On Wed, Apr 18, 2018 at 10:27:57AM +0300, Nikolay Borisov wrote:
> do_chunk_alloc implements logic to detect whether there is currently
> pending chunk allocation (by means of space_info->chunk_alloc being
> set) and if so it loops around to the 'again' label. Additionally,
> based on the state of the space_info (e.g. whether it's full or not)
> and the return value of should_alloc_chunk() it decides whether this
> is a "hard" error (ENOSPC) or we can just return 0.
>
> This patch refactors all of this:
>
> 1. Put order to the scattered ifs handling the various cases in an
> easy-to-read if {} else if{} branches. This makes clear the various
> cases we are interested in handling.
>
> 2. Call should_alloc_chunk only once and use the result in the
> if/else if constructs. All of this is done under space_info->lock, so
> even before multiple calls of should_alloc_chunk were unnecessary.
>
> 3. Rewrite the "do {} while()" loop currently implemented via label
> into an explicit loop construct.
>
> 4. Move the mutex locking for the case where the caller is the one doing the
> allocation. For the case where the caller needs to wait a concurrent allocation,
> introduce a pair of mutex_lock/mutex_unlock to act as a barrier and reword the
> comment.
>
> 5. Switch local vars to bool type where pertinent.
>
> All in all this shouldn't introduce any functional changes.
>
> Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
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