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From: Xiao Ni <xni@redhat.com>
To: songliubraving@fb.com
Cc: linux-raid@vger.kernel.org, matthew.ruffell@canonical.com,
	colyli@suse.de, guoqing.jiang@cloud.ionos.com,
	ncroxon@redhat.com
Subject: [PATCH 0/5] md/raid10: Improve handling raid10 discard request
Date: Wed,  3 Feb 2021 21:45:26 +0800
Message-ID: <1612359931-24209-1-git-send-email-xni@redhat.com> (raw)

Hi all

Now mkfs on raid10 which is combined with ssd/nvme disks takes a long time.
This patch set tries to resolve this problem.

This patch set had been reverted because of a data corruption problem. This
version fix this problem. The root cause which causes the data corruption is
the wrong calculation of start address of near copies disks.

Now we use a similar way with raid0 to handle discard request for raid10.
Because the discard region is very big, we can calculate the start/end
address for each disk. Then we can submit the discard request to each disk.
But for raid10, it has copies. For near layout, if the discard request
doesn't align with chunk size, we calculate a start_disk_offset. Now we only
use start_disk_offset for the first disk, but it should be used for the
near copies disks too.

[  789.709501] discard bio start : 70968, size : 191176
[  789.709507] first stripe index 69, start disk index 0, start disk offset 70968
[  789.709509] last stripe index 256, end disk index 0, end disk offset 262144
[  789.709511] disk 0, dev start : 70968, dev end : 262144
[  789.709515] disk 1, dev start : 70656, dev end : 262144

For example, in this test case, it has 2 near copies. The start_disk_offset
for the first disk is 70968. It should use the same offset address for second disk.
But it uses the start address of this chunk. It discard more region. This version
simply spilt the un-aligned part with strip size.

And it fixes another problem. The calculation of stripe_size is wrong in reverted version.

Xiao Ni (5):
  md: add md_submit_discard_bio() for submitting discard bio
  md/raid10: extend r10bio devs to raid disks
  md/raid10: pull codes that wait for blocked dev into one function
  md/raid10: improve raid10 discard request
  md/raid10: improve discard request for far layout

 drivers/md/md.c     |  20 +++
 drivers/md/md.h     |   2 +
 drivers/md/raid0.c  |  14 +-
 drivers/md/raid10.c | 429 +++++++++++++++++++++++++++++++++++++++++++++-------
 drivers/md/raid10.h |   1 +
 5 files changed, 397 insertions(+), 69 deletions(-)

-- 
2.7.5


             reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-03 13:45 Xiao Ni [this message]
2021-02-03 13:45 ` [PATCH 1/5] md: add md_submit_discard_bio() for submitting discard bio Xiao Ni
2021-02-03 15:44   ` Christoph Hellwig
2021-02-04  1:51     ` Xiao Ni
2021-02-04  4:07     ` Xiao Ni
2021-02-04  7:19       ` Christoph Hellwig
2021-02-04  7:37         ` Xiao Ni
2021-02-03 13:45 ` [PATCH 2/5] md/raid10: extend r10bio devs to raid disks Xiao Ni
2021-02-03 15:44   ` Christoph Hellwig
2021-02-03 13:45 ` [PATCH 3/5] md/raid10: pull codes that wait for blocked dev into one function Xiao Ni
2021-02-03 15:46   ` Christoph Hellwig
2021-02-04  1:54     ` Xiao Ni
2021-02-03 13:45 ` [PATCH 4/5] md/raid10: improve raid10 discard request Xiao Ni
2021-02-03 15:50   ` Christoph Hellwig
2021-02-04  2:00     ` Xiao Ni
2021-02-03 13:45 ` [PATCH 5/5] md/raid10: improve discard request for far layout Xiao Ni

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