->key);
- down(&dc->in_flight);
- /*
- * We've acquired a semaphore for the maximum
- * simultaneous number of writebacks; from here
- * everything happens asynchronously.
- */
- closure_call(&io->cl, read_dirty_submit, NULL, &cl);
- }
- delay = writeback_delay(dc, size);
- while (!kthread_should_stop() &&
- !test_bit(CACHE_SET_IO_DISABLE, &dc->disk.c->flags) &&
- delay) {
- schedule_timeout_interruptible(delay);
- delay = writeback_delay(dc, 0);
- }
- }
- if (0) {
- err_free:
- kfree(w->private);
- err:
- bch_keybuf_del(&dc->writeback_keys, w);
- }
- /*
- * Wait for outstanding writeback IOs to finish (and keybuf slots to be
- * freed) before refilling again
- */
- closure_sync(&cl);
- }
- /* Scan for dirty data */
- void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned int inode,
- uint64_t offset, int nr_sectors)
- {
- struct bcache_device *d = c->devices[inode];
- unsigned int stripe_offset, sectors_dirty;
- int stripe;
- if (!d)
- return;
- stripe = offset_to_stripe(d, offset);
- if (stripe < 0)
- return;
- if (UUID_FLASH_ONLY(&c->uuids[inode]))
- atomic_long_add(nr_sectors, &c->flash_dev_dirty_sectors);
- stripe_offset = offset & (d->stripe_size - 1);
- while (nr_sectors) {
- int s = min_t(unsigned int, abs(nr_sectors),
- d->stripe_size - stripe_offset);
- if (nr_sectors < 0)
- s = -s;
- if (stripe >= d->nr_stripes)
- return;
- sectors_dirty = atomic_add_return(s,
- d->stripe_sectors_dirty + stripe);
- if (sectors_dirty == d->stripe_size) {
- if (!test_bit(stripe, d->full_dirty_stripes))
- set_bit(stripe, d->full_dirty_stripes);
- } else {
- if (test_bit(stripe, d->full_dirty_stripes))
- clear_bit(stripe, d->full_dirty_stripes);
- }
- nr_sectors -= s;
- stripe_offset = 0;
- stripe++;
- }
- }
- static bool dirty_pred(struct keybuf *buf, struct bkey *k)
- {
- struct cached_dev *dc = container_of(buf,
- struct cached_dev,
- writeback_keys);
- BUG_ON(KEY_INODE(k) != dc->disk.id);
- return KEY_DIRTY(k);
- }
- static void refill_full_stripes(struct cached_dev *dc)
- {
- struct keybuf *buf = &dc->writeback_keys;
- unsigned int start_stripe, next_stripe;
- int stripe;
- bool wrapped = false;
- stripe = offset_to_stripe(&dc->disk, KEY_OFFSET(&buf->last_scanned));
- if (stripe < 0)
- stripe = 0;
- start_stripe = stripe;
- while (1) {
- stripe = find_next_bit(dc->disk.full_dirty_stripes,
- dc->disk.nr_stripes, stripe);
- if (stripe == dc->disk.nr_stripes)
- goto next;
- next_stripe = find_next_zero_bit(dc->disk.full_dirty_stripes,
- dc->disk.nr_stripes, stripe);
- buf->last_scanned = KEY(dc->disk.id,
- stripe * dc->disk.stripe_size, 0);
- bch_refill_keybuf(dc->disk.c, buf,
- &KEY(dc->disk.id,
- next_stripe * dc->disk.stripe_size, 0),
- dirty_pred);
- if (array_freelist_empty(&buf->freelist))
- return;
- stripe = next_stripe;
- next:
- if (wrapped && stripe > start_stripe)
- return;
- if (stripe == dc->disk.nr_stripes) {
- stripe = 0;
- wrapped = true;
- }
- }
- }
- /*
- * Returns true if we scanned the entire disk
- */
- static bool refill_dirty(struct cached_dev *dc)
- {
- struct keybuf *buf = &dc->writeback_keys;
- struct bkey start = KEY(dc->disk.id, 0, 0);
