linux-kernel - Re: [PATCH] ubifs: Fix O_TMPFILE corner case in ubifs

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Date:   Thu, 30 Mar 2017 12:23:01 +0200
From:   Richard Weinberger <richard@....at>
To:     Adrian Hunter <adrian.hunter@...el.com>,
        linux-mtd@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org, dedekind1@...il.com,
        stable@...r.kernel.org,
        Ralph Sennhauser <ralph.sennhauser@...il.com>,
        Amir Goldstein <amir73il@...il.com>
Subject: Re: [PATCH] ubifs: Fix O_TMPFILE corner case in ubifs_link()

Am 30.03.2017 um 11:49 schrieb Richard Weinberger:
> Am 30.03.2017 um 11:32 schrieb Adrian Hunter:
>>> diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
>>> index 0858213a4e63..0139155045fe 100644
>>> --- a/fs/ubifs/dir.c
>>> +++ b/fs/ubifs/dir.c
>>> @@ -748,6 +748,11 @@ static int ubifs_link(struct dentry *old_dentry, struct inode *dir,
>>>  		goto out_fname;
>>>  
>>>  	lock_2_inodes(dir, inode);
>>> +
>>> +	/* Handle O_TMPFILE corner case, it is allowed to link a O_TMPFILE. */
>>> +	if (inode->i_nlink == 0)
>>> +		ubifs_delete_orphan(c, inode->i_ino);
>>
>> Isn't there also a deletion inode in the journal?  If the recovery sees that
>> won't it delete the file data?
> 
> Yes, but ubifs_link() adds a new journal entry which revives the inode.
> This should cancel out the deletion, right?
> You know the UBIFS journal better than I do. :-)

Reading deeper into the proved that I was wrong.
AFAIKT UBIFS' journal has currently no way to revive a deleted inode.
So, we have to think about a new solution.

Thanks,
//richard