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From: "J. R. Okajima" <hooanon05@yahoo.co.jp>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: viro@ZenIV.linux.org.uk, torvalds@linux-foundation.org,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	hch@infradead.org, akpm@linux-foundation.org, apw@canonical.com,
	nbd@openwrt.org, neilb@suse.de, jordipujolp@gmail.com,
	ezk@fsl.cs.sunysb.edu, dhowells@redhat.com,
	sedat.dilek@googlemail.com, mszeredi@suse.cz
Subject: Re: [PATCH 00/13] overlay filesystem: request for inclusion (v16)
Date: Wed, 13 Mar 2013 02:22:13 +0900	[thread overview]
Message-ID: <9427.1363108933@jrobl> (raw)
In-Reply-To: <1363102908-28956-1-git-send-email-miklos@szeredi.hu>


Miklos Szeredi:
> Please consider overlayfs for inclusion into 3.10.

Thank you for CCing me.

First, I'd suggest you to follow some recent activities in mainline
kernel such as
- MODULE_ALIAS_FS
- file_inode()
- d_weak_revalidate() which may not be necessary for overlayfs as long
  as it prohibit users the direct-access to layers (bypassing
  overlayfs).


> It's included in Ubuntu and openSUSE, used by OpenWrt and various other
> projects.  I regularly get emails asking when it will be included in mainline.

Such situation is very similar which AUFS had a few years ago. At that
time, AUFS was rejected since UnionMount was chosen. Years passed, the
development of UnionMount seems to stop and linux mainline doesn't have
generic stackable filesytem yet. I had pointed out some defects in
overlayfs (and UnionMount too). They are all based upon the "name-based"
behaviour instead of "inode-based" one. Other than "Non-standard
behavior" in the overlayfs document, the are, for example,
- read(2) may get an obsoleted filedata (fstat(2) for metadata too).
- fcntl(F_SETLK) may be broken by copy-up.
- inotify may not work when it refers to the file before being
  copied-up.
- unnecessary copy-up may happen, for example mmap(MAP_PRIVATE) after
  open(O_RDWR).

AUFS is an "inode-based" stackable filesystem and solved them many years
ago. But I have to admit that AUFS is big. Yes it is grown up.
I don't stop including overlayfs into mainline, but if the development
of UnionMount is really stopped, then I'd ask people to consider merging
aufs as well as overlayfs.


J. R. Okajima

  parent reply	other threads:[~2013-03-12 17:32 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 [this message]
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             ` 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

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