Re: [PATCH] V7: Add support for non-PDP11 v7 filesystems

[Randy Dunlap <rdunlap@xenotime.net>]

On Mon, 26 Jul 2010 00:59:16 +0200 Lubomir Rintel wrote:

> This adds byte order autodetection (of PDP-11 and LE filesystems).
> No attempt is made to detect big-endian filesystems -- were there any?
> Tested with PDP-11 v7 filesystems and PC-IX maintenance floppy.
> 
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Al Viro <viro@ZenIV.linux.org.uk>
> Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
> ---
>  fs/sysv/super.c |   74 +++++++++++++++++++++++++++++++++++++------------------
>  1 files changed, 50 insertions(+), 24 deletions(-)
> 
> diff --git a/fs/sysv/super.c b/fs/sysv/super.c
> index ac7b008..0433f23 100644
> --- a/fs/sysv/super.c
> +++ b/fs/sysv/super.c
> @@ -435,12 +436,46 @@ Ebadsize:
>  	goto failed;
>  }
>  
> -static int v7_fill_super(struct super_block *sb, void *data, int silent)
> +static int v7_sanity_check(struct super_block *sb, struct buffer_head *bh)
>  {
> -	struct sysv_sb_info *sbi;
> -	struct buffer_head *bh, *bh2 = NULL;
>  	struct v7_super_block *v7sb;
>  	struct sysv_inode *v7i;
> +	struct buffer_head *bh2;
> +	struct sysv_sb_info *sbi;
> +
> +	sbi = sb->s_fs_info;
> +
> +	/* plausibility check on superblock */
> +	v7sb = (struct v7_super_block *) bh->b_data;
> +	if (fs16_to_cpu(sbi, v7sb->s_nfree) > V7_NICFREE ||
> +	    fs16_to_cpu(sbi, v7sb->s_ninode) > V7_NICINOD ||
> +	    fs32_to_cpu(sbi, v7sb->s_fsize) > V7_MAXSIZE)
> +		return 0;
> +
> +	/* plausibility check on root inode: it is a directory,
> +	   with a nonzero size that is a multiple of 16 */
> +	if ((bh2 = sb_bread(sb, 2)) == NULL) {
> +		return 0;
> +	}

Don't need the braces.

> +
> +	v7i = (struct sysv_inode *)(bh2->b_data + 64);
> +	if ((fs16_to_cpu(sbi, v7i->i_mode) & ~0777) != S_IFDIR ||
> +	    (fs32_to_cpu(sbi, v7i->i_size) == 0) ||
> +	    (fs32_to_cpu(sbi, v7i->i_size) & 017) ||
> +	    (fs32_to_cpu(sbi, v7i->i_size) > V7_NFILES *
> +             sizeof (struct sysv_dir_entry))) {

	        sizeof(struct sysv_dir_entry))) {

> +		brelse(bh2);
> +		return 0;
> +	}
> +
> +	brelse(bh2);
> +	return 1;
> +}
> +
> +static int v7_fill_super(struct super_block *sb, void *data, int silent)
> +{
> +	struct sysv_sb_info *sbi;
> +	struct buffer_head *bh;
>  
>  	if (440 != sizeof (struct v7_super_block))
>  		panic("V7 FS: bad super-block size");
> @@ -454,7 +489,6 @@ static int v7_fill_super(struct super_block *sb, void *data, int silent)
>  	sbi->s_sb = sb;
>  	sbi->s_block_base = 0;
>  	sbi->s_type = FSTYPE_V7;
> -	sbi->s_bytesex = BYTESEX_PDP;
>  	sb->s_fs_info = sbi;
>  	
>  	sb_set_blocksize(sb, 512);
> @@ -466,34 +500,26 @@ static int v7_fill_super(struct super_block *sb, void *data, int silent)
>  		goto failed;
>  	}
>  
> -	/* plausibility check on superblock */
> -	v7sb = (struct v7_super_block *) bh->b_data;
> -	if (fs16_to_cpu(sbi, v7sb->s_nfree) > V7_NICFREE ||
> -	    fs16_to_cpu(sbi, v7sb->s_ninode) > V7_NICINOD ||
> -	    fs32_to_cpu(sbi, v7sb->s_fsize) > V7_MAXSIZE)
> -		goto failed;
> +	/* Try PDP-11 UNIX */
> +	sbi->s_bytesex = BYTESEX_PDP;
> +	if (v7_sanity_check (sb, bh))
> +		goto detected;
>  
> -	/* plausibility check on root inode: it is a directory,
> -	   with a nonzero size that is a multiple of 16 */
> -	if ((bh2 = sb_bread(sb, 2)) == NULL)
> -		goto failed;
> -	v7i = (struct sysv_inode *)(bh2->b_data + 64);
> -	if ((fs16_to_cpu(sbi, v7i->i_mode) & ~0777) != S_IFDIR ||
> -	    (fs32_to_cpu(sbi, v7i->i_size) == 0) ||
> -	    (fs32_to_cpu(sbi, v7i->i_size) & 017) ||
> -	    (fs32_to_cpu(sbi, v7i->i_size) > V7_NFILES *
> -	     sizeof (struct sysv_dir_entry)))
> -		goto failed;
> -	brelse(bh2);
> -	bh2 = NULL;
> +	/* Try PC/IX, v7/x86 */
> +	sbi->s_bytesex = BYTESEX_LE;
> +	if (v7_sanity_check (sb, bh))
> +		goto detected;
>  
> +	goto failed;
> +
> +detected:
>  	sbi->s_bh1 = bh;
>  	sbi->s_bh2 = bh;
>  	if (complete_read_super(sb, silent, 1))
>  		return 0;
>  
>  failed:
> -	brelse(bh2);
> +	printk("VFS: could not find a valid V7 on %s.\n", sb->s_id);

	                                    V7 fs (or V7 filesystem)

>  	brelse(bh);
>  	kfree(sbi);
>  	return -EINVAL;
> -- 


---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***