xfs
[Top] [All Lists]

Re: Ext4 and xfs problems in dm-thin on allocation and discard

To: Lukáš Czerner <lczerner@xxxxxxxxxx>
Subject: Re: Ext4 and xfs problems in dm-thin on allocation and discard
From: Spelic <spelic@xxxxxxxxxxxxx>
Date: Tue, 19 Jun 2012 13:29:55 +0200
Cc: Mike Snitzer <snitzer@xxxxxxxxxx>, Dave Chinner <david@xxxxxxxxxxxxx>, Spelic <spelic@xxxxxxxxxxxxx>, device-mapper development <dm-devel@xxxxxxxxxx>, linux-ext4@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx
In-reply-to: <alpine.LFD.2.00.1206190816440.2241@xxxxxxxxxxxxxxxxxxxxxxxxx>
References: <4FDF9EBE.2030809@xxxxxxxxxxxxx> <20120619015745.GJ25389@dastard> <20120619031241.GA3884@xxxxxxxxxx> <alpine.LFD.2.00.1206190816440.2241@xxxxxxxxxxxxxxxxxxxxxxxxx>
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.2) Gecko/20120216 Thunderbird/10.0.2
On 06/19/12 08:32, Lukáš Czerner wrote:

So do I understand correctly that even though the discard came
through and thinp took advantage of it it still returns EOPNOTSUPP ?
This seems rather suboptimal. IIRC there was a discussion to add an
option to enable/disable sending discard in thinp target down
to the device.

I'll ask this too...
do I understand correctly that dm-thin returns EOPNOTSUPP to the filesystem layer even though it is using the discard to unmap blocks, and at that point XFS stops sending discards down there (while ext4 keeps sending them)?

This looks like a bug of dm-thin to me. Discards are "supported" in such a scenario.

Do you have a patch for dm-thin so to prevent it sending EOPTNOTSUPP ?

Thank you
S.

<Prev in Thread] Current Thread [Next in Thread>