Re: [PATCH] xfsrestore: suggest -x rather than assert for false roots

["Darrick J. Wong" <djwong@kernel.org>]

On Fri, Jun 23, 2023 at 04:29:18PM +1000, Donald Douwsma wrote:
> If we're going to have a fix for false root problems its a good idea to
> let people know that there's a way to recover, error out with a useful
> message that mentions the `-x` option rather than just assert.
> 
> Before
> 
>   xfsrestore: searching media for directory dump
>   xfsrestore: reading directories
>   xfsrestore: tree.c:757: tree_begindir: Assertion `ino != persp->p_rootino || hardh == persp->p_rooth' failed.
>   Aborted
> 
> After
> 
>   xfsrestore: ERROR: tree.c:791: tree_begindir: Assertion `ino != persp->p_rootino || hardh == persp->p_rooth` failed.
>   xfsrestore: ERROR: False root detected. Recovery may be possible using the `-x` option
>   Aborted
> 
> Fixes: d7cba74 ("xfsrestore: fix rootdir due to xfsdump bulkstat misuse")
> Signed-off-by: Donald Douwsma <ddouwsma@redhat.com>
> ---
>  restore/tree.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/restore/tree.c b/restore/tree.c
> index bfa07fe..0b65d0f 100644
> --- a/restore/tree.c
> +++ b/restore/tree.c
> @@ -783,8 +783,17 @@ tree_begindir(filehdr_t *fhdrp, dah_t *dahp)
>  	/* lookup head of hardlink list
>  	 */
>  	hardh = link_hardh(ino, gen);
> -	if (need_fixrootdir == BOOL_FALSE)
> -		assert(ino != persp->p_rootino || hardh == persp->p_rooth);
> +	if (need_fixrootdir == BOOL_FALSE
> +		&& !(ino != persp->p_rootino || hardh == persp->p_rooth)) {

Usually we put the && operator on the line above.  But ignore that
comment if that's actually the predominant style in xfsrestore.

	if (need_fixrootdir == BOOL_FALSE &&
	    !(ino != persp->p_rootino || hardh == persp->p_rooth)) {

> +		mlog(MLOG_ERROR | MLOG_TREE, 

Trailing space.

> +			"%s:%d: %s: Assertion "
> +			"`ino != persp->p_rootino || hardh == persp->p_rooth` failed.\n",

Might be nice to put the entire string on one line for greppability?

		mlog(MLOG_ERROR | MLOG_TREE,
 "%s:%d: %s: Assertion `ino != persp->p_rootino || hardh == persp->p_rooth` failed.\n",

> +			__FILE__, __LINE__, __FUNCTION__);
> +		mlog(MLOG_ERROR | MLOG_TREE, _(
> +			"False root detected. "
> +			"Recovery may be possible using the `-x` option\n"));

Same here.

Otherwise this looks like a good improvement.

--D

> +		return NH_NULL;
> +	};
>  
>  	/* already present
>  	 */
> -- 
> 2.39.3
>