From: Qu Wenruo <quwenruo.btrfs@gmx.com>
To: Qu Wenruo <wqu@suse.com>, dm-devel@redhat.com
Cc: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 0/2] dm log writes: Add support for filter bios based on its type
Date: Thu, 8 Aug 2019 20:54:40 +0800 [thread overview]
Message-ID: <256f2ccc-af5b-e30a-76c1-a911f242d252@gmx.com> (raw)
In-Reply-To: <20190619080312.11549-1-wqu@suse.com>
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Gentle ping?
This feature would be pretty useful if we want to really log heavy
operations on a relatively small log devices.
Thanks,
Qu
On 2019/6/19 下午4:03, Qu Wenruo wrote:
> Current dm-log-writes will record all bios, no matter if the bios is
> METADATA (normally what we care) or is DATA (normally we cares less for
> the log-replay context).
>
> This causes a lot of extra space required for log device. E.g write 10M,
> sync, overwrite that 10M file, this would cause over 20M for log device
> just for the data.
>
> This patchset introduces two way to specify the dump type:
> - dump_type=%s optional option for constructor
> The default dump_type is ALL, thus no behavior change.
>
> - dump_type=%s message type to change type on the fly
>
> Also to cooperate the new dump_type= option, always output the dump_type
> for STATUSTYPE_TABLE.
>
> A common use case would be:
> # dmsetup create log --table 0 $(blockdev --getsz $dev) log-writes $dev $log_dev
> # mkfs.btrfs -f /dev/mapper/log
> # dmsetup suspend log
> # dmsetup message log 0 dump_type=METADATA|FUA|FLUSH|DISCARD|MARK
> # dmsetup resume log
> # mount /dev/mapper/log <mnt>
> # <do some work load>
> # umount <mnt>
> # dmsetup remove log
> # <replay>
>
> Now the log device will not record data writes, thus hugely reduce the
> space requirement for log device, allowing more operations to be down
> before hitting the space limit.
>
> Currently btrfs check doesn't check data checksum by default, thus even
> we have wrong data on-disk, we should be fine checking the metadata.
>
> I'm not 100% sure if this applies to other filesystems, but as long as
> metadata writes is marked correctly, other filesystems can also benifit
> from this feature.
>
> Qu Wenruo (2):
> dm log writes: Allow dm-log-writes to filter bios based on types to
> reduce log device space usage
> dm log writes: Introduce dump_type= message type to change dump_type
> on the fly
>
> drivers/md/dm-log-writes.c | 177 ++++++++++++++++++++++++++++++++++---
> 1 file changed, 167 insertions(+), 10 deletions(-)
>
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prev parent reply other threads:[~2019-08-08 12:55 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-19 8:03 [PATCH 0/2] dm log writes: Add support for filter bios based on its type Qu Wenruo
2019-06-19 8:03 ` [PATCH 1/2] dm log writes: Allow dm-log-writes to filter bios based on types to reduce log device space usage Qu Wenruo
2019-06-19 8:03 ` [PATCH 2/2] dm log writes: Introduce dump_type= message type to change dump_type on the fly Qu Wenruo
2019-08-08 12:54 ` Qu Wenruo [this message]
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