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From:   Amir Goldstein <amir73il@gmail.com>
Date:   Sat, 25 Apr 2020 11:54:25 +0300
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Subject: Re: [PATCH 4/5] overlayfs: Check for range bounds before calling i_op->fiemap()
To:     Ritesh Harjani <riteshh@linux.ibm.com>
Cc:     Ext4 <linux-ext4@vger.kernel.org>, Jan Kara <jack@suse.cz>,
        Theodore Tso <tytso@mit.edu>,
        Andreas Dilger <adilger@dilger.ca>,
        "Darrick J. Wong" <darrick.wong@oracle.com>,
        Christoph Hellwig <hch@infradead.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
        Murphy Zhou <jencce.kernel@gmail.com>,
        Miklos Szeredi <miklos@szeredi.hu>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        overlayfs <linux-unionfs@vger.kernel.org>
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On Thu, Apr 23, 2020 at 1:48 PM Ritesh Harjani <riteshh@linux.ibm.com> wrote:
>
> Underlying fs may not be able to handle the length in fiemap
> beyond sb->s_maxbytes. So similar to how VFS ioctl does it,
> add fiemap_check_ranges() check in ovl_fiemap() as well
> before calling underlying fs i_op->fiemap() call.
>
> Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
> ---
>  fs/overlayfs/inode.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
> index 79e8994e3bc1..9bcd2e96faad 100644
> --- a/fs/overlayfs/inode.c
> +++ b/fs/overlayfs/inode.c
> @@ -455,16 +455,21 @@ static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
>         int err;
>         struct inode *realinode = ovl_inode_real(inode);
>         const struct cred *old_cred;
> +       u64 length;

To be more clear, I would call that reallen, but apart from that, you may add:

Reviewed-by: Amir Goldstein <amir73il@gmail.com>

Thanks,
Amir.