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From: Gao Xiang via Linux-erofs <linux-erofs@lists.ozlabs.org>
To: David Michael <fedora.dm0@gmail.com>
Cc: linux-erofs@lists.ozlabs.org
Subject: Re: Compatibility with overlayfs
Date: Sat, 30 Nov 2019 09:29:04 +0800
Message-ID: <20191130012900.GA2862@hsiangkao-HP-ZHAN-66-Pro-G1> (raw)
In-Reply-To: <CAEvUa7nxnby+rxK-KRMA46=exeOMApkDMAV08AjMkkPnTPV4CQ@mail.gmail.com>

Hi David,

On Fri, Nov 29, 2019 at 03:22:15PM -0500, David Michael wrote:
> Hi,
> 
> I tried to test EROFS on Linux 5.4 as the root file system and mounted
> a writable overlay (with upper layer on tmpfs) over /etc, but I get
> ENODATA errors when attempting to modify files.  For example, adding a
> user results in "Failed to take /etc/passwd lock: No data available".
> Files can be modified after unlinking and restoring them so they're
> created on the upper layer.  This is not necessary with other
> read-only file systems (at least squashfs or ext4 with the read-only
> feature).  I tried while forcing compact and extended inodes.
> 
> Is EROFS intended to be usable as a lower layer with overlayfs?

Yes, and overlayfs were used on our smartphones for development use
only as well. I think it's weird, I will try it on the latest kernel
now, and see if I can reproduce this issue soon...

Thanks for your report!

Thanks,
Gao Xiang

> 
> Thanks.
> 
> David

  reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-29 20:22 David Michael
2019-11-30  1:29 ` Gao Xiang via Linux-erofs [this message]
2019-11-30  2:13   ` Gao Xiang via Linux-erofs
2019-11-30 15:15     ` David Michael
2019-11-30 16:27       ` Gao Xiang via Linux-erofs

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