Re: [PATCH] btrfs-progs: tests/misc/058: reduce the space requirement and speed up the test

[David Sterba <dsterba@suse.cz>]

On Wed, Aug 09, 2023 at 02:26:49PM +0200, David Sterba wrote:
> On Tue, Aug 08, 2023 at 02:55:21PM +0800, Qu Wenruo wrote:
> > [BUG]
> > When I was testing misc/058, the fs still has around 7GiB free space,
> > but during that test case, btrfs kernel module reports write failures
> > and even git commands failed inside that fs.
> > 
> > And obviously the test case failed.
> > 
> > [CAUSE]
> > It turns out that, the test case itself would require 6GiB (4 data
> > disks) + 1.5GiB x 2 (the two replace target), thus it requires 9 GiB
> > free space.
> > 
> > And obviously my partition is not that large and failed.
> 
> The file sizes were picked so the replace is not too fast, this again
> depends on the system. Please add more space for tests.
> 
> > [FIX]
> > In fact, we really don't need that much space at all.
> > 
> > Our objective is to test "btrfs device replace --enqueue" functionality,
> > there is not much need to wait for 1 second, we can just do the enqueue
> > immediately.
> 
> This depends on the system and the sleep might be needed if the first
> command does not start the first replace. The test is not testing just
> the --enqueue, but that two replaces can be enqueued on top each other.
> So we need the first one to start.
> 
> > So this patch would reduce the file size to a more sane (and rounded)
> > 2GiB, and do the enqueue immediately.
> 
> I'm not sure that the test would actually work as intended after the
> changes. The sleeps and dependency on system is fragile but we don't
> have anything better than to over allocate and provide enough time for
> the other commands to catch up.

The reduced test still reliably verifies the fix so I'll apply it.
Thanks.