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

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Message-ID: <cd165532-9425-bc93-a28e-b7d383508b62@intel.com>
Date:   Thu, 30 Mar 2017 12:32:18 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Richard Weinberger <richard@....at>, 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()

On 30/03/17 11:56, Richard Weinberger wrote:
> It is perfectly fine to link a tmpfile back using linkat().
> Since tmpfiles are created with a link count of 0 they appear
> on the orphan list, upon re-linking the inode has to be removed
> from the orphan list again.
> 
> Cc: <stable@...r.kernel.org>
> Cc: Ralph Sennhauser <ralph.sennhauser@...il.com>
> Cc: Amir Goldstein <amir73il@...il.com
> Reported-by: Ralph Sennhauser <ralph.sennhauser@...il.com>
> Tested-by: Ralph Sennhauser <ralph.sennhauser@...il.com>
> Reported-by: Amir Goldstein <amir73il@...il.com
> Fixes: 474b93704f321 ("ubifs: Implement O_TMPFILE")
> Signed-off-by: Richard Weinberger <richard@....at>
> ---
>  fs/ubifs/dir.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> 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?