sh->lock is now mainly used to ensure that two threads aren't running
in the locked part of handle_stripe[56] at the same time.
That can more neatly be achieved with an 'active' flag which we set
while running handle_stripe. If we find the flag is set, we simply
requeue the stripe for later by setting STRIPE_HANDLE.
For safety we take ->device_lock while examining the state of the
stripe and creating a summary in 'stripe_head_state / r6_state'.
This possibly isn't needed but as shared fields like ->toread,
->towrite are checked it is safer for now at least.
We leave the label after the old 'unlock' called "unlock" because it
will disappear in a few patches, so renaming seems pointless.
This leaves the stripe 'locked' for longer as we clear STRIPE_ACTIVE
later, but that is not a problem.
Signed-off-by: NeilBrown <neilb@xxxxxxx>
---
drivers/md/raid5.c | 26 +++++++++++++-------------
drivers/md/raid5.h | 2 +-
2 files changed, 14 insertions(+), 14 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 9985138..f8275b5 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1020,14 +1020,12 @@ ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
if (test_and_clear_bit(R5_Wantdrain, &dev->flags)) {
struct bio *wbi;
- spin_lock(&sh->lock);
spin_lock_irq(&sh->raid_conf->device_lock);
chosen = dev->towrite;
dev->towrite = NULL;
BUG_ON(dev->written);
wbi = dev->written = chosen;
spin_unlock_irq(&sh->raid_conf->device_lock);
- spin_unlock(&sh->lock);
while (wbi && wbi->bi_sector <
dev->sector + STRIPE_SECTORS) {
@@ -1322,7 +1320,6 @@ static int grow_one_stripe(raid5_conf_t *conf)
return 0;
sh->raid_conf = conf;
- spin_lock_init(&sh->lock);
#ifdef CONFIG_MULTICORE_RAID456
init_waitqueue_head(&sh->ops.wait_for_ops);
#endif
@@ -1442,7 +1439,6 @@ static int resize_stripes(raid5_conf_t *conf, int newsize)
break;
nsh->raid_conf = conf;
- spin_lock_init(&nsh->lock);
#ifdef CONFIG_MULTICORE_RAID456
init_waitqueue_head(&nsh->ops.wait_for_ops);
#endif
@@ -2148,7 +2144,6 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in
(unsigned long long)sh->sector);
- spin_lock(&sh->lock);
spin_lock_irq(&conf->device_lock);
if (forwrite) {
bip = &sh->dev[dd_idx].towrite;
@@ -2184,7 +2179,6 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in
set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
}
spin_unlock_irq(&conf->device_lock);
- spin_unlock(&sh->lock);
pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
(unsigned long long)(*bip)->bi_sector,
@@ -2201,7 +2195,6 @@ static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, in
overlap:
set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
spin_unlock_irq(&conf->device_lock);
- spin_unlock(&sh->lock);
return 0;
}
@@ -3023,12 +3016,10 @@ static void handle_stripe5(struct stripe_head *sh)
atomic_read(&sh->count), sh->pd_idx, sh->check_state,
sh->reconstruct_state);
- spin_lock(&sh->lock);
if (test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
set_bit(STRIPE_SYNCING, &sh->state);
clear_bit(STRIPE_INSYNC, &sh->state);
}
- clear_bit(STRIPE_HANDLE, &sh->state);
clear_bit(STRIPE_DELAYED, &sh->state);
s.syncing = test_bit(STRIPE_SYNCING, &sh->state);
@@ -3037,6 +3028,7 @@ static void handle_stripe5(struct stripe_head *sh)
/* Now to look around and see what can be done */
rcu_read_lock();
+ spin_lock_irq(&conf->device_lock);
for (i=disks; i--; ) {
mdk_rdev_t *rdev;
@@ -3099,6 +3091,7 @@ static void handle_stripe5(struct stripe_head *sh)
s.failed_num = i;
}
}
+ spin_unlock_irq(&conf->device_lock);
rcu_read_unlock();
if (unlikely(blocked_rdev)) {
@@ -3275,7 +3268,6 @@ static void handle_stripe5(struct stripe_head *sh)
handle_stripe_expansion(conf, sh, NULL);
unlock:
- spin_unlock(&sh->lock);
/* wait for this device to become unblocked */
if (unlikely(blocked_rdev))
@@ -3318,12 +3310,10 @@ static void handle_stripe6(struct stripe_head *sh)
sh->check_state, sh->reconstruct_state);
memset(&s, 0, sizeof(s));
- spin_lock(&sh->lock);
if (test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
set_bit(STRIPE_SYNCING, &sh->state);
clear_bit(STRIPE_INSYNC, &sh->state);
}
- clear_bit(STRIPE_HANDLE, &sh->state);
clear_bit(STRIPE_DELAYED, &sh->state);
s.syncing = test_bit(STRIPE_SYNCING, &sh->state);
@@ -3332,6 +3322,7 @@ static void handle_stripe6(struct stripe_head *sh)
/* Now to look around and see what can be done */
rcu_read_lock();
+ spin_lock_irq(&conf->device_lock);
for (i=disks; i--; ) {
mdk_rdev_t *rdev;
dev = &sh->dev[i];
@@ -3395,6 +3386,7 @@ static void handle_stripe6(struct stripe_head *sh)
s.failed++;
}
}
+ spin_unlock_irq(&conf->device_lock);
rcu_read_unlock();
if (unlikely(blocked_rdev)) {
@@ -3580,7 +3572,6 @@ static void handle_stripe6(struct stripe_head *sh)
handle_stripe_expansion(conf, sh, &r6s);
unlock:
- spin_unlock(&sh->lock);
/* wait for this device to become unblocked */
if (unlikely(blocked_rdev))
@@ -3608,10 +3599,19 @@ static void handle_stripe6(struct stripe_head *sh)
static void handle_stripe(struct stripe_head *sh)
{
+ clear_bit(STRIPE_HANDLE, &sh->state);
+ if (test_and_set_bit(STRIPE_ACTIVE, &sh->state)) {
+ /* already being handled, ensure it gets handled
+ * again when current action finishes */
+ set_bit(STRIPE_HANDLE, &sh->state);
+ return;
+ }
+
if (sh->raid_conf->level == 6)
handle_stripe6(sh);
else
handle_stripe5(sh);
+ clear_bit(STRIPE_ACTIVE, &sh->state);
}
static void raid5_activate_delayed(raid5_conf_t *conf)
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index a330011..217a9d4 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -209,7 +209,6 @@ struct stripe_head {
short ddf_layout;/* use DDF ordering to calculate Q */
unsigned long state; /* state flags */
atomic_t count; /* nr of active thread/requests */
- spinlock_t lock;
int bm_seq; /* sequence number for bitmap flushes */
int disks; /* disks in stripe */
enum check_states check_state;
@@ -290,6 +289,7 @@ struct r6_state {
* Stripe state
*/
enum {
+ STRIPE_ACTIVE,
STRIPE_HANDLE,
STRIPE_SYNC_REQUESTED,
STRIPE_SYNCING,
--
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