Re: [PATCH] mkfs: default to CRC enabled filesystems

[Eric Sandeen <sandeen@sandeen.net>]

On 3/18/15 6:22 PM, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> It's time to change the mkfs defaults to enable CRCs for all new
> filesystems. While there, also enable the free inode btree by
> default, too, as that functioanlity has also had long enough to make

"functionality" ;)

> it into distro kernels, too.

> 
> Signed-off-by: Dave Chinner <dchinner@redhat.com>

> ---
>  mkfs/xfs_mkfs.c | 21 ++++++++++-----------
>  1 file changed, 10 insertions(+), 11 deletions(-)
> 
> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
> index 484e7a8..d7e70fa 100644
> --- a/mkfs/xfs_mkfs.c
> +++ b/mkfs/xfs_mkfs.c
> @@ -1024,8 +1024,8 @@ main(
>  	force_overwrite = 0;
>  	worst_freelist = 0;
>  	lazy_sb_counters = 1;
> -	crcs_enabled = 0;
> -	finobt = 0;
> +	crcs_enabled = 1;
> +	finobt = 1;
>  	memset(&fsx, 0, sizeof(fsx));
>  
>  	memset(&xi, 0, sizeof(xi));
> @@ -1866,15 +1866,14 @@ _("V2 attribute format always enabled on CRC enabled filesytems\n"));
>  _("32 bit Project IDs always enabled on CRC enabled filesytems\n"));
>  			usage();
>  		}
> -	}
> -
> -	/*
> -	 * The kernel doesn't currently support crc=0,finobt=1 filesystems.
> -	 * Catch it here, disable finobt and warn the user.
> -	 */
> -	if (finobt && !crcs_enabled) {
> -		fprintf(stderr,
> -_("warning: finobt not supported without CRC support, disabled.\n"));
> +	} else {
> +		/*
> +		 * The kernel doesn't currently support crc=0,finobt=1
> +		 * filesystems. If crcs are not enabled, the user has
> +		 * explicitly turned them off, so just silently turn off finobt
> +		 * so that we don't issue unnecessary warnings when non-default
> +		 * options are selected.
> +		 */
>  		finobt = 0;
>  	}

Problem here is that if both are explicitly specified, one is ignored, rather
than letting the user know they've selected an invalid set of options:

# mkfs/mkfs.xfs -dfile,name=fsfile,size=1g -m crc=0,finobt=1
meta-data=fsfile                 isize=256    agcount=4, agsize=65536 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=0        finobt=0
...

This might require a "finobtflag" to keep track of whether it's user-specified,
as we do with other options?

-Eric

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