On Sun, Nov 14, 2021 at 08:51:01PM +0800, Qu Wenruo wrote:

In the coming btrfs-progs v5.15 release, mkfs.btrfs will change to use
v2 cache by default.

However nospace_cache mount option will not work with v2 cache, as it
would make v2 cache out of sync with on-disk used space.

So mounting a btrfs with v2 cache using "nospace_cache" will make btrfs
to reject the mount.

There are quite some test cases relying on nospace_cache to prevent v1
cache to take up data space.

For those test cases, we no longer need the "nospace_cache" mount option
if the filesystem is already using v2 cache.
Since v2 cache is using metadata space, it will no longer take up data
space, thus no extra mount options for those test cases.

By this, we can keep those existing tests to run without problem for
both v1 and v2 cache.

Signed-off-by: Qu Wenruo <redacted>

Reviewed-by: Josef Bacik <josef@toxicpanda.com>

Thanks, this explains a weird failure state that I've been seeing with btrfs/199
writing into /tmp and filling everything, which causes the rest of the tests to
fail.

Josef