[PATCH 17/19] xfsprogs: disable truncating of files

[Dave Chinner]

On Thu, Mar 24, 2016 at 12:15:34PM +0100, jtulak at redhat.com wrote:
> From: Jan Tulak <jtulak at redhat.com>
> 
> Unify mkfs.xfs behaviour a bit and never truncate files. If the user
> is trying to mkfs an existing file, we don't want to destroy anything
> he did with the file before (sparse file, allocations...)

Why not? We do that with discard-by-default to block devices,
O_TRUNC is exactly the same situation with a file - we completely
re-initialise the file from a known state if mkfs has been asked to
create the file.


> @@ -1059,9 +1063,9 @@ check_device_type(
>  	}
>  
>  	/*
> -	 * We only want to completely truncate and recreate an existing file if
> -	 * we were specifically told it was a file. Set the create flag only in
> -	 * this case to trigger that behaviour.
> +	 * We only want to create a file only if we were specifically told
> +	 * we want a file. Set the create flag only in this case to trigger
> +	 * that behaviour.
>  	 */
>  	if (S_ISREG(statbuf.st_mode)) {
>  		if (!*isfile)

i.e. this situation.

Cheers,

Dave.
-- 
Dave Chinner
david at fromorbit.com