When cache trys to flush data to raid, we must be very careful about
stripe release. The issue is if we release a stripe and the stripe is
handling by raid5d and we add a new bio into the stripe later, the
stripe will enter the raid5 state machine several times, which
r5cache_write_parity can't handle well. This could happen if
get_active_stripe() sleeps in adding bio to several stripes. To solve
this issue, we guarantee stripe release after all bio are added to
corresponding stripes. This is a performance win too if the bug happens.
Signed-off-by: Shaohua Li <shli@xxxxxx>
---
drivers/md/raid5-cache.c | 28 +++++++++-------
drivers/md/raid5.c | 84 +++++++++++++++++++++++++++++++-----------------
drivers/md/raid5.h | 11 ++++++-
3 files changed, 80 insertions(+), 43 deletions(-)
diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 332230a..7d5292c 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -1830,7 +1830,7 @@ static void r5c_write_bio(struct r5c_cache *cache, struct bio *bio)
r5c_enter_error_mode(cache, -ENOMEM);
r5c_check_wait_error_mode(cache);
error_mode:
- raid5_make_request(cache->mddev, bio);
+ raid5_make_request(cache->mddev, bio, NULL);
}
static void r5c_read_bio(struct r5c_cache *cache, struct bio *bio)
@@ -1846,7 +1846,7 @@ static void r5c_read_bio(struct r5c_cache *cache, struct bio *bio)
stripe = r5c_get_stripe(cache, stripe_index);
if (!stripe) {
- raid5_make_request(cache->mddev, bio);
+ raid5_make_request(cache->mddev, bio, NULL);
return;
}
@@ -1885,7 +1885,7 @@ static void r5c_read_bio(struct r5c_cache *cache, struct bio *bio)
} else
split = bio;
- raid5_make_request(cache->mddev, split);
+ raid5_make_request(cache->mddev, split, NULL);
start = tmp;
}
@@ -1996,7 +1996,7 @@ static void r5c_flush_endio(struct bio *bio, int err)
}
static void r5c_flush_one(struct r5c_cache *cache, struct r5c_stripe *stripe,
- int start, int pages)
+ int start, int pages, struct raid5_plug_context *pc)
{
sector_t base;
struct bio *bio;
@@ -2031,7 +2031,7 @@ static void r5c_flush_one(struct r5c_cache *cache, struct r5c_stripe *stripe,
atomic64_inc(&cache->out_cache_rq);
atomic64_add(bio_sectors(bio), &cache->out_cache_sectors);
- raid5_make_request(cache->mddev, bio);
+ raid5_make_request(cache->mddev, bio, pc);
}
}
@@ -2044,7 +2044,8 @@ static void r5c_put_stripe_dirty(struct r5c_cache *cache,
}
}
-static void r5c_flush_stripe(struct r5c_cache *cache, struct r5c_stripe *stripe)
+static void r5c_flush_stripe(struct r5c_cache *cache, struct r5c_stripe *stripe,
+ struct raid5_plug_context *pc)
{
unsigned long *stripe_bits;
int chunk_stripes;
@@ -2073,7 +2074,7 @@ static void r5c_flush_stripe(struct r5c_cache *cache, struct r5c_stripe *stripe)
while (end < cache->stripe_data_pages &&
stripe->data_pages[end])
end++;
- r5c_flush_one(cache, stripe, start, end - start);
+ r5c_flush_one(cache, stripe, start, end - start, pc);
}
r5c_put_stripe_dirty(cache, stripe);
}
@@ -2207,11 +2208,14 @@ static void r5c_reclaim_stripe_list(struct r5c_cache *cache,
struct r5c_io_range *range;
u64 seq;
sector_t meta;
- struct blk_plug plug;
size_t size = 0;
+ struct raid5_plug_context pc;
if (list_empty(stripe_list))
return;
+
+ raid5_context_init(&pc);
+
list_sort(NULL, stripe_list, r5c_stripe_list_cmp);
list_for_each_entry(stripe, stripe_list, lru) {
cache->stripe_flush_data[size] =
@@ -2220,11 +2224,11 @@ static void r5c_reclaim_stripe_list(struct r5c_cache *cache,
}
