[PATCH v2 05/17] md/raid5-cache: Refactor r5l_wake_reclaim() to take a struct r5conf

Logan Gunthorpe
2022-05-26T16:37:24Z

All calls to r5l_wake_reclaim() have to dereference conf to get the
log. The log pointer should be protected by RCU, but isn't. Push
the dereference of conf->log into r5l_wake_reclaim() to reduce
the number of sites that dereference conf->log so this can be improved.

No functional changes intended.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
drivers/md/raid5-cache.c | 41 +++++++++++++++++++++-------------------
drivers/md/raid5-log.h | 2 +-
drivers/md/raid5.c | 2 +-
3 files changed, 24 insertions(+), 21 deletions(-)

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index edff4e8d07dc..3427f95cb358 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -326,7 +326,20 @@ void r5c_handle_cached_data_endio(struct r5conf *conf,
}
}

-void r5l_wake_reclaim(struct r5l_log *log, sector_t space);
+static void __r5l_wake_reclaim(struct r5l_log *log, sector_t space)
+{
+ unsigned long target;
+ unsigned long new = (unsigned long)space; /* overflow in theory */
+
+ if (!log)
+ return;
+ do {
+ target = log->reclaim_target;
+ if (new < target)
+ return;
+ } while (cmpxchg(&log->reclaim_target, target, new) != target);
+ md_wakeup_thread(log->reclaim_thread);
+}

/* Check whether we should flush some stripes to free up stripe cache */
void r5c_check_stripe_cache_usage(struct r5conf *conf)
@@ -349,7 +362,7 @@ void r5c_check_stripe_cache_usage(struct r5conf *conf)
*/
if (total_cached > conf->min_nr_stripes * 1 / 2 ||
atomic_read(&conf->empty_inactive_list_nr) > 0)
- r5l_wake_reclaim(conf->log, 0);
+ __r5l_wake_reclaim(conf->log, 0);
}

/*
@@ -368,7 +381,7 @@ void r5c_check_cached_full_stripe(struct r5conf *conf)
if (atomic_read(&conf->r5c_cached_full_stripes) >=
min(R5C_FULL_STRIPE_FLUSH_BATCH(conf),
conf->chunk_sectors >> RAID5_STRIPE_SHIFT(conf)))
- r5l_wake_reclaim(conf->log, 0);
+ __r5l_wake_reclaim(conf->log, 0);
}

/*
@@ -444,7 +457,7 @@ static inline void r5c_update_log_state(struct r5l_log *log)
clear_bit(R5C_LOG_TIGHT, &conf->cache_state);

if (wake_reclaim)
- r5l_wake_reclaim(log, 0);
+ __r5l_wake_reclaim(log, 0);
}

/*
@@ -1087,7 +1100,7 @@ int r5l_write_stripe(struct r5l_log *log, struct stripe_head *sh)

mutex_unlock(&log->io_mutex);
if (wake_reclaim)
- r5l_wake_reclaim(log, reserve);
+ __r5l_wake_reclaim(log, reserve);
return 0;
}

@@ -1239,7 +1252,7 @@ static void __r5l_stripe_write_finished(struct r5l_io_unit *io)

if (r5l_reclaimable_space(log) > log->max_free_space ||
test_bit(R5C_LOG_TIGHT, &conf->cache_state))
- r5l_wake_reclaim(log, 0);
+ __r5l_wake_reclaim(log, 0);

spin_unlock_irqrestore(&log->io_list_lock, flags);
wake_up(&log->iounit_wait);
@@ -1564,19 +1577,9 @@ static void r5l_reclaim_thread(struct md_thread *thread)
r5l_do_reclaim(log);
}

-void r5l_wake_reclaim(struct r5l_log *log, sector_t space)
+void r5l_wake_reclaim(struct r5conf *conf, sector_t space)
{
- unsigned long target;
- unsigned long new = (unsigned long)space; /* overflow in theory */
-
- if (!log)
- return;
- do {
- target = log->reclaim_target;
- if (new < target)
- return;
- } while (cmpxchg(&log->reclaim_target, target, new) != target);
- md_wakeup_thread(log->reclaim_thread);
+ __r5l_wake_reclaim(conf->log, space);
}

void r5l_quiesce(struct r5l_log *log, int quiesce)
@@ -1588,7 +1591,7 @@ void r5l_quiesce(struct r5l_log *log, int quiesce)
mddev = log->rdev->mddev;
wake_up(&mddev->sb_wait);
kthread_park(log->reclaim_thread->tsk);
- r5l_wake_reclaim(log, MaxSector);
+ __r5l_wake_reclaim(log, MaxSector);
r5l_do_reclaim(log);
} else
kthread_unpark(log->reclaim_thread->tsk);
diff --git a/drivers/md/raid5-log.h b/drivers/md/raid5-log.h
index 5ace25d11ea4..7594d2d80520 100644
--- a/drivers/md/raid5-log.h
+++ b/drivers/md/raid5-log.h
@@ -18,7 +18,7 @@ void r5c_finish_stripe_write_out(struct r5conf *conf, struct stripe_head *sh,
struct stripe_head_state *s);
void r5c_release_extra_page(struct stripe_head *sh);
void r5c_use_extra_page(struct stripe_head *sh);
-void r5l_wake_reclaim(struct r5l_log *log, sector_t space);
+void r5l_wake_reclaim(struct r5conf *conf, sector_t space);
void r5c_handle_cached_data_endio(struct r5conf *conf,
struct stripe_head *sh, int disks);
int r5c_cache_data(struct r5l_log *log, struct stripe_head *sh);
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index f1b55495de53..0d486f8aaf87 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -742,7 +742,7 @@ raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
if (!sh) {
set_bit(R5_INACTIVE_BLOCKED,
&conf->cache_state);
- r5l_wake_reclaim(conf->log, 0);
+ r5l_wake_reclaim(conf, 0);
wait_event_lock_irq(
conf->wait_for_stripe,
!list_empty(conf->inactive_list + hash) &&
--
2.30.2