1101 lines
28 KiB
C
1101 lines
28 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* background writeback - scan btree for dirty data and write it to the backing
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* device
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*
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* Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
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* Copyright 2012 Google, Inc.
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*/
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#include "bcache.h"
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#include "btree.h"
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#include "debug.h"
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#include "writeback.h"
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#include <linux/delay.h>
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#include <linux/kthread.h>
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#include <linux/sched/clock.h>
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#include <trace/events/bcache.h>
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static void update_gc_after_writeback(struct cache_set *c)
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{
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if (c->gc_after_writeback != (BCH_ENABLE_AUTO_GC) ||
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c->gc_stats.in_use < BCH_AUTO_GC_DIRTY_THRESHOLD)
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return;
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c->gc_after_writeback |= BCH_DO_AUTO_GC;
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}
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/* Rate limiting */
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static uint64_t __calc_target_rate(struct cached_dev *dc)
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{
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struct cache_set *c = dc->disk.c;
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/*
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* This is the size of the cache, minus the amount used for
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* flash-only devices
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*/
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uint64_t cache_sectors = c->nbuckets * c->cache->sb.bucket_size -
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atomic_long_read(&c->flash_dev_dirty_sectors);
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/*
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* Unfortunately there is no control of global dirty data. If the
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* user states that they want 10% dirty data in the cache, and has,
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* e.g., 5 backing volumes of equal size, we try and ensure each
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* backing volume uses about 2% of the cache for dirty data.
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*/
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uint32_t bdev_share =
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div64_u64(bdev_nr_sectors(dc->bdev) << WRITEBACK_SHARE_SHIFT,
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c->cached_dev_sectors);
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uint64_t cache_dirty_target =
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div_u64(cache_sectors * dc->writeback_percent, 100);
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/* Ensure each backing dev gets at least one dirty share */
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if (bdev_share < 1)
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bdev_share = 1;
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return (cache_dirty_target * bdev_share) >> WRITEBACK_SHARE_SHIFT;
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}
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static void __update_writeback_rate(struct cached_dev *dc)
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{
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/*
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* PI controller:
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* Figures out the amount that should be written per second.
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*
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* First, the error (number of sectors that are dirty beyond our
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* target) is calculated. The error is accumulated (numerically
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* integrated).
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*
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* Then, the proportional value and integral value are scaled
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* based on configured values. These are stored as inverses to
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* avoid fixed point math and to make configuration easy-- e.g.
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* the default value of 40 for writeback_rate_p_term_inverse
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* attempts to write at a rate that would retire all the dirty
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* blocks in 40 seconds.
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*
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* The writeback_rate_i_inverse value of 10000 means that 1/10000th
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* of the error is accumulated in the integral term per second.
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* This acts as a slow, long-term average that is not subject to
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* variations in usage like the p term.
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*/
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int64_t target = __calc_target_rate(dc);
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int64_t dirty = bcache_dev_sectors_dirty(&dc->disk);
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int64_t error = dirty - target;
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int64_t proportional_scaled =
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div_s64(error, dc->writeback_rate_p_term_inverse);
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int64_t integral_scaled;
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uint32_t new_rate;
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/*
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* We need to consider the number of dirty buckets as well
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* when calculating the proportional_scaled, Otherwise we might
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* have an unreasonable small writeback rate at a highly fragmented situation
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* when very few dirty sectors consumed a lot dirty buckets, the
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* worst case is when dirty buckets reached cutoff_writeback_sync and
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* dirty data is still not even reached to writeback percent, so the rate
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* still will be at the minimum value, which will cause the write
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* stuck at a non-writeback mode.
