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Subject[patch 18/40] md: raid5: fix clearing of biofill operations

-stable review patch. If anyone has any objections, please let us know.

------------------
From: Dan Williams <dan.j.williams@intel.com>

raid5: fix clearing of biofill operations

This is the correct merge of the two upstream patches for this issue (it
was mis-merged...)

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@intel.com>
Tested-by: Joel Bertrand <joel.bertrand@systella.fr>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/md/raid5.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -377,7 +377,12 @@ static unsigned long get_stripe_work(str
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 *s
}
}
}
- 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
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;
--
-
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