size *= sizeof(__le64);
- blk_start_plug(&plug);
/* step 1: start write to raid */
list_for_each_entry(stripe, stripe_list, lru)
- r5c_flush_stripe(cache, stripe);
- blk_finish_plug(&plug);
+ r5c_flush_stripe(cache, stripe, &pc);
+
+ raid5_context_unplug(&pc, cache->mddev, false);
/* step 2: wait parity write to cache */
list_for_each_entry_reverse(stripe, stripe_list, lru)
@@ -2337,7 +2341,7 @@ static void r5c_reclaim_thread(struct md_thread *thread)
* retry error IO and dispatch it to raid disks directly
**/
while ((bio = bio_list_pop(&cache->retry_bio_list)) != NULL)
- raid5_make_request(cache->mddev, bio);
+ raid5_make_request(cache->mddev, bio, NULL);
if (++cache->retry_cnt < MAX_RETRY) {
cache->next_retry_time = jiffies +
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index f3b22f2..75964e9 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4972,26 +4972,26 @@ static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
return sh;
}
-struct raid5_plug_cb {
- struct blk_plug_cb cb;
- struct list_head list;
- struct list_head temp_inactive_list[NR_STRIPE_HASH_LOCKS];
-};
+void raid5_context_init(struct raid5_plug_context *context)
+{
+ int i;
+ INIT_LIST_HEAD(&context->list);
+ for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
+ INIT_LIST_HEAD(context->temp_inactive_list + i);
+}
-static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
+void raid5_context_unplug(struct raid5_plug_context *context,
+ struct mddev *mddev, bool from_schedule)
{
- struct raid5_plug_cb *cb = container_of(
- blk_cb, struct raid5_plug_cb, cb);
struct stripe_head *sh;
- struct mddev *mddev = cb->cb.data;
struct r5conf *conf = mddev->private;
int cnt = 0;
int hash;
- if (cb->list.next && !list_empty(&cb->list)) {
+ if (context->list.next && !list_empty(&context->list)) {
spin_lock_irq(&conf->device_lock);
- while (!list_empty(&cb->list)) {
- sh = list_first_entry(&cb->list, struct stripe_head, lru);
+ while (!list_empty(&context->list)) {
+ sh = list_first_entry(&context->list, struct stripe_head, lru);
list_del_init(&sh->lru);
/*
* avoid race release_stripe_plug() sees
@@ -5005,15 +5005,38 @@ static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
* case, the count is always > 1 here
*/
hash = sh->hash_lock_index;
- __release_stripe(conf, sh, &cb->temp_inactive_list[hash]);
+ __release_stripe(conf, sh, &context->temp_inactive_list[hash]);
cnt++;
}
spin_unlock_irq(&conf->device_lock);
}
- release_inactive_stripe_list(conf, cb->temp_inactive_list,
+ release_inactive_stripe_list(conf, context->temp_inactive_list,
NR_STRIPE_HASH_LOCKS);
if (mddev->queue)
trace_block_unplug(mddev->queue, cnt, !from_schedule);
+}
+
+static void raid5_context_plug(struct raid5_plug_context *context,
+ struct stripe_head *sh)
+{
+ if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
+ list_add_tail(&sh->lru, &context->list);
+ else
+ release_stripe(sh);
+}
+
+struct raid5_plug_cb {
+ struct blk_plug_cb cb;
+ struct raid5_plug_context context;
+};
+
+static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
+{
+ struct raid5_plug_cb *cb = container_of(
+ blk_cb, struct raid5_plug_cb, cb);
+ struct mddev *mddev = cb->cb.data;
+
+ raid5_context_unplug(&cb->context, mddev, from_schedule);
kfree(cb);
}
@@ -5032,20 +5055,14 @@ static void release_stripe_plug(struct mddev *mddev,
cb = container_of(blk_cb, struct raid5_plug_cb, cb);
- if (cb->list.next == NULL) {
- int i;
