Re: [PATCH] ext4: Support "check=none" "nocheck" mount options

[Eric Sandeen <sandeen@redhat.com>]

On 1/10/12 11:41 AM, Josh Boyer wrote:
> The ext2/ext3 filesystems supported "check=none" and "nocheck" as mount options
> even though that was already the default behavior and it essentially did
> nothing.  When using ext4 to mount ext2/ext3 filesystems, that mount option
> causes the mount to fail.  That isn't as backward compatible as it could be,
> so add support to ext4 to accept the option.

The only thing ext2 does with those options today is to clear the flag,
and I can't find anything in userspace or kernelspace which would have set
it in any case.  It seem dead, but we do need the compatibility in ext4
if it's to handle ext2&3 seamlessly, I guess.

> Signed-off-by: Josh Boyer <jwboyer@redhat.com>

Reviewed-by: Eric Sandeen <sandeen@redhat.com>

> 
> ---
>  fs/ext4/super.c |    7 ++++++-
>  1 files changed, 6 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 3e1329e..5ff09e7 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1333,7 +1333,7 @@ enum {
>  	Opt_nomblk_io_submit, Opt_block_validity, Opt_noblock_validity,
>  	Opt_inode_readahead_blks, Opt_journal_ioprio,
>  	Opt_dioread_nolock, Opt_dioread_lock,
> -	Opt_discard, Opt_nodiscard, Opt_init_itable, Opt_noinit_itable,
> +	Opt_discard, Opt_nodiscard, Opt_init_itable, Opt_noinit_itable, Opt_nocheck,
>  };
>  
>  static const match_table_t tokens = {
> @@ -1409,6 +1409,8 @@ static const match_table_t tokens = {
>  	{Opt_init_itable, "init_itable=%u"},
>  	{Opt_init_itable, "init_itable"},
>  	{Opt_noinit_itable, "noinit_itable"},
> +	{Opt_nocheck, "check=none"},
> +	{Opt_nocheck, "nocheck"},
>  	{Opt_err, NULL},
>  };
>  
> @@ -1905,6 +1907,9 @@ set_qf_format:
>  		case Opt_noinit_itable:
>  			clear_opt(sb, INIT_INODE_TABLE);
>  			break;
> +		case Opt_nocheck:
> +			/* ext2/ext3 used to "support" this option.  Silently eat it */
> +			break;
>  		default:
>  			ext4_msg(sb, KERN_ERR,
>  			       "Unrecognized mount option \"%s\" "