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From: "J. R. Okajima" <hooanon05@yahoo.co.jp>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
	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>
Subject: DT_WHT (Re: [PATCH 00/13] overlay filesystem: request for inclusion (v16))
Date: Thu, 14 Mar 2013 21:57:46 +0900	[thread overview]
Message-ID: <1402.1363265866@jrobl> (raw)
In-Reply-To: <CAJfpegsCirmYYimr6Nn4Q4Kdc7rMYaxWhk+fsmp+BLp6mjb_MQ@mail.gmail.com>


Miklos Szeredi:
> On Thu, Mar 14, 2013 at 12:19 AM, Al Viro <viro@zeniv.linux.org.uk> wrote:
	:::
> > 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?

Introducing a new d_type value can be a headache for other filesystems
or other OSs. Whiteout and opaque by xattr is an idea, but I prefer more
primitive way (special hidden filename) since xattr may force users to
change their configuration and it consumes disk space a little.
Filesystems may have a limit for the consumed size by xattr. If xattr
reaches the limit, then several operation in overlayfs will be unusable.


J. R. Okajima

  reply	other threads:[~2013-03-14 12:58 UTC|newest]

Thread overview: 31+ 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
2013-03-14 12:57             ` J. R. Okajima [this message]
2013-03-14 22:59             ` Al Viro
2013-03-18 11:27               ` Miklos Szeredi
2013-03-13 10:09 ` Sedat Dilek
2013-03-13 10:57   ` Miklos Szeredi

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