Re: [PATCH] generic/386: check the correct field from df output

From: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
To: Theodore Ts'o <tytso@mit.edu>
Cc: <fstests@vger.kernel.org>, <sandeen@sandeen.net>
Subject: Re: [PATCH] generic/386: check the correct field from df output
Date: Mon, 23 Dec 2019 09:24:56 +0800	[thread overview]
Message-ID: <ae961477-f14a-60b3-9784-909470bc2bc8@cn.fujitsu.com> (raw)
In-Reply-To: <20191222212730.378358-1-tytso@mit.edu>

on 2019/12/23 5:27, Theodore Ts'o wrote:
> The generic/386 test was checking the "Available" field when it should
> have been checking the "1k-blocks" field, which represents the project
> quota's hard limit.  On xfs, an empty directory takes no space, so it
> doesn't matter.  But for ext4, an empty directory still takes 4k (or
> whatever the file system's block size happens to be):
> 
> Filesystem           1K-blocks       Used  Available  Use% Pathname
> /dev/vdc                512000          4     511996    0% /vdc/test
> 
> This causes generic/386 to falsely fail.  There was a confusing
> comment claiming that for a very long device name, the df output would
> have a line break, and for that reason, the test would extract the
> field using $(NF-2).  However, looking at xfsprogs's quota command, I
> see no evidence that there is any line breaking logic.  Since we now
> want to use the second field, even if there was some line breaking
> going on, using $2 should be a better choice.
> 
> This fix is needed to fix generic/386 from failing on ext4:
Hi Theodore

I have a same fix but I use $(NF-4) field of df command. Also I wrongly 
think project quota uses a block size.
url:
https://patchwork.kernel.org/patch/11296657/

Best Regards
Yang Xu
> 
>      hard limit 524283904 bytes, expected 524288000
> 
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> ---
>   tests/generic/386 | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/tests/generic/386 b/tests/generic/386
> index 0c44c80e..37e9b943 100755
> --- a/tests/generic/386
> +++ b/tests/generic/386
> @@ -62,8 +62,6 @@ _require_scratch
>   # both the "df" and the "report" output.  For "report", the line we're
>   # interested in contains our project name in the first field.  For "df"
>   # it contains our project directory in the last field.
> -# But if the device name is too long, the "df" output is broke into two
> -# lines, the fourth field is not correct, so take $(NF-2) of "df"
>   _filter_quota_rpt() {
>   	awk '
>   	BEGIN {
> @@ -89,7 +87,7 @@ _filter_quota_rpt() {
>   			bsize = byte_size($4);
>   		} else if ($NF ~ proj_dir) {
>   			# this is the "df" output
> -			bsize = byte_size($(NF-2));
> +			bsize = byte_size($2));
>   		} else {
>   			next;
>   		}
> 