From: Christoph Hellwig <hch@infradead.org>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: Bart Van Assche <bart.vanassche@sandisk.com>,
Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, dm-devel@redhat.com,
"Alasdair G. Kergon" <agk@redhat.com>,
Mike Snitzer <snitzer@redhat.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>
Subject: REQ_OP for zeroing, was Re: [dm-devel] [PATCH 1/4] brd: handle misaligned discard
Date: Wed, 26 Oct 2016 14:50:52 -0700 [thread overview]
Message-ID: <20161026215052.GA11679@infradead.org> (raw)
In-Reply-To: <alpine.LRH.2.02.1610261733190.25893@file01.intranet.prod.int.rdu2.redhat.com>
On Wed, Oct 26, 2016 at 05:46:11PM -0400, Mikulas Patocka wrote:
> I think the proper thing would be to move "discard_zeroes_data" flag into
> the bio itself - there would be REQ_OP_DISCARD and REQ_OP_DISCARD_ZERO -
> and if the device doesn't support REQ_OP_DISCARD_ZERO, it rejects the bio
> and the caller is supposed to do zeroing manually.
Yes, Martin and I have come to a similar conclusion recently. An
additional aspect is that NVMe has a Write Zeroes command which is more
limited than what REQ_OP_WRITE_SAME does.
So I think the right way is to add a REQ_OP_WRITE_ZEROES (or
REQ_OP_ZERO) and have modifies if it may discard or not.
next prev parent reply other threads:[~2016-10-26 21:50 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-21 18:33 device mapper and the BLKFLSBUF ioctl Mikulas Patocka
2016-10-21 20:00 ` Mike Snitzer
2016-10-21 20:18 ` Mikulas Patocka
2016-10-24 15:57 ` Mike Snitzer
2016-10-25 13:07 ` Christoph Hellwig
2016-10-25 14:37 ` [PATCH] brd: remove support for BLKFLSBUF Mike Snitzer
2016-10-25 14:46 ` Jens Axboe
2016-10-26 20:25 ` [PATCH 0/4] brd: support discard Mikulas Patocka
2016-10-26 20:26 ` [PATCH 1/4] brd: handle misaligned discard Mikulas Patocka
2016-10-26 20:38 ` [dm-devel] " Bart Van Assche
2016-10-26 20:38 ` Bart Van Assche
2016-10-26 21:46 ` Mikulas Patocka
2016-10-26 21:50 ` Christoph Hellwig [this message]
2016-10-28 11:43 ` REQ_OP for zeroing, was " Mikulas Patocka
2016-10-28 13:14 ` Christoph Hellwig
2016-10-31 16:36 ` Mikulas Patocka
2016-10-26 21:57 ` Bart Van Assche
2016-10-26 21:57 ` Bart Van Assche
2016-10-28 11:39 ` Mikulas Patocka
2016-10-28 15:55 ` Bart Van Assche
2016-10-28 15:55 ` Bart Van Assche
2016-10-31 16:31 ` Mikulas Patocka
2016-10-26 20:26 ` [PATCH 2/4] brd: extend rcu read sections Mikulas Patocka
2016-10-26 20:27 ` [PATCH 3/4] brd: implement discard Mikulas Patocka
2016-10-26 20:27 ` [PATCH 4/4] brd: remove unused brd_zero_page Mikulas Patocka
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