[PATCH v2 02/17] md/raid5-cache: Add r5c_conf_is_writeback() helper

Logan Gunthorpe
2022-05-26T16:36:27Z

Most calls to r5c_is_writeback() 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 a new r5c_conf_is_writeback() helper
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>
---
drivers/md/raid5-cache.c | 7 ++++++-
drivers/md/raid5-log.h | 2 +-
drivers/md/raid5.c | 16 ++++++++--------
3 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 83c184eddbda..96f51ce9b6c1 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -247,12 +247,17 @@ enum r5l_io_unit_state {
IO_UNIT_STRIPE_END = 3, /* stripes data finished writing to raid */
};

-bool r5c_is_writeback(struct r5l_log *log)
+static bool r5c_is_writeback(struct r5l_log *log)
{
return (log != NULL &&
log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_BACK);
}

+bool r5c_conf_is_writeback(struct r5conf *conf)
+{
+ return r5c_is_writeback(conf->log);
+}
+
static sector_t r5l_ring_add(struct r5l_log *log, sector_t start, sector_t inc)
{
start += inc;
diff --git a/drivers/md/raid5-log.h b/drivers/md/raid5-log.h
index 270ced4f770f..720e164e4d4d 100644
--- a/drivers/md/raid5-log.h
+++ b/drivers/md/raid5-log.h
@@ -11,7 +11,7 @@ void r5l_stripe_write_finished(struct stripe_head *sh);
int r5l_handle_flush_request(struct r5l_log *log, struct bio *bio);
void r5l_quiesce(struct r5l_log *log, int quiesce);
bool r5l_log_disk_error(struct r5conf *conf);
-bool r5c_is_writeback(struct r5l_log *log);
+bool r5c_conf_is_writeback(struct r5conf *conf);
int r5c_try_caching_write(struct r5conf *conf, struct stripe_head *sh,
struct stripe_head_state *s, int disks);
void r5c_finish_stripe_write_out(struct r5conf *conf, struct stripe_head *sh,
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 5d09256d7f81..458d88faf2e9 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -224,7 +224,7 @@ static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
BUG_ON(!list_empty(&sh->lru));
BUG_ON(atomic_read(&conf->active_stripes)==0);

- if (r5c_is_writeback(conf->log))
+ if (r5c_conf_is_writeback(conf))
for (i = sh->disks; i--; )
if (test_bit(R5_InJournal, &sh->dev[i].flags))
injournal++;
@@ -236,7 +236,7 @@ static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
* 2. when resync is requested fot the stripe.
*/
if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state) ||
- (conf->quiesce && r5c_is_writeback(conf->log) &&
+ (conf->quiesce && r5c_conf_is_writeback(conf) &&
!test_bit(STRIPE_HANDLE, &sh->state) && injournal != 0)) {
if (test_bit(STRIPE_R5C_CACHING, &sh->state))
r5c_make_stripe_write_out(sh);
@@ -274,7 +274,7 @@ static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
md_wakeup_thread(conf->mddev->thread);
atomic_dec(&conf->active_stripes);
if (!test_bit(STRIPE_EXPANDING, &sh->state)) {
- if (!r5c_is_writeback(conf->log))
+ if (!r5c_conf_is_writeback(conf))
list_add_tail(&sh->lru, temp_inactive_list);
else {
WARN_ON(test_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags));
@@ -1786,7 +1786,7 @@ static void ops_complete_prexor(void *stripe_head_ref)
pr_debug("%s: stripe %llu\n", __func__,
(unsigned long long)sh->sector);

- if (r5c_is_writeback(sh->raid_conf->log))
+ if (r5c_conf_is_writeback(sh->raid_conf))
/*
* raid5-cache write back uses orig_page during prexor.
* After prexor, it is time to free orig_page
@@ -1905,9 +1905,9 @@ ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
tx = async_copy_data(1, wbi, &dev->page,
dev->offset,
dev->sector, tx, sh,
- r5c_is_writeback(conf->log));
+ r5c_conf_is_writeback(conf));
if (dev->page != dev->orig_page &&
- !r5c_is_writeback(conf->log)) {
+ !r5c_conf_is_writeback(conf)) {
set_bit(R5_SkipCopy, &dev->flags);
clear_bit(R5_UPTODATE, &dev->flags);
clear_bit(R5_OVERWRITE, &dev->flags);
@@ -5085,7 +5085,7 @@ static void handle_stripe(struct stripe_head *sh)
*/

if (!sh->reconstruct_state && !sh->check_state && !sh->log_io) {
- if (!r5c_is_writeback(conf->log)) {
+ if (!r5c_conf_is_writeback(conf)) {
if (s.to_write)
handle_stripe_dirtying(conf, sh, &s, disks);
} else { /* write back cache */
@@ -5533,7 +5533,7 @@ static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
struct stripe_head *sh, *tmp;
struct list_head *handle_list = NULL;
struct r5worker_group *wg;
- bool second_try = !r5c_is_writeback(conf->log) &&
+ bool second_try = !r5c_conf_is_writeback(conf) &&
!r5l_log_disk_error(conf);
bool try_loprio = test_bit(R5C_LOG_TIGHT, &conf->cache_state) ||
r5l_log_disk_error(conf);
--
2.30.2