Add a per-stripe lock to protect stripe specific data, like dev->read,
written, ... The purpose is to reduce lock contention of conf->device_lock.
Signed-off-by: Shaohua Li <shli@xxxxxxxxxxxx>
---
drivers/md/raid5.c | 17 +++++++++++++++++
drivers/md/raid5.h | 1 +
2 files changed, 18 insertions(+)
Index: linux/drivers/md/raid5.c
===================================================================
--- linux.orig/drivers/md/raid5.c 2012-06-06 09:35:56.338257401 +0800
+++ linux/drivers/md/raid5.c 2012-06-13 08:37:43.005641057 +0800
@@ -749,6 +749,7 @@ static void ops_complete_biofill(void *s
/* clear completed biofills */
spin_lock_irq(&conf->device_lock);
+ spin_lock(&sh->stripe_lock);
for (i = sh->disks; i--; ) {
struct r5dev *dev = &sh->dev[i];
@@ -774,6 +775,7 @@ static void ops_complete_biofill(void *s
}
}
}
+ spin_unlock(&sh->stripe_lock);
spin_unlock_irq(&conf->device_lock);
clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
@@ -798,8 +800,10 @@ static void ops_run_biofill(struct strip
if (test_bit(R5_Wantfill, &dev->flags)) {
struct bio *rbi;
spin_lock_irq(&conf->device_lock);
+ spin_lock(&sh->stripe_lock);
dev->read = rbi = dev->toread;
dev->toread = NULL;
+ spin_unlock(&sh->stripe_lock);
spin_unlock_irq(&conf->device_lock);
while (rbi && rbi->bi_sector <
dev->sector + STRIPE_SECTORS) {
@@ -1137,10 +1141,12 @@ ops_run_biodrain(struct stripe_head *sh,
struct bio *wbi;
spin_lock_irq(&sh->raid_conf->device_lock);
+ spin_lock(&sh->stripe_lock);
chosen = dev->towrite;
dev->towrite = NULL;
BUG_ON(dev->written);
wbi = dev->written = chosen;
+ spin_unlock(&sh->stripe_lock);
spin_unlock_irq(&sh->raid_conf->device_lock);
while (wbi && wbi->bi_sector <
@@ -1446,6 +1452,8 @@ static int grow_one_stripe(struct r5conf
init_waitqueue_head(&sh->ops.wait_for_ops);
#endif
+ spin_lock_init(&sh->stripe_lock);
+
if (grow_buffers(sh)) {
shrink_buffers(sh);
kmem_cache_free(conf->slab_cache, sh);
@@ -2327,6 +2335,7 @@ static int add_stripe_bio(struct stripe_
spin_lock_irq(&conf->device_lock);
+ spin_lock(&sh->stripe_lock);
if (forwrite) {
bip = &sh->dev[dd_idx].towrite;
if (*bip == NULL && sh->dev[dd_idx].written == NULL)
@@ -2360,6 +2369,7 @@ static int add_stripe_bio(struct stripe_
if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
}
+ spin_unlock(&sh->stripe_lock);
spin_unlock_irq(&conf->device_lock);
pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
@@ -2376,6 +2386,7 @@ static int add_stripe_bio(struct stripe_
overlap:
set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
+ spin_unlock(&sh->stripe_lock);
spin_unlock_irq(&conf->device_lock);
return 0;
}
@@ -2427,6 +2438,7 @@ handle_failed_stripe(struct r5conf *conf
}
}
spin_lock_irq(&conf->device_lock);
+ spin_lock(&sh->stripe_lock);
/* fail all writes first */
bi = sh->dev[i].towrite;
sh->dev[i].towrite = NULL;
@@ -2488,6 +2500,7 @@ handle_failed_stripe(struct r5conf *conf
bi = nextbi;
}
}
+ spin_unlock(&sh->stripe_lock);
spin_unlock_irq(&conf->device_lock);
if (bitmap_end)
bitmap_endwrite(conf->mddev->bitmap, sh->sector,
@@ -2695,6 +2708,7 @@ static void handle_stripe_clean_event(st
int bitmap_end = 0;
pr_debug("Return write for disc %d\n", i);
spin_lock_irq(&conf->device_lock);
+ spin_lock(&sh->stripe_lock);
wbi = dev->written;
dev->written = NULL;
while (wbi && wbi->bi_sector <
@@ -2709,6 +2723,7 @@ static void handle_stripe_clean_event(st
}
if (dev->towrite == NULL)
bitmap_end = 1;
+ spin_unlock(&sh->stripe_lock);
spin_unlock_irq(&conf->device_lock);
if (bitmap_end)
bitmap_endwrite(conf->mddev->bitmap,
@@ -3168,6 +3183,7 @@ static void analyse_stripe(struct stripe
/* Now to look around and see what can be done */
rcu_read_lock();
spin_lock_irq(&conf->device_lock);
+ spin_lock(&sh->stripe_lock);
for (i=disks; i--; ) {
struct md_rdev *rdev;
sector_t first_bad;
@@ -3313,6 +3329,7 @@ static void analyse_stripe(struct stripe
do_recovery = 1;
}
}
+ spin_unlock(&sh->stripe_lock);
spin_unlock_irq(&conf->device_lock);
if (test_bit(STRIPE_SYNCING, &sh->state)) {
/* If there is a failed device being replaced,
Index: linux/drivers/md/raid5.h
===================================================================
--- linux.orig/drivers/md/raid5.h 2012-06-06 09:35:56.350257250 +0800
+++ linux/drivers/md/raid5.h 2012-06-13 08:34:13.660272415 +0800
@@ -210,6 +210,7 @@ struct stripe_head {
int disks; /* disks in stripe */
enum check_states check_state;
enum reconstruct_states reconstruct_state;
+ spinlock_t stripe_lock;
/**
* struct stripe_operations
* @target - STRIPE_OP_COMPUTE_BLK target
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