From: David Michael <fedora.dm0@gmail.com>
To: Gao Xiang <hsiangkao@aol.com>
Cc: linux-erofs@lists.ozlabs.org
Subject: Re: Compatibility with overlayfs
Date: Sat, 30 Nov 2019 10:15:25 -0500 [thread overview]
Message-ID: <CAEvUa7nG9Akp3Uv59P4+eGYYZ+nTfdO4OywiqZaLfY3_ag-vcQ@mail.gmail.com> (raw)
In-Reply-To: <20191130021257.GA5562@hsiangkao-HP-ZHAN-66-Pro-G1>
On Fri, Nov 29, 2019 at 9:13 PM Gao Xiang <hsiangkao@aol.com> wrote:
> On Sat, Nov 30, 2019 at 09:29:04AM +0800, Gao Xiang via Linux-erofs wrote:
> > 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
>
> I have reproduced this issue -- That is due to erofs will return an
> unexpected -ENODATA when calling listxattr without xattr and cause
> copy_up fail:
Oh, sorry I forgot to mention I had xattrs disabled during my testing.
I confirmed it works with xattrs, so I can use that as a workaround in
binary distros until a fix is upstream.
> since our products using xattr enabled EROFS with overlayfs,
> so we didn't observe this issue before. So could you try
> the following patch (If it can resolve the issue, I will
> send it for 5.5-rc2 and backport to all stable version)?
> Look forward to your feekback.
Yes, I applied the patch and everything works now.
Thanks.
David
next prev parent reply other threads:[~2019-11-30 15:16 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-29 20:22 Compatibility with overlayfs David Michael
2019-11-30 1:29 ` Gao Xiang via Linux-erofs
2019-11-30 2:13 ` Gao Xiang via Linux-erofs
2019-11-30 15:15 ` David Michael [this message]
2019-11-30 16:27 ` Gao Xiang via Linux-erofs
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