- struct bkey end = KEY(dc->disk.id, MAX_KEY_OFFSET, 0);
- struct bkey start_pos;
- /*
- * make sure keybuf pos is inside the range for this disk - at bringup
- * we might not be attached yet so this disk's inode nr isn't
- * initialized then
- */
- if (bkey_cmp(&buf->last_scanned, &start) < 0 ||
- bkey_cmp(&buf->last_scanned, &end) > 0)
- buf->last_scanned = start;
- if (dc->partial_stripes_expensive) {
- refill_full_stripes(dc);
- if (array_freelist_empty(&buf->freelist))
- return false;
- }
- start_pos = buf->last_scanned;
- bch_refill_keybuf(dc->disk.c, buf, &end, dirty_pred);
- if (bkey_cmp(&buf->last_scanned, &end) < 0)
- return false;
- /*
- * If we get to the end start scanning again from the beginning, and
- * only scan up to where we initially started scanning from:
- */
- buf->last_scanned = start;
- bch_refill_keybuf(dc->disk.c, buf, &start_pos, dirty_pred);
- return bkey_cmp(&buf->last_scanned, &start_pos) >= 0;
- }
- static int bch_writeback_thread(void *arg)
- {
- struct cached_dev *dc = arg;
- struct cache_set *c = dc->disk.c;
- bool searched_full_index;
- bch_ratelimit_reset(&dc->writeback_rate);
- while (!kthread_should_stop() &&
- !test_bit(CACHE_SET_IO_DISABLE, &c->flags)) {
- down_write(&dc->writeback_lock);
- set_current_state(TASK_INTERRUPTIBLE);
- /*
- * If the bache device is detaching, skip here and continue
- * to perform writeback. Otherwise, if no dirty data on cache,
- * or there is dirty data on cache but writeback is disabled,
- * the writeback thread should sleep here and wait for others
- * to wake up it.
- */
- if (!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) &&
- (!atomic_read(&dc->has_dirty) || !dc->writeback_running)) {
- up_write(&dc->writeback_lock);
- if (kthread_should_stop() ||
- test_bit(CACHE_SET_IO_DISABLE, &c->flags)) {
- set_current_state(TASK_RUNNING);
- break;
- }
- schedule();
- continue;
- }
- set_current_state(TASK_RUNNING);
- searched_full_index = refill_dirty(dc);
- if (searched_full_index &&
- RB_EMPTY_ROOT(&dc->writeback_keys.keys)) {
- atomic_set(&dc->has_dirty, 0);
- SET_BDEV_STATE(&dc->sb, BDEV_STATE_CLEAN);
- bch_write_bdev_super(dc, NULL);
- /*
- * If bcache device is detaching via sysfs interface,
- * writeback thread should stop after there is no dirty
- * data on cache. BCACHE_DEV_DETACHING flag is set in
- * bch_cached_dev_detach().
- */
- if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags)) {
- struct closure cl;
- closure_init_stack(&cl);
- memset(&dc->sb.set_uuid, 0, 16);
- SET_BDEV_STATE(&dc->sb, BDEV_STATE_NONE);
- bch_write_bdev_super(dc, &cl);
- closure_sync(&cl);
- up_write(&dc->writeback_lock);
- break;
- }
- /*
- * When dirty data rate is high (e.g. 50%+), there might
- * be heavy buckets fragmentation after writeback
- * finished, which hurts following write performance.
- * If users really care about write performance they
- * may set BCH_ENABLE_AUTO_GC via sysfs, then when
- * BCH_DO_AUTO_GC is set, garbage collection thread
- * will be wake up here. After moving gc, the shrunk
- * btree and discarded free buckets SSD space may be
- * helpful for following write requests.
