Messages in this thread |  | | Subject | Re: [PATCH v3 4/4] io_uring: add support for zone-append | From | Jens Axboe <> | Date | Thu, 9 Jul 2020 07:58:04 -0600 |
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On 7/9/20 4:15 AM, Christoph Hellwig wrote: > On Sun, Jul 05, 2020 at 03:00:47PM -0600, Jens Axboe wrote: >>> diff --git a/fs/io_uring.c b/fs/io_uring.c >>> index 155f3d8..cbde4df 100644 >>> --- a/fs/io_uring.c >>> +++ b/fs/io_uring.c >>> @@ -402,6 +402,8 @@ struct io_rw { >>> struct kiocb kiocb; >>> u64 addr; >>> u64 len; >>> + /* zone-relative offset for append, in sectors */ >>> + u32 append_offset; >>> }; >> >> I don't like this very much at all. As it stands, the first cacheline >> of io_kiocb is set aside for request-private data. io_rw is already >> exactly 64 bytes, which means that you're now growing io_rw beyond >> a cacheline and increasing the size of io_kiocb as a whole. >> >> Maybe you can reuse io_rw->len for this, as that is only used on the >> submission side of things. > > We don't actually need any new field at all. By the time the write > returned ki_pos contains the offset after the write, and the res > argument to ->ki_complete contains the amount of bytes written, which > allow us to trivially derive the starting position.
Then let's just do that instead of jumping through hoops either justifying growing io_rw/io_kiocb or turning kiocb into a global completion thing.
-- Jens Axboe
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