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Date: Wed, 20 Apr 2022 13:54:17 -0600
From: Logan Gunthorpe <logang@...tatee.com>
To: linux-kernel@...r.kernel.org, linux-raid@...r.kernel.org,
Song Liu <song@...nel.org>
Cc: Christoph Hellwig <hch@...radead.org>,
Guoqing Jiang <guoqing.jiang@...ux.dev>,
Stephen Bates <sbates@...thlin.com>,
Martin Oliveira <Martin.Oliveira@...eticom.com>,
David Sloan <David.Sloan@...eticom.com>,
Logan Gunthorpe <logang@...tatee.com>
Subject: [PATCH v2 04/12] md/raid5: Move common stripe count increment code into __find_stripe()
Both uses of find_stripe() require a fairly complicated dance to
increment the reference count. Move this into a common find_get_stripe()
helper.
No functional changes intended.
Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
---
drivers/md/raid5.c | 133 ++++++++++++++++++++++-----------------------
1 file changed, 65 insertions(+), 68 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 8e1ece5ce984..a0946af5b1ac 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -612,7 +612,7 @@ static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
}
static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
- short generation)
+ short generation, int hash)
{
struct stripe_head *sh;
@@ -624,6 +624,49 @@ static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
return NULL;
}
+static struct stripe_head *find_get_stripe(struct r5conf *conf,
+ sector_t sector, short generation, int hash)
+{
+ int inc_empty_inactive_list_flag;
+ struct stripe_head *sh;
+
+ sh = __find_stripe(conf, sector, generation, hash);
+ if (!sh)
+ return NULL;
+
+ if (atomic_inc_not_zero(&sh->count))
+ return sh;
+
+ /*
+ * Slow path. The reference count is zero which means the stripe must
+ * be on a list (sh->lru). Must remove the stripe from the list that
+ * references it with the device_lock held.
+ */
+
+ spin_lock(&conf->device_lock);
+ if (!atomic_read(&sh->count)) {
+ if (!test_bit(STRIPE_HANDLE, &sh->state))
+ atomic_inc(&conf->active_stripes);
+ BUG_ON(list_empty(&sh->lru) &&
+ !test_bit(STRIPE_EXPANDING, &sh->state));
+ inc_empty_inactive_list_flag = 0;
+ if (!list_empty(conf->inactive_list + hash))
+ inc_empty_inactive_list_flag = 1;
+ list_del_init(&sh->lru);
+ if (list_empty(conf->inactive_list + hash) &&
+ inc_empty_inactive_list_flag)
+ atomic_inc(&conf->empty_inactive_list_nr);
+ if (sh->group) {
+ sh->group->stripes_cnt--;
+ sh->group = NULL;
+ }
+ }
+ atomic_inc(&sh->count);
+ spin_unlock(&conf->device_lock);
+
+ return sh;
+}
+
/*
* Need to check if array has failed when deciding whether to:
* - start an array
@@ -716,7 +759,6 @@ raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
{
struct stripe_head *sh;
int hash = stripe_hash_locks_hash(conf, sector);
- int inc_empty_inactive_list_flag;
pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
@@ -726,57 +768,34 @@ raid5_get_active_stripe(struct r5conf *conf, sector_t sector,
wait_event_lock_irq(conf->wait_for_quiescent,
conf->quiesce == 0 || noquiesce,
*(conf->hash_locks + hash));
- sh = __find_stripe(conf, sector, conf->generation - previous);
- if (!sh) {
- if (!test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state)) {
- sh = get_free_stripe(conf, hash);
- if (!sh && !test_bit(R5_DID_ALLOC,
- &conf->cache_state))
- set_bit(R5_ALLOC_MORE,