- */
- if (c->gc_after_writeback ==
- (BCH_ENABLE_AUTO_GC|BCH_DO_AUTO_GC)) {
- c->gc_after_writeback &= ~BCH_DO_AUTO_GC;
- force_wake_up_gc(c);
- }
- }
- up_write(&dc->writeback_lock);
- read_dirty(dc);
- if (searched_full_index) {
- unsigned int delay = dc->writeback_delay * HZ;
- while (delay &&
- !kthread_should_stop() &&
- !test_bit(CACHE_SET_IO_DISABLE, &c->flags) &&
- !test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags))
- delay = schedule_timeout_interruptible(delay);
- bch_ratelimit_reset(&dc->writeback_rate);
- }
- }
- if (dc->writeback_write_wq)
- destroy_workqueue(dc->writeback_write_wq);
- cached_dev_put(dc);
- wait_for_kthread_stop();
- return 0;
- }
- /* Init */
- #define INIT_KEYS_EACH_TIME 500000
- struct sectors_dirty_init {
- struct btree_op op;
- unsigned int inode;
- size_t count;
- };
- static int sectors_dirty_init_fn(struct btree_op *_op, struct btree *b,
- struct bkey *k)
- {
- struct sectors_dirty_init *op = container_of(_op,
- struct sectors_dirty_init, op);
- if (KEY_INODE(k) > op->inode)
- return MAP_DONE;
- if (KEY_DIRTY(k))
- bcache_dev_sectors_dirty_add(b->c, KEY_INODE(k),
- KEY_START(k), KEY_SIZE(k));
- op->count++;
- if (!(op->count % INIT_KEYS_EACH_TIME))
- cond_resched();
- return MAP_CONTINUE;
- }
- static int bch_root_node_dirty_init(struct cache_set *c,
- struct bcache_device *d,
- struct bkey *k)
- {
- struct sectors_dirty_init op;
- int ret;
- bch_btree_op_init(&op.op, -1);
- op.inode = d->id;
- op.count = 0;
- ret = bcache_btree(map_keys_recurse,
- k,
- c->root,
- &op.op,
- &KEY(op.inode, 0, 0),
- sectors_dirty_init_fn,
- 0);
- if (ret < 0)
- pr_warn("sectors dirty init failed, ret=%d!\n", ret);
- /*
- * The op may be added to cache_set's btree_cache_wait
- * in mca_cannibalize(), must ensure it is removed from
- * the list and release btree_cache_alloc_lock before
- * free op memory.
- * Otherwise, the btree_cache_wait will be damaged.
- */
- bch_cannibalize_unlock(c);
- finish_wait(&c->btree_cache_wait, &(&op.op)->wait);
- return ret;
- }
- static int bch_dirty_init_thread(void *arg)
- {
- struct dirty_init_thrd_info *info = arg;
- struct bch_dirty_init_state *state = info->state;
- struct cache_set *c = state->c;
- struct btree_iter iter;
- struct bkey *k, *p;
- int cur_idx, prev_idx, skip_nr;
- k = p = NULL;
- cur_idx = prev_idx = 0;
- bch_btree_iter_init(&c->root->keys, &iter, NULL);
- k = bch_btree_iter_next_filter(&iter, &c->root->keys, bch_ptr_bad);
- BUG_ON(!k);
- p = k;
- while (k) {
- spin_lock(&state->idx_lock);
- cur_idx = state->key_idx;
- state->key_idx++;
- spin_unlock(&state->idx_lock);
- skip_nr = cur_idx - prev_idx;
- while (skip_nr) {
- k = bch_btree_iter_next_filter(&iter,
- &c->root->keys,
- bch_ptr_bad);
- if (k)
- p = k;
- else {
- atomic_set(&state->enough, 1);
- /* Update state->enough earlier */
- smp_mb__after_atomic();
- goto out;
- }
- skip_nr--;
- }
- if (p) {
- if (bch_root_node_dirty_init(c, state->d, p) < 0)
- goto out;
- }
- p = NULL;
- prev_idx = cur_idx;
- }
- out:
- /* In order to wake up state->wait in time */
- smp_mb__before_atomic();
- if (atomic_dec_and_test(&state->started))
- wake_up(&state->wait);
- return 0;
- }
- static int bch_btre_dirty_init_thread_nr(void)
- {
- int n = num_online_cpus()/2;
- if (n == 0)
- n = 1;
- else if (n > BCH_DIRTY_INIT_THRD_MAX)
- n = BCH_DIRTY_INIT_THRD_MAX;
- return n;
- }