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*/
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struct cache_set *c = dc->disk.c;
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int64_t dirty_buckets = c->nbuckets - c->avail_nbuckets;
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if (dc->writeback_consider_fragment &&
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c->gc_stats.in_use > BCH_WRITEBACK_FRAGMENT_THRESHOLD_LOW && dirty > 0) {
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int64_t fragment =
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div_s64((dirty_buckets * c->cache->sb.bucket_size), dirty);
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int64_t fp_term;
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int64_t fps;
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if (c->gc_stats.in_use <= BCH_WRITEBACK_FRAGMENT_THRESHOLD_MID) {
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fp_term = (int64_t)dc->writeback_rate_fp_term_low *
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(c->gc_stats.in_use - BCH_WRITEBACK_FRAGMENT_THRESHOLD_LOW);
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} else if (c->gc_stats.in_use <= BCH_WRITEBACK_FRAGMENT_THRESHOLD_HIGH) {
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fp_term = (int64_t)dc->writeback_rate_fp_term_mid *
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(c->gc_stats.in_use - BCH_WRITEBACK_FRAGMENT_THRESHOLD_MID);
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} else {
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fp_term = (int64_t)dc->writeback_rate_fp_term_high *
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(c->gc_stats.in_use - BCH_WRITEBACK_FRAGMENT_THRESHOLD_HIGH);
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}
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fps = div_s64(dirty, dirty_buckets) * fp_term;
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if (fragment > 3 && fps > proportional_scaled) {
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/* Only overrite the p when fragment > 3 */
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proportional_scaled = fps;
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}
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}
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if ((error < 0 && dc->writeback_rate_integral > 0) ||
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(error > 0 && time_before64(local_clock(),
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dc->writeback_rate.next + NSEC_PER_MSEC))) {
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/*
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* Only decrease the integral term if it's more than
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* zero. Only increase the integral term if the device
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* is keeping up. (Don't wind up the integral
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* ineffectively in either case).
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*
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* It's necessary to scale this by
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* writeback_rate_update_seconds to keep the integral
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* term dimensioned properly.
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*/
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dc->writeback_rate_integral += error *
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dc->writeback_rate_update_seconds;
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}
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integral_scaled = div_s64(dc->writeback_rate_integral,
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dc->writeback_rate_i_term_inverse);
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new_rate = clamp_t(int32_t, (proportional_scaled + integral_scaled),
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dc->writeback_rate_minimum, NSEC_PER_SEC);
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dc->writeback_rate_proportional = proportional_scaled;
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dc->writeback_rate_integral_scaled = integral_scaled;
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dc->writeback_rate_change = new_rate -
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atomic_long_read(&dc->writeback_rate.rate);
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atomic_long_set(&dc->writeback_rate.rate, new_rate);
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dc->writeback_rate_target = target;
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}
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static bool idle_counter_exceeded(struct cache_set *c)
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{
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int counter, dev_nr;
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/*
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* If c->idle_counter is overflow (idel for really long time),
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* reset as 0 and not set maximum rate this time for code
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* simplicity.
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*/
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counter = atomic_inc_return(&c->idle_counter);
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if (counter <= 0) {
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atomic_set(&c->idle_counter, 0);
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return false;
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}
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dev_nr = atomic_read(&c->attached_dev_nr);
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if (dev_nr == 0)
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return false;
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/*
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* c->idle_counter is increased by writeback thread of all
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* attached backing devices, in order to represent a rough
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* time period, counter should be divided by dev_nr.
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* Otherwise the idle time cannot be larger with more backing
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* device attached.
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* The following calculation equals to checking
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* (counter / dev_nr) < (dev_nr * 6)
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*/
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if (counter < (dev_nr * dev_nr * 6))
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return false;
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return true;
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}
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/*
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* Idle_counter is increased every time when update_writeback_rate() is
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* called. If all backing devices attached to the same cache set have
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* identical dc->writeback_rate_update_seconds values, it is about 6
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* rounds of update_writeback_rate() on each backing device before
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* c->at_max_writeback_rate is set to 1, and then max wrteback rate set
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* to each dc->writeback_rate.rate.
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* In order to avoid extra locking cost for counting exact dirty cached
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* devices number, c->attached_dev_nr is used to calculate the idle
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* throushold. It might be bigger if not all cached device are in write-
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* back mode, but it still works well with limited extra rounds of
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* update_writeback_rate().
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*/
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static bool set_at_max_writeback_rate(struct cache_set *c,
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struct cached_dev *dc)
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{
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/* Don't sst max writeback rate if it is disabled */
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if (!c->idle_max_writeback_rate_enabled)
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return false;
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/* Don't set max writeback rate if gc is running */
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if (!c->gc_mark_valid)
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return false;
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if (!idle_counter_exceeded(c))
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return false;
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if (atomic_read(&c->at_max_writeback_rate) != 1)
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atomic_set(&c->at_max_writeback_rate, 1);
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atomic_long_set(&dc->writeback_rate.rate, INT_MAX);
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/* keep writeback_rate_target as existing value */
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dc->writeback_rate_proportional = 0;
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dc->writeback_rate_integral_scaled = 0;
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dc->writeback_rate_change = 0;
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/*
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* In case new I/O arrives during before
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* set_at_max_writeback_rate() returns.
