linux/drivers/md/dm-stats.h
Mike Snitzer 0cdb90f0f3 dm stats: fix too short end duration_ns when using precise_timestamps
dm_stats_account_io()'s STAT_PRECISE_TIMESTAMPS support doesn't handle
the fact that with commit b879f915bc ("dm: properly fix redundant
bio-based IO accounting") io->start_time _may_ be in the past (meaning
the start_io_acct() was deferred until later).

Add a new dm_stats_recalc_precise_timestamps() helper that will
set/clear a new 'precise_timestamps' flag in the dm_stats struct based
on whether any configured stats enable STAT_PRECISE_TIMESTAMPS.
And update DM core's alloc_io() to use dm_stats_record_start() to set
stats_aux.duration_ns if stats->precise_timestamps is true.

Also, remove unused 'last_sector' and 'last_rw' members from the
dm_stats struct.

Fixes: b879f915bc ("dm: properly fix redundant bio-based IO accounting")
Cc: stable@vger.kernel.org
Co-developed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2022-02-21 15:35:39 -05:00

49 lines
1.1 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef DM_STATS_H
#define DM_STATS_H
#include <linux/types.h>
#include <linux/mutex.h>
#include <linux/list.h>
int dm_statistics_init(void);
void dm_statistics_exit(void);
struct dm_stats {
struct mutex mutex;
struct list_head list; /* list of struct dm_stat */
struct dm_stats_last_position __percpu *last;
bool precise_timestamps;
};
struct dm_stats_aux {
bool merged;
unsigned long long duration_ns;
};
void dm_stats_init(struct dm_stats *st);
void dm_stats_cleanup(struct dm_stats *st);
struct mapped_device;
int dm_stats_message(struct mapped_device *md, unsigned argc, char **argv,
char *result, unsigned maxlen);
void dm_stats_account_io(struct dm_stats *stats, unsigned long bi_rw,
sector_t bi_sector, unsigned bi_sectors, bool end,
unsigned long start_time,
struct dm_stats_aux *aux);
static inline bool dm_stats_used(struct dm_stats *st)
{
return !list_empty(&st->list);
}
static inline void dm_stats_record_start(struct dm_stats *stats, struct dm_stats_aux *aux)
{
if (unlikely(stats->precise_timestamps))
aux->duration_ns = ktime_to_ns(ktime_get());
}
#endif