lazy free space tree creation, deprecation of space cache v1

lazy free space tree creation, deprecation of space cache v1

[Chris Murphy]

Hi,

Recent kernels warn about the deprecation of space cache v1, advising users to switch to v2. Many desktop users don't see this message and won't switch to v2 on their own.

I think the concern with silently and forcefully converting users from v1 to v2 automatically is the potentially long time it takes for large file systems? e.g. Zygo has reported days for some of his large file systems.

Since the free space tree can just be deleted and recreated again, is there a possibility of a lazy free space tree creation? Similar to ext4 lazy init (totally different structure and reasoning but high level, same idea - reduce the offline wait for initializing something).

Thanks,

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Chris Murphy