Re: [PATCH v2 3/3] iotests: Filter out ZFS in several tests

[Fiona Ebner <f.ebner@proxmox.com>]

Am 23.05.25 um 18:27 schrieb Eric Blake:
> Fiona reported that ZFS makes sparse file testing awkward, since:
> - it has asynchronous allocation (not even 'fsync $file' makes du see
>   the desired size; it takes the slower 'fsync -f $file' which is not
>   appropriate for the tests)
> - for tests of fully allocated files, ZFS with compression enabled
>   still reports smaller disk usage
> 
> Add a new _require_sparse_file that quickly probes whether an attempt

It's called _require_disk_usage in the implementation.

> to create a sparse 5M file shows as less than 1M usage, while the same
> file with -o preallocation=full shows as more than 4M usage without
> sync, which should filter out ZFS behavior.  Then use it in various
> affected tests.
> 
> This does not add the new filter on all tests that Fiona is seeing ZFS
> failures on, but only those where I could quickly spot that there is
> at least one place where the test depends on the output of 'du -b' or
> 'stat -c %b'.
> 
> Reported-by: Fiona Ebner <f.ebner@proxmox.com>
> Signed-off-by: Eric Blake <eblake@redhat.com>

Reviewed-by: Fiona Ebner <f.ebner@proxmox.com>
Tested-by: Fiona Ebner <f.ebner@proxmox.com>