From: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
To: hooanon05@yahoo.co.jp
Cc: Goswin von Brederlow <goswin-v-b@web.de>,
Miklos Szeredi <miklos@szeredi.hu>,
linux-fsdevel@vger.kernel.org, fuse-devel@lists.sourceforge.net
Subject: Re: [fuse-devel] delta filesystem prototype
Date: Tue, 03 Mar 2009 09:27:58 -0600 [thread overview]
Message-ID: <1236094078.6988.3.camel@norville.austin.ibm.com> (raw)
In-Reply-To: <7200.1236085884@jrobl>
On Tue, 2009-03-03 at 22:11 +0900, hooanon05@yahoo.co.jp wrote:
> Goswin von Brederlow:
> > Why? When a page is accessed the filesystem gets a read request and
> > reads it either from the RO branch or the delta branch. Why should it
> > need to copy up the full file?
>
> For example,
> - you have two mmap for a single file
> - the first mapping is done, it may map the file on the lower rdonly
> layer
> - the other mapping modifies the contents
> - can the first mapping see the new content?
The lower read-only file would not appear to user-space as the same file
at all. It would have its own address space. It clearly would not see
the new content.
There wouldn't be any problem with reading pages from the lower file for
the upper file one at a time as they are faulted.
Shaggy
--
David Kleikamp
IBM Linux Technology Center
next prev parent reply other threads:[~2009-03-03 15:28 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-28 14:42 delta filesystem prototype Miklos Szeredi
2009-02-28 17:22 ` [fuse-devel] " Goswin von Brederlow
2009-03-01 0:38 ` Bernd Schubert
2009-03-01 10:17 ` Goswin von Brederlow
2009-03-04 11:21 ` Miklos Szeredi
2009-03-04 14:12 ` Goswin von Brederlow
2009-03-05 13:06 ` Miklos Szeredi
2009-03-05 19:58 ` Goswin von Brederlow
2009-03-06 4:10 ` hooanon05
2009-03-06 12:37 ` Goswin von Brederlow
2009-03-07 1:16 ` hooanon05
2009-03-07 9:01 ` Goswin von Brederlow
2009-03-07 9:12 ` hooanon05
2009-03-09 12:21 ` Goswin von Brederlow
2009-03-09 13:35 ` hooanon05
2009-03-09 14:22 ` Goswin von Brederlow
2009-03-09 15:25 ` hooanon05
2009-03-10 8:14 ` Goswin von Brederlow
2009-03-09 16:36 ` Miklos Szeredi
2009-03-06 11:35 ` Miklos Szeredi
2009-03-06 12:50 ` Goswin von Brederlow
2009-03-06 13:21 ` Miklos Szeredi
2009-03-07 8:56 ` Goswin von Brederlow
2009-03-07 1:19 ` hooanon05
2009-03-07 9:03 ` Goswin von Brederlow
2009-03-07 9:16 ` hooanon05
2009-03-09 12:28 ` Goswin von Brederlow
2009-03-09 13:36 ` hooanon05
2009-03-09 14:25 ` Goswin von Brederlow
2009-03-09 15:20 ` hooanon05
2009-03-10 8:06 ` Goswin von Brederlow
2009-03-10 8:44 ` hooanon05
2009-03-12 9:22 ` Tomas M
2009-03-12 9:40 ` Goswin von Brederlow
2009-03-12 9:19 ` Tomas M
2009-03-09 14:13 ` Nikolaus Rath
2009-03-03 8:31 ` hooanon05
2009-03-03 10:59 ` [fuse-devel] " Goswin von Brederlow
2009-03-03 13:11 ` hooanon05
2009-03-03 15:27 ` Dave Kleikamp [this message]
2009-03-03 15:50 ` hooanon05
2009-03-03 15:54 ` Dave Kleikamp
2009-03-03 16:02 ` hooanon05
2009-03-03 16:14 ` Dave Kleikamp
2009-03-03 16:19 ` hooanon05
2009-03-03 16:46 ` Dave Kleikamp
2009-03-03 17:13 ` hooanon05
2009-03-04 11:52 ` Goswin von Brederlow
2009-03-04 14:10 ` Dave Kleikamp
2009-03-04 16:23 ` hooanon05
2009-03-04 11:49 ` Goswin von Brederlow
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