From: Amir Goldstein <amir73il@gmail.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: Miklos Szeredi <mszeredi@redhat.com>,
"linux-unionfs@vger.kernel.org" <linux-unionfs@vger.kernel.org>,
Guillem Jover <guillem@debian.org>,
Raphael Hertzog <hertzog@debian.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/3] ovl: redirect on rename-dir
Date: Wed, 26 Oct 2016 22:56:07 +0300 [thread overview]
Message-ID: <CAOQ4uxidCNkXNVBZFM9q9261DGZ_mmBNjWkDTsZii7Z12dyRKg@mail.gmail.com> (raw)
In-Reply-To: <CAJfpegs+NDycOda67y5-8zDYHk90gxdQuQsRQ2pLq58UcUqa9A@mail.gmail.com>
On Wed, Oct 26, 2016 at 2:26 PM, Miklos Szeredi <miklos@szeredi.hu> wrote:
> On Tue, Oct 25, 2016 at 2:49 PM, Amir Goldstein <amir73il@gmail.com> wrote:
>
>>> @@ -880,31 +913,34 @@ static int ovl_rename(struct inode *olddir, struct dentry *old,
>>> if (WARN_ON(olddentry->d_inode == newdentry->d_inode))
>>> goto out_dput;
>>>
>>> - if (is_dir && !old_opaque && ovl_lower_positive(new)) {
>>> - err = ovl_set_opaque(olddentry);
>>> - if (err)
>>> - goto out_dput;
>>> - ovl_dentry_set_opaque(old, true);
>>> + if (is_dir) {
>>> + if (ovl_type_merge_or_lower(old)) {
>>> + err = ovl_set_redirect(old);
>>
>> There is a fair chance of getting ENOSPC/EDQUOT here and confuse user space.
>> Would it be better to convert these non fatal errors with EXDEV, so
>> user space will
>> gracefully fallback to recursive rename/clone/copy?
>
> Recursive copy up will surely consume more space than an xattr?
>
>>> @@ -162,6 +223,23 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
>>> stack[ctr].dentry = this;
>>> stack[ctr].mnt = lowerpath.mnt;
>>> ctr++;
>>> +
>>> + if (!stop && i != poe->numlower - 1 &&
>>> + d_is_dir(this) && ovl_redirect_dir(dentry->d_sb)) {
>>> + err = ovl_check_redirect(this, &redirect);
>>> + if (err)
>>> + goto out_put;
>>> +
>>> + if (redirect && poe != dentry->d_sb->s_root->d_fsdata) {
>>> + poe = dentry->d_sb->s_root->d_fsdata;
>>> +
>>
>> Now you are about to continue looping until new value of poe->numlower,
>> which is >= then olf value of poe->numlower, but 'stack' was allocated
>> according to old value of poe->numlower, so aren't you in danger of
>> overflowing it?
>>
>> Please add a comment to explain the purpose of this loop rewind.
>
> We are jumping to a stack possibly wider than the current one and need
> to find the layer where to continue the downward traversal. I'll add
> the comment.
>
OK. my point was that you need to allocate an sb max depth stack in advance,
in case you need to jump to a wider stack.
> BTW I don't remember having tested this, so it might possibly be
> buggy. Automatic multi-layer testing would really be good. What we
> basically need is:
>
> - create normal (two layer) overlay (with interesting constructs,
> whiteout, opaque dir, redirect)
> - umount
> - create three layer overlay where the two lower layers come from the
> previous upper/lower layers
> - do more interesting things
>
> There's one such test in xfstests but it would be good to have more.
>
I just sent 2 patches to fix 2 overlayfs xfstests failures.
With these 2 changes, the entire quick test group passes on my setup
(short of one test that also fails on ext4 and xfs).
Now I will start to think about instrumenting generic xfstests with lower/upper
files and then with rotating upper (i.e. layer stack).
Amir.
next prev parent reply other threads:[~2016-10-26 19:56 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-25 7:34 [PATCH 0/3] overlayfs: allow moving directory trees Miklos Szeredi
2016-10-25 7:34 ` [PATCH 1/3] ovl: check fs features Miklos Szeredi
2016-10-25 11:24 ` Amir Goldstein
2016-11-05 20:40 ` Amir Goldstein
2016-10-25 7:34 ` [PATCH 2/3] vfs: export vfs_path_lookup() Miklos Szeredi
2016-10-25 7:34 ` [PATCH 3/3] ovl: redirect on rename-dir Miklos Szeredi
2016-10-25 11:57 ` Raphael Hertzog
2016-10-26 11:12 ` Miklos Szeredi
2016-10-28 12:56 ` Raphael Hertzog
2016-10-28 12:59 ` Miklos Szeredi
2016-11-06 19:14 ` Konstantin Khlebnikov
2016-11-07 8:07 ` Miklos Szeredi
2016-11-07 9:58 ` Konstantin Khlebnikov
2016-11-07 10:04 ` Miklos Szeredi
2016-11-07 10:08 ` Konstantin Khlebnikov
2016-11-07 13:38 ` Amir Goldstein
2016-11-10 22:56 ` Amir Goldstein
2016-11-11 9:46 ` Konstantin Khlebnikov
2016-11-11 10:06 ` Miklos Szeredi
2016-11-11 12:42 ` Amir Goldstein
2016-11-13 9:11 ` Amir Goldstein
2016-11-07 11:03 ` Raphael Hertzog
2016-11-07 11:31 ` Konstantin Khlebnikov
2016-11-07 13:42 ` Raphael Hertzog
2016-11-10 22:39 ` Miklos Szeredi
2016-11-11 9:41 ` Konstantin Khlebnikov
2016-11-13 10:00 ` Amir Goldstein
2016-11-14 16:25 ` Amir Goldstein
2016-11-16 22:00 ` Miklos Szeredi
2016-11-18 15:37 ` Amir Goldstein
2016-11-20 11:39 ` Amir Goldstein
2016-11-21 9:54 ` Miklos Szeredi
2016-11-21 10:13 ` Amir Goldstein
2016-11-21 10:16 ` Miklos Szeredi
2016-11-22 13:42 ` Amir Goldstein
2016-10-25 12:49 ` Amir Goldstein
2016-10-26 11:26 ` Miklos Szeredi
2016-10-26 12:11 ` Amir Goldstein
2016-10-26 12:51 ` Miklos Szeredi
2016-10-26 19:56 ` Amir Goldstein [this message]
2016-10-28 16:15 ` Al Viro
2016-11-03 15:50 ` Miklos Szeredi
2016-11-04 9:29 ` Amir Goldstein
2016-11-04 13:48 ` Miklos Szeredi
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