Bcache power loss

Bcache power loss

[Stefan Priebe - Profihost AG]

Has anybody ever tested bcache against power loss?

Stefan

Re: Bcache power loss

[Eric Wheeler]

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> Has anybody ever tested bcache against power loss?

We have had to hard reset our machine many times during the process of 
troubleshooting various lockups that have been since resolved by some of 
the patches posted to this list (attached).

I did notice in the logs that it said something about replaying 
transactions when it came up after a hard reset, so that is promising. 
Still, we reformatted all of our bcache volumes after the lockups were 
resolved just to make sure that there were no unexpected side effects and 
have not had any issues since.

 
> Stefan
> --
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> 

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: Type: TEXT/x-diff; name=bcache-rcu-sched-bugfix.patch, Size: 498 bytes --]

diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 00cde40..d14560a 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -2162,8 +2162,10 @@ int bch_btree_insert_check_key(struct btree *b, struct btree_op *op,
 		rw_lock(true, b, b->level);
 
 		if (b->key.ptr[0] != btree_ptr ||
-		    b->seq != seq + 1)
+		    b->seq != seq + 1) {
+			op->lock = b->c->root->level + 1;
 			goto out;
+		}
 	}
 
 	SET_KEY_PTRS(check_key, 1);
-- 
1.7.1

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #3: Type: TEXT/x-diff; name=bcache-cond_resched.patch, Size: 334 bytes --]

--- a/drivers/md/bcache/btree.c	2014-11-03 16:51:01.720000000 -0800
+++ b/drivers/md/bcache/btree.c	2014-11-03 16:51:26.456000000 -0800
@@ -1741,6 +1741,7 @@
 	do {
 		ret = btree_root(gc_root, c, &op, &writes, &stats);
 		closure_sync(&writes);
+		cond_resched();
 
 		if (ret && ret != -EAGAIN)
 			pr_warn("gc failed!");

Re: Bcache power loss

[Stefan Priebe]

Great, thanks!

Kent any chance to get those upstream? A lot of people really like 
bcache and even rely on it. It would be great to have a stable version 
in the kernel.

Greets,
Stefan
Am 31.12.2014 um 21:46 schrieb Eric Wheeler:
>> Has anybody ever tested bcache against power loss?
>
> We have had to hard reset our machine many times during the process of
> troubleshooting various lockups that have been since resolved by some of
> the patches posted to this list (attached).
>
> I did notice in the logs that it said something about replaying
> transactions when it came up after a hard reset, so that is promising.
> Still, we reformatted all of our bcache volumes after the lockups were
> resolved just to make sure that there were no unexpected side effects and
> have not had any issues since.
>
>
>> Stefan
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-bcache" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html