Re: [PATCH 1/8] gadgetfs: use schedule_work() instead of EIOCBRETRY

[Jeff Moyer <jmoyer@redhat.com>]

Zach Brown <zach.brown@oracle.com> writes:

> gadgetfs was the sole mainline user of the retry mechanism offered by fs/aio.c.
> It would set the iocb's ki_retry to a tiny function that is executed once an
> async read completed.  The function would simply copy data that was dmaed into
> a kernel buffer out to the userspace buffer for the read.
>
> This use was not worth the complexity and volume of code needed to support
> retrying iocbs in the aio core.  Many other file systems already do this kind
> of post processing work in their own threads today.  This work that gadgetfs
> does pales in comparison to the work that btrfs and xfs do.
>
> This patch moves this trivial copying into a work struct that is processed by
> keventd.  It uses the {un,}use_mm() calls which were recently promoted out of
> aio into a proper API.
>
> This paves the way for removing the dangerous and slow retry functionality from
> the aio core.
>
> Signed-off-by: Zach Brown <zach.brown@oracle.com>

Looks ok to me.

Reviewed-by: Jeff Moyer <jmoyer@redhat.com>