From: "hch@infradead.org" <hch@infradead.org>
To: Johannes Thumshirn <Johannes.Thumshirn@wdc.com>
Cc: Qu Wenruo <quwenruo.btrfs@gmx.com>,
"hch@infradead.org" <hch@infradead.org>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>,
"dm-devel@redhat.com" <dm-devel@redhat.com>,
"linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>
Subject: Re: Any bio_clone_slow() implementation which doesn't share bi_io_vec?
Date: Tue, 23 Nov 2021 06:28:28 -0800 [thread overview]
Message-ID: <YZz6jAVXun8yC/6k@infradead.org> (raw)
In-Reply-To: <PH0PR04MB74169757F9CF740289B790C49B609@PH0PR04MB7416.namprd04.prod.outlook.com>
On Tue, Nov 23, 2021 at 11:39:11AM +0000, Johannes Thumshirn wrote:
> I think we have to differentiate two cases here:
> A "regular" REQ_OP_ZONE_APPEND bio and a RAID stripe REQ_OP_ZONE_APPEND
> bio. The 1st one (i.e. the regular REQ_OP_ZONE_APPEND bio) can't be split
> because we cannot guarantee the order the device writes the data to disk.
> For the RAID stripe bio we can split it into the two (or more) parts that
> will end up on _different_ devices. All we need to do is a) ensure it
> doesn't cross the device's zone append limit and b) clamp all
> bi_iter.bi_sector down to the start of the target zone, a.k.a sticking to
> the rules of REQ_OP_ZONE_APPEND.
Exactly. A stacking driver must never split a REQ_OP_ZONE_APPEND bio.
But the file system itself can of course split it as long as each split
off bio has it's own bi_end_io handler to record where it has been
written to.
next prev parent reply other threads:[~2021-11-23 14:28 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-23 6:44 Any bio_clone_slow() implementation which doesn't share bi_io_vec? Qu Wenruo
2021-11-23 7:43 ` Christoph Hellwig
2021-11-23 8:10 ` Qu Wenruo
2021-11-23 8:13 ` Christoph Hellwig
2021-11-23 11:09 ` Qu Wenruo
2021-11-23 11:39 ` Johannes Thumshirn
2021-11-23 14:28 ` hch [this message]
2021-11-23 23:07 ` Qu Wenruo
2021-11-24 6:09 ` hch
2021-11-24 6:18 ` Qu Wenruo
2021-11-24 7:02 ` hch
2021-11-24 7:22 ` hch
2021-11-24 7:25 ` Naohiro Aota
2021-11-24 7:39 ` Qu Wenruo
2021-11-26 12:33 ` Qu Wenruo
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