Re: [PATCH] fsstress: improve error message on check_cwd() error

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

On Mon, Nov 01, 2021 at 08:55:59AM -0700, Luis Chamberlain wrote:
> I ran into an error with generic/083 with xfs due to check_cwd() but
> why it failed is not clear because there are two types of
> failures:
> 
>   o stat64() failed (likely -ENOMEM is my guess)
>   o the inode actually changed
> 
> Throw a bone out to developers so that in case en error does happen
> they know which rabbit hole to go down on.

<cough> word choice on those last three words...

> 
> Cc: Anthony Iliopoulos <ailiopoulos@suse.de>
> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
> ---
>  ltp/fsstress.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/ltp/fsstress.c b/ltp/fsstress.c
> index 90ae432e..a576afea 100644
> --- a/ltp/fsstress.c
> +++ b/ltp/fsstress.c
> @@ -9,6 +9,7 @@
>  #include <sys/uio.h>
>  #include <stddef.h>
>  #include <stdbool.h>
> +#include <string.h>
>  #include "global.h"
>  
>  #ifdef HAVE_BTRFSUTIL_H
> @@ -943,9 +944,21 @@ check_cwd(void)
>  {
>  #ifdef DEBUG
>  	struct stat64	statbuf;
> +	int ret;
> +
> +	ret = stat64(".", &statbuf);
> +	if (ret !=0) {

Nit: space between '!=' and '0'.

> +		fprintf(stderr, "fsstress: check_cwd stat64 failed with: %d (%s)\n",
> +			ret, strerror(ret));

ret is set to -1 on error, according to the manpage; to get the real
error you'd have to call strerror(errno) as the last arg, or be lazy
and:

		perror("fsstress check_cwd stat64");

> +		goto out;
> +	}
>  
> -	if (stat64(".", &statbuf) == 0 && statbuf.st_ino == top_ino)
> +	if (statbuf.st_ino == top_ino)
>  		return;
> +
> +	fprintf(stderr, "fsstress: check_cwd statbuf.st_ino (%lu) != top_ino (%lu)\n",
> +		statbuf.st_ino, top_ino);

This might want some explicit casting, since this can be defined as
anything between unsigned long to uint64_t, at least according to the
glibc headers on my system.

--D

> +out:
>  	assert(chdir(homedir) == 0);
>  	fprintf(stderr, "fsstress: check_cwd failure\n");
>  	abort();
> -- 
> 2.33.0
>