From: "J. R. Okajima" <hooanon05@yahoo.co.jp>
To: sedat.dilek@gmail.com
Cc: Andrew Watts <akwatts@ymail.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-fsdevel@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>,
Daniel Baumann <daniel@debian.org>
Subject: Re: [overlayfs/port] overlayfs: v13 port attempt to kernel 3.5
Date: Mon, 20 Aug 2012 19:38:18 +0900 [thread overview]
Message-ID: <8326.1345459098@jrobl> (raw)
In-Reply-To: <CA+icZUU6KS_8T5uhQZw6QKDD4iLp76xphr2N9KJ6Dvj_ib_sig@mail.gmail.com>
Sedat Dilek:
> The other part to run a Linux live-system is a "Union FileSystem" -
> this part is missing (speaking of upstream).
>
> Since years AUFS seems to be the choice #1 in a lot of distros to
> workaround the problem.
> NOTE: AUFS was rejected from upstream (to say not accepted).
Exactly.
The reason was that linux rejects all union-type filesystems but
UnionMount (which is union-type mount).
Later, the development of UnionMount seems to be almost stopped. The
essential design of overlayfs is based upon UnionMount, and I have
pointed out several issues such as
- for users, the inode number may change silently. eg. copy-up.
- hardlinks may break by copy-up.
- read(2) may get an obsoleted filedata (fstat(2) for metadata too).
- fcntl(F_SETLK) may be broken by copy-up.
- unnecessary copy-up may happen, for example mmap(MAP_PRIVATE) after
open(O_RDWR).
- Later I noticed one more thing. /proc/PID/{fd/,exe} may not work
correctly for overlayfs ...
- etc...
They are called "unPOSIXy behavior", and unforunately many of them are
NOT seem to be addressed in recent patches either.
Also I have posted
If the development of UnionMount is really stopped, then I'd ask people
to consider merging aufs as well as overlayfs.
but I am not sure whether LKML people are still waiting for UnionMount
and rejecting aufs.
J. R. Okajima
next prev parent reply other threads:[~2012-08-20 10:46 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20120816204440.GA8808@ymail.com>
[not found] ` <CA+icZUX+4mMYqNn5_5EKXTdqbZ25K1HFbsRR5TrToaGJaSPttw@mail.gmail.com>
[not found] ` <20120817010519.GA2440@ymail.com>
2012-08-17 9:18 ` [overlayfs/port] overlayfs: v13 port attempt to kernel 3.5 Sedat Dilek
2012-08-20 10:38 ` J. R. Okajima [this message]
2012-08-20 11:26 ` Sedat Dilek
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