From: Feng Shuo <steve.shuo.feng-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: "Maxim V. Patlasov" <mpatlasov-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
Cc: dev-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org,
miklos-sUDqSbJrdHQHWmgEVkV9KA@public.gmane.org,
"fuse-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org"
<fuse-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
jbottomley-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org,
viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org,
linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Pavel Emelyanov <xemul-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org>
Subject: Re: [PATCH v2 00/14] fuse: An attempt to implement a write-back cache policy
Date: Tue, 27 Nov 2012 23:19:22 +0800 [thread overview]
Message-ID: <CALmpHyY=g-cKw==DSaBhLaqLYhq6N0_t-5jHbwM2zoK61OGKwQ@mail.gmail.com> (raw)
In-Reply-To: <50B47243.9080706-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
Thank you Maxim. This is very much clear and makes sense for me.
On Tue, Nov 27, 2012 at 3:56 PM, Maxim V. Patlasov
<mpatlasov@parallels.com>wrote:
> Hi Feng,
>
> 11/27/2012 05:04 AM, Feng Shuo пишет:
>
> Hi Maxim,
>>
>> I'm new to fuse but have some experience with NFS. From my
>> understanding after reviewing your patchset, it seems only work with
>> local file system or a distributed file system whose file is never
>> modified (could be grown but no or very few modified) because it
>> doesn't exam the pre/post status of the writing object (e.g. a file).
>> So if a file is modified outside, fuse might not get any chance to
>> handle it...... Correct me if I got wrong since I'm really new to
>> fuse. :-)
>>
>
> This topic was discussed when Pavel sent initial version of patches (you
> can find it in fuse-devel archives). Brian asked:
>
> Would this pose a problem for a filesystem in which the size of the
>> inode can change remotely (i.e., not visible to the local instance of
>> fuse)? I haven't tested this, but it seems like it could be an issue
>> based on the implementation.
>>
>
> And Pavel replied:
>
> Yes, it will. The model of i_size management I implemented here is based
>> on an assumption that the userspace is just a storage for data and should
>> catch up with the kernel i_size value. In order to make it possible for
>> user
>> space to update i_size in kernel we'd have to implement some (probably)
>> tricky algorithm, I haven't yet thought about it.
>>
>
> The patch-set follows the model "trust kernel i_size only". This works
> fine at least in case of userspace fuse wtih exclusive write semantics. In
> case of mutual concurrent internal/external read/write access, sysad should
> not turn the feature on (it's turned off by default). I wouldn't like to
> complicate the patch-set further adding bits for that case. This area is
> opened for future enhancements :)
>
> Thanks,
> Maxim
>
> --
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>
--
Feng Shuo
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next prev parent reply other threads:[~2012-11-27 15:19 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-16 17:04 [PATCH v2 00/14] fuse: An attempt to implement a write-back cache policy Maxim Patlasov
[not found] ` <20121116170123.3196.93431.stgit-vWG5eQQidJHciZdyczg/7Q@public.gmane.org>
2012-11-16 17:05 ` [PATCH 01/14] fuse: Linking file to inode helper Maxim Patlasov
2012-11-16 17:05 ` [PATCH 02/14] fuse: Getting file for writeback helper Maxim Patlasov
2012-11-16 17:06 ` [PATCH 03/14] fuse: Prepare to handle short reads Maxim Patlasov
2012-11-16 17:07 ` [PATCH 04/14] fuse: Prepare to handle multiple pages in writeback Maxim Patlasov
2012-11-16 17:07 ` [PATCH 05/14] fuse: Connection bit for enabling writeback Maxim Patlasov
2012-11-16 17:07 ` [PATCH 06/14] fuse: Trust kernel i_size only Maxim Patlasov
[not found] ` <20121116170731.3196.47157.stgit-vWG5eQQidJHciZdyczg/7Q@public.gmane.org>
2012-12-05 16:39 ` [PATCH] fuse: Trust kernel i_size only - v2 Maxim Patlasov
2012-12-05 16:40 ` [PATCH] fuse: Implement writepages and write_begin/write_end callbacks " Maxim Patlasov
2012-11-16 17:09 ` [PATCH 07/14] fuse: Update i_mtime on buffered writes Maxim Patlasov
2012-11-16 17:09 ` [PATCH 08/14] fuse: Flush files on wb close Maxim Patlasov
2012-11-16 17:09 ` [PATCH 09/14] fuse: Implement writepages and write_begin/write_end callbacks Maxim Patlasov
2012-11-16 17:09 ` [PATCH 10/14] fuse: fuse_writepage_locked() should wait on writeback Maxim Patlasov
2012-11-16 17:10 ` [PATCH 11/14] fuse: fuse_flush() " Maxim Patlasov
2012-11-16 17:10 ` [PATCH 12/14] fuse: Fix O_DIRECT operations vs cached writeback misorder Maxim Patlasov
[not found] ` <20121116171012.3196.35933.stgit-vWG5eQQidJHciZdyczg/7Q@public.gmane.org>
2012-12-05 16:43 ` [PATCH] fuse: Fix O_DIRECT operations vs cached writeback misorder - v2 Maxim Patlasov
2012-11-16 17:10 ` [PATCH 13/14] fuse: Turn writeback cache on Maxim Patlasov
2012-11-16 17:10 ` [PATCH 14/14] mm: Account for WRITEBACK_TEMP in balance_dirty_pages Maxim Patlasov
2012-11-21 12:01 ` Maxim Patlasov
2012-11-22 13:27 ` Jaegeuk Hanse
2012-11-22 13:56 ` Maxim V. Patlasov
2012-11-27 1:04 ` [PATCH v2 00/14] fuse: An attempt to implement a write-back cache policy Feng Shuo
2012-11-27 7:56 ` Maxim V. Patlasov
[not found] ` <50B47243.9080706-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
2012-11-27 15:19 ` Feng Shuo [this message]
2012-12-12 14:53 ` Maxim V. Patlasov
2013-01-15 15:20 ` Maxim V. Patlasov
2013-01-25 10:21 ` Miklos Szeredi
2013-01-25 12:50 ` Maxim V. Patlasov
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