Re: [RFC 1/1 linux-next] udf: allow implicit blocksize specification during mount

[Jan Kara]

On Wed 18-01-17 19:39:35, Fabian Frederick wrote:
> udf_fill_super() used udf_parse_options() to flag UDF_FLAG_BLOCKSIZE_SET
> when blocksize was specified otherwise used 512 bytes
> (bdev_logical_block_size) and 2048 bytes (UDF_DEFAULT_BLOCKSIZE)
> IOW both 1024 and 4096 specifications were required or resulted in
> 
> "mount: wrong fs type, bad option, bad superblock on /dev/loop1"
> 
> This patch loops through different block values but also updates
> udf_load_vrs() to return -EINVAL instead of 0 when udf_check_vsd()
> fails (and uopt->novrs = 0).
> The later being the reason for the RFC; we have that case when mounting
> a 4kb blocksize against other values but maybe VRS is not mandatory 
> there ?
> 
> Tested with 512, 1024, 2048 and 4096 blocksize
> 
> Reported-by: Jan Kara <jack@xxxxxxxx>
> Signed-off-by: Fabian Frederick <fabf@xxxxxxxxx>

Thanks for the patch. It looks good to me. I'll test it a bit and pick it
up.

								Honza

> ---
>  fs/udf/super.c | 22 +++++++++++++---------
>  1 file changed, 13 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/udf/super.c b/fs/udf/super.c
> index 967ad87..078a144 100644
> --- a/fs/udf/super.c
> +++ b/fs/udf/super.c
> @@ -1957,7 +1957,7 @@ static int udf_load_vrs(struct super_block *sb, struct udf_options *uopt,
>  		if (!nsr_off) {
>  			if (!silent)
>  				udf_warn(sb, "No VRS found\n");
> -			return 0;
> +			return -EINVAL;
>  		}
>  		if (nsr_off == -1)
>  			udf_debug("Failed to read sector at offset %d. "
> @@ -2161,15 +2161,19 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
>  		ret = udf_load_vrs(sb, &uopt, silent, &fileset);
>  	} else {
>  		uopt.blocksize = bdev_logical_block_size(sb->s_bdev);
> -		ret = udf_load_vrs(sb, &uopt, silent, &fileset);
> -		if (ret == -EAGAIN && uopt.blocksize != UDF_DEFAULT_BLOCKSIZE) {
> -			if (!silent)
> -				pr_notice("Rescanning with blocksize %d\n",
> -					  UDF_DEFAULT_BLOCKSIZE);
> -			brelse(sbi->s_lvid_bh);
> -			sbi->s_lvid_bh = NULL;
> -			uopt.blocksize = UDF_DEFAULT_BLOCKSIZE;
> +		while (uopt.blocksize <= 4096) {
>  			ret = udf_load_vrs(sb, &uopt, silent, &fileset);
> +			if (ret < 0) {
> +				if (!silent) {
> +					pr_notice("Scanning with blocksize %d failed\n",
> +						  uopt.blocksize);
> +				}
> +				brelse(sbi->s_lvid_bh);
> +				sbi->s_lvid_bh = NULL;
> +			} else
> +				break;
> +
> +			uopt.blocksize <<= 1;
>  		}
>  	}
>  	if (ret < 0) {
> -- 
> 2.9.3
> 
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR