Re: [PATCH 00/23][v4] Change data reservations to use the ticketing infra

Nikolay Borisov
2020-07-22T08:35:21Z

On 21.07.20 г. 17:22 ч., Josef Bacik wrote:
> v3->v4:
> - Rebased onto a recent misc-next, slight fixup because of commenting around the
> flush states.
>
> v2->v3:
> - Rebased onto a recent misc-next
>
> v1->v2:
> - Adjusted a comment in may_commit_transaction.
> - Fixed one of the intermediate patches to properly update ->reclaim_size.
>
> We've had two different things in place to reserve data and metadata space,
> because generally speaking data is much simpler. However the data reservations
> still suffered from the same issues that plagued metadata reservations, you
> could get multiple tasks racing in to get reservations. This causes problems
> with cases like write/delete loops where we should be able to fill up the fs,
> delete everything, and go again. You would sometimes race with a flusher that's
> trying to unpin the free space, take it's reservations, and then it would fail.
>
> Fix this by moving the data reservations under the metadata ticketing
> infrastructure. This gets rid of that problem, and simplifies our enospc code
> more by consolidating it into a single path. Thanks,
>
> Josef
>

I've gone through the series again and it looks good. However,
btrfs_alloc_data_chunk_ondemand no longer allocates a data chunk but
simply tries to reserve the requested data space. This means this series
needs another patch giving it a more becoming name, something like
btrfs_(alloc|reserve)_data_space or some such ?