On Sat, 23 Jan 2021 16:42:33 +0800
Qu Wenruo [off-list ref] wrote:

For the worst case, btrfs can allocate a 128 MiB file extent, and have
good luck to write 127MiB into the extent. It will take 127MiB + 128MiB
space, until the last 1MiB of the original extent get freed, the full
128MiB can be freed.

Does it mean enabling compression actually mitigates this issue as a
side-effect? Since each extent will be limited to only 128K.

What are the typical extent sizes without compression?

-- 
With respect,
Roman