From: Eric Sandeen <sandeen@redhat.com>
To: Lukas Czerner <lczerner@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>,
Christoph Hellwig <hch@infradead.org>,
device-mapper development <dm-devel@redhat.com>,
DarkNovaNick@gmail.com, linux-lvm@redhat.com,
linux-ext4@vger.kernel.org, Alasdair G Kergon <agk@redhat.com>
Subject: Re: [linux-lvm] do not disable ext4 discards on first discard failure? [was: Re: dm snapshot: ignore discards issued to the snapshot-origin target]
Date: Mon, 02 May 2011 09:47:16 -0500 [thread overview]
Message-ID: <4DBEC3F4.3050804@redhat.com> (raw)
In-Reply-To: <alpine.LFD.2.00.1105021458480.3778@dhcp-27-109.brq.redhat.com>
On 5/2/11 8:05 AM, Lukas Czerner wrote:
> On Mon, 2 May 2011, Mike Snitzer wrote:
...
>> The blkdev_issue_discard() change you propose could be fine (mask
>> EOPNOTSUPP return if device advertises support for discards) -- though
>> Eric said we shouldn't ever say we did something when we didn't.
>
> Exactly, so we should not say that it is not supported when it is, but
> we just hit the "wrong" part of the device:) I would just very much like
> to keep the abstraction of having one consistent device underneath the
> file system and not deal with several devices, or regions with different
> behaviour in the file system itself (let the pixies underneath deal with
> that, after all not all of us are btrfs:))
I still think we need to stick with the simple rule: "EOPNOTSUPP returned for a particular bio means that it is not supported for that particular bio" - I don't know what else we can do, without creating an ambiguity...
This does, however, suck for the layer calling in to a complex device.
What is the overhead for sending discard bios down to a device that does not support it?
-Eric
next prev parent reply other threads:[~2011-05-02 14:47 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-12 14:59 [linux-lvm] Testing TRIM with LVM DarkNovaNick
2011-04-12 23:47 ` Mike Snitzer
2011-04-13 1:47 ` DarkNovaNick
2011-04-13 8:41 ` Zdenek Kabelac
2011-04-13 15:38 ` DarkNovaNick
2011-04-13 22:40 ` [linux-lvm] [PATCH] dm snapshot: add discard support to the snapshot-origin target [was: Re: Testing TRIM with LVM] Mike Snitzer
2011-04-13 23:48 ` [linux-lvm] " Mike Snitzer
2011-04-26 17:32 ` Mike Snitzer
2011-04-28 0:19 ` [linux-lvm] [PATCH] dm snapshot: ignore discards issued to the snapshot-origin target Mike Snitzer
2011-04-28 7:53 ` [linux-lvm] [dm-devel] " Christoph Hellwig
2011-04-28 20:59 ` [linux-lvm] do not disable ext4 discards on first discard failure? [was: Re: dm snapshot: ignore discards issued to the snapshot-origin target] Mike Snitzer
2011-04-28 21:28 ` Eric Sandeen
2011-04-28 22:59 ` Alasdair G Kergon
2011-04-28 23:01 ` Eric Sandeen
2011-04-28 23:11 ` Alasdair G Kergon
2011-04-29 1:12 ` Andreas Dilger
2011-04-29 13:55 ` Mike Snitzer
2011-04-29 9:30 ` Lukas Czerner
2011-04-29 12:24 ` [linux-lvm] [dm-devel] " Alasdair G Kergon
2011-04-29 12:29 ` Christoph Hellwig
2011-04-29 14:28 ` Eric Sandeen
2011-04-29 15:13 ` Ray Morris
2011-05-04 16:33 ` Ted Ts'o
2011-05-04 17:02 ` Lukas Czerner
2011-05-02 7:16 ` Lukas Czerner
2011-05-02 8:13 ` Alasdair G Kergon
2011-05-02 8:19 ` Christoph Hellwig
2011-05-02 10:24 ` Lukas Czerner
2011-05-02 12:48 ` [linux-lvm] " Mike Snitzer
2011-05-02 13:05 ` Lukas Czerner
2011-05-02 14:47 ` Eric Sandeen [this message]
2011-05-02 14:48 ` Christoph Hellwig
2011-05-02 14:58 ` Lukas Czerner
2011-05-02 13:48 ` [linux-lvm] [dm-devel] " Martin K. Petersen
2011-05-02 14:20 ` Martin K. Petersen
2011-05-02 14:39 ` Lukas Czerner
2011-05-02 14:50 ` Martin K. Petersen
2011-05-02 14:58 ` [linux-lvm] " Mike Snitzer
2011-05-02 16:58 ` [linux-lvm] [dm-devel] " Martin K. Petersen
2011-05-03 8:57 ` Lukas Czerner
2011-05-04 15:10 ` Martin K. Petersen
2011-05-04 16:02 ` [linux-lvm] " Mike Snitzer
2011-05-04 16:50 ` Martin K. Petersen
2011-05-04 18:03 ` Mike Snitzer
2011-05-04 17:10 ` [linux-lvm] [dm-devel] " Lukas Czerner
2011-05-04 17:32 ` Martin K. Petersen
2011-05-04 17:35 ` Lukas Czerner
2011-05-18 12:16 ` [linux-lvm] " Mike Snitzer
2011-05-18 12:52 ` Mike Snitzer
2011-05-04 15:16 ` [linux-lvm] [dm-devel] " Martin K. Petersen
2011-05-04 16:12 ` Lukas Czerner
2011-05-05 8:33 ` Karel Zak
2011-05-05 10:48 ` Lukas Czerner
2011-04-14 15:31 ` [linux-lvm] [PATCH] dm snapshot: add discard support to the snapshot-origin target [was: Re: Testing TRIM wi DarkNovaNick
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