From: Jeff Mahoney <jeffm@suse.com>
To: Duncan <1i5t5.duncan@cox.net>, linux-btrfs@vger.kernel.org
Subject: Re: trim not working and irreparable errors from btrfsck
Date: Fri, 14 Aug 2015 11:11:59 -0400 [thread overview]
Message-ID: <55CE053F.2090805@suse.com> (raw)
In-Reply-To: <pan$e2fd3$4225d55d$123c95d2$8d29df22@cox.net>
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On 6/18/15 1:25 AM, Duncan wrote:
> Austin S Hemmelgarn posted on Wed, 17 Jun 2015 13:17:22 -0400 as
> excerpted:
>
>> On 2015-06-17 11:40, Christian wrote:
>>> On 06/17/2015 11:28 AM, Chris Murphy wrote:
>>>
>>>
>>>>> However, fstrim still gives me "0 B (0 bytes) trimmed, so
>>>>> that may be another problem. Is there a way to check if
>>>>> trim works?
>>>>
>>>> That sounds like maybe your SSD is blacklisted for trim, is
>>>> all I can think of. So trim shouldn't be the cause of the
>>>> problem if it's being blacklisted. The recent problems appear
>>>> to be around newer SSDs that support queue trim and newer
>>>> kernels that issue queued trim. There have been some patches
>>>> related to trim to the kernel, but the existence of
>>>> blacklisting and claims of bugs in firmware make it difficult
>>>> to test and isolate.
>>>>
>>>> http://techreport.com/news/28473/some-samsung-ssds-may-suffer-from-
a-
>
>>>>
buggy-trim-implementation
>>>>
>>>>
>>> This is an Intel SSD in a Lenovo Thinkpad X1 Carbon. Trim
>>> worked until a few weeks ago and still works for my small ext4
>>> boot partition (just ran it to check). I will keep looking for
>>> a solution. Thanks!
>>>
>> I'm seeing the same issue here, but with a Crucial brand SSD.
>> Somewhat interestingly, I don't see any issues like this with
>> BTRFS on top of LVM's thin-provisioning volumes, or with any
>> other filesystems, so I think it has something to do with how
>> BTRFS is reporting unused space or how it is submitting the
>> discard requests.
>
> FWIW, there's a current btrfs patch in progress that relates to
> problems with btrfs trim.
>
> But while I do have SSDs, I purposefully overprovisioned them by
> nearly 100% (IOW I partitioned only about 55%, the rest is entirely
> unused), so trim isn't as critical here as it is for many. I don't
> use the discard mount option, and have a systemd timer job setup to
> automate my fstrims and don't worry about the output too much, so I
> haven't been following the patch progress /that/ closely.
>
> But I do know that recent kernel btrfs trims (either fstrim or
> discard mount option triggered) haven't been working as originally
> intended due to some bug, and this patch is supposed to fix it.
>
> I'd thus conclude that you're very likely hitting this known issue,
> and that either for 4.1 or 4.2 (again, I'm not following progress
> that closely, and don't remember for sure if it's in 4.1, altho
> I've been running the rcs since rc6 or so), the problem should be
> fixed as that patch gets into mainline.
>
> Anyone wishing to investigate further can of course check the list
> (and/ or possibly the kernel's git log) for discard/trim related
> patches and follow the progress once found.
>
> ... Actually, just checked myself. Looks like the patches were
> first posted on March 30 @ 15:12:17 -0400 or so (that's the time
> for one of them). There's one for the discard mount option, and
> another for FITRIM (which may or may not be a typo for FSTRIM, I'm
> not actually sure). Jeff Mahoney <jeffm@suse.com> author. That
> should be enough to find the threads. And I don't see the patches
> in the late 4.1-rc I'm running so either my git log search foo is
> bad or it'll be (at least) 4.2.
It's not a typo. FITRIM is the name of the ioctl that fstrim calls.
The final version of that patch set is ready to go. Mostly. It
probably needs to be re-integrated now. The reason it was delayed for
inclusion is that it makes other bugs more obvious and irrecoverable
since the data is completely gone.
I'm not sure what Chris's timeline for inclusion is.
- -Jeff
- --
Jeff Mahoney
SUSE Labs
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next prev parent reply other threads:[~2015-08-14 15:12 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-16 14:18 trim not working and irreparable errors from btrfsck Christian
2015-06-16 21:14 ` Chris Murphy
[not found] ` <55816E7B.5040905@gmail.com>
2015-06-17 14:22 ` Chris Murphy
2015-06-17 14:33 ` Christian
2015-06-17 15:28 ` Chris Murphy
2015-06-17 15:40 ` Christian
2015-06-17 17:17 ` Austin S Hemmelgarn
2015-06-18 5:25 ` Duncan
2015-08-14 15:11 ` Jeff Mahoney [this message]
2015-06-20 14:11 ` Lutz Euler
2015-06-21 7:21 ` Paul Jones
2015-08-13 9:23 ` Marc Joliet
2015-08-13 23:14 ` Chris Murphy
2015-08-14 8:05 ` Marc Joliet
2015-08-14 8:15 ` Marc Joliet
2015-08-14 10:51 ` Paul Jones
2015-06-18 2:20 ` Paul Jones
2015-06-18 4:15 ` Chris Murphy
2015-06-18 4:19 ` Chris Murphy
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