From: Jeff Moyer <jmoyer@redhat.com>
To: majianpeng <majianpeng@gmail.com>
Cc: axboe <axboe@kernel.dk>, viro <viro@zeniv.linux.org.uk>,
LKML <linux-kernel@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH V2 0/2] Auto stop async-write on block device when device removed.
Date: Wed, 25 Sep 2013 11:44:58 -0400 [thread overview]
Message-ID: <x49siwsewhx.fsf@segfault.boston.devel.redhat.com> (raw)
In-Reply-To: <201309250932532670454@gmail.com> (majianpeng@gmail.com's message of "Wed, 25 Sep 2013 09:32:55 +0800")
majianpeng <majianpeng@gmail.com> writes:
>>The bigger question is whether we want to change this long-standing
>>behaviour of how our write-back cache works. I don't know that it's
>>really worth it, honestly. If you want to ensure data is on disk, you
>>open the file O_SYNC or you issue an fsync, and those calls will return
>>an error for a removed block device. So, I guess I'll ask the same
>>question again: why are you looking at this? Is there some application
>>you care about that does buffered I/O to the block device and never does
>>an fsync?
>>
> Yes, for my company, we used our filesystem in userspace on block-device.
> For the performance, we used buffer-wrtite not sync-write.
> For my workload, we allow user to remove disk whether disk working or not.
> Now, we check the state of disk from /proc/partitions at the same interval.
>
> This patchset don't change write-back cache works.It only let vfs know
> the state of lower-device. I think it make a sense.
I'm still curious to know how you maintain a consistent file system
without the use of fsync, but that's an unrelated issue.
I looked at the rescan partition code path more closely, and it will
only really trigger if the partitions themselves aren't open. So, I
don't think there is a problem in your approach.
I'll ack patch 1. I still think patch 2 is not neessary. Please
correct me if I'm wrong.
Cheers,
Jeff
next prev parent reply other threads:[~2013-09-25 15:45 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-17 3:21 [PATCH V2 0/2] Auto stop async-write on block device when device removed majianpeng
2013-09-23 14:47 ` Jeff Moyer
2013-09-24 3:07 ` majianpeng
2013-09-24 13:54 ` Jeff Moyer
2013-09-25 1:32 ` majianpeng
2013-09-25 15:44 ` Jeff Moyer [this message]
2013-09-29 8:46 ` majianpeng
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