- INIT_LIST_HEAD(&cb->list);
- for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
- INIT_LIST_HEAD(cb->temp_inactive_list + i);
- }
+ if (cb->context.list.next == NULL)
+ raid5_context_init(&cb->context);
- if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
- list_add_tail(&sh->lru, &cb->list);
- else
- release_stripe(sh);
+ raid5_context_plug(&cb->context, sh);
}
-static void make_discard_request(struct mddev *mddev, struct bio *bi)
+static void make_discard_request(struct mddev *mddev, struct bio *bi,
+ struct raid5_plug_context *context)
{
struct r5conf *conf = mddev->private;
sector_t logical_sector, last_sector;
@@ -5127,7 +5144,10 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi)
clear_bit(STRIPE_DELAYED, &sh->state);
if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
atomic_inc(&conf->preread_active_stripes);
- release_stripe_plug(mddev, sh);
+ if (context)
+ raid5_context_plug(context, sh);
+ else
+ release_stripe_plug(mddev, sh);
}
remaining = raid5_dec_bi_active_stripes(bi);
@@ -5137,7 +5157,8 @@ static void make_discard_request(struct mddev *mddev, struct bio *bi)
}
}
-void raid5_make_request(struct mddev *mddev, struct bio * bi)
+void raid5_make_request(struct mddev *mddev, struct bio * bi,
+ struct raid5_plug_context *context)
{
struct r5conf *conf = mddev->private;
int dd_idx;
@@ -5167,7 +5188,7 @@ void raid5_make_request(struct mddev *mddev, struct bio * bi)
return;
if (unlikely(bi->bi_rw & REQ_DISCARD)) {
- make_discard_request(mddev, bi);
+ make_discard_request(mddev, bi, context);
return;
}
@@ -5295,7 +5316,10 @@ void raid5_make_request(struct mddev *mddev, struct bio * bi)
((bi->bi_rw & REQ_SYNC) || conf->cache) &&
!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
atomic_inc(&conf->preread_active_stripes);
- release_stripe_plug(mddev, sh);
+ if (context)
+ raid5_context_plug(context, sh);
+ else
+ release_stripe_plug(mddev, sh);
} else {
/* cannot get stripe for read-ahead, just give-up */
clear_bit(BIO_UPTODATE, &bi->bi_flags);
@@ -5322,7 +5346,7 @@ static void make_request(struct mddev *mddev, struct bio *bi)
if (conf->cache)
r5c_handle_bio(conf->cache, bi);
else
- raid5_make_request(mddev, bi);
+ raid5_make_request(mddev, bi, NULL);
}
static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 25d9014..2d78f1e 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -608,10 +608,19 @@ static inline int algorithm_is_DDF(int layout)
extern void md_raid5_kick_device(struct r5conf *conf);
extern int raid5_set_cache_size(struct mddev *mddev, int size);
+struct raid5_plug_context {
+ struct list_head list;
+ struct list_head temp_inactive_list[NR_STRIPE_HASH_LOCKS];
+};
+void raid5_context_init(struct raid5_plug_context *context);
+void raid5_context_unplug(struct raid5_plug_context *context,
+ struct mddev *mddev, bool from_schedule);
+
void release_stripe(struct stripe_head *sh);
int r5c_write_parity(struct r5c_cache *cache, struct stripe_head *sh);
void r5c_flush_pending_parity(struct r5c_cache *cache);
-void raid5_make_request(struct mddev *mddev, struct bio *bi);
+void raid5_make_request(struct mddev *mddev, struct bio *bi,
+ struct raid5_plug_context *context);
void r5c_handle_bio(struct r5c_cache *cache, struct bio *bi);
struct r5c_cache *r5c_init_cache(struct r5conf *conf, struct md_rdev *rdev);
void r5c_exit_cache(struct r5c_cache *cache);
--
1.8.1
--
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