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*/
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if (!idle_counter_exceeded(c) ||
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!atomic_read(&c->at_max_writeback_rate))
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return false;
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return true;
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}
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static void update_writeback_rate(struct work_struct *work)
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{
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struct cached_dev *dc = container_of(to_delayed_work(work),
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struct cached_dev,
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writeback_rate_update);
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struct cache_set *c = dc->disk.c;
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/*
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* should check BCACHE_DEV_RATE_DW_RUNNING before calling
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* cancel_delayed_work_sync().
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*/
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set_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags);
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/* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */
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smp_mb__after_atomic();
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/*
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* CACHE_SET_IO_DISABLE might be set via sysfs interface,
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* check it here too.
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*/
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if (!test_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags) ||
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test_bit(CACHE_SET_IO_DISABLE, &c->flags)) {
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clear_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags);
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/* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */
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smp_mb__after_atomic();
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return;
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}
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/*
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* If the whole cache set is idle, set_at_max_writeback_rate()
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* will set writeback rate to a max number. Then it is
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* unncessary to update writeback rate for an idle cache set
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* in maximum writeback rate number(s).
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*/
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if (atomic_read(&dc->has_dirty) && dc->writeback_percent &&
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!set_at_max_writeback_rate(c, dc)) {
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do {
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if (!down_read_trylock((&dc->writeback_lock))) {
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dc->rate_update_retry++;
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if (dc->rate_update_retry <=
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BCH_WBRATE_UPDATE_MAX_SKIPS)
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break;
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down_read(&dc->writeback_lock);
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dc->rate_update_retry = 0;
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}
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__update_writeback_rate(dc);
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update_gc_after_writeback(c);
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up_read(&dc->writeback_lock);
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} while (0);
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}
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/*
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* CACHE_SET_IO_DISABLE might be set via sysfs interface,
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* check it here too.
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*/
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if (test_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags) &&
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!test_bit(CACHE_SET_IO_DISABLE, &c->flags)) {
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schedule_delayed_work(&dc->writeback_rate_update,
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dc->writeback_rate_update_seconds * HZ);
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}
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/*
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* should check BCACHE_DEV_RATE_DW_RUNNING before calling
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* cancel_delayed_work_sync().
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*/
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clear_bit(BCACHE_DEV_RATE_DW_RUNNING, &dc->disk.flags);
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/* paired with where BCACHE_DEV_RATE_DW_RUNNING is tested */
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smp_mb__after_atomic();
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}
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static unsigned int writeback_delay(struct cached_dev *dc,
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unsigned int sectors)
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{
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if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
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!dc->writeback_percent)
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return 0;
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return bch_next_delay(&dc->writeback_rate, sectors);
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}
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struct dirty_io {
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struct closure cl;
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struct cached_dev *dc;
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uint16_t sequence;
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struct bio bio;
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};
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static void dirty_init(struct keybuf_key *w)
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{
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struct dirty_io *io = w->private;
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struct bio *bio = &io->bio;
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bio_init(bio, NULL, bio->bi_inline_vecs,
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DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS), 0);
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if (!io->dc->writeback_percent)
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bio_set_prio(bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
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bio->bi_iter.bi_size = KEY_SIZE(&w->key) << 9;
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bio->bi_private = w;
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bch_bio_map(bio, NULL);
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}
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static void dirty_io_destructor(struct closure *cl)
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{
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struct dirty_io *io = container_of(cl, struct dirty_io, cl);
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kfree(io);
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}
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static void write_dirty_finish(struct closure *cl)
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{
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struct dirty_io *io = container_of(cl, struct dirty_io, cl);
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struct keybuf_key *w = io->bio.bi_private;
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struct cached_dev *dc = io->dc;
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bio_free_pages(&io->bio);
