From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
axboe@kernel.dk, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org,
tytso@mit.edu, adilger.kernel@dilger.ca, ming.lei@redhat.com,
osandov@fb.com, jthumshirn@suse.de, minwoo.im.dev@gmail.com,
damien.lemoal@wdc.com, andrea.parri@amarulasolutions.com,
hare@suse.com, tj@kernel.org, ajay.joshi@wdc.com,
sagi@grimberg.me, dsterba@suse.com, chaitanya.kulkarni@wdc.com,
bvanassche@acm.org, dhowells@redhat.com, asml.silence@gmail.com
Subject: Re: [PATCH RFC 1/3] block: Add support for REQ_OP_ASSIGN_RANGE operation
Date: Mon, 06 Jan 2020 22:24:09 -0500 [thread overview]
Message-ID: <yq1o8vg2bl2.fsf@oracle.com> (raw)
In-Reply-To: <405b9106-0a97-0821-c41d-58ab8d0e2d09@virtuozzo.com> (Kirill Tkhai's message of "Mon, 23 Dec 2019 11:51:34 +0300")
Kirill,
Sorry, the holiday break got in the way.
> But I also worry about NOFALLBACK case. There are possible block
> devices, which support write zeroes, but they can't allocate blocks
> (block allocation are just not appliable for them, say, these are all
> ordinary hdd).
Correct. We shouldn't go down this path unless a device is thinly
provisioned (i.e. max_discard_sectors > 0).
> But won't it be a good thing to return EOPNOTSUPP right from
> __blkdev_issue_write_zeroes() in case of block device can't allocate
> blocks (q->limits.write_zeroes_can_allocate in the patch below)? Here
> is just a way to underline block devices, which support write zeroes,
> but allocation of blocks is meant nothing for them (wasting of time).
I don't like "write_zeroes_can_allocate" because that makes assumptions
about WRITE ZEROES being the command of choice. I suggest we call it
"max_allocate_sectors" to mirror "max_discard_sectors". I.e. put
emphasis on the semantic operation and not the plumbing.
--
Martin K. Petersen Oracle Linux Engineering
next prev parent reply other threads:[~2020-01-07 3:24 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-10 16:56 [PATCH RFC 0/3] block,ext4: Introduce REQ_OP_ASSIGN_RANGE to reflect extents allocation in block device internals Kirill Tkhai
2019-12-10 16:56 ` [PATCH RFC 1/3] block: Add support for REQ_OP_ASSIGN_RANGE operation Kirill Tkhai
2019-12-19 3:03 ` Martin K. Petersen
2019-12-19 11:07 ` Kirill Tkhai
2019-12-19 22:03 ` Chaitanya Kulkarni
2019-12-19 22:37 ` Martin K. Petersen
2019-12-20 1:53 ` Darrick J. Wong
2019-12-20 2:22 ` Martin K. Petersen
2019-12-20 11:55 ` Kirill Tkhai
2019-12-21 18:54 ` Martin K. Petersen
2019-12-23 8:51 ` Kirill Tkhai
2020-01-07 3:24 ` Martin K. Petersen [this message]
2020-01-07 13:59 ` Kirill Tkhai
2020-01-08 2:49 ` Martin K. Petersen
2020-01-09 9:43 ` Kirill Tkhai
2019-12-10 16:56 ` [PATCH RFC 2/3] loop: Forward REQ_OP_ASSIGN_RANGE into fallocate(0) Kirill Tkhai
2019-12-10 16:56 ` [PATCH RFC 3/3] ext4: Notify block device about fallocate(0)-assigned blocks Kirill Tkhai
2019-12-11 1:02 ` kbuild test robot
2019-12-11 12:55 ` [PATCH RFC v2 " Kirill Tkhai
2019-12-15 15:35 ` [PATCH RFC " kbuild test robot
2019-12-11 7:42 ` [PATCH RFC 0/3] block,ext4: Introduce REQ_OP_ASSIGN_RANGE to reflect extents allocation in block device internals Chaitanya Kulkarni
2019-12-11 8:50 ` Kirill Tkhai
2019-12-17 14:16 ` Kirill Tkhai
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