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From: David Sterba <dsterba@suse.cz>
To: Johannes Thumshirn <Johannes.Thumshirn@wdc.com>
Cc: David Sterba <dsterba@suse.com>,
	"linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>,
	Filipe Manana <fdmanana@suse.com>,
	Naohiro Aota <Naohiro.Aota@wdc.com>
Subject: Re: [PATCH] btrfs: zoned: exclude relocation and page writeback
Date: Wed, 18 Aug 2021 11:36:48 +0200	[thread overview]
Message-ID: <20210818093648.GP5047@suse.cz> (raw)
In-Reply-To: <PH0PR04MB741690FBBB6A43279E9F1ED89BFE9@PH0PR04MB7416.namprd04.prod.outlook.com>

On Tue, Aug 17, 2021 at 02:21:51PM +0000, Johannes Thumshirn wrote:
> On 12/08/2021 16:53, David Sterba wrote:
> > On Thu, Aug 12, 2021 at 02:40:59PM +0000, Johannes Thumshirn wrote:
> >> On 12/08/2021 16:28, David Sterba wrote:

> I did some testing with the inode lock and it looks good but does not 
> necessarily fix all possible problems, i.e. if a ordered extent is being
> split due to whatever device limits (zone append, max sector size, etc),
> the assumptions we have in relocation code aren't met again.
> 
> So the heavy lifting solution with having a dedicated temporary relocation
> block group (like the treelog block group we already have for zoned) and using
> regular writes looks like the only solution taking care of all of these problems.

So that means that the minimum number of zones increases again, right.
If the separate relocation zone fixes this and possibly other problems
then fine, but as you said this is heavy weight solution.

We will need a mechanims with a spare block group/zone for emergency
cases where we're running out of usable metadata space and need to
relocate so this could be building on the same framework. But for first
implementation reserving another block group sounds easier.

  reply	other threads:[~2021-08-18  9:39 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-12 13:53 [PATCH] btrfs: zoned: exclude relocation and page writeback Johannes Thumshirn
2021-08-12 14:25 ` David Sterba
2021-08-12 14:40   ` Johannes Thumshirn
2021-08-12 14:50     ` David Sterba
2021-08-17 14:21       ` Johannes Thumshirn
2021-08-18  9:36         ` David Sterba [this message]
2021-08-18  9:55           ` Johannes Thumshirn

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