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Date:   Mon, 24 Apr 2023 08:01:39 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Damien Le Moal <dlemoal@kernel.org>
Cc:     Jaegeuk Kim <jaegeuk@kernel.org>,
        Bart Van Assche <bvanassche@acm.org>,
        Niklas Cassel <nks@flawful.org>, Jens Axboe <axboe@kernel.dk>,
        linux-block@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
        Ming Lei <ming.lei@redhat.com>,
        Matias Bjorling <mb@lightnvm.io>
Subject: Re: [PATCH v2 10/11] block: Add support for the zone capacity
 concept
Message-ID: <20230424060139.GA9805@lst.de>
References: <f9d35d19-d0ba-fcb7-e44b-f0b8c55ba399@acm.org> <141aee35-4288-1670-6424-e6c41c8ef4c9@kernel.org> <ec7cdc7d-9eb7-65a4-6ba9-1ae6cf6f43d2@acm.org> <a5d9a370-6264-ebdf-f9f8-7b3263c2b6f0@kernel.org> <490ed061-6d82-f9fb-2050-4a386e2e4c8e@acm.org> <c4a52bff-5cab-5029-ad7f-e5f9452bc0e2@kernel.org> <ZEHY2PIRCCLOZsC4@google.com> <c12582e0-f2c8-d001-1fc1-6f7e17eeba7c@kernel.org> <ZELu0yKwnGg3iBmA@google.com> <335b63b0-5a9e-472d-2cce-c0158ae93cf3@kernel.org>
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On Sat, Apr 22, 2023 at 07:25:33AM +0900, Damien Le Moal wrote:
> >> for allocating blocks. This is a resource management issue.
> > 
> > Ok, so it seems I overlooked there might be something in the zone allocation
> > policy. So, f2fs already manages 6 open zones by design.
> 
> Yes, so as long as the device allows for at least 6 active zones, there are no
> issues with f2fs.

I don't think it's quite as rosy, because f2fs can still schedule
I/O to the old zone after already scheduling I/O to a new zone for
any of these 6 slots.  It'll need code to wait for all I/O to the old
zone to finish first, similar to btrfs.