From: Miklos Szeredi <miklos@szeredi.hu>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Christoph Hellwig <hch@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Robo Bot <apw@canonical.com>, Felix Fietkau <nbd@openwrt.org>,
Neil Brown <neilb@suse.de>, Jordi Pujol <jordipujolp@gmail.com>,
ezk@fsl.cs.sunysb.edu, David Howells <dhowells@redhat.com>,
Sedat Dilek <sedat.dilek@googlemail.com>,
"J. R. Okajima" <hooanon05@yahoo.co.jp>
Subject: Re: [PATCH 00/13] overlay filesystem: request for inclusion (v16)
Date: Thu, 14 Mar 2013 11:37:50 +0100 [thread overview]
Message-ID: <CAJfpegsCirmYYimr6Nn4Q4Kdc7rMYaxWhk+fsmp+BLp6mjb_MQ@mail.gmail.com> (raw)
In-Reply-To: <20130313231918.GP21522@ZenIV.linux.org.uk>
On Thu, Mar 14, 2013 at 12:19 AM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Wed, Mar 13, 2013 at 11:09:07PM +0100, Miklos Szeredi wrote:
>> As for same upper on unrelated lower: just don't do it. As I said, we
>> could enforce this, but I don't think this is top priority.
>
> Tell that to container crowd - they seem to be hell-bent on making everything
> mount-related non-priveleged ;-/
Which is good, but it does need some care. I'm happy to review those changes.
>> > * ->follow_link(): Why the hell do you bother with struct ovl_link_data???
>> > Just to avoid calling ovl_dentry_real() in ovl_put_link()?
>>
>> Yes, a copy-up between ovl_follow_link and ovl_put_link will break that.
>
> *blink*
>
> Er... What's wrong with simply unhashing the sucker on copyup if it's
> a symlink?
Nothing, so I'll do that. Actually we can do that for all except
directory dentries and save some worry.
> BTW, looking at your ovl_copy_up() - you do realize that dget_parent(d)
> does *not* guarantee that returned dentry will remain the parent of d?
> rename() can very well move it away just as dget_parent() is returning
> to caller. As the result, you are not guaranteed that ovl_copy_up_one()
> arguments will be anywhere near each other in the tree. Your locking
> and rechecks might be enough to prevent trouble there, but it's not
> obvious, to put it mildly.
This issue is documented above ovl_copy_up_one(). It's not all that
complicated, I think.
> I'm _very_ sceptical about the idea of delaying copyups that much, BTW;
> there's a damn good reason why all implementations starting with Sun's
> one in 80s did copy directories up as soon as they got looked up. Saves
> a lot of headache...
Maybe. If we find not trivially fixable holes in the current
implementation I'm open to that direction.
Delayed copy up has the advantage of allowing pure read-only overlays.
> As for whiteouts... I think we ought to pull these bits of unionmoun
> queue into the common stem and add the missing filesystems to them;
> ext* and ufs are trivial (keep in mind that FFS derivatives, including
> ext*, have d_type in directory entry and type 14 (DT_WHT) is there
> precisely for that purpose). btrfs also has "dir_type" thing - 8bit
> field...
What about userspace interfaces? Are we allowed to extend d_type and
st_mode without breaking things?
Thanks,
Miklos
next prev parent reply other threads:[~2013-03-14 10:47 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-12 15:41 [PATCH 00/13] overlay filesystem: request for inclusion (v16) Miklos Szeredi
2013-03-12 15:41 ` [PATCH 01/13] vfs-add-i_op-dentry_open Miklos Szeredi
2013-03-12 15:41 ` [PATCH 02/13] vfs-export-do_splice_direct-to-modules Miklos Szeredi
2013-03-12 15:41 ` [PATCH 03/13] vfs-introduce-clone_private_mount Miklos Szeredi
2013-03-12 15:41 ` [PATCH 04/13] overlay filesystem Miklos Szeredi
2013-03-12 15:41 ` [PATCH 05/13] overlayfs-add-statfs-support Miklos Szeredi
2013-03-12 15:41 ` [PATCH 06/13] overlayfs-implement-show_options Miklos Szeredi
2013-03-12 15:41 ` [PATCH 07/13] overlay-overlay-filesystem-documentation Miklos Szeredi
2013-03-12 15:41 ` [PATCH 08/13] fs-limit-filesystem-stacking-depth Miklos Szeredi
2013-03-12 15:41 ` [PATCH 09/13] overlayfs-fix-possible-leak-in-ovl_new_inode Miklos Szeredi
2013-03-12 15:41 ` [PATCH 10/13] overlayfs-create-new-inode-in-ovl_link Miklos Szeredi
2013-03-12 15:41 ` [PATCH 11/13] vfs-export-inode_permission-to-modules Miklos Szeredi
2013-03-12 15:41 ` [PATCH 12/13] ovl-switch-to-inode_permission Miklos Szeredi
2013-03-12 15:41 ` [PATCH 13/13] overlayfs-copy-up-i_uid-i_gid-from-the-underlying-inode Miklos Szeredi
2013-03-12 16:49 ` [PATCH 00/13] overlay filesystem: request for inclusion (v16) Sedat Dilek
2013-03-12 20:00 ` Miklos Szeredi
2013-03-12 17:22 ` J. R. Okajima
2013-03-12 20:01 ` Miklos Szeredi
2013-03-12 21:50 ` Linus Torvalds
2013-03-12 22:23 ` Al Viro
2013-03-13 9:42 ` Sedat Dilek
2013-03-13 15:24 ` Miklos Szeredi
2013-03-13 18:52 ` Al Viro
2013-03-13 22:09 ` Miklos Szeredi
2013-03-13 23:19 ` Al Viro
2013-03-14 10:37 ` Miklos Szeredi [this message]
2013-03-14 12:57 ` DT_WHT (Re: [PATCH 00/13] overlay filesystem: request for inclusion (v16)) J. R. Okajima
2013-03-14 22:59 ` [PATCH 00/13] overlay filesystem: request for inclusion (v16) Al Viro
2013-03-18 11:27 ` Miklos Szeredi
2013-03-13 10:09 ` Sedat Dilek
2013-03-13 10:57 ` Miklos Szeredi
2013-03-20 19:41 George Spelvin
2013-03-20 21:32 ` Al Viro
2013-03-22 5:15 ` Rob Landley
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=CAJfpegsCirmYYimr6Nn4Q4Kdc7rMYaxWhk+fsmp+BLp6mjb_MQ@mail.gmail.com \
--to=miklos@szeredi.hu \
--cc=akpm@linux-foundation.org \
--cc=apw@canonical.com \
--cc=dhowells@redhat.com \
--cc=ezk@fsl.cs.sunysb.edu \
--cc=hch@infradead.org \
--cc=hooanon05@yahoo.co.jp \
--cc=jordipujolp@gmail.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=nbd@openwrt.org \
--cc=neilb@suse.de \
--cc=sedat.dilek@googlemail.com \
--cc=torvalds@linux-foundation.org \
--cc=viro@zeniv.linux.org.uk \
/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).