From: Christoph Hellwig <hch@lst.de>
To: Coly Li <colyli@suse.de>
Cc: Christoph Hellwig <hch@lst.de>,
linux-block@vger.kernel.org, damien.lemoal@wdc.com,
hare@suse.com, axboe@kernel.dk, linux-bcache@vger.kernel.org,
kbusch@kernel.org, Hannes Reinecke <hare@suse.de>,
Jens Axboe <axboe@fb.com>,
Johannes Thumshirn <johannes.thumshirn@wdc.com>,
Shaun Tancheff <shaun.tancheff@seagate.com>
Subject: Re: [RFC PATCH v2 1/4] block: change REQ_OP_ZONE_RESET from 6 to 13
Date: Sat, 16 May 2020 17:36:49 +0200 [thread overview]
Message-ID: <20200516153649.GB16693@lst.de> (raw)
In-Reply-To: <f57da1e7-1563-db1e-8730-8daca219cbe7@suse.de>
On Sat, May 16, 2020 at 09:05:39PM +0800, Coly Li wrote:
> On 2020/5/16 20:50, Christoph Hellwig wrote:
> > On Sat, May 16, 2020 at 08:44:45PM +0800, Coly Li wrote:
> >> Yes you are right, just like REQ_OP_DISCARD which does not transfer any
> >> data but changes the data on device. If the request changes the stored
> >> data, it does transfer data.
> >
> > REQ_OP_DISCARD is a special case, because most implementation end up
> > transferring data, it just gets attached in the low-level driver.
> >
>
> Yes, REQ_OP_ZONE_RESET and REQ_OP_ZONE_RESET_ALL are quite similar to
> REQ_OP_DISCARD. Data read from the LBA range of reset zone is not
> suggested and the content is undefined.
>
> For bcache, similar to REQ_OP_DISCARD, REQ_OP_ZONE_RESET and
> REQ_OP_ZONE_RESET_ALL are handled in same way: If the backing device
> supports discard/zone_reset, and the operation successes, then cached
> data on SSD covered by the LBA range should be invalid, otherwise users
> will read outdated and garbage data.
>
> We should treat REQ_OP_ZONE_RESET and REQ_OP_ZONE_RESET_ALL being in
> WRITE direction.
No, the difference is that the underlying SCSI/ATA/NVMe command tend to
usually actually transfer data. Take a look at the special_vec field
in struct request and the RQF_SPECIAL_PAYLOAD flag.
next prev parent reply other threads:[~2020-05-16 15:36 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-16 3:54 [RFC PATCH v2 0/4] block layer change necessary for bcache zoned device support Coly Li
2020-05-16 3:54 ` [RFC PATCH v2 1/4] block: change REQ_OP_ZONE_RESET from 6 to 13 Coly Li
2020-05-16 4:06 ` Chaitanya Kulkarni
2020-05-16 9:33 ` Coly Li
2020-05-16 12:38 ` Christoph Hellwig
2020-05-16 12:44 ` Coly Li
2020-05-16 12:50 ` Christoph Hellwig
2020-05-16 13:05 ` Coly Li
2020-05-16 15:36 ` Christoph Hellwig [this message]
2020-05-17 5:30 ` Coly Li
2020-05-18 6:53 ` Hannes Reinecke
2020-05-18 6:56 ` Damien Le Moal
2020-05-18 0:33 ` Damien Le Moal
2020-05-18 5:09 ` Chaitanya Kulkarni
2020-05-16 3:54 ` [RFC PATCH v2 2/4] block: block: change REQ_OP_ZONE_RESET_ALL from 8 to 15 Coly Li
2020-05-18 0:36 ` Damien Le Moal
2020-05-16 3:54 ` [RFC PATCH v2 3/4] block: remove queue_is_mq restriction from blk_revalidate_disk_zones() Coly Li
2020-05-16 12:40 ` Christoph Hellwig
2020-05-16 13:13 ` Coly Li
2020-05-16 15:35 ` Christoph Hellwig
2020-05-18 1:07 ` Damien Le Moal
2020-05-18 0:39 ` Damien Le Moal
2020-05-16 3:54 ` [RFC PATCH v2 4/4] block: set bi_size to REQ_OP_ZONE_RESET bio Coly Li
2020-05-16 12:53 ` Christoph Hellwig
2020-05-18 0:59 ` Damien Le Moal
2020-05-18 2:32 ` Coly Li
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