linux-kernel - Re: [PATCH v5 5/8] fat: restructure export

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Date:	Mon, 03 Dec 2012 18:51:16 +0900
From:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:	Namjae Jeon <linkinjeon@...il.com>
Cc:	akpm@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Namjae Jeon <namjae.jeon@...sung.com>,
	Ravishankar N <ravi.n1@...sung.com>,
	Amit Sahrawat <a.sahrawat@...sung.com>
Subject: Re: [PATCH v5 5/8] fat: restructure export_operations

Namjae Jeon <linkinjeon@...il.com> writes:

> +	if (MSDOS_SB(inode->i_sb)->options.nfs == FAT_NFS_NOSTALE_RO) {
> +		/* Use i_pos for ino. This is used as fileid of nfs. */
> +		stat->ino = fat_i_pos_read(MSDOS_SB(inode->i_sb), inode);

BTW, what number is used for root dir? If it is 0 (0 is special ino in
glibc), we have to use MSDOS_ROOT_INO instead.

> +#define FAT_FID_SIZE_WITHOUT_PARENT (offsetof(struct fat_fid, \
> +					      parent_i_pos_hi)/4)

(offset parent_i_pos_hi) / 4 == 2. Wrong.

> +#define FAT_FID_SIZE_WITH_PARENT (sizeof(struct fat_fid)/4)

4 should be sizeof(u32). Or simplely use immediate value.

> +static int
> +fat_encode_fh_nostale(struct inode *inode, __u32 *fh, int *lenp,
> +		      struct inode *parent)
> +{
> +	int len = *lenp;
> +	struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
> +	struct fat_fid *fid = (struct fat_fid *) fh;
> +	loff_t i_pos;
> +	int type = FILEID_FAT_WITHOUT_PARENT;
> +
> +	if (parent && (len < FAT_FID_SIZE_WITH_PARENT)) {
> +		*lenp = FAT_FID_SIZE_WITH_PARENT;
> +		return 255;

255 is now FILEID_INVALID, I think.

> +	} else if (len < FAT_FID_SIZE_WITHOUT_PARENT) {
> +		*lenp = FAT_FID_SIZE_WITHOUT_PARENT;
> +		return 255;
> +	}
> +
> +	i_pos = fat_i_pos_read(sbi, inode);
> +	*lenp = FAT_FID_SIZE_WITHOUT_PARENT;
> +	fid->i_gen = inode->i_generation;
> +	fid->i_pos_low = i_pos & 0xFFFFFFFF;
> +	fid->i_pos_hi = (i_pos >> 32) & 0xFFFF;
> +	if (parent) {
> +		i_pos = fat_i_pos_read(sbi, parent);
> +		fid->parent_i_pos_hi = (i_pos >> 32) & 0xFFFF;
> +		fid->parent_i_pos_low = i_pos & 0xFFFFFFFF;
> +		fid->parent_i_gen = parent->i_generation;
> +		type = FILEID_FAT_WITH_PARENT;
> +		*lenp = FAT_FID_SIZE_WITH_PARENT;
> +	}
> +
> +	return type;
> +}
> +
>  /**
>   * Map a NFS file handle to a corresponding dentry.
>   * The dentry may or may not be connected to the filesystem root.
>   */
> -struct dentry *fat_fh_to_dentry(struct super_block *sb, struct fid *fid,
> +static struct dentry *fat_fh_to_dentry(struct super_block *sb, struct fid *fid,
>  				int fh_len, int fh_type)
>  {
>  	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
>  				    fat_nfs_get_inode);
>  }
>  
> +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;
> +	case FILEID_FAT_WITH_PARENT:
> +		if ((fh_len < FAT_FID_SIZE_WITH_PARENT) &&
> +			(fh_type == FILEID_FAT_WITH_PARENT))
> +			return NULL;

Do we have to care (FILEID_FAT_WITH_PARENT and fh_len < 5) here?

	if (fh_len < 2)
		return NULL;

	switch (fh_type) {
	case FILEID_INO32_GEN:
	case FILEID_INO32_GEN_PARENT:
		inode = get_inode(sb, fid->i32.ino, fid->i32.gen);
		break;
	}

	return d_obtain_alias(inode);

generic_fh_to_dentry() is above. I wonder why we have to care
fat_fid->parent* here.
-- 
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
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