On Wed, 2007-10-17 at 09:44 -0700, BERTRAND Joël wrote:
> Dan,
>
> I have modified get_stripe_work like this :
>
> static unsigned long get_stripe_work(struct stripe_head *sh)
> {
> unsigned long pending;
> int ack = 0;
> int a,b,c,d,e,f,g;
>
> pending = sh->ops.pending;
>
> test_and_ack_op(STRIPE_OP_BIOFILL, pending);
> a=ack;
> test_and_ack_op(STRIPE_OP_COMPUTE_BLK, pending);
> b=ack;
> test_and_ack_op(STRIPE_OP_PREXOR, pending);
> c=ack;
> test_and_ack_op(STRIPE_OP_BIODRAIN, pending);
> d=ack;
> test_and_ack_op(STRIPE_OP_POSTXOR, pending);
> e=ack;
> test_and_ack_op(STRIPE_OP_CHECK, pending);
> f=ack;
> if (test_and_clear_bit(STRIPE_OP_IO, &sh->ops.pending))
> ack++;
> g=ack;
>
> sh->ops.count -= ack;
>
> if (sh->ops.count<0) printk("%d %d %d %d %d %d %d\n",
> a,b,c,d,e,f,g);
> BUG_ON(sh->ops.count < 0);
>
> return pending;
> }
>
> and I obtain on console :
>
> 1 1 1 1 1 2
> kernel BUG at drivers/md/raid5.c:390!
> \|/ ____ \|/
> "@'/ .. \`@"
> /_| \__/ |_\
> \__U_/
> md7_resync(5409): Kernel bad sw trap 5 [#1]
>
> If that can help you...
>
> JKB
This gives more evidence that it is probably mishandling of
STRIPE_OP_BIOFILL. The attached patch (replacing the previous) moves
the clearing of these bits into handle_stripe5 and adds some debug
information.
--
Dan
raid5: fix clearing of biofill operations (try2)
From: Dan Williams <dan.j.williams@xxxxxxxxx>
ops_complete_biofill() runs outside of spin_lock(&sh->lock) and clears the
'pending' and 'ack' bits. Since the test_and_ack_op() macro only checks
against 'complete' it can get an inconsistent snapshot of pending work.
Move the clearing of these bits to handle_stripe5(), under the lock.
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/md/raid5.c | 17 ++++++++++++++---
1 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index f96dea9..3808f52 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -377,7 +377,12 @@ static unsigned long get_stripe_work(struct stripe_head *sh)
ack++;
sh->ops.count -= ack;
- BUG_ON(sh->ops.count < 0);
+ if (unlikely(sh->ops.count < 0)) {
+ printk(KERN_ERR "pending: %#lx ops.pending: %#lx ops.ack: %#lx "
+ "ops.complete: %#lx\n", pending, sh->ops.pending,
+ sh->ops.ack, sh->ops.complete);
+ BUG();
+ }
return pending;
}
@@ -551,8 +556,7 @@ static void ops_complete_biofill(void *stripe_head_ref)
}
}
}
- clear_bit(STRIPE_OP_BIOFILL, &sh->ops.ack);
- clear_bit(STRIPE_OP_BIOFILL, &sh->ops.pending);
+ set_bit(STRIPE_OP_BIOFILL, &sh->ops.complete);
return_io(return_bi);
@@ -2630,6 +2634,13 @@ static void handle_stripe5(struct stripe_head *sh)
s.expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
/* Now to look around and see what can be done */
+ /* clean-up completed biofill operations */
+ if (test_bit(STRIPE_OP_BIOFILL, &sh->ops.complete)) {
+ clear_bit(STRIPE_OP_BIOFILL, &sh->ops.pending);
+ clear_bit(STRIPE_OP_BIOFILL, &sh->ops.ack);
+ clear_bit(STRIPE_OP_BIOFILL, &sh->ops.complete);
+ }
+
rcu_read_lock();
for (i=disks; i--; ) {
mdk_rdev_t *rdev;
