From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Pavel Emelyanov <xemul@parallels.com>,
"J. Bruce Fields" <bfields@fieldses.org>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>,
"linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-fsdevel\@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Alexey Dobriyan <adobriyan@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
James Bottomley <jbottomley@parallels.com>,
Matthew Helsley <matt.helsley@gmail.com>
Subject: Re: [patch 4/8] fs, exportfs: Add export_encode_inode_fh helper
Date: Tue, 21 Aug 2012 16:12:56 +0530 [thread overview]
Message-ID: <87wr0sle4v.fsf@skywalker.in.ibm.com> (raw)
In-Reply-To: <50335261.5090504@parallels.com>
Pavel Emelyanov <xemul@parallels.com> writes:
> On 08/20/2012 11:32 PM, J. Bruce Fields wrote:
>> On Mon, Aug 20, 2012 at 11:06:06PM +0400, Cyrill Gorcunov wrote:
>>> On Mon, Aug 20, 2012 at 02:32:25PM -0400, J. Bruce Fields wrote:
>>>> On Mon, Aug 20, 2012 at 08:33:38PM +0400, Cyrill Gorcunov wrote:
>>>>> On Mon, Aug 20, 2012 at 07:49:23PM +0530, Aneesh Kumar K.V wrote:
>>>>>> Cyrill Gorcunov <gorcunov@openvz.org> writes:
>>>>>>
>>>>>>> To provide fsnotify object inodes being watched without
>>>>>>> binding to alphabetical path we need to encode them with
>>>>>>> exportfs help. This patch adds a helper which operates
>>>>>>> with plain inodes directly.
>>>>>>
>>>>>> doesn't name_to_handle_at() work for you ? It also allows to get a file
>>>>>> handle using file descriptor.
>>>>>
>>>>> Hi, sorry for dealy. Well, the last idea is to get rid of this helper,
>>>>> I've sent out an updated version where ino+dev is only printed.
>>>>
>>>> I don't understand how ino and dev are useful to you, though, if you're
>>>> still hoping to be able to look up inodes using this information later
>>>> on.
>>>
>>> Hi Bruce, I believe having ino+dev is better than nothing. Otherwise we
>>> simply have no clue which targets are bound to inotify mark. Sometime
>>> (!) we can try to generate fhandle in userspace from this ino+dev bundle
>>> and then open the target file.
>>
>> That's insufficient to generate a filehandle in general.
>
> Yes, sure, but for live migration having inode and device is enough and that's why.
> We can use two ways of having a filesystem on the target machine in the same
> state (from paths points of view) as it was on destination one:
>
> 1. copy file tree in a rsync manner
> 2. copy a virtual disk image file
>
> In the 1st case we can map inode number to path easily, since we iterate over a filesystem
> anyway. I agree, that rsync is not perfect for migration but still.
>
> In the 2nd case we can generate filehandle out of an inode number only since we _do_ know
> that inode will not get reused.
If you are going to to use open_by_handle, then that handle is not
sufficient right ? Or do you have open_by_inode ? as part of c/r ?
>
>
> However, if you have some better ideas on what information about inode should be exported
> to the userspace please share.
>
Why not use name_to_handle(fd,...) and open_by_handle(handle,..) ?
>> (Also: there's the usual inode-number aliasing problem: the inode number
>> could get reused by another file. Unless you know the file is being
>> held open the whole time.)
