Re: [PATCH v2] xfsrestore: suggest -x rather than assert for false roots

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

On Mon, Aug 07, 2023 at 02:53:57PM +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: d7cba7410710 ("xfsrestore: fix rootdir due to xfsdump bulkstat misuse")
> Signed-off-by: Donald Douwsma <ddouwsma@redhat.com>
> 
> ---
> Changes for v2
> - Use xfsprogs style for conditional
> - Remove trailing white-space
> - Place printf format all on one line for grepability
> - use __func__ instead of gcc specific __FUNCTION__
> ---
>  restore/tree.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/restore/tree.c b/restore/tree.c
> index bfa07fe..e959aa1 100644
> --- a/restore/tree.c
> +++ b/restore/tree.c
> @@ -783,8 +783,15 @@ 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)) {
> +		mlog(MLOG_ERROR | MLOG_TREE,

Nit: Second line of the if test has the same level of indentation as the
if body.

With that fixed,
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> +"%s:%d: %s: Assertion `ino != persp->p_rootino || hardh == persp->p_rooth` failed.\n",
> +			__FILE__, __LINE__, __func__);
> +		mlog(MLOG_ERROR | MLOG_TREE, _(
> +"False root detected. Recovery may be possible using the `-x` option\n"));
> +		return NH_NULL;
> +	}
>  
>  	/* already present
>  	 */
> -- 
> 2.39.3
>