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From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
To: Namjae Jeon <linkinjeon@gmail.com>
Cc: akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, Namjae Jeon <namjae.jeon@samsung.com>,
        Ravishankar N <ravi.n1@samsung.com>,
        Amit Sahrawat <a.sahrawat@samsung.com>
Subject: Re: [PATCH v5 5/8] fat: restructure export_operations
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Date: Thu, 06 Dec 2012 18:24:48 +0900
In-Reply-To: <CAKYAXd-CAhBDNYRTF22Yh8iGDb1_6+0V-U2wJsSuAjU3Q4q-SQ@mail.gmail.com>
	(Namjae Jeon's message of "Thu, 6 Dec 2012 16:37:41 +0900")
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Namjae Jeon <linkinjeon@gmail.com> writes:

>> I know encode_fh(). But NFS is network protocol, and network can input
>> any data, and I guess the userland interface (open_by_handle()?) can be
>> any too.
>>
>> And generic_fh_to_dentry()'s input verify choose to check the minimum
>> length only. But your logic choose the exact length.
>>
>> I think the both is sane and correct. But I wonder why did you changed it.
> There was no particular reason for us to put those conditions. It is
> just we knew what fh lengths we have chosen for the 2 cases
> WITH/WITHOUT parent.
> i.e., we checked with encoded length.
> Now, when I check the export functions of other filesystems(btrfs,
> nilfs2, udf). They also adopt the same method of checking the exact
> length and type.
> If there is any particular reason, we will look into that and can also
> updated on that.

OK. Then, just cleanup code, and let's use strict checking version.

Removing strange fallthrou, something like the following.

static struct dentry *fat_fh_to_dentry_nostale(struct super_block *sb,
					       struct fid *fh, int fh_len,
					       int fh_type)
{
	struct inode *inode = NULL;
	struct fat_fid *fid = (struct fat_fid *)fh;
	loff_t i_pos;

	switch (fh_type) {
	case FILEID_FAT_WITHOUT_PARENT:
		if (fh_len < FAT_FID_SIZE_WITHOUT_PARENT)
			return NULL;
		break;
	case FILEID_FAT_WITH_PARENT:
		if (fh_len < FAT_FID_SIZE_WITH_PARENT)
			return NULL;
		break;
	default:
		return NULL;
	}

	i_pos = fid->i_pos_hi;
	i_pos = (i_pos << 32) | (fid->i_pos_low);
	inode = __fat_nfs_get_inode(sb, 0, fid->i_gen, i_pos);

	return d_obtain_alias(inode);
}


-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>