From: Mike Snitzer snitzer@redhat.com
commit 0cdb90f0f306384ecbc60dfd6dc48cdbc1f2d0d8 upstream.
dm_stats_account_io()'s STAT_PRECISE_TIMESTAMPS support doesn't handle the fact that with commit b879f915bc48 ("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: b879f915bc48 ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/md/dm-stats.c | 28 +++++++++++++++++++++++++--- drivers/md/dm-stats.h | 9 +++++++-- drivers/md/dm.c | 2 ++ 3 files changed, 34 insertions(+), 5 deletions(-)
--- a/drivers/md/dm-stats.c +++ b/drivers/md/dm-stats.c @@ -195,6 +195,7 @@ void dm_stats_init(struct dm_stats *stat
mutex_init(&stats->mutex); INIT_LIST_HEAD(&stats->list); + stats->precise_timestamps = false; stats->last = alloc_percpu(struct dm_stats_last_position); for_each_possible_cpu(cpu) { last = per_cpu_ptr(stats->last, cpu); @@ -231,6 +232,22 @@ void dm_stats_cleanup(struct dm_stats *s mutex_destroy(&stats->mutex); }
+static void dm_stats_recalc_precise_timestamps(struct dm_stats *stats) +{ + struct list_head *l; + struct dm_stat *tmp_s; + bool precise_timestamps = false; + + list_for_each(l, &stats->list) { + tmp_s = container_of(l, struct dm_stat, list_entry); + if (tmp_s->stat_flags & STAT_PRECISE_TIMESTAMPS) { + precise_timestamps = true; + break; + } + } + stats->precise_timestamps = precise_timestamps; +} + static int dm_stats_create(struct dm_stats *stats, sector_t start, sector_t end, sector_t step, unsigned stat_flags, unsigned n_histogram_entries, @@ -376,6 +393,9 @@ static int dm_stats_create(struct dm_sta } ret_id = s->id; list_add_tail_rcu(&s->list_entry, l); + + dm_stats_recalc_precise_timestamps(stats); + mutex_unlock(&stats->mutex);
resume_callback(md); @@ -418,6 +438,9 @@ static int dm_stats_delete(struct dm_sta }
list_del_rcu(&s->list_entry); + + dm_stats_recalc_precise_timestamps(stats); + mutex_unlock(&stats->mutex);
/* @@ -654,9 +677,8 @@ void dm_stats_account_io(struct dm_stats got_precise_time = false; list_for_each_entry_rcu(s, &stats->list, list_entry) { if (s->stat_flags & STAT_PRECISE_TIMESTAMPS && !got_precise_time) { - if (!end) - stats_aux->duration_ns = ktime_to_ns(ktime_get()); - else + /* start (!end) duration_ns is set by DM core's alloc_io() */ + if (end) stats_aux->duration_ns = ktime_to_ns(ktime_get()) - stats_aux->duration_ns; got_precise_time = true; } --- a/drivers/md/dm-stats.h +++ b/drivers/md/dm-stats.h @@ -13,8 +13,7 @@ struct dm_stats { struct mutex mutex; struct list_head list; /* list of struct dm_stat */ struct dm_stats_last_position __percpu *last; - sector_t last_sector; - unsigned last_rw; + bool precise_timestamps; };
struct dm_stats_aux { @@ -40,4 +39,10 @@ static inline bool dm_stats_used(struct 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 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -537,6 +537,8 @@ static struct dm_io *alloc_io(struct map
io->start_time = jiffies;
+ dm_stats_record_start(&md->stats, &io->stats_aux); + return io; }