[LTP] LTP/fanotify01 corner case

[Amir Goldstein]

On Tue, May 14, 2024 at 1:21 AM Murphy Zhou <jencce.kernel@gmail.com> wrote:
>
> Hi Amir,
>
> When TMPDIR is on NFS, fanotify01 get ENODEV when testing if it supports reporting events with fid from multi fs in setup():
>
>>         if (fanotify_flags_supported_on_fs(FAN_REPORT_FID, FAN_MARK_MOUNT, FAN_OPEN, ".")) {
>>                 inode_mark_fid_xdev = errno;
>>                 tst_res(TINFO, "TMPDIR does not support reporting events with fid from multi fs");
>>         }
>
>
> later in test_fanotify(), fd_notify firstly gets added a mark for the fs mounted within the NFS TMPDIR,
>
> and then at the end of test_fanotify(), added another mark for the TMPDIR which is NFS in this case, and check on the errno:
>
>>         ret = report_fid ? inode_mark_fid_xdev : 0;
>>         TST_EXP_FD_OR_FAIL(fanotify_mark(fd_notify, FAN_MARK_ADD, FAN_CLOSE_WRITE,
>>                                          AT_FDCWD, "."), ret);
>
>
>
> It worked fine till
>
>> commit 30ad1938326bf9303ca38090339d948975a626f5
>> Author: Amir Goldstein <amir73il@gmail.com>
>> Date:   Thu Nov 30 18:56:19 2023 +0200
>>
>>     fanotify: allow "weak" fsid when watching a single filesystem
>
>
> After this commit was merged, the first check got ENODEV and the second check got EXDEV.
>
> The both values make sense in their situation, but it seems like using one value as expected value for another seems not accurate here for me. I don't know much here, your help is much appreciated.

Your analysis is exact and correct.

The commit above caused a behavior change in that case moving from one
error that makes sense to another error that makes sense and the test
should cope with that.

The easiest would be to open code TST_EXP_FD_OR_FAIL()
helper and check for either
errno == inode_mark_fid_xdev || errno == EXDEV.
not sure if there is an LTP helper for this pattern.

Thanks,
Amir.