- &conf->cache_state);
- }
- if (noblock && sh == NULL)
- break;
+ sh = find_get_stripe(conf, sector, conf->generation - previous,
+ hash);
+ if (sh)
+ break;
- r5c_check_stripe_cache_usage(conf);
- if (!sh) {
- set_bit(R5_INACTIVE_BLOCKED,
- &conf->cache_state);
- r5l_wake_reclaim(conf->log, 0);
- wait_event_lock_irq(
- conf->wait_for_stripe,
+ if (!test_bit(R5_INACTIVE_BLOCKED, &conf->cache_state)) {
+ sh = get_free_stripe(conf, hash);
+ if (!sh && !test_bit(R5_DID_ALLOC, &conf->cache_state))
+ set_bit(R5_ALLOC_MORE, &conf->cache_state);
+ }
+ if (noblock && !sh)
+ break;
+
+ r5c_check_stripe_cache_usage(conf);
+ if (!sh) {
+ set_bit(R5_INACTIVE_BLOCKED, &conf->cache_state);
+ r5l_wake_reclaim(conf->log, 0);
+ wait_event_lock_irq(conf->wait_for_stripe,
!list_empty(conf->inactive_list + hash) &&
(atomic_read(&conf->active_stripes)
< (conf->max_nr_stripes * 3 / 4)
|| !test_bit(R5_INACTIVE_BLOCKED,
&conf->cache_state)),
*(conf->hash_locks + hash));
- clear_bit(R5_INACTIVE_BLOCKED,
- &conf->cache_state);
- } else {
- init_stripe(sh, sector, previous);
- atomic_inc(&sh->count);
- }
- } else if (!atomic_inc_not_zero(&sh->count)) {
- spin_lock(&conf->device_lock);
- if (!atomic_read(&sh->count)) {
- if (!test_bit(STRIPE_HANDLE, &sh->state))
- atomic_inc(&conf->active_stripes);
- BUG_ON(list_empty(&sh->lru) &&
- !test_bit(STRIPE_EXPANDING, &sh->state));
- inc_empty_inactive_list_flag = 0;
- if (!list_empty(conf->inactive_list + hash))
- inc_empty_inactive_list_flag = 1;
- list_del_init(&sh->lru);
- if (list_empty(conf->inactive_list + hash) && inc_empty_inactive_list_flag)
- atomic_inc(&conf->empty_inactive_list_nr);
- if (sh->group) {
- sh->group->stripes_cnt--;
- sh->group = NULL;
- }
- }
+ clear_bit(R5_INACTIVE_BLOCKED, &conf->cache_state);
+ } else {
+ init_stripe(sh, sector, previous);
atomic_inc(&sh->count);
- spin_unlock(&conf->device_lock);
}
} while (sh == NULL);
@@ -830,7 +849,6 @@ static void stripe_add_to_batch_list(struct r5conf *conf, struct stripe_head *sh
sector_t head_sector, tmp_sec;
int hash;
int dd_idx;
- int inc_empty_inactive_list_flag;
/* Don't cross chunks, so stripe pd_idx/qd_idx is the same */
tmp_sec = sh->sector;
@@ -840,28 +858,7 @@ static void stripe_add_to_batch_list(struct r5conf *conf, struct stripe_head *sh
hash = stripe_hash_locks_hash(conf, head_sector);
spin_lock_irq(conf->hash_locks + hash);
- head = __find_stripe(conf, head_sector, conf->generation);
- if (head && !atomic_inc_not_zero(&head->count)) {
- spin_lock(&conf->device_lock);
- if (!atomic_read(&head->count)) {
- if (!test_bit(STRIPE_HANDLE, &head->state))
- atomic_inc(&conf->active_stripes);
- BUG_ON(list_empty(&head->lru) &&
- !test_bit(STRIPE_EXPANDING, &head->state));
- inc_empty_inactive_list_flag = 0;
- if (!list_empty(conf->inactive_list + hash))
- inc_empty_inactive_list_flag = 1;
- list_del_init(&head->lru);
- if (list_empty(conf->inactive_list + hash) && inc_empty_inactive_list_flag)
- atomic_inc(&conf->empty_inactive_list_nr);
- if (head->group) {
- head->group->stripes_cnt--;
- head->group = NULL;
- }
- }
- atomic_inc(&head->count);
- spin_unlock(&conf->device_lock);
- }
+ head = find_get_stripe(conf, head_sector, conf->generation, hash);
spin_unlock_irq(conf->hash_locks + hash);
if (!head)
--
2.30.2
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