From: jim owens <jowens@hp.com>
To: CSights <csights@fastmail.fm>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: metadata copied/data not copied?
Date: Mon, 16 Mar 2009 11:28:03 -0400 [thread overview]
Message-ID: <49BE7003.2050404@hp.com> (raw)
In-Reply-To: <200903161035.19446.csights@fastmail.fm>
CSights wrote:
> Hi everyone,
> I'm curious what would happen in btrfs if the following commands were issued:
>
> # cp file1 file2
> # chown newuser:newgroup file2
>
> Where file1 was owned by olduser:oldgroup.
>
>
> If I understand copy-on-write correctly the "cp" would merely create a new
> pointer (or whatever it is called :( ) containing the files' metadata but the
> file contents would not actually be duplicated.
NO. The concept you describe requires "deduplicate".
What you are forgetting is that "cp" is a user-space program that
reads data and writes it to a new file. The kernel does not see
this as a Copy.
jim
next prev parent reply other threads:[~2009-03-16 15:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-16 14:35 metadata copied/data not copied? CSights
2009-03-16 15:28 ` jim owens [this message]
2009-03-17 0:25 ` Chris Mason
2009-03-17 15:34 ` CSights
2009-03-17 15:56 ` Chris Mason
2009-03-17 17:08 ` CSights
2009-03-17 17:24 ` Chris Mason
2009-03-16 21:14 ` Dmitri Nikulin
2009-03-16 21:18 ` Dmitri Nikulin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=49BE7003.2050404@hp.com \
--to=jowens@hp.com \
--cc=csights@fastmail.fm \
--cc=linux-btrfs@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox