linux-kernel - Re: [REGRESSION 4.11] Commit d8514d8edb5b ("ovl: copy up regular file using O

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Message-ID: <CAOQ4uxjKTdK5MiiEysBSGRSb6NYyu079COBLj5zpWjmJGxM7cQ@mail.gmail.com>
Date:   Thu, 30 Mar 2017 09:34:15 +0300
From:   Amir Goldstein <amir73il@...il.com>
To:     Ralph Sennhauser <ralph.sennhauser@...il.com>
Cc:     Richard Weinberger <richard@....at>,
        Miklos Szeredi <miklos@...redi.hu>,
        linux-unionfs@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-mtd@...ts.infradead.org, regressions@...mhuis.info,
        Artem Bityutskiy <dedekind1@...il.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        David Oberhollenzer <goliath@...ma-star.at>
Subject: Re: [REGRESSION 4.11] Commit d8514d8edb5b ("ovl: copy up regular file
 using O_TMPFILE") breaks ubifs

On Thu, Mar 30, 2017 at 8:53 AM, Ralph Sennhauser
<ralph.sennhauser@...il.com> wrote:
> Hi Richard,
>
> On Thu, 30 Mar 2017 00:15:31 +0200
> Richard Weinberger <richard@....at> wrote:
>
>> Ralph,
>>
>> Am 29.03.2017 um 23:26 schrieb Ralph Sennhauser:
>> >> # create and link a tmpfile - then remove it
>> >> sudo rm -rf foo; sudo xfs_io -T -c "flink foo" . ; ls -l foo; sudo
>> >> rm foo
>> >
>> > next-20170328, obviously without your patch:
>> >
>> >   # xfs_io -T -c "flink foo" .
>> >   .: Not supported
>>
>> -T tells xfs_io to create a tmpfile but you have it disabled in UBIFS.
>
> Bash history says I booted the other partition than I flashed (uname
> just happened to match), the downside of the dual boot layout. :)
>
>   # rm -rf foo
>   # xfs_io -T -c "flink foo" .
>   # ls -l foo
>   -rw-------    1 root     root             0 Mar 30 02:00 foo
>   # rm foo
>   [  305.001436] UBIFS error (ubi0:0 pid 2493): ubifs_add_orphan: orphaned twice
>
> However, unlike with the overlay setup the filesystem can be mounted
> just fine without imediatly visible side effects.
>

Maybe try to rename instead of rm . that's how you reproduces with overlayfs.

>>
>> Anyway, can you please test the attached patch?
>> Amir was right, UBIFS misses a corner case in ubifs_link(). ;-\
>>
>> I think I understand also why we never noticed this in xfstests,
>> UBIFS prints only a non-fatal error while umounting the filesystem in
>> this case. But will test tomorrow in more detail, need some sleep now.
>>
>> diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
>> index 30825d882aa9..95e348a2da29 100644
>> --- a/fs/ubifs/dir.c
>> +++ b/fs/ubifs/dir.c
>> @@ -748,6 +748,9 @@ static int ubifs_link(struct dentry *old_dentry,
>> struct inode *dir, goto out_fname;
>>
>>       lock_2_inodes(dir, inode);
>> +     if (inode->i_nlink == 0)
>> +             ubifs_delete_orphan(c, inode->i_ino);
>> +
>>       inc_nlink(inode);
>>       ihold(inode);
>>       inode->i_ctime = ubifs_current_time(inode);
>>
>> Thanks,
>> //richard
>
> With this patch I'm no longer able to reproduce _this_ issue, however,
> rename no longer works either:
>
>   # mv /etc/config/wireless /etc/config/wireless.back
>   mv: can't rename '/etc/config/wireless': Invalid argument
>   # ls /etc/config/wireless
>   /etc/config/wireless
>   # rm /etc/config/wireless
>   # ls /etc/config/wireless
>   ls: /etc/config/wireless: No such file or directory
>
>
> Thanks
> Ralph