linux/drivers/md/bcache/writeback.h
Coly Li 7a5e3ecbe5 bcache: set writeback_rate_update_seconds in range [1, 60] seconds
dc->writeback_rate_update_seconds can be set via sysfs and its value can
be set to [1, ULONG_MAX].  It does not make sense to set such a large
value, 60 seconds is long enough value considering the default 5 seconds
works well for long time.

Because dc->writeback_rate_update is a special delayed work, it re-arms
itself inside the delayed work routine update_writeback_rate(). When
stopping it by cancel_delayed_work_sync(), there should be a timeout to
wait and make sure the re-armed delayed work is stopped too. A small max
value of dc->writeback_rate_update_seconds is also helpful to decide a
reasonable small timeout.

This patch limits sysfs interface to set dc->writeback_rate_update_seconds
in range of [1, 60] seconds, and replaces the hand-coded number by macros.

Changelog:
v2: fix a rebase typo in v4, which is pointed out by Michael Lyle.
v1: initial version.

Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Michael Lyle <mlyle@lyle.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-02-07 12:50:01 -07:00

127 lines
3.0 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _BCACHE_WRITEBACK_H
#define _BCACHE_WRITEBACK_H
#define CUTOFF_WRITEBACK 40
#define CUTOFF_WRITEBACK_SYNC 70
#define MAX_WRITEBACKS_IN_PASS 5
#define MAX_WRITESIZE_IN_PASS 5000 /* *512b */
#define WRITEBACK_RATE_UPDATE_SECS_MAX 60
#define WRITEBACK_RATE_UPDATE_SECS_DEFAULT 5
/*
* 14 (16384ths) is chosen here as something that each backing device
* should be a reasonable fraction of the share, and not to blow up
* until individual backing devices are a petabyte.
*/
#define WRITEBACK_SHARE_SHIFT 14
static inline uint64_t bcache_dev_sectors_dirty(struct bcache_device *d)
{
uint64_t i, ret = 0;
for (i = 0; i < d->nr_stripes; i++)
ret += atomic_read(d->stripe_sectors_dirty + i);
return ret;
}
static inline uint64_t bcache_flash_devs_sectors_dirty(struct cache_set *c)
{
uint64_t i, ret = 0;
mutex_lock(&bch_register_lock);
for (i = 0; i < c->devices_max_used; i++) {
struct bcache_device *d = c->devices[i];
if (!d || !UUID_FLASH_ONLY(&c->uuids[i]))
continue;
ret += bcache_dev_sectors_dirty(d);
}
mutex_unlock(&bch_register_lock);
return ret;
}
static inline unsigned offset_to_stripe(struct bcache_device *d,
uint64_t offset)
{
do_div(offset, d->stripe_size);
return offset;
}
static inline bool bcache_dev_stripe_dirty(struct cached_dev *dc,
uint64_t offset,
unsigned nr_sectors)
{
unsigned stripe = offset_to_stripe(&dc->disk, offset);
while (1) {
if (atomic_read(dc->disk.stripe_sectors_dirty + stripe))
return true;
if (nr_sectors <= dc->disk.stripe_size)
return false;
nr_sectors -= dc->disk.stripe_size;
stripe++;
}
}
static inline bool should_writeback(struct cached_dev *dc, struct bio *bio,
unsigned cache_mode, bool would_skip)
{
unsigned in_use = dc->disk.c->gc_stats.in_use;
if (cache_mode != CACHE_MODE_WRITEBACK ||
test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
in_use > CUTOFF_WRITEBACK_SYNC)
return false;
if (dc->partial_stripes_expensive &&
bcache_dev_stripe_dirty(dc, bio->bi_iter.bi_sector,
bio_sectors(bio)))
return true;
if (would_skip)
return false;
return (op_is_sync(bio->bi_opf) ||
bio->bi_opf & (REQ_META|REQ_PRIO) ||
in_use <= CUTOFF_WRITEBACK);
}
static inline void bch_writeback_queue(struct cached_dev *dc)
{
if (!IS_ERR_OR_NULL(dc->writeback_thread))
wake_up_process(dc->writeback_thread);
}
static inline void bch_writeback_add(struct cached_dev *dc)
{
if (!atomic_read(&dc->has_dirty) &&
!atomic_xchg(&dc->has_dirty, 1)) {
refcount_inc(&dc->count);
if (BDEV_STATE(&dc->sb) != BDEV_STATE_DIRTY) {
SET_BDEV_STATE(&dc->sb, BDEV_STATE_DIRTY);
/* XXX: should do this synchronously */
bch_write_bdev_super(dc, NULL);
}
bch_writeback_queue(dc);
}
}
void bcache_dev_sectors_dirty_add(struct cache_set *, unsigned, uint64_t, int);
void bch_sectors_dirty_init(struct bcache_device *);
void bch_cached_dev_writeback_init(struct cached_dev *);
int bch_cached_dev_writeback_start(struct cached_dev *);
#endif