>>
-aneesh
next prev parent reply other threads:[~2012-08-21 10:43 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-15 9:21 [patch 0/8] procfs, fdinfo updated Cyrill Gorcunov
2012-08-15 9:21 ` [patch 1/8] procfs: Move /proc/pid/fd[info] handling code to fd.[ch] Cyrill Gorcunov
2012-08-15 9:21 ` [patch 2/8] procfs: Convert /proc/pid/fdinfo/ handling routines to seq-file Cyrill Gorcunov
2012-08-15 9:21 ` [patch 3/8] procfs: Add ability to plug in auxiliary fdinfo providers Cyrill Gorcunov
2012-08-15 21:16 ` Al Viro
2012-08-15 21:31 ` Cyrill Gorcunov
2012-08-15 21:29 ` Al Viro
2012-08-15 21:34 ` Cyrill Gorcunov
2012-08-16 10:58 ` Cyrill Gorcunov
2012-08-15 9:21 ` [patch 4/8] fs, exportfs: Add export_encode_inode_fh helper Cyrill Gorcunov
2012-08-15 20:45 ` J. Bruce Fields
2012-08-15 21:02 ` Cyrill Gorcunov
2012-08-15 22:06 ` J. Bruce Fields
2012-08-16 6:24 ` Cyrill Gorcunov
2012-08-16 12:38 ` Cyrill Gorcunov
2012-08-16 12:47 ` J. Bruce Fields
2012-08-16 13:16 ` Cyrill Gorcunov
2012-08-16 14:57 ` Cyrill Gorcunov
2012-08-16 15:05 ` Al Viro
2012-08-16 15:09 ` Cyrill Gorcunov
2012-08-16 13:43 ` Al Viro
2012-08-16 13:47 ` Pavel Emelyanov
2012-08-16 13:50 ` Al Viro
2012-08-16 13:53 ` Pavel Emelyanov
2012-08-16 13:54 ` Cyrill Gorcunov
2012-08-16 14:03 ` James Bottomley
2012-08-16 14:13 ` Pavel Emelyanov
2012-08-16 14:15 ` Cyrill Gorcunov
2012-08-16 14:41 ` Al Viro
2012-08-16 14:48 ` Cyrill Gorcunov
2012-08-16 14:54 ` J. Bruce Fields
2012-08-16 14:55 ` Al Viro
2012-08-16 15:06 ` Pavel Emelyanov
2012-08-16 15:35 ` Cyrill Gorcunov
2012-08-16 15:07 ` Cyrill Gorcunov
2012-08-17 20:58 ` Eric W. Biederman
2012-08-16 13:48 ` Al Viro
2012-08-20 14:19 ` Aneesh Kumar K.V
2012-08-20 16:33 ` Cyrill Gorcunov
2012-08-20 18:32 ` J. Bruce Fields
2012-08-20 19:06 ` Cyrill Gorcunov
2012-08-20 19:32 ` J. Bruce Fields
2012-08-20 19:40 ` Cyrill Gorcunov
2012-08-21 9:18 ` Pavel Emelyanov
2012-08-21 10:42 ` Aneesh Kumar K.V [this message]
2012-08-21 10:49 ` Pavel Emelyanov
2012-08-21 10:54 ` Cyrill Gorcunov
2012-08-21 11:09 ` Pavel Emelyanov
2012-08-21 12:11 ` J. Bruce Fields
2012-08-21 12:22 ` Pavel Emelyanov
2012-08-21 12:29 ` J. Bruce Fields
2012-08-21 12:40 ` Pavel Emelyanov
2012-08-21 12:51 ` Boaz Harrosh
2012-08-21 12:59 ` Pavel Emelyanov
2012-08-21 13:08 ` Boaz Harrosh
2012-08-21 13:12 ` Al Viro
2012-08-21 13:40 ` Cyrill Gorcunov
2012-08-21 12:09 ` J. Bruce Fields
2012-08-21 12:25 ` Pavel Emelyanov
2012-08-22 5:49 ` Aneesh Kumar K.V
2012-08-23 8:06 ` Cyrill Gorcunov
2012-08-23 8:54 ` Marco Stornelli
2012-08-23 9:29 ` Cyrill Gorcunov
2012-08-15 9:21 ` [patch 5/8] fs, notify: Add procfs fdinfo helper v3 Cyrill Gorcunov
2012-08-15 9:21 ` [patch 6/8] fs, eventfd: Add procfs fdinfo helper Cyrill Gorcunov
2012-08-15 9:21 ` [patch 7/8] fs, epoll: Add procfs fdinfo helper v2 Cyrill Gorcunov
2012-08-15 9:21 ` [patch 8/8] fdinfo: Show sigmask for signalfd fd v2 Cyrill Gorcunov
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=87wr0sle4v.fsf@skywalker.in.ibm.com \
--to=aneesh.kumar@linux.vnet.ibm.com \
--cc=adobriyan@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=bfields@fieldses.org \
--cc=gorcunov@openvz.org \
--cc=jbottomley@parallels.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=matt.helsley@gmail.com \
--cc=viro@zeniv.linux.org.uk \
--cc=xemul@parallels.com \
/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;
as well as URLs for NNTP newsgroup(s).