Orange Pi5 kernel

// 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 <kent.overstreet@gmail.com>
 * 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_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;
 
<------>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 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;
<------>/*
<------> * Idle_counter is increased everytime 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().
<------> */
<------>if (atomic_inc_return(&c->idle_counter) <
<------>    atomic_read(&c->attached_dev_nr) * 6)
<------><------>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;
 
<------>/*
<------> * Check c->idle_counter and c->at_max_writeback_rate agagain in case
<------> * new I/O arrives during before set_at_max_writeback_rate() returns.
<------> * Then the writeback rate is set to 1, and its new value should be
<------> * decided via __update_writeback_rate().
<------> */
<------>if ((atomic_read(&c->idle_counter) <
<------>     atomic_read(&c->attached_dev_nr) * 6) ||
<------>    !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 (atomic_read(&dc->has_dirty) && dc->writeback_percent) {
<------><------>/*
<------><------> * 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 (!set_at_max_writeback_rate(c, dc)) {
<------><------><------>down_read(&dc->writeback_lock);
<------><------><------>__update_writeback_rate(dc);
<------><------><------>update_gc_after_writeback(c);
<------><------><------>up_read(&dc->writeback_lock);
<------><------>}
<------>}
 
 
<------>/*
<------> * 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, bio->bi_inline_vecs,
<------><------> DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS));
<------>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(PTR_CACHE(io->dc->disk.c, &w->key, 0),
<------><------><------>    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,
<------><------><------><------>    PTR_CACHE(dc->disk.c, &w->key, 0)->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)
<------><------><------>set_bit(stripe, d->full_dirty_stripes);
<------><------>else
<------><------><------>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)) {
<------><------><------><------>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) {
<------><------>flush_workqueue(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
#define INIT_KEYS_SLEEP_MS	100
 
struct sectors_dirty_init {
<------>struct btree_op	op;
<------>unsigned int	inode;
<------>size_t		count;
<------>struct bkey	start;
};
 
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 (atomic_read(&b->c->search_inflight) &&
<------>    !(op->count % INIT_KEYS_EACH_TIME)) {
<------><------>bkey_copy_key(&op->start, k);
<------><------>return -EAGAIN;
<------>}
 
<------>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;
<------>op.start = KEY(op.inode, 0, 0);
 
<------>do {
<------><------>ret = bcache_btree(map_keys_recurse,
<------><------><------><------>   k,
<------><------><------><------>   c->root,
<------><------><------><------>   &op.op,
<------><------><------><------>   &op.start,
<------><------><------><------>   sectors_dirty_init_fn,
<------><------><------><------>   0);
<------><------>if (ret == -EAGAIN)
<------><------><------>schedule_timeout_interruptible(
<------><------><------><------>msecs_to_jiffies(INIT_KEYS_SLEEP_MS));
<------><------>else if (ret < 0) {
<------><------><------>pr_warn("sectors dirty init failed, ret=%d!\n", ret);
<------><------><------>break;
<------><------>}
<------>} while (ret == -EAGAIN);
 
<------>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--;
<------><------><------>cond_resched();
<------><------>}
 
<------><------>if (p) {
<------><------><------>if (bch_root_node_dirty_init(c, state->d, p) < 0)
<------><------><------><------>goto out;
<------><------>}
 
<------><------>p = NULL;
<------><------>prev_idx = cur_idx;
<------><------>cond_resched();
<------>}
 
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 bkey *k = NULL;
<------>struct btree_iter iter;
<------>struct sectors_dirty_init op;
<------>struct cache_set *c = d->c;
<------>struct bch_dirty_init_state *state;
<------>char name[32];
 
<------>/* 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;
<------><------>op.start = KEY(op.inode, 0, 0);
 
<------><------>for_each_key_filter(&c->root->keys,
<------><------><------><------>    k, &iter, bch_ptr_invalid)
<------><------><------>sectors_dirty_init_fn(&op.op, c->root, k);
<------><------>return;
<------>}
 
<------>state = kzalloc(sizeof(struct bch_dirty_init_state), GFP_KERNEL);
<------>if (!state) {
<------><------>pr_warn("sectors dirty init failed: cannot allocate memory\n");
<------><------>return;
<------>}
 
<------>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;
 
<------><------>state->infos[i].state = state;
<------><------>atomic_inc(&state->started);
<------><------>snprintf(name, sizeof(name), "bch_dirty_init[%d]", i);
 
<------><------>state->infos[i].thread =
<------><------><------>kthread_run(bch_dirty_init_thread,
<------><------><------><------>    &state->infos[i],
<------><------><------><------>    name);
<------><------>if (IS_ERR(state->infos[i].thread)) {
<------><------><------>pr_err("fails to run thread bch_dirty_init[%d]\n", i);
<------><------><------>for (--i; i >= 0; i--)
<------><------><------><------>kthread_stop(state->infos[i].thread);
<------><------><------>goto out;
<------><------>}
<------>}
 
<------>/*
<------> * Must wait for all threads to stop.
<------> */
<------>wait_event_interruptible(state->wait,
<------><------> atomic_read(&state->started) == 0);
 
out:
<------>kfree(state);
}
 
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_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_i_term_inverse = 10000;
 
<------>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;
}