- void bch_sectors_dirty_init(struct bcache_device *d)
- {
- int i;
- struct btree *b = NULL;
- struct bkey *k = NULL;
- struct btree_iter iter;
- struct sectors_dirty_init op;
- struct cache_set *c = d->c;
- struct bch_dirty_init_state state;
- retry_lock:
- b = c->root;
- rw_lock(0, b, b->level);
- if (b != c->root) {
- rw_unlock(0, b);
- goto retry_lock;
- }
- /* Just count root keys if no leaf node */
- if (c->root->level == 0) {
- bch_btree_op_init(&op.op, -1);
- op.inode = d->id;
- op.count = 0;
- for_each_key_filter(&c->root->keys,
- k, &iter, bch_ptr_invalid) {
- if (KEY_INODE(k) != op.inode)
- continue;
- sectors_dirty_init_fn(&op.op, c->root, k);
- }
- rw_unlock(0, b);
- return;
- }
- memset(&state, 0, sizeof(struct bch_dirty_init_state));
- state.c = c;
- state.d = d;
- state.total_threads = bch_btre_dirty_init_thread_nr();
- state.key_idx = 0;
- spin_lock_init(&state.idx_lock);
- atomic_set(&state.started, 0);
- atomic_set(&state.enough, 0);
- init_waitqueue_head(&state.wait);
- for (i = 0; i < state.total_threads; i++) {
- /* Fetch latest state.enough earlier */
- smp_mb__before_atomic();
- if (atomic_read(&state.enough))
- break;
- atomic_inc(&state.started);
- state.infos[i].state = &state;
- state.infos[i].thread =
- kthread_run(bch_dirty_init_thread, &state.infos[i],
- "bch_dirtcnt[%d]", i);
- if (IS_ERR(state.infos[i].thread)) {
- pr_err("fails to run thread bch_dirty_init[%d]\n", i);
- atomic_dec(&state.started);
- for (--i; i >= 0; i--)
- kthread_stop(state.infos[i].thread);
- goto out;
- }
- }
- out:
- /* Must wait for all threads to stop. */
- wait_event(state.wait, atomic_read(&state.started) == 0);
- rw_unlock(0, b);
- }
- void bch_cached_dev_writeback_init(struct cached_dev *dc)
- {
- sema_init(&dc->in_flight, 64);
- init_rwsem(&dc->writeback_lock);
- bch_keybuf_init(&dc->writeback_keys);
- dc->writeback_metadata = true;
- dc->writeback_running = false;
- dc->writeback_consider_fragment = true;
- dc->writeback_percent = 10;
- dc->writeback_delay = 30;
- atomic_long_set(&dc->writeback_rate.rate, 1024);
- dc->writeback_rate_minimum = 8;
- dc->writeback_rate_update_seconds = WRITEBACK_RATE_UPDATE_SECS_DEFAULT;
- dc->writeback_rate_p_term_inverse = 40;
- dc->writeback_rate_fp_term_low = 1;
- dc->writeback_rate_fp_term_mid = 10;
- dc->writeback_rate_fp_term_high = 1000;
- dc->writeback_rate_i_term_inverse = 10000;
- /* For dc->writeback_lock contention in update_writeback_rate() */
- dc->rate_update_retry = 0;
- WARN_ON(test_and_clear_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags));
- INIT_DELAYED_WORK(&dc->writeback_rate_update, update_writeback_rate);
- }
- int bch_cached_dev_writeback_start(struct cached_dev *dc)
- {
- dc->writeback_write_wq = alloc_workqueue("bcache_writeback_wq",
- WQ_MEM_RECLAIM, 0);
- if (!dc->writeback_write_wq)
- return -ENOMEM;
- cached_dev_get(dc);
- dc->writeback_thread = kthread_create(bch_writeback_thread, dc,
- "bcache_writeback");
- if (IS_ERR(dc->writeback_thread)) {
- cached_dev_put(dc);
- destroy_workqueue(dc->writeback_write_wq);
- return PTR_ERR(dc->writeback_thread);
- }
- dc->writeback_running = true;
- WARN_ON(test_and_set_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags));
- schedule_delayed_work(&dc->writeback_rate_update,
- dc->writeback_rate_update_seconds * HZ);
- bch_writeback_queue(dc);
- return 0;
- }
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