From: Alex Elder <aelder@sgi.com>
To: Lukas Czerner <lczerner@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>, xfs@oss.sgi.com
Subject: Re: [PATCH 1/4] xfs: add online discard support
Date: Fri, 20 May 2011 08:57:17 -0500 [thread overview]
Message-ID: <1305899837.3976.27.camel@doink> (raw)
In-Reply-To: <alpine.LFD.2.00.1105201330360.5226@dhcp-27-109.brq.redhat.com>
On Fri, 2011-05-20 at 13:43 +0200, Lukas Czerner wrote:
> On Fri, 20 May 2011, Christoph Hellwig wrote:
>
> > On Thu, May 19, 2011 at 04:53:44PM -0500, Alex Elder wrote:
> > > The first is, why not support it for non-delaylog?
> >
> > Because:
> >
. . .
> >
> > It's a bad idea to do the sort twice for no good reason, and adding
> > another parameter to further overload xfs_alloc_busy_clear behaviour
> > doesn't seem smart either.
> >
> > > if (error == EOPNOTSUPP) {
> > > /*
> > > * Report this once per mount point somehow?
> Actually, this is a good idea see https://lkml.org/lkml/2011/5/5/162. So
> you will get EOPNOTSUPP *only* if the device (as a whole) does not
> support discard.
I.e., if *any* component of the underlying storage supports
discard, the aggregate device supports discard. (Rather than
only if *all* components support it.) This seems pretty reasonable.
> > > * If so, turn off the mount option?
> Not so good idea, as some people mentioned several times, you can change
> the devices in dmsetup to SSD (for example) without umount and you would
> like your previous mount option to work. In the opposite case, the user
> just gets warning (once a day perhaps?) and its up to him to deal with
> it.
Sorry, I wasn't following that discussion closely.
> Or, we can turn it of (with warning) and rely on the user to notice that
> it is turned off. But I would rather not rely on that.
I agree with you. I didn't realize the underlying storage could
change attributes without notification of some kind. The FS layer
might benefit from knowing when such changes take place.
-Alex
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next prev parent reply other threads:[~2011-05-20 13:57 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-04 18:55 [PATCH 0/4] online discard support V3 Christoph Hellwig
2011-05-04 18:55 ` [PATCH 1/4] xfs: add online discard support Christoph Hellwig
2011-05-19 21:53 ` Alex Elder
2011-05-20 10:24 ` Christoph Hellwig
2011-05-20 11:43 ` Lukas Czerner
2011-05-20 13:57 ` Alex Elder [this message]
2011-05-20 13:40 ` Alex Elder
2011-05-20 13:45 ` [PATCH 1/4 v2] " Christoph Hellwig
2011-05-20 15:42 ` Alex Elder
2011-05-04 18:55 ` [PATCH 2/4] xfs: do not discard alloc btree blocks Christoph Hellwig
2011-05-19 21:54 ` Alex Elder
2011-05-04 18:55 ` [PATCH 3/4] xfs: add a reference count to the CIL context Christoph Hellwig
2011-05-19 21:54 ` Alex Elder
2011-05-20 10:25 ` Christoph Hellwig
2011-05-04 18:55 ` [PATCH 4/4] xfs: make discard operations asynchronous Christoph Hellwig
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