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/* This is kind of a dumb way of signalling errors. */
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if (KEY_DIRTY(&w->key)) {
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int ret;
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unsigned int i;
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struct keylist keys;
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bch_keylist_init(&keys);
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bkey_copy(keys.top, &w->key);
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SET_KEY_DIRTY(keys.top, false);
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bch_keylist_push(&keys);
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for (i = 0; i < KEY_PTRS(&w->key); i++)
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atomic_inc(&PTR_BUCKET(dc->disk.c, &w->key, i)->pin);
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ret = bch_btree_insert(dc->disk.c, &keys, NULL, &w->key);
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if (ret)
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trace_bcache_writeback_collision(&w->key);
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atomic_long_inc(ret
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? &dc->disk.c->writeback_keys_failed
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: &dc->disk.c->writeback_keys_done);
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}
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bch_keybuf_del(&dc->writeback_keys, w);
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up(&dc->in_flight);
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closure_return_with_destructor(cl, dirty_io_destructor);
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}
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static void dirty_endio(struct bio *bio)
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{
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struct keybuf_key *w = bio->bi_private;
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struct dirty_io *io = w->private;
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if (bio->bi_status) {
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SET_KEY_DIRTY(&w->key, false);
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bch_count_backing_io_errors(io->dc, bio);
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}
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closure_put(&io->cl);
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}
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static void write_dirty(struct closure *cl)
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{
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struct dirty_io *io = container_of(cl, struct dirty_io, cl);
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struct keybuf_key *w = io->bio.bi_private;
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struct cached_dev *dc = io->dc;
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uint16_t next_sequence;
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if (atomic_read(&dc->writeback_sequence_next) != io->sequence) {
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/* Not our turn to write; wait for a write to complete */
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closure_wait(&dc->writeback_ordering_wait, cl);
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if (atomic_read(&dc->writeback_sequence_next) == io->sequence) {
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/*
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* Edge case-- it happened in indeterminate order
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* relative to when we were added to wait list..
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*/
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closure_wake_up(&dc->writeback_ordering_wait);
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}
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continue_at(cl, write_dirty, io->dc->writeback_write_wq);
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return;
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}
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next_sequence = io->sequence + 1;
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/*
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* IO errors are signalled using the dirty bit on the key.
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* If we failed to read, we should not attempt to write to the
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* backing device. Instead, immediately go to write_dirty_finish
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* to clean up.
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*/
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if (KEY_DIRTY(&w->key)) {
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dirty_init(w);
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bio_set_op_attrs(&io->bio, REQ_OP_WRITE, 0);
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io->bio.bi_iter.bi_sector = KEY_START(&w->key);
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bio_set_dev(&io->bio, io->dc->bdev);
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io->bio.bi_end_io = dirty_endio;
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/* I/O request sent to backing device */
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closure_bio_submit(io->dc->disk.c, &io->bio, cl);
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}
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atomic_set(&dc->writeback_sequence_next, next_sequence);
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closure_wake_up(&dc->writeback_ordering_wait);
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continue_at(cl, write_dirty_finish, io->dc->writeback_write_wq);
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}
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static void read_dirty_endio(struct bio *bio)
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{
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struct keybuf_key *w = bio->bi_private;
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struct dirty_io *io = w->private;
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/* is_read = 1 */
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bch_count_io_errors(io->dc->disk.c->cache,
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bio->bi_status, 1,
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"reading dirty data from cache");
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dirty_endio(bio);
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}
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static void read_dirty_submit(struct closure *cl)
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{
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struct dirty_io *io = container_of(cl, struct dirty_io, cl);
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closure_bio_submit(io->dc->disk.c, &io->bio, cl);
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continue_at(cl, write_dirty, io->dc->writeback_write_wq);
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}
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static void read_dirty(struct cached_dev *dc)
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{
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unsigned int delay = 0;
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struct keybuf_key *next, *keys[MAX_WRITEBACKS_IN_PASS], *w;
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size_t size;
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int nk, i;
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struct dirty_io *io;
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struct closure cl;
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uint16_t sequence = 0;
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BUG_ON(!llist_empty(&dc->writeback_ordering_wait.list));
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atomic_set(&dc->writeback_sequence_next, sequence);
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closure_init_stack(&cl);
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/*
|
|
* 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_stack iter;
|
|
struct bkey *k, *p;
|
|
int cur_idx, prev_idx, skip_nr;
|
|
|
|
k = p = NULL;
|
|
prev_idx = 0;
|
|
|
|
bch_btree_iter_stack_init(&c->root->keys, &iter, NULL);
|
|
k = bch_btree_iter_next_filter(&iter.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.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_stack 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;
|
|
}
|