Re: LTP test df01.sh detected different size of loop device in v5.19

Hi all,

LTP test df01.sh found different size of loop device in v5.19.
Test uses loop device formatted on various file systems, only XFS fails.
It randomly fails during verifying that loop size usage changes:

grep ${TST_DEVICE} output | grep -q "${total}.*${used}" [1]

How to reproduce:
# PATH="/opt/ltp/testcases/bin:$PATH" df01.sh -f xfs # it needs several tries to hit

df saved output:
Filesystem     1024-blocks    Used Available Capacity Mounted on
...
/dev/loop0          256672   16208    240464       7% /tmp/LTP_df01.1kRwoUCCR7/mntpoint
df output:
Filesystem     1024-blocks    Used Available Capacity Mounted on
...
tmpfs               201780       0    201780       0% /run/user/0
/dev/loop0          256672   15160    241512       6% /tmp/LTP_df01.1kRwoUCCR7/mntpoint
=> different size
df01 4 TFAIL: 'df -k -P' failed, not expected.

Also 'df -T -P' fails.

It might be a false positive / bug in the test, but it's at least a changed behavior.
I was able to reproduce it on v5.19 distro kernels (openSUSE, Debian).
I haven't bisected (yet), nor checked Jens' git tree (maybe it has been fixed).

Forget to note dmesg "operation not supported error" warning on *each* run (even
successful) on affected v5.19:
[ 5097.594021] loop0: detected capacity change from 0 to 524288
[ 5097.658201] operation not supported error, dev loop0, sector 262192 op 0x9:(WRITE_ZEROES) flags 0x8000800 phys_seg 0 prio class 0
[ 5097.675670] XFS (loop0): Mounting V5 Filesystem
[ 5097.681668] XFS (loop0): Ending clean mount
[ 5097.956445] XFS (loop0): Unmounting Filesystem

Kind regards,
Petr

Kind regards,
Petr

[1] https://github.com/linux-test-project/ltp/blob/f42f6f3b4671f447b743afe8612917ba4362b8a6/testcases/commands/df/df01.sh#L103-L110